Bug 1800044 [wpt PR 36907] - Fix same URL navigation test, a=testonly

[gecko.git] / layout / generic / nsTextFrame.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* rendering object for textual content of elements */

#include "nsTextFrame.h"

#include "gfx2DGlue.h"

#include "gfxUtils.h"
#include "mozilla/Attributes.h"
#include "mozilla/ComputedStyle.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/Likely.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/PresShell.h"
#include "mozilla/StaticPrefs_layout.h"
#include "mozilla/StaticPresData.h"
#include "mozilla/SVGTextFrame.h"
#include "mozilla/SVGUtils.h"
#include "mozilla/TextEditor.h"
#include "mozilla/TextEvents.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/IntegerRange.h"
#include "mozilla/Unused.h"
#include "mozilla/PodOperations.h"

#include "nsCOMPtr.h"
#include "nsBlockFrame.h"
#include "nsFontMetrics.h"
#include "nsSplittableFrame.h"
#include "nsLineLayout.h"
#include "nsString.h"
#include "nsUnicharUtils.h"
#include "nsPresContext.h"
#include "nsIContent.h"
#include "nsStyleConsts.h"
#include "nsStyleStruct.h"
#include "nsStyleStructInlines.h"
#include "nsCoord.h"
#include "gfxContext.h"
#include "nsTArray.h"
#include "nsCSSPseudoElements.h"
#include "nsCSSFrameConstructor.h"
#include "nsCompatibility.h"
#include "nsCSSColorUtils.h"
#include "nsLayoutUtils.h"
#include "nsDisplayList.h"
#include "nsIFrame.h"
#include "nsIMathMLFrame.h"
#include "nsPlaceholderFrame.h"
#include "nsTextFrameUtils.h"
#include "nsTextRunTransformations.h"
#include "MathMLTextRunFactory.h"
#include "nsUnicodeProperties.h"
#include "nsStyleUtil.h"
#include "nsRubyFrame.h"
#include "TextDrawTarget.h"

#include "nsTextFragment.h"
#include "nsGkAtoms.h"
#include "nsFrameSelection.h"
#include "nsRange.h"
#include "nsCSSRendering.h"
#include "nsContentUtils.h"
#include "nsLineBreaker.h"
#include "nsIFrameInlines.h"
#include "mozilla/intl/Bidi.h"
#include "mozilla/intl/Segmenter.h"
#include "mozilla/intl/UnicodeProperties.h"
#include "mozilla/ServoStyleSet.h"

#include <algorithm>
#include <limits>
#include <type_traits>
#ifdef ACCESSIBILITY
#  include "nsAccessibilityService.h"
#endif

#include "nsPrintfCString.h"

#include "mozilla/gfx/DrawTargetRecording.h"

#include "mozilla/UniquePtr.h"
#include "mozilla/dom/Element.h"
#include "mozilla/LookAndFeel.h"
#include "mozilla/ProfilerLabels.h"

#ifdef DEBUG
#  undef NOISY_REFLOW
#  undef NOISY_TRIM
#else
#  undef NOISY_REFLOW
#  undef NOISY_TRIM
#endif

#ifdef DrawText
#  undef DrawText
#endif

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::gfx;

typedef mozilla::layout::TextDrawTarget TextDrawTarget;

static bool NeedsToMaskPassword(nsTextFrame* aFrame) {
  MOZ_ASSERT(aFrame);
  MOZ_ASSERT(aFrame->GetContent());
  if (!aFrame->GetContent()->HasFlag(NS_MAYBE_MASKED)) {
    return false;
  }
  nsIFrame* frame =
      nsLayoutUtils::GetClosestFrameOfType(aFrame, LayoutFrameType::TextInput);
  MOZ_ASSERT(frame, "How do we have a masked text node without a text input?");
  return !frame || !frame->GetContent()->AsElement()->State().HasState(
                       ElementState::REVEALED);
}

struct TabWidth {
  TabWidth(uint32_t aOffset, uint32_t aWidth)
      : mOffset(aOffset), mWidth(float(aWidth)) {}

  uint32_t mOffset;  // DOM offset relative to the current frame's offset.
  float mWidth;      // extra space to be added at this position (in app units)
};

struct nsTextFrame::TabWidthStore {
  explicit TabWidthStore(int32_t aValidForContentOffset)
      : mLimit(0), mValidForContentOffset(aValidForContentOffset) {}

  // Apply tab widths to the aSpacing array, which corresponds to characters
  // beginning at aOffset and has length aLength. (Width records outside this
  // range will be ignored.)
  void ApplySpacing(gfxTextRun::PropertyProvider::Spacing* aSpacing,
                    uint32_t aOffset, uint32_t aLength);

  // Offset up to which tabs have been measured; positions beyond this have not
  // been calculated yet but may be appended if needed later.  It's a DOM
  // offset relative to the current frame's offset.
  uint32_t mLimit;

  // Need to recalc tab offsets if frame content offset differs from this.
  int32_t mValidForContentOffset;

  // A TabWidth record for each tab character measured so far.
  nsTArray<TabWidth> mWidths;
};

namespace {

struct TabwidthAdaptor {
  const nsTArray<TabWidth>& mWidths;
  explicit TabwidthAdaptor(const nsTArray<TabWidth>& aWidths)
      : mWidths(aWidths) {}
  uint32_t operator[](size_t aIdx) const { return mWidths[aIdx].mOffset; }
};

}  // namespace

void nsTextFrame::TabWidthStore::ApplySpacing(
    gfxTextRun::PropertyProvider::Spacing* aSpacing, uint32_t aOffset,
    uint32_t aLength) {
  size_t i = 0;
  const size_t len = mWidths.Length();

  // If aOffset is non-zero, do a binary search to find where to start
  // processing the tab widths, in case the list is really long. (See bug
  // 953247.)
  // We need to start from the first entry where mOffset >= aOffset.
  if (aOffset > 0) {
    mozilla::BinarySearch(TabwidthAdaptor(mWidths), 0, len, aOffset, &i);
  }

  uint32_t limit = aOffset + aLength;
  while (i < len) {
    const TabWidth& tw = mWidths[i];
    if (tw.mOffset >= limit) {
      break;
    }
    aSpacing[tw.mOffset - aOffset].mAfter += tw.mWidth;
    i++;
  }
}

NS_DECLARE_FRAME_PROPERTY_DELETABLE(TabWidthProperty,
                                    nsTextFrame::TabWidthStore)

NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(OffsetToFrameProperty, nsTextFrame)

NS_DECLARE_FRAME_PROPERTY_RELEASABLE(UninflatedTextRunProperty, gfxTextRun)

NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(FontSizeInflationProperty, float)

struct nsTextFrame::PaintTextSelectionParams : nsTextFrame::PaintTextParams {
  Point textBaselinePt;
  PropertyProvider* provider = nullptr;
  Range contentRange;
  nsTextPaintStyle* textPaintStyle = nullptr;
  Range glyphRange;
  explicit PaintTextSelectionParams(const PaintTextParams& aParams)
      : PaintTextParams(aParams) {}
};

struct nsTextFrame::DrawTextRunParams {
  gfxContext* context;
  PropertyProvider* provider = nullptr;
  gfxFloat* advanceWidth = nullptr;
  mozilla::SVGContextPaint* contextPaint = nullptr;
  DrawPathCallbacks* callbacks = nullptr;
  nscolor textColor = NS_RGBA(0, 0, 0, 0);
  nscolor textStrokeColor = NS_RGBA(0, 0, 0, 0);
  nsAtom* fontPalette = nullptr;
  gfx::FontPaletteValueSet* paletteValueSet = nullptr;
  float textStrokeWidth = 0.0f;
  bool drawSoftHyphen = false;
  explicit DrawTextRunParams(gfxContext* aContext) : context(aContext) {}
};

struct nsTextFrame::ClipEdges {
  ClipEdges(const nsIFrame* aFrame, const nsPoint& aToReferenceFrame,
            nscoord aVisIStartEdge, nscoord aVisIEndEdge) {
    nsRect r = aFrame->ScrollableOverflowRect() + aToReferenceFrame;
    if (aFrame->GetWritingMode().IsVertical()) {
      mVisIStart = aVisIStartEdge > 0 ? r.y + aVisIStartEdge : nscoord_MIN;
      mVisIEnd = aVisIEndEdge > 0
                     ? std::max(r.YMost() - aVisIEndEdge, mVisIStart)
                     : nscoord_MAX;
    } else {
      mVisIStart = aVisIStartEdge > 0 ? r.x + aVisIStartEdge : nscoord_MIN;
      mVisIEnd = aVisIEndEdge > 0
                     ? std::max(r.XMost() - aVisIEndEdge, mVisIStart)
                     : nscoord_MAX;
    }
  }

  void Intersect(nscoord* aVisIStart, nscoord* aVisISize) const {
    nscoord end = *aVisIStart + *aVisISize;
    *aVisIStart = std::max(*aVisIStart, mVisIStart);
    *aVisISize = std::max(std::min(end, mVisIEnd) - *aVisIStart, 0);
  }

  nscoord mVisIStart;
  nscoord mVisIEnd;
};

struct nsTextFrame::DrawTextParams : nsTextFrame::DrawTextRunParams {
  Point framePt;
  LayoutDeviceRect dirtyRect;
  const nsTextPaintStyle* textStyle = nullptr;
  const ClipEdges* clipEdges = nullptr;
  const nscolor* decorationOverrideColor = nullptr;
  Range glyphRange;
  explicit DrawTextParams(gfxContext* aContext) : DrawTextRunParams(aContext) {}
};

struct nsTextFrame::PaintShadowParams {
  gfxTextRun::Range range;
  LayoutDeviceRect dirtyRect;
  Point framePt;
  Point textBaselinePt;
  gfxContext* context;
  nscolor foregroundColor = NS_RGBA(0, 0, 0, 0);
  const ClipEdges* clipEdges = nullptr;
  PropertyProvider* provider = nullptr;
  nscoord leftSideOffset = 0;
  explicit PaintShadowParams(const PaintTextParams& aParams)
      : dirtyRect(aParams.dirtyRect),
        framePt(aParams.framePt),
        context(aParams.context) {}
};

/**
 * A glyph observer for the change of a font glyph in a text run.
 *
 * This is stored in {Simple, Complex}TextRunUserData.
 */
class GlyphObserver final : public gfxFont::GlyphChangeObserver {
 public:
  GlyphObserver(gfxFont* aFont, gfxTextRun* aTextRun)
      : gfxFont::GlyphChangeObserver(aFont), mTextRun(aTextRun) {
    MOZ_ASSERT(aTextRun->GetUserData());
  }
  void NotifyGlyphsChanged() override;

 private:
  gfxTextRun* mTextRun;
};

static const nsFrameState TEXT_REFLOW_FLAGS =
    TEXT_FIRST_LETTER | TEXT_START_OF_LINE | TEXT_END_OF_LINE |
    TEXT_HYPHEN_BREAK | TEXT_TRIMMED_TRAILING_WHITESPACE |
    TEXT_JUSTIFICATION_ENABLED | TEXT_HAS_NONCOLLAPSED_CHARACTERS |
    TEXT_SELECTION_UNDERLINE_OVERFLOWED | TEXT_NO_RENDERED_GLYPHS;

static const nsFrameState TEXT_WHITESPACE_FLAGS =
    TEXT_IS_ONLY_WHITESPACE | TEXT_ISNOT_ONLY_WHITESPACE;

/*
 * Some general notes
 *
 * Text frames delegate work to gfxTextRun objects. The gfxTextRun object
 * transforms text to positioned glyphs. It can report the geometry of the
 * glyphs and paint them. Text frames configure gfxTextRuns by providing text,
 * spacing, language, and other information.
 *
 * A gfxTextRun can cover more than one DOM text node. This is necessary to
 * get kerning, ligatures and shaping for text that spans multiple text nodes
 * but is all the same font.
 *
 * The userdata for a gfxTextRun object can be:
 *
 *   - A nsTextFrame* in the case a text run maps to only one flow. In this
 *   case, the textrun's user data pointer is a pointer to mStartFrame for that
 *   flow, mDOMOffsetToBeforeTransformOffset is zero, and mContentLength is the
 *   length of the text node.
 *
 *   - A SimpleTextRunUserData in the case a text run maps to one flow, but we
 *   still have to keep a list of glyph observers.
 *
 *   - A ComplexTextRunUserData in the case a text run maps to multiple flows,
 *   but we need to keep a list of glyph observers.
 *
 *   - A TextRunUserData in the case a text run maps multiple flows, but it
 *   doesn't have any glyph observer for changes in SVG fonts.
 *
 * You can differentiate between the four different cases with the
 * IsSimpleFlow and MightHaveGlyphChanges flags.
 *
 * We go to considerable effort to make sure things work even if in-flow
 * siblings have different ComputedStyles (i.e., first-letter and first-line).
 *
 * Our convention is that unsigned integer character offsets are offsets into
 * the transformed string. Signed integer character offsets are offsets into
 * the DOM string.
 *
 * XXX currently we don't handle hyphenated breaks between text frames where the
 * hyphen occurs at the end of the first text frame, e.g.
 *   <b>Kit&shy;</b>ty
 */

/**
 * This is our user data for the textrun, when textRun->GetFlags2() has
 * IsSimpleFlow set, and also MightHaveGlyphChanges.
 *
 * This allows having an array of observers if there are fonts whose glyphs
 * might change, but also avoid allocation in the simple case that there aren't.
 */
struct SimpleTextRunUserData {
  nsTArray<UniquePtr<GlyphObserver>> mGlyphObservers;
  nsTextFrame* mFrame;
  explicit SimpleTextRunUserData(nsTextFrame* aFrame) : mFrame(aFrame) {}
};

/**
 * We use an array of these objects to record which text frames
 * are associated with the textrun. mStartFrame is the start of a list of
 * text frames. Some sequence of its continuations are covered by the textrun.
 * A content textnode can have at most one TextRunMappedFlow associated with it
 * for a given textrun.
 *
 * mDOMOffsetToBeforeTransformOffset is added to DOM offsets for those frames to
 * obtain the offset into the before-transformation text of the textrun. It can
 * be positive (when a text node starts in the middle of a text run) or negative
 * (when a text run starts in the middle of a text node). Of course it can also
 * be zero.
 */
struct TextRunMappedFlow {
  nsTextFrame* mStartFrame;
  int32_t mDOMOffsetToBeforeTransformOffset;
  // The text mapped starts at mStartFrame->GetContentOffset() and is this long
  uint32_t mContentLength;
};

/**
 * This is the type in the gfxTextRun's userdata field in the common case that
 * the text run maps to multiple flows, but no fonts have been found with
 * animatable glyphs.
 *
 * This way, we avoid allocating and constructing the extra nsTArray.
 */
struct TextRunUserData {
#ifdef DEBUG
  TextRunMappedFlow* mMappedFlows;
#endif
  uint32_t mMappedFlowCount;
  uint32_t mLastFlowIndex;
};

/**
 * This is our user data for the textrun, when textRun->GetFlags2() does not
 * have IsSimpleFlow set and has the MightHaveGlyphChanges flag.
 */
struct ComplexTextRunUserData : public TextRunUserData {
  nsTArray<UniquePtr<GlyphObserver>> mGlyphObservers;
};

/**
 * This helper object computes colors used for painting, and also IME
 * underline information. The data is computed lazily and cached as necessary.
 * These live for just the duration of one paint operation.
 */
class nsTextPaintStyle {
 public:
  explicit nsTextPaintStyle(nsTextFrame* aFrame);

  void SetResolveColors(bool aResolveColors) {
    mResolveColors = aResolveColors;
  }

  nscolor GetTextColor();

  // SVG text has its own painting process, so we should never get its stroke
  // property from here.
  nscolor GetWebkitTextStrokeColor() {
    if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
      return 0;
    }
    return mFrame->StyleText()->mWebkitTextStrokeColor.CalcColor(mFrame);
  }
  float GetWebkitTextStrokeWidth() {
    if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
      return 0.0f;
    }
    nscoord coord = mFrame->StyleText()->mWebkitTextStrokeWidth;
    return mFrame->PresContext()->AppUnitsToFloatDevPixels(coord);
  }

  /**
   * Compute the colors for normally-selected text. Returns false if
   * the normal selection is not being displayed.
   */
  bool GetSelectionColors(nscolor* aForeColor, nscolor* aBackColor);
  void GetHighlightColors(nscolor* aForeColor, nscolor* aBackColor);
  void GetURLSecondaryColor(nscolor* aForeColor);
  void GetIMESelectionColors(int32_t aIndex, nscolor* aForeColor,
                             nscolor* aBackColor);
  // if this returns false, we don't need to draw underline.
  bool GetSelectionUnderlineForPaint(int32_t aIndex, nscolor* aLineColor,
                                     float* aRelativeSize, uint8_t* aStyle);

  // if this returns false, we don't need to draw underline.
  static bool GetSelectionUnderline(nsIFrame*, int32_t aIndex,
                                    nscolor* aLineColor, float* aRelativeSize,
                                    uint8_t* aStyle);

  // if this returns false, no text-shadow was specified for the selection
  // and the *aShadow parameter was not modified.
  bool GetSelectionShadow(Span<const StyleSimpleShadow>* aShadows);

  nsPresContext* PresContext() const { return mPresContext; }

  enum {
    eIndexRawInput = 0,
    eIndexSelRawText,
    eIndexConvText,
    eIndexSelConvText,
    eIndexSpellChecker
  };

  static int32_t GetUnderlineStyleIndexForSelectionType(
      SelectionType aSelectionType) {
    switch (aSelectionType) {
      case SelectionType::eIMERawClause:
        return eIndexRawInput;
      case SelectionType::eIMESelectedRawClause:
        return eIndexSelRawText;
      case SelectionType::eIMEConvertedClause:
        return eIndexConvText;
      case SelectionType::eIMESelectedClause:
        return eIndexSelConvText;
      case SelectionType::eSpellCheck:
        return eIndexSpellChecker;
      default:
        NS_WARNING("non-IME selection type");
        return eIndexRawInput;
    }
  }

  nscolor GetSystemFieldForegroundColor();
  nscolor GetSystemFieldBackgroundColor();

 protected:
  nsTextFrame* mFrame;
  nsPresContext* mPresContext;
  bool mInitCommonColors;
  bool mInitSelectionColorsAndShadow;
  bool mResolveColors;

  // Selection data

  nscolor mSelectionTextColor;
  nscolor mSelectionBGColor;
  RefPtr<ComputedStyle> mSelectionPseudoStyle;

  // Common data

  int32_t mSufficientContrast;
  nscolor mFrameBackgroundColor;
  nscolor mSystemFieldForegroundColor;
  nscolor mSystemFieldBackgroundColor;

  // selection colors and underline info, the colors are resolved colors if
  // mResolveColors is true (which is the default), i.e., the foreground color
  // and background color are swapped if it's needed. And also line color will
  // be resolved from them.
  struct nsSelectionStyle {
    bool mInit;
    nscolor mTextColor;
    nscolor mBGColor;
    nscolor mUnderlineColor;
    uint8_t mUnderlineStyle;
    float mUnderlineRelativeSize;
  };
  nsSelectionStyle mSelectionStyle[5];

  // Color initializations
  void InitCommonColors();
  bool InitSelectionColorsAndShadow();

  nsSelectionStyle* GetSelectionStyle(int32_t aIndex);
  void InitSelectionStyle(int32_t aIndex);

  // Ensures sufficient contrast between the frame background color and the
  // selection background color, and swaps the selection text and background
  // colors accordingly.
  bool EnsureSufficientContrast(nscolor* aForeColor, nscolor* aBackColor);

  nscolor GetResolvedForeColor(nscolor aColor, nscolor aDefaultForeColor,
                               nscolor aBackColor);
};

static TextRunUserData* CreateUserData(uint32_t aMappedFlowCount) {
  TextRunUserData* data = static_cast<TextRunUserData*>(moz_xmalloc(
      sizeof(TextRunUserData) + aMappedFlowCount * sizeof(TextRunMappedFlow)));
#ifdef DEBUG
  data->mMappedFlows = reinterpret_cast<TextRunMappedFlow*>(data + 1);
#endif
  data->mMappedFlowCount = aMappedFlowCount;
  data->mLastFlowIndex = 0;
  return data;
}

static void DestroyUserData(TextRunUserData* aUserData) {
  if (aUserData) {
    free(aUserData);
  }
}

static ComplexTextRunUserData* CreateComplexUserData(
    uint32_t aMappedFlowCount) {
  ComplexTextRunUserData* data = static_cast<ComplexTextRunUserData*>(
      moz_xmalloc(sizeof(ComplexTextRunUserData) +
                  aMappedFlowCount * sizeof(TextRunMappedFlow)));
  new (data) ComplexTextRunUserData();
#ifdef DEBUG
  data->mMappedFlows = reinterpret_cast<TextRunMappedFlow*>(data + 1);
#endif
  data->mMappedFlowCount = aMappedFlowCount;
  data->mLastFlowIndex = 0;
  return data;
}

static void DestroyComplexUserData(ComplexTextRunUserData* aUserData) {
  if (aUserData) {
    aUserData->~ComplexTextRunUserData();
    free(aUserData);
  }
}

static void DestroyTextRunUserData(gfxTextRun* aTextRun) {
  MOZ_ASSERT(aTextRun->GetUserData());
  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    if (aTextRun->GetFlags2() &
        nsTextFrameUtils::Flags::MightHaveGlyphChanges) {
      delete static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData());
    }
  } else {
    if (aTextRun->GetFlags2() &
        nsTextFrameUtils::Flags::MightHaveGlyphChanges) {
      DestroyComplexUserData(
          static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData()));
    } else {
      DestroyUserData(static_cast<TextRunUserData*>(aTextRun->GetUserData()));
    }
  }
  aTextRun->ClearFlagBits(nsTextFrameUtils::Flags::MightHaveGlyphChanges);
  aTextRun->SetUserData(nullptr);
}

static TextRunMappedFlow* GetMappedFlows(const gfxTextRun* aTextRun) {
  MOZ_ASSERT(aTextRun->GetUserData(), "UserData must exist.");
  MOZ_ASSERT(!(aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow),
             "The method should not be called for simple flows.");
  TextRunMappedFlow* flows;
  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::MightHaveGlyphChanges) {
    flows = reinterpret_cast<TextRunMappedFlow*>(
        static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData()) + 1);
  } else {
    flows = reinterpret_cast<TextRunMappedFlow*>(
        static_cast<TextRunUserData*>(aTextRun->GetUserData()) + 1);
  }
  MOZ_ASSERT(
      static_cast<TextRunUserData*>(aTextRun->GetUserData())->mMappedFlows ==
          flows,
      "GetMappedFlows should return the same pointer as mMappedFlows.");
  return flows;
}

/**
 * These are utility functions just for helping with the complexity related with
 * the text runs user data.
 */
static nsTextFrame* GetFrameForSimpleFlow(const gfxTextRun* aTextRun) {
  MOZ_ASSERT(aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow,
             "Not so simple flow?");
  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::MightHaveGlyphChanges) {
    return static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData())->mFrame;
  }

  return static_cast<nsTextFrame*>(aTextRun->GetUserData());
}

/**
 * Remove |aTextRun| from the frame continuation chain starting at
 * |aStartContinuation| if non-null, otherwise starting at |aFrame|.
 * Unmark |aFrame| as a text run owner if it's the frame we start at.
 * Return true if |aStartContinuation| is non-null and was found
 * in the next-continuation chain of |aFrame|.
 */
static bool ClearAllTextRunReferences(nsTextFrame* aFrame, gfxTextRun* aTextRun,
                                      nsTextFrame* aStartContinuation,
                                      nsFrameState aWhichTextRunState) {
  MOZ_ASSERT(aFrame, "null frame");
  MOZ_ASSERT(!aStartContinuation ||
                 (!aStartContinuation->GetTextRun(nsTextFrame::eInflated) ||
                  aStartContinuation->GetTextRun(nsTextFrame::eInflated) ==
                      aTextRun) ||
                 (!aStartContinuation->GetTextRun(nsTextFrame::eNotInflated) ||
                  aStartContinuation->GetTextRun(nsTextFrame::eNotInflated) ==
                      aTextRun),
             "wrong aStartContinuation for this text run");

  if (!aStartContinuation || aStartContinuation == aFrame) {
    aFrame->RemoveStateBits(aWhichTextRunState);
  } else {
    do {
      NS_ASSERTION(aFrame->IsTextFrame(), "Bad frame");
      aFrame = aFrame->GetNextContinuation();
    } while (aFrame && aFrame != aStartContinuation);
  }
  bool found = aStartContinuation == aFrame;
  while (aFrame) {
    NS_ASSERTION(aFrame->IsTextFrame(), "Bad frame");
    if (!aFrame->RemoveTextRun(aTextRun)) {
      break;
    }
    aFrame = aFrame->GetNextContinuation();
  }

  MOZ_ASSERT(!found || aStartContinuation, "how did we find null?");
  return found;
}

/**
 * Kill all references to |aTextRun| starting at |aStartContinuation|.
 * It could be referenced by any of its owners, and all their in-flows.
 * If |aStartContinuation| is null then process all userdata frames
 * and their continuations.
 * @note the caller is expected to take care of possibly destroying the
 * text run if all userdata frames were reset (userdata is deallocated
 * by this function though). The caller can detect this has occured by
 * checking |aTextRun->GetUserData() == nullptr|.
 */
static void UnhookTextRunFromFrames(gfxTextRun* aTextRun,
                                    nsTextFrame* aStartContinuation) {
  if (!aTextRun->GetUserData()) {
    return;
  }

  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    nsTextFrame* userDataFrame = GetFrameForSimpleFlow(aTextRun);
    nsFrameState whichTextRunState =
        userDataFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
            ? TEXT_IN_TEXTRUN_USER_DATA
            : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
    DebugOnly<bool> found = ClearAllTextRunReferences(
        userDataFrame, aTextRun, aStartContinuation, whichTextRunState);
    NS_ASSERTION(!aStartContinuation || found,
                 "aStartContinuation wasn't found in simple flow text run");
    if (!userDataFrame->HasAnyStateBits(whichTextRunState)) {
      DestroyTextRunUserData(aTextRun);
    }
  } else {
    auto userData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
    TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
    int32_t destroyFromIndex = aStartContinuation ? -1 : 0;
    for (uint32_t i = 0; i < userData->mMappedFlowCount; ++i) {
      nsTextFrame* userDataFrame = userMappedFlows[i].mStartFrame;
      nsFrameState whichTextRunState =
          userDataFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
              ? TEXT_IN_TEXTRUN_USER_DATA
              : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
      bool found = ClearAllTextRunReferences(
          userDataFrame, aTextRun, aStartContinuation, whichTextRunState);
      if (found) {
        if (userDataFrame->HasAnyStateBits(whichTextRunState)) {
          destroyFromIndex = i + 1;
        } else {
          destroyFromIndex = i;
        }
        aStartContinuation = nullptr;
      }
    }
    NS_ASSERTION(destroyFromIndex >= 0,
                 "aStartContinuation wasn't found in multi flow text run");
    if (destroyFromIndex == 0) {
      DestroyTextRunUserData(aTextRun);
    } else {
      userData->mMappedFlowCount = uint32_t(destroyFromIndex);
      if (userData->mLastFlowIndex >= uint32_t(destroyFromIndex)) {
        userData->mLastFlowIndex = uint32_t(destroyFromIndex) - 1;
      }
    }
  }
}

static void InvalidateFrameDueToGlyphsChanged(nsIFrame* aFrame) {
  MOZ_ASSERT(aFrame);

  PresShell* presShell = aFrame->PresShell();
  for (nsIFrame* f = aFrame; f;
       f = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(f)) {
    f->InvalidateFrame();

    // If this is a non-display text frame within SVG <text>, we need
    // to reflow the SVGTextFrame. (This is similar to reflowing the
    // SVGTextFrame in response to style changes, in
    // SVGTextFrame::DidSetComputedStyle.)
    if (SVGUtils::IsInSVGTextSubtree(f) &&
        f->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY)) {
      auto svgTextFrame = static_cast<SVGTextFrame*>(
          nsLayoutUtils::GetClosestFrameOfType(f, LayoutFrameType::SVGText));
      svgTextFrame->ScheduleReflowSVGNonDisplayText(IntrinsicDirty::Resize);
    } else {
      // Theoretically we could just update overflow areas, perhaps using
      // OverflowChangedTracker, but that would do a bunch of work eagerly that
      // we should probably do lazily here since there could be a lot
      // of text frames affected and we'd like to coalesce the work. So that's
      // not easy to do well.
      presShell->FrameNeedsReflow(f, IntrinsicDirty::Resize, NS_FRAME_IS_DIRTY);
    }
  }
}

void GlyphObserver::NotifyGlyphsChanged() {
  if (mTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    InvalidateFrameDueToGlyphsChanged(GetFrameForSimpleFlow(mTextRun));
    return;
  }

  auto data = static_cast<TextRunUserData*>(mTextRun->GetUserData());
  TextRunMappedFlow* userMappedFlows = GetMappedFlows(mTextRun);
  for (uint32_t i = 0; i < data->mMappedFlowCount; ++i) {
    InvalidateFrameDueToGlyphsChanged(userMappedFlows[i].mStartFrame);
  }
}

int32_t nsTextFrame::GetContentEnd() const {
  nsTextFrame* next = GetNextContinuation();
  return next ? next->GetContentOffset() : TextFragment()->GetLength();
}

struct FlowLengthProperty {
  int32_t mStartOffset;
  // The offset of the next fixed continuation after mStartOffset, or
  // of the end of the text if there is none
  int32_t mEndFlowOffset;
};

int32_t nsTextFrame::GetInFlowContentLength() {
  if (!(mState & NS_FRAME_IS_BIDI)) {
    return mContent->TextLength() - mContentOffset;
  }

  FlowLengthProperty* flowLength =
      mContent->HasFlag(NS_HAS_FLOWLENGTH_PROPERTY)
          ? static_cast<FlowLengthProperty*>(
                mContent->GetProperty(nsGkAtoms::flowlength))
          : nullptr;

  /**
   * This frame must start inside the cached flow. If the flow starts at
   * mContentOffset but this frame is empty, logically it might be before the
   * start of the cached flow.
   */
  if (flowLength &&
      (flowLength->mStartOffset < mContentOffset ||
       (flowLength->mStartOffset == mContentOffset &&
        GetContentEnd() > mContentOffset)) &&
      flowLength->mEndFlowOffset > mContentOffset) {
#ifdef DEBUG
    NS_ASSERTION(flowLength->mEndFlowOffset >= GetContentEnd(),
                 "frame crosses fixed continuation boundary");
#endif
    return flowLength->mEndFlowOffset - mContentOffset;
  }

  nsTextFrame* nextBidi = LastInFlow()->GetNextContinuation();
  int32_t endFlow =
      nextBidi ? nextBidi->GetContentOffset() : GetContent()->TextLength();

  if (!flowLength) {
    flowLength = new FlowLengthProperty;
    if (NS_FAILED(mContent->SetProperty(
            nsGkAtoms::flowlength, flowLength,
            nsINode::DeleteProperty<FlowLengthProperty>))) {
      delete flowLength;
      flowLength = nullptr;
    }
    mContent->SetFlags(NS_HAS_FLOWLENGTH_PROPERTY);
  }
  if (flowLength) {
    flowLength->mStartOffset = mContentOffset;
    flowLength->mEndFlowOffset = endFlow;
  }

  return endFlow - mContentOffset;
}

// Smarter versions of dom::IsSpaceCharacter.
// Unicode is really annoying; sometimes a space character isn't whitespace ---
// when it combines with another character
// So we have several versions of IsSpace for use in different contexts.

static bool IsSpaceCombiningSequenceTail(const nsTextFragment* aFrag,
                                         uint32_t aPos) {
  NS_ASSERTION(aPos <= aFrag->GetLength(), "Bad offset");
  if (!aFrag->Is2b()) {
    return false;
  }
  return nsTextFrameUtils::IsSpaceCombiningSequenceTail(
      aFrag->Get2b() + aPos, aFrag->GetLength() - aPos);
}

// Check whether aPos is a space for CSS 'word-spacing' purposes
static bool IsCSSWordSpacingSpace(const nsTextFragment* aFrag, uint32_t aPos,
                                  const nsTextFrame* aFrame,
                                  const nsStyleText* aStyleText) {
  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSpace!");

  char16_t ch = aFrag->CharAt(aPos);
  switch (ch) {
    case ' ':
    case CH_NBSP:
      return !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
    case '\r':
    case '\t':
      return !aStyleText->WhiteSpaceIsSignificant();
    case '\n':
      return !aStyleText->NewlineIsSignificant(aFrame);
    default:
      return false;
  }
}

constexpr char16_t kOghamSpaceMark = 0x1680;

// Check whether the string aChars/aLength starts with space that's
// trimmable according to CSS 'white-space:normal/nowrap'.
static bool IsTrimmableSpace(const char16_t* aChars, uint32_t aLength) {
  NS_ASSERTION(aLength > 0, "No text for IsSpace!");

  char16_t ch = *aChars;
  if (ch == ' ' || ch == kOghamSpaceMark) {
    return !nsTextFrameUtils::IsSpaceCombiningSequenceTail(aChars + 1,
                                                           aLength - 1);
  }
  return ch == '\t' || ch == '\f' || ch == '\n' || ch == '\r';
}

// Check whether the character aCh is trimmable according to CSS
// 'white-space:normal/nowrap'
static bool IsTrimmableSpace(char aCh) {
  return aCh == ' ' || aCh == '\t' || aCh == '\f' || aCh == '\n' || aCh == '\r';
}

static bool IsTrimmableSpace(const nsTextFragment* aFrag, uint32_t aPos,
                             const nsStyleText* aStyleText,
                             bool aAllowHangingWS = false) {
  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSpace!");

  switch (aFrag->CharAt(aPos)) {
    case ' ':
    case kOghamSpaceMark:
      return (!aStyleText->WhiteSpaceIsSignificant() || aAllowHangingWS) &&
             !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
    case '\n':
      return !aStyleText->NewlineIsSignificantStyle() &&
             aStyleText->mWhiteSpace != mozilla::StyleWhiteSpace::PreSpace;
    case '\t':
    case '\r':
    case '\f':
      return !aStyleText->WhiteSpaceIsSignificant() || aAllowHangingWS;
    default:
      return false;
  }
}

static bool IsSelectionInlineWhitespace(const nsTextFragment* aFrag,
                                        uint32_t aPos) {
  NS_ASSERTION(aPos < aFrag->GetLength(),
               "No text for IsSelectionInlineWhitespace!");
  char16_t ch = aFrag->CharAt(aPos);
  if (ch == ' ' || ch == CH_NBSP)
    return !IsSpaceCombiningSequenceTail(aFrag, aPos + 1);
  return ch == '\t' || ch == '\f';
}

static bool IsSelectionNewline(const nsTextFragment* aFrag, uint32_t aPos) {
  NS_ASSERTION(aPos < aFrag->GetLength(), "No text for IsSelectionNewline!");
  char16_t ch = aFrag->CharAt(aPos);
  return ch == '\n' || ch == '\r';
}

// Count the amount of trimmable whitespace (as per CSS
// 'white-space:normal/nowrap') in a text fragment. The first
// character is at offset aStartOffset; the maximum number of characters
// to check is aLength. aDirection is -1 or 1 depending on whether we should
// progress backwards or forwards.
static uint32_t GetTrimmableWhitespaceCount(const nsTextFragment* aFrag,
                                            int32_t aStartOffset,
                                            int32_t aLength,
                                            int32_t aDirection) {
  if (!aLength) {
    return 0;
  }

  int32_t count = 0;
  if (aFrag->Is2b()) {
    const char16_t* str = aFrag->Get2b() + aStartOffset;
    int32_t fragLen = aFrag->GetLength() - aStartOffset;
    for (; count < aLength; ++count) {
      if (!IsTrimmableSpace(str, fragLen)) {
        break;
      }
      str += aDirection;
      fragLen -= aDirection;
    }
  } else {
    const char* str = aFrag->Get1b() + aStartOffset;
    for (; count < aLength; ++count) {
      if (!IsTrimmableSpace(*str)) {
        break;
      }
      str += aDirection;
    }
  }
  return count;
}

static bool IsAllWhitespace(const nsTextFragment* aFrag, bool aAllowNewline) {
  if (aFrag->Is2b()) {
    return false;
  }
  int32_t len = aFrag->GetLength();
  const char* str = aFrag->Get1b();
  for (int32_t i = 0; i < len; ++i) {
    char ch = str[i];
    if (ch == ' ' || ch == '\t' || ch == '\r' || (ch == '\n' && aAllowNewline))
      continue;
    return false;
  }
  return true;
}

static void ClearObserversFromTextRun(gfxTextRun* aTextRun) {
  if (!(aTextRun->GetFlags2() &
        nsTextFrameUtils::Flags::MightHaveGlyphChanges)) {
    return;
  }

  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData())
        ->mGlyphObservers.Clear();
  } else {
    static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData())
        ->mGlyphObservers.Clear();
  }
}

static void CreateObserversForAnimatedGlyphs(gfxTextRun* aTextRun) {
  if (!aTextRun->GetUserData()) {
    return;
  }

  ClearObserversFromTextRun(aTextRun);

  nsTArray<gfxFont*> fontsWithAnimatedGlyphs;
  uint32_t numGlyphRuns;
  const gfxTextRun::GlyphRun* glyphRuns = aTextRun->GetGlyphRuns(&numGlyphRuns);
  for (uint32_t i = 0; i < numGlyphRuns; ++i) {
    gfxFont* font = glyphRuns[i].mFont;
    if (font->GlyphsMayChange() && !fontsWithAnimatedGlyphs.Contains(font)) {
      fontsWithAnimatedGlyphs.AppendElement(font);
    }
  }
  if (fontsWithAnimatedGlyphs.IsEmpty()) {
    // NB: Theoretically, we should clear the MightHaveGlyphChanges
    // here. That would involve de-allocating the simple user data struct if
    // present too, and resetting the pointer to the frame. In practice, I
    // don't think worth doing that work here, given the flag's only purpose is
    // to distinguish what kind of user data is there.
    return;
  }

  nsTArray<UniquePtr<GlyphObserver>>* observers;

  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    // Swap the frame pointer for a just-allocated SimpleTextRunUserData if
    // appropriate.
    if (!(aTextRun->GetFlags2() &
          nsTextFrameUtils::Flags::MightHaveGlyphChanges)) {
      auto frame = static_cast<nsTextFrame*>(aTextRun->GetUserData());
      aTextRun->SetUserData(new SimpleTextRunUserData(frame));
    }

    auto data = static_cast<SimpleTextRunUserData*>(aTextRun->GetUserData());
    observers = &data->mGlyphObservers;
  } else {
    if (!(aTextRun->GetFlags2() &
          nsTextFrameUtils::Flags::MightHaveGlyphChanges)) {
      auto oldData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
      TextRunMappedFlow* oldMappedFlows = GetMappedFlows(aTextRun);
      ComplexTextRunUserData* data =
          CreateComplexUserData(oldData->mMappedFlowCount);
      TextRunMappedFlow* dataMappedFlows =
          reinterpret_cast<TextRunMappedFlow*>(data + 1);
      data->mLastFlowIndex = oldData->mLastFlowIndex;
      for (uint32_t i = 0; i < oldData->mMappedFlowCount; ++i) {
        dataMappedFlows[i] = oldMappedFlows[i];
      }
      DestroyUserData(oldData);
      aTextRun->SetUserData(data);
    }
    auto data = static_cast<ComplexTextRunUserData*>(aTextRun->GetUserData());
    observers = &data->mGlyphObservers;
  }

  aTextRun->SetFlagBits(nsTextFrameUtils::Flags::MightHaveGlyphChanges);

  for (auto font : fontsWithAnimatedGlyphs) {
    observers->AppendElement(MakeUnique<GlyphObserver>(font, aTextRun));
  }
}

/**
 * This class accumulates state as we scan a paragraph of text. It detects
 * textrun boundaries (changes from text to non-text, hard
 * line breaks, and font changes) and builds a gfxTextRun at each boundary.
 * It also detects linebreaker run boundaries (changes from text to non-text,
 * and hard line breaks) and at each boundary runs the linebreaker to compute
 * potential line breaks. It also records actual line breaks to store them in
 * the textruns.
 */
class BuildTextRunsScanner {
 public:
  BuildTextRunsScanner(nsPresContext* aPresContext, DrawTarget* aDrawTarget,
                       nsIFrame* aLineContainer,
                       nsTextFrame::TextRunType aWhichTextRun,
                       bool aDoLineBreaking)
      : mDrawTarget(aDrawTarget),
        mLineContainer(aLineContainer),
        mCommonAncestorWithLastFrame(nullptr),
        mMissingFonts(aPresContext->MissingFontRecorder()),
        mBidiEnabled(aPresContext->BidiEnabled()),
        mStartOfLine(true),
        mSkipIncompleteTextRuns(false),
        mCanStopOnThisLine(false),
        mDoLineBreaking(aDoLineBreaking),
        mWhichTextRun(aWhichTextRun),
        mNextRunContextInfo(nsTextFrameUtils::INCOMING_NONE),
        mCurrentRunContextInfo(nsTextFrameUtils::INCOMING_NONE) {
    ResetRunInfo();
  }
  ~BuildTextRunsScanner() {
    NS_ASSERTION(mBreakSinks.IsEmpty(), "Should have been cleared");
    NS_ASSERTION(mLineBreakBeforeFrames.IsEmpty(), "Should have been cleared");
    NS_ASSERTION(mMappedFlows.IsEmpty(), "Should have been cleared");
  }

  void SetAtStartOfLine() {
    mStartOfLine = true;
    mCanStopOnThisLine = false;
  }
  void SetSkipIncompleteTextRuns(bool aSkip) {
    mSkipIncompleteTextRuns = aSkip;
  }
  void SetCommonAncestorWithLastFrame(nsIFrame* aFrame) {
    mCommonAncestorWithLastFrame = aFrame;
  }
  bool CanStopOnThisLine() { return mCanStopOnThisLine; }
  nsIFrame* GetCommonAncestorWithLastFrame() {
    return mCommonAncestorWithLastFrame;
  }
  void LiftCommonAncestorWithLastFrameToParent(nsIFrame* aFrame) {
    if (mCommonAncestorWithLastFrame &&
        mCommonAncestorWithLastFrame->GetParent() == aFrame) {
      mCommonAncestorWithLastFrame = aFrame;
    }
  }
  void ScanFrame(nsIFrame* aFrame);
  bool IsTextRunValidForMappedFlows(const gfxTextRun* aTextRun);
  void FlushFrames(bool aFlushLineBreaks, bool aSuppressTrailingBreak);
  void FlushLineBreaks(gfxTextRun* aTrailingTextRun);
  void ResetRunInfo() {
    mLastFrame = nullptr;
    mMappedFlows.Clear();
    mLineBreakBeforeFrames.Clear();
    mMaxTextLength = 0;
    mDoubleByteText = false;
  }
  void AccumulateRunInfo(nsTextFrame* aFrame);
  /**
   * @return null to indicate either textrun construction failed or
   * we constructed just a partial textrun to set up linebreaker and other
   * state for following textruns.
   */
  already_AddRefed<gfxTextRun> BuildTextRunForFrames(void* aTextBuffer);
  bool SetupLineBreakerContext(gfxTextRun* aTextRun);
  void AssignTextRun(gfxTextRun* aTextRun, float aInflation);
  nsTextFrame* GetNextBreakBeforeFrame(uint32_t* aIndex);
  void SetupBreakSinksForTextRun(gfxTextRun* aTextRun, const void* aTextPtr);
  void SetupTextEmphasisForTextRun(gfxTextRun* aTextRun, const void* aTextPtr);
  struct FindBoundaryState {
    nsIFrame* mStopAtFrame;
    nsTextFrame* mFirstTextFrame;
    nsTextFrame* mLastTextFrame;
    bool mSeenTextRunBoundaryOnLaterLine;
    bool mSeenTextRunBoundaryOnThisLine;
    bool mSeenSpaceForLineBreakingOnThisLine;
    nsTArray<char16_t>& mBuffer;
  };
  enum FindBoundaryResult {
    FB_CONTINUE,
    FB_STOPPED_AT_STOP_FRAME,
    FB_FOUND_VALID_TEXTRUN_BOUNDARY
  };
  FindBoundaryResult FindBoundaries(nsIFrame* aFrame,
                                    FindBoundaryState* aState);

  bool ContinueTextRunAcrossFrames(nsTextFrame* aFrame1, nsTextFrame* aFrame2);

  // Like TextRunMappedFlow but with some differences. mStartFrame to mEndFrame
  // (exclusive) are a sequence of in-flow frames (if mEndFrame is null, then
  // continuations starting from mStartFrame are a sequence of in-flow frames).
  struct MappedFlow {
    nsTextFrame* mStartFrame;
    nsTextFrame* mEndFrame;
    // When we consider breaking between elements, the nearest common
    // ancestor of the elements containing the characters is the one whose
    // CSS 'white-space' property governs. So this records the nearest common
    // ancestor of mStartFrame and the previous text frame, or null if there
    // was no previous text frame on this line.
    nsIFrame* mAncestorControllingInitialBreak;

    int32_t GetContentEnd() {
      return mEndFrame ? mEndFrame->GetContentOffset()
                       : mStartFrame->TextFragment()->GetLength();
    }
  };

  class BreakSink final : public nsILineBreakSink {
   public:
    BreakSink(gfxTextRun* aTextRun, DrawTarget* aDrawTarget,
              uint32_t aOffsetIntoTextRun)
        : mTextRun(aTextRun),
          mDrawTarget(aDrawTarget),
          mOffsetIntoTextRun(aOffsetIntoTextRun) {}

    void SetBreaks(uint32_t aOffset, uint32_t aLength,
                   uint8_t* aBreakBefore) final {
      gfxTextRun::Range range(aOffset + mOffsetIntoTextRun,
                              aOffset + mOffsetIntoTextRun + aLength);
      if (mTextRun->SetPotentialLineBreaks(range, aBreakBefore)) {
        // Be conservative and assume that some breaks have been set
        mTextRun->ClearFlagBits(nsTextFrameUtils::Flags::NoBreaks);
      }
    }

    void SetCapitalization(uint32_t aOffset, uint32_t aLength,
                           bool* aCapitalize) final {
      MOZ_ASSERT(mTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed,
                 "Text run should be transformed!");
      if (mTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed) {
        nsTransformedTextRun* transformedTextRun =
            static_cast<nsTransformedTextRun*>(mTextRun.get());
        transformedTextRun->SetCapitalization(aOffset + mOffsetIntoTextRun,
                                              aLength, aCapitalize);
      }
    }

    void Finish(gfxMissingFontRecorder* aMFR) {
      MOZ_ASSERT(
          !(mTextRun->GetFlags2() & nsTextFrameUtils::Flags::UnusedFlags),
          "Flag set that should never be set! (memory safety error?)");
      if (mTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed) {
        nsTransformedTextRun* transformedTextRun =
            static_cast<nsTransformedTextRun*>(mTextRun.get());
        transformedTextRun->FinishSettingProperties(mDrawTarget, aMFR);
      }
      // The way nsTransformedTextRun is implemented, its glyph runs aren't
      // available until after nsTransformedTextRun::FinishSettingProperties()
      // is called. So that's why we defer checking for animated glyphs to here.
      CreateObserversForAnimatedGlyphs(mTextRun);
    }

    RefPtr<gfxTextRun> mTextRun;
    DrawTarget* mDrawTarget;
    uint32_t mOffsetIntoTextRun;
  };

 private:
  AutoTArray<MappedFlow, 10> mMappedFlows;
  AutoTArray<nsTextFrame*, 50> mLineBreakBeforeFrames;
  AutoTArray<UniquePtr<BreakSink>, 10> mBreakSinks;
  nsLineBreaker mLineBreaker;
  RefPtr<gfxTextRun> mCurrentFramesAllSameTextRun;
  DrawTarget* mDrawTarget;
  nsIFrame* mLineContainer;
  nsTextFrame* mLastFrame;
  // The common ancestor of the current frame and the previous leaf frame
  // on the line, or null if there was no previous leaf frame.
  nsIFrame* mCommonAncestorWithLastFrame;
  gfxMissingFontRecorder* mMissingFonts;
  // mMaxTextLength is an upper bound on the size of the text in all mapped
  // frames The value UINT32_MAX represents overflow; text will be discarded
  uint32_t mMaxTextLength;
  bool mDoubleByteText;
  bool mBidiEnabled;
  bool mStartOfLine;
  bool mSkipIncompleteTextRuns;
  bool mCanStopOnThisLine;
  bool mDoLineBreaking;
  nsTextFrame::TextRunType mWhichTextRun;
  uint8_t mNextRunContextInfo;
  uint8_t mCurrentRunContextInfo;
};

static nsIFrame* FindLineContainer(nsIFrame* aFrame) {
  while (aFrame && (aFrame->IsFrameOfType(nsIFrame::eLineParticipant) ||
                    aFrame->CanContinueTextRun())) {
    aFrame = aFrame->GetParent();
  }
  return aFrame;
}

static bool IsLineBreakingWhiteSpace(char16_t aChar) {
  // 0x0A (\n) is not handled as white-space by the line breaker, since
  // we break before it, if it isn't transformed to a normal space.
  // (If we treat it as normal white-space then we'd only break after it.)
  // However, it does induce a line break or is converted to a regular
  // space, and either way it can be used to bound the region of text
  // that needs to be analyzed for line breaking.
  return nsLineBreaker::IsSpace(aChar) || aChar == 0x0A;
}

static bool TextContainsLineBreakerWhiteSpace(const void* aText,
                                              uint32_t aLength,
                                              bool aIsDoubleByte) {
  if (aIsDoubleByte) {
    const char16_t* chars = static_cast<const char16_t*>(aText);
    for (uint32_t i = 0; i < aLength; ++i) {
      if (IsLineBreakingWhiteSpace(chars[i])) {
        return true;
      }
    }
    return false;
  } else {
    const uint8_t* chars = static_cast<const uint8_t*>(aText);
    for (uint32_t i = 0; i < aLength; ++i) {
      if (IsLineBreakingWhiteSpace(chars[i])) {
        return true;
      }
    }
    return false;
  }
}

static nsTextFrameUtils::CompressionMode GetCSSWhitespaceToCompressionMode(
    nsTextFrame* aFrame, const nsStyleText* aStyleText) {
  switch (aStyleText->mWhiteSpace) {
    case StyleWhiteSpace::Normal:
    case StyleWhiteSpace::Nowrap:
      return nsTextFrameUtils::COMPRESS_WHITESPACE_NEWLINE;
    case StyleWhiteSpace::Pre:
    case StyleWhiteSpace::PreWrap:
    case StyleWhiteSpace::BreakSpaces:
      if (!aStyleText->NewlineIsSignificant(aFrame)) {
        // If newline is set to be preserved, but then suppressed,
        // transform newline to space.
        return nsTextFrameUtils::COMPRESS_NONE_TRANSFORM_TO_SPACE;
      }
      return nsTextFrameUtils::COMPRESS_NONE;
    case StyleWhiteSpace::PreSpace:
      return nsTextFrameUtils::COMPRESS_NONE_TRANSFORM_TO_SPACE;
    case StyleWhiteSpace::PreLine:
      return nsTextFrameUtils::COMPRESS_WHITESPACE;
    default:
      MOZ_ASSERT_UNREACHABLE("Unknown white-space value");
      return nsTextFrameUtils::COMPRESS_WHITESPACE_NEWLINE;
  }
}

struct FrameTextTraversal {
  FrameTextTraversal()
      : mFrameToScan(nullptr),
        mOverflowFrameToScan(nullptr),
        mScanSiblings(false),
        mLineBreakerCanCrossFrameBoundary(false),
        mTextRunCanCrossFrameBoundary(false) {}

  // These fields identify which frames should be recursively scanned
  // The first normal frame to scan (or null, if no such frame should be
  // scanned)
  nsIFrame* mFrameToScan;
  // The first overflow frame to scan (or null, if no such frame should be
  // scanned)
  nsIFrame* mOverflowFrameToScan;
  // Whether to scan the siblings of
  // mFrameToDescendInto/mOverflowFrameToDescendInto
  bool mScanSiblings;

  // These identify the boundaries of the context required for
  // line breaking or textrun construction
  bool mLineBreakerCanCrossFrameBoundary;
  bool mTextRunCanCrossFrameBoundary;

  nsIFrame* NextFrameToScan() {
    nsIFrame* f;
    if (mFrameToScan) {
      f = mFrameToScan;
      mFrameToScan = mScanSiblings ? f->GetNextSibling() : nullptr;
    } else if (mOverflowFrameToScan) {
      f = mOverflowFrameToScan;
      mOverflowFrameToScan = mScanSiblings ? f->GetNextSibling() : nullptr;
    } else {
      f = nullptr;
    }
    return f;
  }
};

static FrameTextTraversal CanTextCrossFrameBoundary(nsIFrame* aFrame) {
  FrameTextTraversal result;

  bool continuesTextRun = aFrame->CanContinueTextRun();
  if (aFrame->IsPlaceholderFrame()) {
    // placeholders are "invisible", so a text run should be able to span
    // across one. But don't descend into the out-of-flow.
    result.mLineBreakerCanCrossFrameBoundary = true;
    if (continuesTextRun) {
      // ... Except for first-letter floats, which are really in-flow
      // from the point of view of capitalization etc, so we'd better
      // descend into them. But we actually need to break the textrun for
      // first-letter floats since things look bad if, say, we try to make a
      // ligature across the float boundary.
      result.mFrameToScan =
          (static_cast<nsPlaceholderFrame*>(aFrame))->GetOutOfFlowFrame();
    } else {
      result.mTextRunCanCrossFrameBoundary = true;
    }
  } else {
    if (continuesTextRun) {
      result.mFrameToScan = aFrame->PrincipalChildList().FirstChild();
      result.mOverflowFrameToScan =
          aFrame->GetChildList(FrameChildListID::Overflow).FirstChild();
      NS_WARNING_ASSERTION(
          !result.mOverflowFrameToScan,
          "Scanning overflow inline frames is something we should avoid");
      result.mScanSiblings = true;
      result.mTextRunCanCrossFrameBoundary = true;
      result.mLineBreakerCanCrossFrameBoundary = true;
    } else {
      MOZ_ASSERT(!aFrame->IsRubyTextContainerFrame(),
                 "Shouldn't call this method for ruby text container");
    }
  }
  return result;
}

BuildTextRunsScanner::FindBoundaryResult BuildTextRunsScanner::FindBoundaries(
    nsIFrame* aFrame, FindBoundaryState* aState) {
  LayoutFrameType frameType = aFrame->Type();
  if (frameType == LayoutFrameType::RubyTextContainer) {
    // Don't stop a text run for ruby text container. We want ruby text
    // containers to be skipped, but continue the text run across them.
    return FB_CONTINUE;
  }

  nsTextFrame* textFrame = frameType == LayoutFrameType::Text
                               ? static_cast<nsTextFrame*>(aFrame)
                               : nullptr;
  if (textFrame) {
    if (aState->mLastTextFrame &&
        textFrame != aState->mLastTextFrame->GetNextInFlow() &&
        !ContinueTextRunAcrossFrames(aState->mLastTextFrame, textFrame)) {
      aState->mSeenTextRunBoundaryOnThisLine = true;
      if (aState->mSeenSpaceForLineBreakingOnThisLine)
        return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
    }
    if (!aState->mFirstTextFrame) {
      aState->mFirstTextFrame = textFrame;
    }
    aState->mLastTextFrame = textFrame;
  }

  if (aFrame == aState->mStopAtFrame) {
    return FB_STOPPED_AT_STOP_FRAME;
  }

  if (textFrame) {
    if (aState->mSeenSpaceForLineBreakingOnThisLine) {
      return FB_CONTINUE;
    }
    const nsTextFragment* frag = textFrame->TextFragment();
    uint32_t start = textFrame->GetContentOffset();
    uint32_t length = textFrame->GetContentLength();
    const void* text;
    if (frag->Is2b()) {
      // It is possible that we may end up removing all whitespace in
      // a piece of text because of The White Space Processing Rules,
      // so we need to transform it before we can check existence of
      // such whitespaces.
      aState->mBuffer.EnsureLengthAtLeast(length);
      nsTextFrameUtils::CompressionMode compression =
          GetCSSWhitespaceToCompressionMode(textFrame, textFrame->StyleText());
      uint8_t incomingFlags = 0;
      gfxSkipChars skipChars;
      nsTextFrameUtils::Flags analysisFlags;
      char16_t* bufStart = aState->mBuffer.Elements();
      char16_t* bufEnd = nsTextFrameUtils::TransformText(
          frag->Get2b() + start, length, bufStart, compression, &incomingFlags,
          &skipChars, &analysisFlags);
      text = bufStart;
      length = bufEnd - bufStart;
    } else {
      // If the text only contains ASCII characters, it is currently
      // impossible that TransformText would remove all whitespaces,
      // and thus the check below should return the same result for
      // transformed text and original text. So we don't need to try
      // transforming it here.
      text = static_cast<const void*>(frag->Get1b() + start);
    }
    if (TextContainsLineBreakerWhiteSpace(text, length, frag->Is2b())) {
      aState->mSeenSpaceForLineBreakingOnThisLine = true;
      if (aState->mSeenTextRunBoundaryOnLaterLine) {
        return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
      }
    }
    return FB_CONTINUE;
  }

  FrameTextTraversal traversal = CanTextCrossFrameBoundary(aFrame);
  if (!traversal.mTextRunCanCrossFrameBoundary) {
    aState->mSeenTextRunBoundaryOnThisLine = true;
    if (aState->mSeenSpaceForLineBreakingOnThisLine)
      return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
  }

  for (nsIFrame* f = traversal.NextFrameToScan(); f;
       f = traversal.NextFrameToScan()) {
    FindBoundaryResult result = FindBoundaries(f, aState);
    if (result != FB_CONTINUE) {
      return result;
    }
  }

  if (!traversal.mTextRunCanCrossFrameBoundary) {
    aState->mSeenTextRunBoundaryOnThisLine = true;
    if (aState->mSeenSpaceForLineBreakingOnThisLine)
      return FB_FOUND_VALID_TEXTRUN_BOUNDARY;
  }

  return FB_CONTINUE;
}

// build text runs for the 200 lines following aForFrame, and stop after that
// when we get a chance.
#define NUM_LINES_TO_BUILD_TEXT_RUNS 200

/**
 * General routine for building text runs. This is hairy because of the need
 * to build text runs that span content nodes.
 *
 * @param aContext The gfxContext we're using to construct this text run.
 * @param aForFrame The nsTextFrame for which we're building this text run.
 * @param aLineContainer the line container containing aForFrame; if null,
 *        we'll walk the ancestors to find it.  It's required to be non-null
 *        when aForFrameLine is non-null.
 * @param aForFrameLine the line containing aForFrame; if null, we'll figure
 *        out the line (slowly)
 * @param aWhichTextRun The type of text run we want to build. If font inflation
 *        is enabled, this will be eInflated, otherwise it's eNotInflated.
 */
static void BuildTextRuns(DrawTarget* aDrawTarget, nsTextFrame* aForFrame,
                          nsIFrame* aLineContainer,
                          const nsLineList::iterator* aForFrameLine,
                          nsTextFrame::TextRunType aWhichTextRun) {
  MOZ_ASSERT(aForFrame, "for no frame?");
  NS_ASSERTION(!aForFrameLine || aLineContainer, "line but no line container");

  nsIFrame* lineContainerChild = aForFrame;
  if (!aLineContainer) {
    if (aForFrame->IsFloatingFirstLetterChild()) {
      lineContainerChild = aForFrame->GetParent()->GetPlaceholderFrame();
    }
    aLineContainer = FindLineContainer(lineContainerChild);
  } else {
    NS_ASSERTION(
        (aLineContainer == FindLineContainer(aForFrame) ||
         (aLineContainer->IsLetterFrame() && aLineContainer->IsFloating())),
        "Wrong line container hint");
  }

  if (aForFrame->HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
    aLineContainer->AddStateBits(TEXT_IS_IN_TOKEN_MATHML);
    if (aForFrame->HasAnyStateBits(NS_FRAME_IS_IN_SINGLE_CHAR_MI)) {
      aLineContainer->AddStateBits(NS_FRAME_IS_IN_SINGLE_CHAR_MI);
    }
  }
  if (aForFrame->HasAnyStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT)) {
    aLineContainer->AddStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT);
  }

  nsPresContext* presContext = aLineContainer->PresContext();
  bool doLineBreaking = !SVGUtils::IsInSVGTextSubtree(aForFrame);
  BuildTextRunsScanner scanner(presContext, aDrawTarget, aLineContainer,
                               aWhichTextRun, doLineBreaking);

  nsBlockFrame* block = do_QueryFrame(aLineContainer);

  if (!block) {
    nsIFrame* textRunContainer = aLineContainer;
    if (aLineContainer->IsRubyTextContainerFrame()) {
      textRunContainer = aForFrame;
      while (textRunContainer && !textRunContainer->IsRubyTextFrame()) {
        textRunContainer = textRunContainer->GetParent();
      }
      MOZ_ASSERT(textRunContainer &&
                 textRunContainer->GetParent() == aLineContainer);
    } else {
      NS_ASSERTION(
          !aLineContainer->GetPrevInFlow() && !aLineContainer->GetNextInFlow(),
          "Breakable non-block line containers other than "
          "ruby text container is not supported");
    }
    // Just loop through all the children of the linecontainer ... it's really
    // just one line
    scanner.SetAtStartOfLine();
    scanner.SetCommonAncestorWithLastFrame(nullptr);
    for (nsIFrame* child : textRunContainer->PrincipalChildList()) {
      scanner.ScanFrame(child);
    }
    // Set mStartOfLine so FlushFrames knows its textrun ends a line
    scanner.SetAtStartOfLine();
    scanner.FlushFrames(true, false);
    return;
  }

  // Find the line containing 'lineContainerChild'.

  bool isValid = true;
  nsBlockInFlowLineIterator backIterator(block, &isValid);
  if (aForFrameLine) {
    backIterator = nsBlockInFlowLineIterator(block, *aForFrameLine);
  } else {
    backIterator =
        nsBlockInFlowLineIterator(block, lineContainerChild, &isValid);
    NS_ASSERTION(isValid, "aForFrame not found in block, someone lied to us");
    NS_ASSERTION(backIterator.GetContainer() == block,
                 "Someone lied to us about the block");
  }
  nsBlockFrame::LineIterator startLine = backIterator.GetLine();

  // Find a line where we can start building text runs. We choose the last line
  // where:
  // -- there is a textrun boundary between the start of the line and the
  // start of aForFrame
  // -- there is a space between the start of the line and the textrun boundary
  // (this is so we can be sure the line breaks will be set properly
  // on the textruns we construct).
  // The possibly-partial text runs up to and including the first space
  // are not reconstructed. We construct partial text runs for that text ---
  // for the sake of simplifying the code and feeding the linebreaker ---
  // but we discard them instead of assigning them to frames.
  // This is a little awkward because we traverse lines in the reverse direction
  // but we traverse the frames in each line in the forward direction.
  nsBlockInFlowLineIterator forwardIterator = backIterator;
  nsIFrame* stopAtFrame = lineContainerChild;
  nsTextFrame* nextLineFirstTextFrame = nullptr;
  AutoTArray<char16_t, BIG_TEXT_NODE_SIZE> buffer;
  bool seenTextRunBoundaryOnLaterLine = false;
  bool mayBeginInTextRun = true;
  while (true) {
    forwardIterator = backIterator;
    nsBlockFrame::LineIterator line = backIterator.GetLine();
    if (!backIterator.Prev() || backIterator.GetLine()->IsBlock()) {
      mayBeginInTextRun = false;
      break;
    }

    BuildTextRunsScanner::FindBoundaryState state = {
        stopAtFrame, nullptr, nullptr, bool(seenTextRunBoundaryOnLaterLine),
        false,       false,   buffer};
    nsIFrame* child = line->mFirstChild;
    bool foundBoundary = false;
    for (int32_t i = line->GetChildCount() - 1; i >= 0; --i) {
      BuildTextRunsScanner::FindBoundaryResult result =
          scanner.FindBoundaries(child, &state);
      if (result == BuildTextRunsScanner::FB_FOUND_VALID_TEXTRUN_BOUNDARY) {
        foundBoundary = true;
        break;
      } else if (result == BuildTextRunsScanner::FB_STOPPED_AT_STOP_FRAME) {
        break;
      }
      child = child->GetNextSibling();
    }
    if (foundBoundary) {
      break;
    }
    if (!stopAtFrame && state.mLastTextFrame && nextLineFirstTextFrame &&
        !scanner.ContinueTextRunAcrossFrames(state.mLastTextFrame,
                                             nextLineFirstTextFrame)) {
      // Found a usable textrun boundary at the end of the line
      if (state.mSeenSpaceForLineBreakingOnThisLine) {
        break;
      }
      seenTextRunBoundaryOnLaterLine = true;
    } else if (state.mSeenTextRunBoundaryOnThisLine) {
      seenTextRunBoundaryOnLaterLine = true;
    }
    stopAtFrame = nullptr;
    if (state.mFirstTextFrame) {
      nextLineFirstTextFrame = state.mFirstTextFrame;
    }
  }
  scanner.SetSkipIncompleteTextRuns(mayBeginInTextRun);

  // Now iterate over all text frames starting from the current line.
  // First-in-flow text frames will be accumulated into textRunFrames as we go.
  // When a text run boundary is required we flush textRunFrames ((re)building
  // their gfxTextRuns as necessary).
  bool seenStartLine = false;
  uint32_t linesAfterStartLine = 0;
  do {
    nsBlockFrame::LineIterator line = forwardIterator.GetLine();
    if (line->IsBlock()) {
      break;
    }
    line->SetInvalidateTextRuns(false);
    scanner.SetAtStartOfLine();
    scanner.SetCommonAncestorWithLastFrame(nullptr);
    nsIFrame* child = line->mFirstChild;
    for (int32_t i = line->GetChildCount() - 1; i >= 0; --i) {
      scanner.ScanFrame(child);
      child = child->GetNextSibling();
    }
    if (line.get() == startLine.get()) {
      seenStartLine = true;
    }
    if (seenStartLine) {
      ++linesAfterStartLine;
      if (linesAfterStartLine >= NUM_LINES_TO_BUILD_TEXT_RUNS &&
          scanner.CanStopOnThisLine()) {
        // Don't flush frames; we may be in the middle of a textrun
        // that we can't end here. That's OK, we just won't build it.
        // Note that we must already have finished the textrun for aForFrame,
        // because we've seen the end of a textrun in a line after the line
        // containing aForFrame.
        scanner.FlushLineBreaks(nullptr);
        // This flushes out mMappedFlows and mLineBreakBeforeFrames, which
        // silences assertions in the scanner destructor.
        scanner.ResetRunInfo();
        return;
      }
    }
  } while (forwardIterator.Next());

  // Set mStartOfLine so FlushFrames knows its textrun ends a line
  scanner.SetAtStartOfLine();
  scanner.FlushFrames(true, false);
}

static char16_t* ExpandBuffer(char16_t* aDest, uint8_t* aSrc, uint32_t aCount) {
  while (aCount) {
    *aDest = *aSrc;
    ++aDest;
    ++aSrc;
    --aCount;
  }
  return aDest;
}

bool BuildTextRunsScanner::IsTextRunValidForMappedFlows(
    const gfxTextRun* aTextRun) {
  if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    return mMappedFlows.Length() == 1 &&
           mMappedFlows[0].mStartFrame == GetFrameForSimpleFlow(aTextRun) &&
           mMappedFlows[0].mEndFrame == nullptr;
  }

  auto userData = static_cast<TextRunUserData*>(aTextRun->GetUserData());
  TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
  if (userData->mMappedFlowCount != mMappedFlows.Length()) {
    return false;
  }
  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
    if (userMappedFlows[i].mStartFrame != mMappedFlows[i].mStartFrame ||
        int32_t(userMappedFlows[i].mContentLength) !=
            mMappedFlows[i].GetContentEnd() -
                mMappedFlows[i].mStartFrame->GetContentOffset()) {
      return false;
    }
  }
  return true;
}

/**
 * This gets called when we need to make a text run for the current list of
 * frames.
 */
void BuildTextRunsScanner::FlushFrames(bool aFlushLineBreaks,
                                       bool aSuppressTrailingBreak) {
  RefPtr<gfxTextRun> textRun;
  if (!mMappedFlows.IsEmpty()) {
    if (!mSkipIncompleteTextRuns && mCurrentFramesAllSameTextRun &&
        !!(mCurrentFramesAllSameTextRun->GetFlags2() &
           nsTextFrameUtils::Flags::IncomingWhitespace) ==
            !!(mCurrentRunContextInfo &
               nsTextFrameUtils::INCOMING_WHITESPACE) &&
        !!(mCurrentFramesAllSameTextRun->GetFlags() &
           gfx::ShapedTextFlags::TEXT_INCOMING_ARABICCHAR) ==
            !!(mCurrentRunContextInfo &
               nsTextFrameUtils::INCOMING_ARABICCHAR) &&
        IsTextRunValidForMappedFlows(mCurrentFramesAllSameTextRun)) {
      // Optimization: We do not need to (re)build the textrun.
      textRun = mCurrentFramesAllSameTextRun;

      if (mDoLineBreaking) {
        // Feed this run's text into the linebreaker to provide context.
        if (!SetupLineBreakerContext(textRun)) {
          return;
        }
      }

      // Update mNextRunContextInfo appropriately
      mNextRunContextInfo = nsTextFrameUtils::INCOMING_NONE;
      if (textRun->GetFlags2() & nsTextFrameUtils::Flags::TrailingWhitespace) {
        mNextRunContextInfo |= nsTextFrameUtils::INCOMING_WHITESPACE;
      }
      if (textRun->GetFlags() &
          gfx::ShapedTextFlags::TEXT_TRAILING_ARABICCHAR) {
        mNextRunContextInfo |= nsTextFrameUtils::INCOMING_ARABICCHAR;
      }
    } else {
      AutoTArray<uint8_t, BIG_TEXT_NODE_SIZE> buffer;
      uint32_t bufferSize = mMaxTextLength * (mDoubleByteText ? 2 : 1);
      if (bufferSize < mMaxTextLength || bufferSize == UINT32_MAX ||
          !buffer.AppendElements(bufferSize, fallible)) {
        return;
      }
      textRun = BuildTextRunForFrames(buffer.Elements());
    }
  }

  if (aFlushLineBreaks) {
    FlushLineBreaks(aSuppressTrailingBreak ? nullptr : textRun.get());
    if (!mDoLineBreaking && textRun) {
      CreateObserversForAnimatedGlyphs(textRun.get());
    }
  }

  mCanStopOnThisLine = true;
  ResetRunInfo();
}

void BuildTextRunsScanner::FlushLineBreaks(gfxTextRun* aTrailingTextRun) {
  // If the line-breaker is buffering a potentially-unfinished word,
  // preserve the state of being in-word so that we don't spuriously
  // capitalize the next letter.
  bool inWord = mLineBreaker.InWord();
  bool trailingLineBreak;
  nsresult rv = mLineBreaker.Reset(&trailingLineBreak);
  mLineBreaker.SetWordContinuation(inWord);
  // textRun may be null for various reasons, including because we constructed
  // a partial textrun just to get the linebreaker and other state set up
  // to build the next textrun.
  if (NS_SUCCEEDED(rv) && trailingLineBreak && aTrailingTextRun) {
    aTrailingTextRun->SetFlagBits(nsTextFrameUtils::Flags::HasTrailingBreak);
  }

  for (uint32_t i = 0; i < mBreakSinks.Length(); ++i) {
    // TODO cause frames associated with the textrun to be reflowed, if they
    // aren't being reflowed already!
    mBreakSinks[i]->Finish(mMissingFonts);
  }
  mBreakSinks.Clear();
}

void BuildTextRunsScanner::AccumulateRunInfo(nsTextFrame* aFrame) {
  if (mMaxTextLength != UINT32_MAX) {
    NS_ASSERTION(mMaxTextLength < UINT32_MAX - aFrame->GetContentLength(),
                 "integer overflow");
    if (mMaxTextLength >= UINT32_MAX - aFrame->GetContentLength()) {
      mMaxTextLength = UINT32_MAX;
    } else {
      mMaxTextLength += aFrame->GetContentLength();
    }
  }
  mDoubleByteText |= aFrame->TextFragment()->Is2b();
  mLastFrame = aFrame;
  mCommonAncestorWithLastFrame = aFrame->GetParent();

  MappedFlow* mappedFlow = &mMappedFlows[mMappedFlows.Length() - 1];
  NS_ASSERTION(mappedFlow->mStartFrame == aFrame ||
                   mappedFlow->GetContentEnd() == aFrame->GetContentOffset(),
               "Overlapping or discontiguous frames => BAD");
  mappedFlow->mEndFrame = aFrame->GetNextContinuation();
  if (mCurrentFramesAllSameTextRun != aFrame->GetTextRun(mWhichTextRun)) {
    mCurrentFramesAllSameTextRun = nullptr;
  }

  if (mStartOfLine) {
    mLineBreakBeforeFrames.AppendElement(aFrame);
    mStartOfLine = false;
  }
}

static bool HasTerminalNewline(const nsTextFrame* aFrame) {
  if (aFrame->GetContentLength() == 0) {
    return false;
  }
  const nsTextFragment* frag = aFrame->TextFragment();
  return frag->CharAt(AssertedCast<uint32_t>(aFrame->GetContentEnd()) - 1) ==
         '\n';
}

static gfxFont::Metrics GetFirstFontMetrics(gfxFontGroup* aFontGroup,
                                            bool aVerticalMetrics) {
  if (!aFontGroup) {
    return gfxFont::Metrics();
  }
  RefPtr<gfxFont> font = aFontGroup->GetFirstValidFont();
  return font->GetMetrics(aVerticalMetrics ? nsFontMetrics::eVertical
                                           : nsFontMetrics::eHorizontal);
}

static nscoord GetSpaceWidthAppUnits(const gfxTextRun* aTextRun) {
  // Round the space width when converting to appunits the same way textruns
  // do.
  gfxFloat spaceWidthAppUnits =
      NS_round(GetFirstFontMetrics(aTextRun->GetFontGroup(),
                                   aTextRun->UseCenterBaseline())
                   .spaceWidth *
               aTextRun->GetAppUnitsPerDevUnit());

  return spaceWidthAppUnits;
}

static gfxFloat GetMinTabAdvanceAppUnits(const gfxTextRun* aTextRun) {
  gfxFloat chWidthAppUnits = NS_round(
      GetFirstFontMetrics(aTextRun->GetFontGroup(), aTextRun->IsVertical())
          .ZeroOrAveCharWidth() *
      aTextRun->GetAppUnitsPerDevUnit());
  return 0.5 * chWidthAppUnits;
}

static float GetSVGFontSizeScaleFactor(nsIFrame* aFrame) {
  if (!SVGUtils::IsInSVGTextSubtree(aFrame)) {
    return 1.0f;
  }
  auto container =
      nsLayoutUtils::GetClosestFrameOfType(aFrame, LayoutFrameType::SVGText);
  MOZ_ASSERT(container);
  return static_cast<SVGTextFrame*>(container)->GetFontSizeScaleFactor();
}

static nscoord LetterSpacing(nsIFrame* aFrame, const nsStyleText& aStyleText) {
  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
    // SVG text can have a scaling factor applied so that very small or very
    // large font-sizes don't suffer from poor glyph placement due to app unit
    // rounding. The used letter-spacing value must be scaled by the same
    // factor.
    Length spacing = aStyleText.mLetterSpacing;
    spacing.ScaleBy(GetSVGFontSizeScaleFactor(aFrame));
    return spacing.ToAppUnits();
  }

  return aStyleText.mLetterSpacing.ToAppUnits();
}

// This function converts non-coord values (e.g. percentages) to nscoord.
static nscoord WordSpacing(nsIFrame* aFrame, const gfxTextRun* aTextRun,
                           const nsStyleText& aStyleText) {
  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
    // SVG text can have a scaling factor applied so that very small or very
    // large font-sizes don't suffer from poor glyph placement due to app unit
    // rounding. The used word-spacing value must be scaled by the same
    // factor, although any percentage basis has already effectively been
    // scaled, since it's the space glyph width, which is based on the already-
    // scaled font-size.
    auto spacing = aStyleText.mWordSpacing;
    spacing.ScaleLengthsBy(GetSVGFontSizeScaleFactor(aFrame));
    return spacing.Resolve([&] { return GetSpaceWidthAppUnits(aTextRun); });
  }

  return aStyleText.mWordSpacing.Resolve(
      [&] { return GetSpaceWidthAppUnits(aTextRun); });
}

// Returns gfxTextRunFactory::TEXT_ENABLE_SPACING if non-standard
// letter-spacing or word-spacing is present.
static gfx::ShapedTextFlags GetSpacingFlags(
    nsIFrame* aFrame, const nsStyleText* aStyleText = nullptr) {
  const nsStyleText* styleText = aFrame->StyleText();
  const auto& ls = styleText->mLetterSpacing;
  const auto& ws = styleText->mWordSpacing;

  // It's possible to have a calc() value that computes to zero but for which
  // IsDefinitelyZero() is false, in which case we'll return
  // TEXT_ENABLE_SPACING unnecessarily. That's ok because such cases are likely
  // to be rare, and avoiding TEXT_ENABLE_SPACING is just an optimization.
  bool nonStandardSpacing = !ls.IsZero() || !ws.IsDefinitelyZero();
  return nonStandardSpacing ? gfx::ShapedTextFlags::TEXT_ENABLE_SPACING
                            : gfx::ShapedTextFlags();
}

bool BuildTextRunsScanner::ContinueTextRunAcrossFrames(nsTextFrame* aFrame1,
                                                       nsTextFrame* aFrame2) {
  // We don't need to check font size inflation, since
  // |FindLineContainer| above (via |nsIFrame::CanContinueTextRun|)
  // ensures that text runs never cross block boundaries.  This means
  // that the font size inflation on all text frames in the text run is
  // already guaranteed to be the same as each other (and for the line
  // container).
  if (mBidiEnabled) {
    FrameBidiData data1 = aFrame1->GetBidiData();
    FrameBidiData data2 = aFrame2->GetBidiData();
    if (data1.embeddingLevel != data2.embeddingLevel ||
        data2.precedingControl != kBidiLevelNone) {
      return false;
    }
  }

  ComputedStyle* sc1 = aFrame1->Style();
  ComputedStyle* sc2 = aFrame2->Style();

  // Any difference in writing-mode/directionality inhibits shaping across
  // the boundary.
  WritingMode wm(sc1);
  if (wm != WritingMode(sc2)) {
    return false;
  }

  const nsStyleText* textStyle1 = sc1->StyleText();
  // If the first frame ends in a preformatted newline, then we end the textrun
  // here. This avoids creating giant textruns for an entire plain text file.
  // Note that we create a single text frame for a preformatted text node,
  // even if it has newlines in it, so typically we won't see trailing newlines
  // until after reflow has broken up the frame into one (or more) frames per
  // line. That's OK though.
  if (textStyle1->NewlineIsSignificant(aFrame1) &&
      HasTerminalNewline(aFrame1)) {
    return false;
  }

  if (aFrame1->GetParent()->GetContent() !=
      aFrame2->GetParent()->GetContent()) {
    // Does aFrame, or any ancestor between it and aAncestor, have a property
    // that should inhibit cross-element-boundary shaping on aSide?
    auto PreventCrossBoundaryShaping = [](const nsIFrame* aFrame,
                                          const nsIFrame* aAncestor,
                                          Side aSide) {
      while (aFrame != aAncestor) {
        ComputedStyle* ctx = aFrame->Style();
        // According to https://drafts.csswg.org/css-text/#boundary-shaping:
        //
        // Text shaping must be broken at inline box boundaries when any of
        // the following are true for any box whose boundary separates the
        // two typographic character units:
        //
        // 1. Any of margin/border/padding separating the two typographic
        //    character units in the inline axis is non-zero.
        const auto& margin = ctx->StyleMargin()->mMargin.Get(aSide);
        if (!margin.ConvertsToLength() ||
            margin.AsLengthPercentage().ToLength() != 0) {
          return true;
        }
        const auto& padding = ctx->StylePadding()->mPadding.Get(aSide);
        if (!padding.ConvertsToLength() || padding.ToLength() != 0) {
          return true;
        }
        if (ctx->StyleBorder()->GetComputedBorderWidth(aSide) != 0) {
          return true;
        }

        // 2. vertical-align is not baseline.
        //
        // FIXME: Should this use VerticalAlignEnum()?
        const auto& verticalAlign = ctx->StyleDisplay()->mVerticalAlign;
        if (!verticalAlign.IsKeyword() ||
            verticalAlign.AsKeyword() != StyleVerticalAlignKeyword::Baseline) {
          return true;
        }

        // 3. The boundary is a bidi isolation boundary.
        const uint8_t unicodeBidi = ctx->StyleTextReset()->mUnicodeBidi;
        if (unicodeBidi == NS_STYLE_UNICODE_BIDI_ISOLATE ||
            unicodeBidi == NS_STYLE_UNICODE_BIDI_ISOLATE_OVERRIDE) {
          return true;
        }

        aFrame = aFrame->GetParent();
      }
      return false;
    };

    const nsIFrame* ancestor =
        nsLayoutUtils::FindNearestCommonAncestorFrameWithinBlock(aFrame1,
                                                                 aFrame2);

    if (!ancestor) {
      // The two frames are within different blocks, e.g. due to block
      // fragmentation. In theory we shouldn't prevent cross-frame shaping
      // here, but it's an edge case where we should rarely decide to allow
      // cross-frame shaping, so we don't try harder here.
      return false;
    }

    // We inhibit cross-element-boundary shaping if we're in SVG content,
    // as there are too many things SVG might be doing (like applying per-
    // element positioning) that wouldn't make sense with shaping across
    // the boundary.
    if (SVGUtils::IsInSVGTextSubtree(ancestor)) {
      return false;
    }

    // Map inline-end and inline-start to physical sides for checking presence
    // of non-zero margin/border/padding.
    Side side1 = wm.PhysicalSide(eLogicalSideIEnd);
    Side side2 = wm.PhysicalSide(eLogicalSideIStart);
    // If the frames have an embedding level that is opposite to the writing
    // mode, we need to swap which sides we're checking.
    if (aFrame1->GetEmbeddingLevel().IsRTL() == wm.IsBidiLTR()) {
      std::swap(side1, side2);
    }

    if (PreventCrossBoundaryShaping(aFrame1, ancestor, side1) ||
        PreventCrossBoundaryShaping(aFrame2, ancestor, side2)) {
      return false;
    }
  }

  if (aFrame1->GetContent() == aFrame2->GetContent() &&
      aFrame1->GetNextInFlow() != aFrame2) {
    // aFrame2 must be a non-fluid continuation of aFrame1. This can happen
    // sometimes when the unicode-bidi property is used; the bidi resolver
    // breaks text into different frames even though the text has the same
    // direction. We can't allow these two frames to share the same textrun
    // because that would violate our invariant that two flows in the same
    // textrun have different content elements.
    return false;
  }

  if (sc1 == sc2) {
    return true;
  }

  const nsStyleText* textStyle2 = sc2->StyleText();
  if (textStyle1->mTextTransform != textStyle2->mTextTransform ||
      textStyle1->EffectiveWordBreak() != textStyle2->EffectiveWordBreak() ||
      textStyle1->mLineBreak != textStyle2->mLineBreak) {
    return false;
  }

  nsPresContext* pc = aFrame1->PresContext();
  MOZ_ASSERT(pc == aFrame2->PresContext());

  const nsStyleFont* fontStyle1 = sc1->StyleFont();
  const nsStyleFont* fontStyle2 = sc2->StyleFont();
  nscoord letterSpacing1 = LetterSpacing(aFrame1, *textStyle1);
  nscoord letterSpacing2 = LetterSpacing(aFrame2, *textStyle2);
  return fontStyle1->mFont == fontStyle2->mFont &&
         fontStyle1->mLanguage == fontStyle2->mLanguage &&
         nsLayoutUtils::GetTextRunFlagsForStyle(sc1, pc, fontStyle1, textStyle1,
                                                letterSpacing1) ==
             nsLayoutUtils::GetTextRunFlagsForStyle(sc2, pc, fontStyle2,
                                                    textStyle2, letterSpacing2);
}

void BuildTextRunsScanner::ScanFrame(nsIFrame* aFrame) {
  LayoutFrameType frameType = aFrame->Type();
  if (frameType == LayoutFrameType::RubyTextContainer) {
    // Don't include any ruby text container into the text run.
    return;
  }

  // First check if we can extend the current mapped frame block. This is
  // common.
  if (mMappedFlows.Length() > 0) {
    MappedFlow* mappedFlow = &mMappedFlows[mMappedFlows.Length() - 1];
    if (mappedFlow->mEndFrame == aFrame &&
        aFrame->HasAnyStateBits(NS_FRAME_IS_FLUID_CONTINUATION)) {
      NS_ASSERTION(frameType == LayoutFrameType::Text,
                   "Flow-sibling of a text frame is not a text frame?");

      // Don't do this optimization if mLastFrame has a terminal newline...
      // it's quite likely preformatted and we might want to end the textrun
      // here. This is almost always true:
      if (mLastFrame->Style() == aFrame->Style() &&
          !HasTerminalNewline(mLastFrame)) {
        AccumulateRunInfo(static_cast<nsTextFrame*>(aFrame));
        return;
      }
    }
  }

  // Now see if we can add a new set of frames to the current textrun
  if (frameType == LayoutFrameType::Text) {
    nsTextFrame* frame = static_cast<nsTextFrame*>(aFrame);

    if (mLastFrame) {
      if (!ContinueTextRunAcrossFrames(mLastFrame, frame)) {
        FlushFrames(false, false);
      } else {
        if (mLastFrame->GetContent() == frame->GetContent()) {
          AccumulateRunInfo(frame);
          return;
        }
      }
    }

    MappedFlow* mappedFlow = mMappedFlows.AppendElement();
    mappedFlow->mStartFrame = frame;
    mappedFlow->mAncestorControllingInitialBreak = mCommonAncestorWithLastFrame;

    AccumulateRunInfo(frame);
    if (mMappedFlows.Length() == 1) {
      mCurrentFramesAllSameTextRun = frame->GetTextRun(mWhichTextRun);
      mCurrentRunContextInfo = mNextRunContextInfo;
    }
    return;
  }

  if (frameType == LayoutFrameType::Placeholder &&
      aFrame->HasAnyStateBits(PLACEHOLDER_FOR_ABSPOS |
                              PLACEHOLDER_FOR_FIXEDPOS)) {
    // Somewhat hacky fix for bug 1418472:
    // If this is a placeholder for an absolute-positioned frame, we need to
    // flush the line-breaker to prevent the placeholder becoming separated
    // from the immediately-following content.
    // XXX This will interrupt text shaping (ligatures, etc) if an abs-pos
    // element occurs within a word where shaping should be in effect, but
    // that's an edge case, unlikely to occur in real content. A more precise
    // fix might require better separation of line-breaking from textrun setup,
    // but that's a big invasive change (and potentially expensive for perf, as
    // it might introduce an additional pass over all the frames).
    FlushFrames(true, false);
  }

  FrameTextTraversal traversal = CanTextCrossFrameBoundary(aFrame);
  bool isBR = frameType == LayoutFrameType::Br;
  if (!traversal.mLineBreakerCanCrossFrameBoundary) {
    // BR frames are special. We do not need or want to record a break
    // opportunity before a BR frame.
    FlushFrames(true, isBR);
    mCommonAncestorWithLastFrame = aFrame;
    mNextRunContextInfo &= ~nsTextFrameUtils::INCOMING_WHITESPACE;
    mStartOfLine = false;
  } else if (!traversal.mTextRunCanCrossFrameBoundary) {
    FlushFrames(false, false);
  }

  for (nsIFrame* f = traversal.NextFrameToScan(); f;
       f = traversal.NextFrameToScan()) {
    ScanFrame(f);
  }

  if (!traversal.mLineBreakerCanCrossFrameBoundary) {
    // Really if we're a BR frame this is unnecessary since descendInto will be
    // false. In fact this whole "if" statement should move into the
    // descendInto.
    FlushFrames(true, isBR);
    mCommonAncestorWithLastFrame = aFrame;
    mNextRunContextInfo &= ~nsTextFrameUtils::INCOMING_WHITESPACE;
  } else if (!traversal.mTextRunCanCrossFrameBoundary) {
    FlushFrames(false, false);
  }

  LiftCommonAncestorWithLastFrameToParent(aFrame->GetParent());
}

nsTextFrame* BuildTextRunsScanner::GetNextBreakBeforeFrame(uint32_t* aIndex) {
  uint32_t index = *aIndex;
  if (index >= mLineBreakBeforeFrames.Length()) {
    return nullptr;
  }
  *aIndex = index + 1;
  return static_cast<nsTextFrame*>(mLineBreakBeforeFrames.ElementAt(index));
}

static gfxFontGroup* GetFontGroupForFrame(
    const nsIFrame* aFrame, float aFontSizeInflation,
    nsFontMetrics** aOutFontMetrics = nullptr) {
  RefPtr<nsFontMetrics> metrics =
      nsLayoutUtils::GetFontMetricsForFrame(aFrame, aFontSizeInflation);
  gfxFontGroup* fontGroup = metrics->GetThebesFontGroup();

  // Populate outparam before we return:
  if (aOutFontMetrics) {
    metrics.forget(aOutFontMetrics);
  }
  // XXX this is a bit bogus, we're releasing 'metrics' so the
  // returned font-group might actually be torn down, although because
  // of the way the device context caches font metrics, this seems to
  // not actually happen. But we should fix this.
  return fontGroup;
}

static gfxFontGroup* GetInflatedFontGroupForFrame(nsTextFrame* aFrame) {
  gfxTextRun* textRun = aFrame->GetTextRun(nsTextFrame::eInflated);
  if (textRun) {
    return textRun->GetFontGroup();
  }
  if (!aFrame->InflatedFontMetrics()) {
    float inflation = nsLayoutUtils::FontSizeInflationFor(aFrame);
    RefPtr<nsFontMetrics> metrics =
        nsLayoutUtils::GetFontMetricsForFrame(aFrame, inflation);
    aFrame->SetInflatedFontMetrics(metrics);
  }
  return aFrame->InflatedFontMetrics()->GetThebesFontGroup();
}

static already_AddRefed<DrawTarget> CreateReferenceDrawTarget(
    const nsTextFrame* aTextFrame) {
  RefPtr<gfxContext> ctx =
      aTextFrame->PresShell()->CreateReferenceRenderingContext();
  RefPtr<DrawTarget> dt = ctx->GetDrawTarget();
  return dt.forget();
}

static already_AddRefed<gfxTextRun> GetHyphenTextRun(nsTextFrame* aTextFrame,
                                                     DrawTarget* aDrawTarget) {
  RefPtr<DrawTarget> dt = aDrawTarget;
  if (!dt) {
    dt = CreateReferenceDrawTarget(aTextFrame);
    if (!dt) {
      return nullptr;
    }
  }

  RefPtr<nsFontMetrics> fm =
      nsLayoutUtils::GetInflatedFontMetricsForFrame(aTextFrame);
  auto* fontGroup = fm->GetThebesFontGroup();
  auto appPerDev = aTextFrame->PresContext()->AppUnitsPerDevPixel();
  const auto& hyphenateChar = aTextFrame->StyleText()->mHyphenateCharacter;
  gfx::ShapedTextFlags flags =
      nsLayoutUtils::GetTextRunOrientFlagsForStyle(aTextFrame->Style());
  // Make the directionality of the hyphen run (in case it is multi-char) match
  // the text frame.
  if (aTextFrame->GetWritingMode().IsBidiRTL()) {
    flags |= gfx::ShapedTextFlags::TEXT_IS_RTL;
  }
  if (hyphenateChar.IsAuto()) {
    return fontGroup->MakeHyphenTextRun(dt, flags, appPerDev);
  }
  auto* missingFonts = aTextFrame->PresContext()->MissingFontRecorder();
  const NS_ConvertUTF8toUTF16 hyphenStr(hyphenateChar.AsString().AsString());
  return fontGroup->MakeTextRun(hyphenStr.BeginReading(), hyphenStr.Length(),
                                dt, appPerDev, flags, nsTextFrameUtils::Flags(),
                                missingFonts);
}

already_AddRefed<gfxTextRun> BuildTextRunsScanner::BuildTextRunForFrames(
    void* aTextBuffer) {
  gfxSkipChars skipChars;

  const void* textPtr = aTextBuffer;
  bool anyTextTransformStyle = false;
  bool anyMathMLStyling = false;
  bool anyTextEmphasis = false;
  uint8_t sstyScriptLevel = 0;
  uint32_t mathFlags = 0;
  gfx::ShapedTextFlags flags = gfx::ShapedTextFlags();
  nsTextFrameUtils::Flags flags2 = nsTextFrameUtils::Flags::NoBreaks;

  if (mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_WHITESPACE) {
    flags2 |= nsTextFrameUtils::Flags::IncomingWhitespace;
  }
  if (mCurrentRunContextInfo & nsTextFrameUtils::INCOMING_ARABICCHAR) {
    flags |= gfx::ShapedTextFlags::TEXT_INCOMING_ARABICCHAR;
  }

  AutoTArray<int32_t, 50> textBreakPoints;
  TextRunUserData dummyData;
  TextRunMappedFlow dummyMappedFlow;
  TextRunMappedFlow* userMappedFlows;
  TextRunUserData* userData;
  TextRunUserData* userDataToDestroy;
  // If the situation is particularly simple (and common) we don't need to
  // allocate userData.
  if (mMappedFlows.Length() == 1 && !mMappedFlows[0].mEndFrame &&
      mMappedFlows[0].mStartFrame->GetContentOffset() == 0) {
    userData = &dummyData;
    userMappedFlows = &dummyMappedFlow;
    userDataToDestroy = nullptr;
    dummyData.mMappedFlowCount = mMappedFlows.Length();
    dummyData.mLastFlowIndex = 0;
  } else {
    userData = CreateUserData(mMappedFlows.Length());
    userMappedFlows = reinterpret_cast<TextRunMappedFlow*>(userData + 1);
    userDataToDestroy = userData;
  }

  uint32_t currentTransformedTextOffset = 0;

  uint32_t nextBreakIndex = 0;
  nsTextFrame* nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
  bool isSVG = SVGUtils::IsInSVGTextSubtree(mLineContainer);
  bool enabledJustification =
      (mLineContainer->StyleText()->mTextAlign == StyleTextAlign::Justify ||
       mLineContainer->StyleText()->mTextAlignLast ==
           StyleTextAlignLast::Justify);

  const nsStyleText* textStyle = nullptr;
  const nsStyleFont* fontStyle = nullptr;
  ComputedStyle* lastComputedStyle = nullptr;
  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
    MappedFlow* mappedFlow = &mMappedFlows[i];
    nsTextFrame* f = mappedFlow->mStartFrame;

    lastComputedStyle = f->Style();
    // Detect use of text-transform or font-variant anywhere in the run
    textStyle = f->StyleText();
    if (!textStyle->mTextTransform.IsNone() ||
        // text-combine-upright requires converting from full-width
        // characters to non-full-width correspendent in some cases.
        lastComputedStyle->IsTextCombined()) {
      anyTextTransformStyle = true;
    }
    if (textStyle->HasEffectiveTextEmphasis()) {
      anyTextEmphasis = true;
    }
    flags |= GetSpacingFlags(f);
    nsTextFrameUtils::CompressionMode compression =
        GetCSSWhitespaceToCompressionMode(f, textStyle);
    if ((enabledJustification || f->ShouldSuppressLineBreak()) &&
        !textStyle->WhiteSpaceIsSignificant() && !isSVG) {
      flags |= gfx::ShapedTextFlags::TEXT_ENABLE_SPACING;
    }
    fontStyle = f->StyleFont();
    nsIFrame* parent = mLineContainer->GetParent();
    if (StyleMathVariant::None != fontStyle->mMathVariant) {
      if (StyleMathVariant::Normal != fontStyle->mMathVariant) {
        anyMathMLStyling = true;
      }
    } else if (mLineContainer->HasAnyStateBits(NS_FRAME_IS_IN_SINGLE_CHAR_MI)) {
      flags2 |= nsTextFrameUtils::Flags::IsSingleCharMi;
      anyMathMLStyling = true;
    }
    if (mLineContainer->HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
      // All MathML tokens except <mtext> use 'math' script.
      if (!(parent && parent->GetContent() &&
            parent->GetContent()->IsMathMLElement(nsGkAtoms::mtext_))) {
        flags |= gfx::ShapedTextFlags::TEXT_USE_MATH_SCRIPT;
      }
      nsIMathMLFrame* mathFrame = do_QueryFrame(parent);
      if (mathFrame) {
        nsPresentationData presData;
        mathFrame->GetPresentationData(presData);
        if (NS_MATHML_IS_DTLS_SET(presData.flags)) {
          mathFlags |= MathMLTextRunFactory::MATH_FONT_FEATURE_DTLS;
          anyMathMLStyling = true;
        }
      }
    }
    nsIFrame* child = mLineContainer;
    uint8_t oldScriptLevel = 0;
    while (parent &&
           child->HasAnyStateBits(NS_FRAME_MATHML_SCRIPT_DESCENDANT)) {
      // Reconstruct the script level ignoring any user overrides. It is
      // calculated this way instead of using scriptlevel to ensure the
      // correct ssty font feature setting is used even if the user sets a
      // different (especially negative) scriptlevel.
      nsIMathMLFrame* mathFrame = do_QueryFrame(parent);
      if (mathFrame) {
        sstyScriptLevel += mathFrame->ScriptIncrement(child);
      }
      if (sstyScriptLevel < oldScriptLevel) {
        // overflow
        sstyScriptLevel = UINT8_MAX;
        break;
      }
      child = parent;
      parent = parent->GetParent();
      oldScriptLevel = sstyScriptLevel;
    }
    if (sstyScriptLevel) {
      anyMathMLStyling = true;
    }

    // Figure out what content is included in this flow.
    nsIContent* content = f->GetContent();
    const nsTextFragment* frag = f->TextFragment();
    int32_t contentStart = mappedFlow->mStartFrame->GetContentOffset();
    int32_t contentEnd = mappedFlow->GetContentEnd();
    int32_t contentLength = contentEnd - contentStart;

    TextRunMappedFlow* newFlow = &userMappedFlows[i];
    newFlow->mStartFrame = mappedFlow->mStartFrame;
    newFlow->mDOMOffsetToBeforeTransformOffset =
        skipChars.GetOriginalCharCount() -
        mappedFlow->mStartFrame->GetContentOffset();
    newFlow->mContentLength = contentLength;

    while (nextBreakBeforeFrame &&
           nextBreakBeforeFrame->GetContent() == content) {
      textBreakPoints.AppendElement(nextBreakBeforeFrame->GetContentOffset() +
                                    newFlow->mDOMOffsetToBeforeTransformOffset);
      nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
    }

    nsTextFrameUtils::Flags analysisFlags;
    if (frag->Is2b()) {
      NS_ASSERTION(mDoubleByteText, "Wrong buffer char size!");
      char16_t* bufStart = static_cast<char16_t*>(aTextBuffer);
      char16_t* bufEnd = nsTextFrameUtils::TransformText(
          frag->Get2b() + contentStart, contentLength, bufStart, compression,
          &mNextRunContextInfo, &skipChars, &analysisFlags);
      aTextBuffer = bufEnd;
      currentTransformedTextOffset =
          bufEnd - static_cast<const char16_t*>(textPtr);
    } else {
      if (mDoubleByteText) {
        // Need to expand the text. First transform it into a temporary buffer,
        // then expand.
        AutoTArray<uint8_t, BIG_TEXT_NODE_SIZE> tempBuf;
        uint8_t* bufStart = tempBuf.AppendElements(contentLength, fallible);
        if (!bufStart) {
          DestroyUserData(userDataToDestroy);
          return nullptr;
        }
        uint8_t* end = nsTextFrameUtils::TransformText(
            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart,
            contentLength, bufStart, compression, &mNextRunContextInfo,
            &skipChars, &analysisFlags);
        aTextBuffer =
            ExpandBuffer(static_cast<char16_t*>(aTextBuffer),
                         tempBuf.Elements(), end - tempBuf.Elements());
        currentTransformedTextOffset = static_cast<char16_t*>(aTextBuffer) -
                                       static_cast<const char16_t*>(textPtr);
      } else {
        uint8_t* bufStart = static_cast<uint8_t*>(aTextBuffer);
        uint8_t* end = nsTextFrameUtils::TransformText(
            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart,
            contentLength, bufStart, compression, &mNextRunContextInfo,
            &skipChars, &analysisFlags);
        aTextBuffer = end;
        currentTransformedTextOffset =
            end - static_cast<const uint8_t*>(textPtr);
      }
    }
    flags2 |= analysisFlags;
  }

  void* finalUserData;
  if (userData == &dummyData) {
    flags2 |= nsTextFrameUtils::Flags::IsSimpleFlow;
    userData = nullptr;
    finalUserData = mMappedFlows[0].mStartFrame;
  } else {
    finalUserData = userData;
  }

  uint32_t transformedLength = currentTransformedTextOffset;

  // Now build the textrun
  nsTextFrame* firstFrame = mMappedFlows[0].mStartFrame;
  float fontInflation;
  gfxFontGroup* fontGroup;
  if (mWhichTextRun == nsTextFrame::eNotInflated) {
    fontInflation = 1.0f;
    fontGroup = GetFontGroupForFrame(firstFrame, fontInflation);
  } else {
    fontInflation = nsLayoutUtils::FontSizeInflationFor(firstFrame);
    fontGroup = GetInflatedFontGroupForFrame(firstFrame);
  }

  if (fontGroup) {
    // Refresh fontgroup if necessary, before trying to build textruns.
    fontGroup->CheckForUpdatedPlatformList();
  } else {
    DestroyUserData(userDataToDestroy);
    return nullptr;
  }

  if (flags2 & nsTextFrameUtils::Flags::HasTab) {
    flags |= gfx::ShapedTextFlags::TEXT_ENABLE_SPACING;
  }
  if (flags2 & nsTextFrameUtils::Flags::HasShy) {
    flags |= gfx::ShapedTextFlags::TEXT_ENABLE_HYPHEN_BREAKS;
  }
  if (mBidiEnabled && (firstFrame->GetEmbeddingLevel().IsRTL())) {
    flags |= gfx::ShapedTextFlags::TEXT_IS_RTL;
  }
  if (mNextRunContextInfo & nsTextFrameUtils::INCOMING_WHITESPACE) {
    flags2 |= nsTextFrameUtils::Flags::TrailingWhitespace;
  }
  if (mNextRunContextInfo & nsTextFrameUtils::INCOMING_ARABICCHAR) {
    flags |= gfx::ShapedTextFlags::TEXT_TRAILING_ARABICCHAR;
  }
  // ContinueTextRunAcrossFrames guarantees that it doesn't matter which
  // frame's style is used, so we use a mixture of the first frame and
  // last frame's style
  flags |= nsLayoutUtils::GetTextRunFlagsForStyle(
      lastComputedStyle, firstFrame->PresContext(), fontStyle, textStyle,
      LetterSpacing(firstFrame, *textStyle));
  // XXX this is a bit of a hack. For performance reasons, if we're favouring
  // performance over quality, don't try to get accurate glyph extents.
  if (!(flags & gfx::ShapedTextFlags::TEXT_OPTIMIZE_SPEED)) {
    flags |= gfx::ShapedTextFlags::TEXT_NEED_BOUNDING_BOX;
  }

  // Convert linebreak coordinates to transformed string offsets
  NS_ASSERTION(nextBreakIndex == mLineBreakBeforeFrames.Length(),
               "Didn't find all the frames to break-before...");
  gfxSkipCharsIterator iter(skipChars);
  AutoTArray<uint32_t, 50> textBreakPointsAfterTransform;
  for (uint32_t i = 0; i < textBreakPoints.Length(); ++i) {
    nsTextFrameUtils::AppendLineBreakOffset(
        &textBreakPointsAfterTransform,
        iter.ConvertOriginalToSkipped(textBreakPoints[i]));
  }
  if (mStartOfLine) {
    nsTextFrameUtils::AppendLineBreakOffset(&textBreakPointsAfterTransform,
                                            transformedLength);
  }

  // Setup factory chain
  bool needsToMaskPassword = NeedsToMaskPassword(firstFrame);
  UniquePtr<nsTransformingTextRunFactory> transformingFactory;
  if (anyTextTransformStyle || needsToMaskPassword) {
    transformingFactory = MakeUnique<nsCaseTransformTextRunFactory>(
        std::move(transformingFactory));
  }
  if (anyMathMLStyling) {
    transformingFactory = MakeUnique<MathMLTextRunFactory>(
        std::move(transformingFactory), mathFlags, sstyScriptLevel,
        fontInflation);
  }
  nsTArray<RefPtr<nsTransformedCharStyle>> styles;
  if (transformingFactory) {
    uint32_t unmaskStart = 0, unmaskEnd = UINT32_MAX;
    if (needsToMaskPassword) {
      unmaskStart = unmaskEnd = UINT32_MAX;
      TextEditor* passwordEditor =
          nsContentUtils::GetTextEditorFromAnonymousNodeWithoutCreation(
              firstFrame->GetContent());
      if (passwordEditor && !passwordEditor->IsAllMasked()) {
        unmaskStart = passwordEditor->UnmaskedStart();
        unmaskEnd = passwordEditor->UnmaskedEnd();
      }
    }

    iter.SetOriginalOffset(0);
    for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
      MappedFlow* mappedFlow = &mMappedFlows[i];
      nsTextFrame* f;
      ComputedStyle* sc = nullptr;
      RefPtr<nsTransformedCharStyle> defaultStyle;
      RefPtr<nsTransformedCharStyle> unmaskStyle;
      for (f = mappedFlow->mStartFrame; f != mappedFlow->mEndFrame;
           f = f->GetNextContinuation()) {
        uint32_t skippedOffset = iter.GetSkippedOffset();
        // Text-combined frames have content-dependent transform, so we
        // want to create new nsTransformedCharStyle for them anyway.
        if (sc != f->Style() || sc->IsTextCombined()) {
          sc = f->Style();
          defaultStyle = new nsTransformedCharStyle(sc, f->PresContext());
          if (sc->IsTextCombined() && f->CountGraphemeClusters() > 1) {
            defaultStyle->mForceNonFullWidth = true;
          }
          if (needsToMaskPassword) {
            defaultStyle->mMaskPassword = true;
            if (unmaskStart != unmaskEnd) {
              unmaskStyle = new nsTransformedCharStyle(sc, f->PresContext());
              unmaskStyle->mForceNonFullWidth =
                  defaultStyle->mForceNonFullWidth;
            }
          }
        }
        iter.AdvanceOriginal(f->GetContentLength());
        uint32_t skippedEnd = iter.GetSkippedOffset();
        if (unmaskStyle) {
          uint32_t skippedUnmaskStart =
              iter.ConvertOriginalToSkipped(unmaskStart);
          uint32_t skippedUnmaskEnd = iter.ConvertOriginalToSkipped(unmaskEnd);
          iter.SetSkippedOffset(skippedEnd);
          for (; skippedOffset < std::min(skippedEnd, skippedUnmaskStart);
               ++skippedOffset) {
            styles.AppendElement(defaultStyle);
          }
          for (; skippedOffset < std::min(skippedEnd, skippedUnmaskEnd);
               ++skippedOffset) {
            styles.AppendElement(unmaskStyle);
          }
          for (; skippedOffset < skippedEnd; ++skippedOffset) {
            styles.AppendElement(defaultStyle);
          }
        } else {
          for (; skippedOffset < skippedEnd; ++skippedOffset) {
            styles.AppendElement(defaultStyle);
          }
        }
      }
    }
    flags2 |= nsTextFrameUtils::Flags::IsTransformed;
    NS_ASSERTION(iter.GetSkippedOffset() == transformedLength,
                 "We didn't cover all the characters in the text run!");
  }

  RefPtr<gfxTextRun> textRun;
  gfxTextRunFactory::Parameters params = {
      mDrawTarget,
      finalUserData,
      &skipChars,
      textBreakPointsAfterTransform.Elements(),
      uint32_t(textBreakPointsAfterTransform.Length()),
      int32_t(firstFrame->PresContext()->AppUnitsPerDevPixel())};

  if (mDoubleByteText) {
    const char16_t* text = static_cast<const char16_t*>(textPtr);
    if (transformingFactory) {
      textRun = transformingFactory->MakeTextRun(
          text, transformedLength, &params, fontGroup, flags, flags2,
          std::move(styles), true);
    } else {
      textRun = fontGroup->MakeTextRun(text, transformedLength, &params, flags,
                                       flags2, mMissingFonts);
    }
  } else {
    const uint8_t* text = static_cast<const uint8_t*>(textPtr);
    flags |= gfx::ShapedTextFlags::TEXT_IS_8BIT;
    if (transformingFactory) {
      textRun = transformingFactory->MakeTextRun(
          text, transformedLength, &params, fontGroup, flags, flags2,
          std::move(styles), true);
    } else {
      textRun = fontGroup->MakeTextRun(text, transformedLength, &params, flags,
                                       flags2, mMissingFonts);
    }
  }
  if (!textRun) {
    DestroyUserData(userDataToDestroy);
    return nullptr;
  }

  // We have to set these up after we've created the textrun, because
  // the breaks may be stored in the textrun during this very call.
  // This is a bit annoying because it requires another loop over the frames
  // making up the textrun, but I don't see a way to avoid this.
  // We have to do this if line-breaking is required OR if a text-transform
  // is in effect, because we depend on the line-breaker's scanner (via
  // BreakSink::Finish) to finish building transformed textruns.
  if (mDoLineBreaking || transformingFactory) {
    SetupBreakSinksForTextRun(textRun.get(), textPtr);
  }

  // Ownership of the factory has passed to the textrun
  // TODO: bug 1285316: clean up ownership transfer from the factory to
  // the textrun
  Unused << transformingFactory.release();

  if (anyTextEmphasis) {
    SetupTextEmphasisForTextRun(textRun.get(), textPtr);
  }

  if (mSkipIncompleteTextRuns) {
    mSkipIncompleteTextRuns = !TextContainsLineBreakerWhiteSpace(
        textPtr, transformedLength, mDoubleByteText);
    // Since we're doing to destroy the user data now, avoid a dangling
    // pointer. Strictly speaking we don't need to do this since it should
    // not be used (since this textrun will not be used and will be
    // itself deleted soon), but it's always better to not have dangling
    // pointers around.
    textRun->SetUserData(nullptr);
    DestroyUserData(userDataToDestroy);
    return nullptr;
  }

  // Actually wipe out the textruns associated with the mapped frames and
  // associate those frames with this text run.
  AssignTextRun(textRun.get(), fontInflation);
  return textRun.forget();
}

// This is a cut-down version of BuildTextRunForFrames used to set up
// context for the line-breaker, when the textrun has already been created.
// So it does the same walk over the mMappedFlows, but doesn't actually
// build a new textrun.
bool BuildTextRunsScanner::SetupLineBreakerContext(gfxTextRun* aTextRun) {
  AutoTArray<uint8_t, BIG_TEXT_NODE_SIZE> buffer;
  uint32_t bufferSize = mMaxTextLength * (mDoubleByteText ? 2 : 1);
  if (bufferSize < mMaxTextLength || bufferSize == UINT32_MAX) {
    return false;
  }
  void* textPtr = buffer.AppendElements(bufferSize, fallible);
  if (!textPtr) {
    return false;
  }

  gfxSkipChars skipChars;

  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
    MappedFlow* mappedFlow = &mMappedFlows[i];
    nsTextFrame* f = mappedFlow->mStartFrame;

    const nsStyleText* textStyle = f->StyleText();
    nsTextFrameUtils::CompressionMode compression =
        GetCSSWhitespaceToCompressionMode(f, textStyle);

    // Figure out what content is included in this flow.
    const nsTextFragment* frag = f->TextFragment();
    int32_t contentStart = mappedFlow->mStartFrame->GetContentOffset();
    int32_t contentEnd = mappedFlow->GetContentEnd();
    int32_t contentLength = contentEnd - contentStart;

    nsTextFrameUtils::Flags analysisFlags;
    if (frag->Is2b()) {
      NS_ASSERTION(mDoubleByteText, "Wrong buffer char size!");
      char16_t* bufStart = static_cast<char16_t*>(textPtr);
      char16_t* bufEnd = nsTextFrameUtils::TransformText(
          frag->Get2b() + contentStart, contentLength, bufStart, compression,
          &mNextRunContextInfo, &skipChars, &analysisFlags);
      textPtr = bufEnd;
    } else {
      if (mDoubleByteText) {
        // Need to expand the text. First transform it into a temporary buffer,
        // then expand.
        AutoTArray<uint8_t, BIG_TEXT_NODE_SIZE> tempBuf;
        uint8_t* bufStart = tempBuf.AppendElements(contentLength, fallible);
        if (!bufStart) {
          return false;
        }
        uint8_t* end = nsTextFrameUtils::TransformText(
            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart,
            contentLength, bufStart, compression, &mNextRunContextInfo,
            &skipChars, &analysisFlags);
        textPtr = ExpandBuffer(static_cast<char16_t*>(textPtr),
                               tempBuf.Elements(), end - tempBuf.Elements());
      } else {
        uint8_t* bufStart = static_cast<uint8_t*>(textPtr);
        uint8_t* end = nsTextFrameUtils::TransformText(
            reinterpret_cast<const uint8_t*>(frag->Get1b()) + contentStart,
            contentLength, bufStart, compression, &mNextRunContextInfo,
            &skipChars, &analysisFlags);
        textPtr = end;
      }
    }
  }

  // We have to set these up after we've created the textrun, because
  // the breaks may be stored in the textrun during this very call.
  // This is a bit annoying because it requires another loop over the frames
  // making up the textrun, but I don't see a way to avoid this.
  SetupBreakSinksForTextRun(aTextRun, buffer.Elements());

  return true;
}

static bool HasCompressedLeadingWhitespace(
    nsTextFrame* aFrame, const nsStyleText* aStyleText,
    int32_t aContentEndOffset, const gfxSkipCharsIterator& aIterator) {
  if (!aIterator.IsOriginalCharSkipped()) {
    return false;
  }

  gfxSkipCharsIterator iter = aIterator;
  int32_t frameContentOffset = aFrame->GetContentOffset();
  const nsTextFragment* frag = aFrame->TextFragment();
  while (frameContentOffset < aContentEndOffset &&
         iter.IsOriginalCharSkipped()) {
    if (IsTrimmableSpace(frag, frameContentOffset, aStyleText)) {
      return true;
    }
    ++frameContentOffset;
    iter.AdvanceOriginal(1);
  }
  return false;
}

void BuildTextRunsScanner::SetupBreakSinksForTextRun(gfxTextRun* aTextRun,
                                                     const void* aTextPtr) {
  using mozilla::intl::LineBreakRule;
  using mozilla::intl::WordBreakRule;

  // textruns have uniform language
  const nsStyleFont* styleFont = mMappedFlows[0].mStartFrame->StyleFont();
  // We should only use a language for hyphenation if it was specified
  // explicitly.
  nsAtom* hyphenationLanguage =
      styleFont->mExplicitLanguage ? styleFont->mLanguage.get() : nullptr;
  // We keep this pointed at the skip-chars data for the current mappedFlow.
  // This lets us cheaply check whether the flow has compressed initial
  // whitespace...
  gfxSkipCharsIterator iter(aTextRun->GetSkipChars());

  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
    MappedFlow* mappedFlow = &mMappedFlows[i];
    // The CSS word-break value may change within a word, so we reset it for
    // each MappedFlow. The line-breaker will flush its text if the property
    // actually changes.
    const auto* styleText = mappedFlow->mStartFrame->StyleText();
    auto wordBreak = styleText->EffectiveWordBreak();
    switch (wordBreak) {
      case StyleWordBreak::BreakAll:
        mLineBreaker.SetWordBreak(WordBreakRule::BreakAll);
        break;
      case StyleWordBreak::KeepAll:
        mLineBreaker.SetWordBreak(WordBreakRule::KeepAll);
        break;
      case StyleWordBreak::Normal:
      default:
        MOZ_ASSERT(wordBreak == StyleWordBreak::Normal);
        mLineBreaker.SetWordBreak(WordBreakRule::Normal);
        break;
    }
    switch (styleText->mLineBreak) {
      case StyleLineBreak::Auto:
        mLineBreaker.SetStrictness(LineBreakRule::Auto);
        break;
      case StyleLineBreak::Normal:
        mLineBreaker.SetStrictness(LineBreakRule::Normal);
        break;
      case StyleLineBreak::Loose:
        mLineBreaker.SetStrictness(LineBreakRule::Loose);
        break;
      case StyleLineBreak::Strict:
        mLineBreaker.SetStrictness(LineBreakRule::Strict);
        break;
      case StyleLineBreak::Anywhere:
        mLineBreaker.SetStrictness(LineBreakRule::Anywhere);
        break;
    }

    uint32_t offset = iter.GetSkippedOffset();
    gfxSkipCharsIterator iterNext = iter;
    iterNext.AdvanceOriginal(mappedFlow->GetContentEnd() -
                             mappedFlow->mStartFrame->GetContentOffset());

    UniquePtr<BreakSink>* breakSink = mBreakSinks.AppendElement(
        MakeUnique<BreakSink>(aTextRun, mDrawTarget, offset));

    uint32_t length = iterNext.GetSkippedOffset() - offset;
    uint32_t flags = 0;
    nsIFrame* initialBreakController =
        mappedFlow->mAncestorControllingInitialBreak;
    if (!initialBreakController) {
      initialBreakController = mLineContainer;
    }
    if (!initialBreakController->StyleText()->WhiteSpaceCanWrap(
            initialBreakController)) {
      flags |= nsLineBreaker::BREAK_SUPPRESS_INITIAL;
    }
    nsTextFrame* startFrame = mappedFlow->mStartFrame;
    const nsStyleText* textStyle = startFrame->StyleText();
    if (!textStyle->WhiteSpaceCanWrap(startFrame)) {
      flags |= nsLineBreaker::BREAK_SUPPRESS_INSIDE;
    }
    if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::NoBreaks) {
      flags |= nsLineBreaker::BREAK_SKIP_SETTING_NO_BREAKS;
    }
    if (textStyle->mTextTransform.case_ == StyleTextTransformCase::Capitalize) {
      flags |= nsLineBreaker::BREAK_NEED_CAPITALIZATION;
    }
    if (textStyle->mHyphens == StyleHyphens::Auto &&
        textStyle->mLineBreak != StyleLineBreak::Anywhere) {
      flags |= nsLineBreaker::BREAK_USE_AUTO_HYPHENATION;
    }

    if (HasCompressedLeadingWhitespace(startFrame, textStyle,
                                       mappedFlow->GetContentEnd(), iter)) {
      mLineBreaker.AppendInvisibleWhitespace(flags);
    }

    if (length > 0) {
      BreakSink* sink = mSkipIncompleteTextRuns ? nullptr : (*breakSink).get();
      if (mDoubleByteText) {
        const char16_t* text = reinterpret_cast<const char16_t*>(aTextPtr);
        mLineBreaker.AppendText(hyphenationLanguage, text + offset, length,
                                flags, sink);
      } else {
        const uint8_t* text = reinterpret_cast<const uint8_t*>(aTextPtr);
        mLineBreaker.AppendText(hyphenationLanguage, text + offset, length,
                                flags, sink);
      }
    }

    iter = iterNext;
  }
}

static bool MayCharacterHaveEmphasisMark(uint32_t aCh) {
  auto category = unicode::GetGeneralCategory(aCh);
  // Comparing an unsigned variable against zero is a compile error,
  // so we use static assert here to ensure we really don't need to
  // compare it with the given constant.
  static_assert(std::is_unsigned_v<decltype(category)> &&
                    HB_UNICODE_GENERAL_CATEGORY_CONTROL == 0,
                "if this constant is not zero, or category is signed, "
                "we need to explicitly do the comparison below");
  return !(category <= HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED ||
           (category >= HB_UNICODE_GENERAL_CATEGORY_LINE_SEPARATOR &&
            category <= HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR));
}

static bool MayCharacterHaveEmphasisMark(uint8_t aCh) {
  // 0x00~0x1f and 0x7f~0x9f are in category Cc
  // 0x20 and 0xa0 are in category Zs
  bool result = !(aCh <= 0x20 || (aCh >= 0x7f && aCh <= 0xa0));
  MOZ_ASSERT(result == MayCharacterHaveEmphasisMark(uint32_t(aCh)),
             "result for uint8_t should match result for uint32_t");
  return result;
}

void BuildTextRunsScanner::SetupTextEmphasisForTextRun(gfxTextRun* aTextRun,
                                                       const void* aTextPtr) {
  if (!mDoubleByteText) {
    auto text = reinterpret_cast<const uint8_t*>(aTextPtr);
    for (auto i : IntegerRange(aTextRun->GetLength())) {
      if (!MayCharacterHaveEmphasisMark(text[i])) {
        aTextRun->SetNoEmphasisMark(i);
      }
    }
  } else {
    auto text = reinterpret_cast<const char16_t*>(aTextPtr);
    auto length = aTextRun->GetLength();
    for (size_t i = 0; i < length; ++i) {
      if (i + 1 < length && NS_IS_SURROGATE_PAIR(text[i], text[i + 1])) {
        uint32_t ch = SURROGATE_TO_UCS4(text[i], text[i + 1]);
        if (!MayCharacterHaveEmphasisMark(ch)) {
          aTextRun->SetNoEmphasisMark(i);
          aTextRun->SetNoEmphasisMark(i + 1);
        }
        ++i;
      } else {
        if (!MayCharacterHaveEmphasisMark(uint32_t(text[i]))) {
          aTextRun->SetNoEmphasisMark(i);
        }
      }
    }
  }
}

// Find the flow corresponding to aContent in aUserData
static inline TextRunMappedFlow* FindFlowForContent(
    TextRunUserData* aUserData, nsIContent* aContent,
    TextRunMappedFlow* userMappedFlows) {
  // Find the flow that contains us
  int32_t i = aUserData->mLastFlowIndex;
  int32_t delta = 1;
  int32_t sign = 1;
  // Search starting at the current position and examine close-by
  // positions first, moving further and further away as we go.
  while (i >= 0 && uint32_t(i) < aUserData->mMappedFlowCount) {
    TextRunMappedFlow* flow = &userMappedFlows[i];
    if (flow->mStartFrame->GetContent() == aContent) {
      return flow;
    }

    i += delta;
    sign = -sign;
    delta = -delta + sign;
  }

  // We ran into an array edge.  Add |delta| to |i| once more to get
  // back to the side where we still need to search, then step in
  // the |sign| direction.
  i += delta;
  if (sign > 0) {
    for (; i < int32_t(aUserData->mMappedFlowCount); ++i) {
      TextRunMappedFlow* flow = &userMappedFlows[i];
      if (flow->mStartFrame->GetContent() == aContent) {
        return flow;
      }
    }
  } else {
    for (; i >= 0; --i) {
      TextRunMappedFlow* flow = &userMappedFlows[i];
      if (flow->mStartFrame->GetContent() == aContent) {
        return flow;
      }
    }
  }

  return nullptr;
}

void BuildTextRunsScanner::AssignTextRun(gfxTextRun* aTextRun,
                                         float aInflation) {
  for (uint32_t i = 0; i < mMappedFlows.Length(); ++i) {
    MappedFlow* mappedFlow = &mMappedFlows[i];
    nsTextFrame* startFrame = mappedFlow->mStartFrame;
    nsTextFrame* endFrame = mappedFlow->mEndFrame;
    nsTextFrame* f;
    for (f = startFrame; f != endFrame; f = f->GetNextContinuation()) {
#ifdef DEBUG_roc
      if (f->GetTextRun(mWhichTextRun)) {
        gfxTextRun* textRun = f->GetTextRun(mWhichTextRun);
        if (textRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
          if (mMappedFlows[0].mStartFrame != GetFrameForSimpleFlow(textRun)) {
            NS_WARNING("REASSIGNING SIMPLE FLOW TEXT RUN!");
          }
        } else {
          auto userData =
              static_cast<TextRunUserData*>(aTextRun->GetUserData());
          TextRunMappedFlow* userMappedFlows = GetMappedFlows(aTextRun);
          if (userData->mMappedFlowCount >= mMappedFlows.Length() ||
              userMappedFlows[userData->mMappedFlowCount - 1].mStartFrame !=
                  mMappedFlows[userdata->mMappedFlowCount - 1].mStartFrame) {
            NS_WARNING("REASSIGNING MULTIFLOW TEXT RUN (not append)!");
          }
        }
      }
#endif

      gfxTextRun* oldTextRun = f->GetTextRun(mWhichTextRun);
      if (oldTextRun) {
        nsTextFrame* firstFrame = nullptr;
        uint32_t startOffset = 0;
        if (oldTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
          firstFrame = GetFrameForSimpleFlow(oldTextRun);
        } else {
          auto userData =
              static_cast<TextRunUserData*>(oldTextRun->GetUserData());
          TextRunMappedFlow* userMappedFlows = GetMappedFlows(oldTextRun);
          firstFrame = userMappedFlows[0].mStartFrame;
          if (MOZ_UNLIKELY(f != firstFrame)) {
            TextRunMappedFlow* flow =
                FindFlowForContent(userData, f->GetContent(), userMappedFlows);
            if (flow) {
              startOffset = flow->mDOMOffsetToBeforeTransformOffset;
            } else {
              NS_ERROR("Can't find flow containing frame 'f'");
            }
          }
        }

        // Optimization: if |f| is the first frame in the flow then there are no
        // prev-continuations that use |oldTextRun|.
        nsTextFrame* clearFrom = nullptr;
        if (MOZ_UNLIKELY(f != firstFrame)) {
          // If all the frames in the mapped flow starting at |f| (inclusive)
          // are empty then we let the prev-continuations keep the old text run.
          gfxSkipCharsIterator iter(oldTextRun->GetSkipChars(), startOffset,
                                    f->GetContentOffset());
          uint32_t textRunOffset =
              iter.ConvertOriginalToSkipped(f->GetContentOffset());
          clearFrom = textRunOffset == oldTextRun->GetLength() ? f : nullptr;
        }
        f->ClearTextRun(clearFrom, mWhichTextRun);

#ifdef DEBUG
        if (firstFrame && !firstFrame->GetTextRun(mWhichTextRun)) {
          // oldTextRun was destroyed - assert that we don't reference it.
          for (uint32_t j = 0; j < mBreakSinks.Length(); ++j) {
            NS_ASSERTION(oldTextRun != mBreakSinks[j]->mTextRun,
                         "destroyed text run is still in use");
          }
        }
#endif
      }
      f->SetTextRun(aTextRun, mWhichTextRun, aInflation);
    }
    // Set this bit now; we can't set it any earlier because
    // f->ClearTextRun() might clear it out.
    nsFrameState whichTextRunState =
        startFrame->GetTextRun(nsTextFrame::eInflated) == aTextRun
            ? TEXT_IN_TEXTRUN_USER_DATA
            : TEXT_IN_UNINFLATED_TEXTRUN_USER_DATA;
    startFrame->AddStateBits(whichTextRunState);
  }
}

NS_QUERYFRAME_HEAD(nsTextFrame)
  NS_QUERYFRAME_ENTRY(nsTextFrame)
NS_QUERYFRAME_TAIL_INHERITING(nsIFrame)

gfxSkipCharsIterator nsTextFrame::EnsureTextRun(
    TextRunType aWhichTextRun, DrawTarget* aRefDrawTarget,
    nsIFrame* aLineContainer, const nsLineList::iterator* aLine,
    uint32_t* aFlowEndInTextRun) {
  gfxTextRun* textRun = GetTextRun(aWhichTextRun);
  if (!textRun || (aLine && (*aLine)->GetInvalidateTextRuns())) {
    RefPtr<DrawTarget> refDT = aRefDrawTarget;
    if (!refDT) {
      refDT = CreateReferenceDrawTarget(this);
    }
    if (refDT) {
      BuildTextRuns(refDT, this, aLineContainer, aLine, aWhichTextRun);
    }
    textRun = GetTextRun(aWhichTextRun);
    if (!textRun) {
      // A text run was not constructed for this frame. This is bad. The caller
      // will check mTextRun.
      return gfxSkipCharsIterator(gfxPlatform::GetPlatform()->EmptySkipChars(),
                                  0);
    }
    TabWidthStore* tabWidths = GetProperty(TabWidthProperty());
    if (tabWidths && tabWidths->mValidForContentOffset != GetContentOffset()) {
      RemoveProperty(TabWidthProperty());
    }
  }

  if (textRun->GetFlags2() & nsTextFrameUtils::Flags::IsSimpleFlow) {
    if (aFlowEndInTextRun) {
      *aFlowEndInTextRun = textRun->GetLength();
    }
    return gfxSkipCharsIterator(textRun->GetSkipChars(), 0, mContentOffset);
  }

  auto userData = static_cast<TextRunUserData*>(textRun->GetUserData());
  TextRunMappedFlow* userMappedFlows = GetMappedFlows(textRun);
  TextRunMappedFlow* flow =
      FindFlowForContent(userData, mContent, userMappedFlows);
  if (flow) {
    // Since textruns can only contain one flow for a given content element,
    // this must be our flow.
    uint32_t flowIndex = flow - userMappedFlows;
    userData->mLastFlowIndex = flowIndex;
    gfxSkipCharsIterator iter(textRun->GetSkipChars(),
                              flow->mDOMOffsetToBeforeTransformOffset,
                              mContentOffset);
    if (aFlowEndInTextRun) {
      if (flowIndex + 1 < userData->mMappedFlowCount) {
        gfxSkipCharsIterator end(textRun->GetSkipChars());
        *aFlowEndInTextRun = end.ConvertOriginalToSkipped(
            flow[1].mStartFrame->GetContentOffset() +
            flow[1].mDOMOffsetToBeforeTransformOffset);
      } else {
        *aFlowEndInTextRun = textRun->GetLength();
      }
    }
    return iter;
  }

  NS_ERROR("Can't find flow containing this frame???");
  return gfxSkipCharsIterator(gfxPlatform::GetPlatform()->EmptySkipChars(), 0);
}

static uint32_t GetEndOfTrimmedText(const nsTextFragment* aFrag,
                                    const nsStyleText* aStyleText,
                                    uint32_t aStart, uint32_t aEnd,
                                    gfxSkipCharsIterator* aIterator,
                                    bool aAllowHangingWS = false) {
  aIterator->SetSkippedOffset(aEnd);
  while (aIterator->GetSkippedOffset() > aStart) {
    aIterator->AdvanceSkipped(-1);
    if (!IsTrimmableSpace(aFrag, aIterator->GetOriginalOffset(), aStyleText,
                          aAllowHangingWS))
      return aIterator->GetSkippedOffset() + 1;
  }
  return aStart;
}

nsTextFrame::TrimmedOffsets nsTextFrame::GetTrimmedOffsets(
    const nsTextFragment* aFrag, TrimmedOffsetFlags aFlags) const {
  NS_ASSERTION(mTextRun, "Need textrun here");
  if (!(aFlags & TrimmedOffsetFlags::NotPostReflow)) {
    // This should not be used during reflow. We need our TEXT_REFLOW_FLAGS
    // to be set correctly.  If our parent wasn't reflowed due to the frame
    // tree being too deep then the return value doesn't matter.
    NS_ASSERTION(
        !HasAnyStateBits(NS_FRAME_FIRST_REFLOW) ||
            GetParent()->HasAnyStateBits(NS_FRAME_TOO_DEEP_IN_FRAME_TREE),
        "Can only call this on frames that have been reflowed");
    NS_ASSERTION(!HasAnyStateBits(NS_FRAME_IN_REFLOW),
                 "Can only call this on frames that are not being reflowed");
  }

  TrimmedOffsets offsets = {GetContentOffset(), GetContentLength()};
  const nsStyleText* textStyle = StyleText();
  // Note that pre-line newlines should still allow us to trim spaces
  // for display
  if (textStyle->WhiteSpaceIsSignificant()) {
    return offsets;
  }

  if (!(aFlags & TrimmedOffsetFlags::NoTrimBefore) &&
      ((aFlags & TrimmedOffsetFlags::NotPostReflow) ||
       HasAnyStateBits(TEXT_START_OF_LINE))) {
    int32_t whitespaceCount =
        GetTrimmableWhitespaceCount(aFrag, offsets.mStart, offsets.mLength, 1);
    offsets.mStart += whitespaceCount;
    offsets.mLength -= whitespaceCount;
  }

  if (!(aFlags & TrimmedOffsetFlags::NoTrimAfter) &&
      ((aFlags & TrimmedOffsetFlags::NotPostReflow) ||
       HasAnyStateBits(TEXT_END_OF_LINE))) {
    // This treats a trailing 'pre-line' newline as trimmable. That's fine,
    // it's actually what we want since we want whitespace before it to
    // be trimmed.
    int32_t whitespaceCount = GetTrimmableWhitespaceCount(
        aFrag, offsets.GetEnd() - 1, offsets.mLength, -1);
    offsets.mLength -= whitespaceCount;
  }
  return offsets;
}

static bool IsJustifiableCharacter(const nsStyleText* aTextStyle,
                                   const nsTextFragment* aFrag, int32_t aPos,
                                   bool aLangIsCJ) {
  NS_ASSERTION(aPos >= 0, "negative position?!");

  StyleTextJustify justifyStyle = aTextStyle->mTextJustify;
  if (justifyStyle == StyleTextJustify::None) {
    return false;
  }

  const char16_t ch = aFrag->CharAt(AssertedCast<uint32_t>(aPos));
  if (ch == '\n' || ch == '\t' || ch == '\r') {
    return true;
  }
  if (ch == ' ' || ch == CH_NBSP) {
    // Don't justify spaces that are combined with diacriticals
    if (!aFrag->Is2b()) {
      return true;
    }
    return !nsTextFrameUtils::IsSpaceCombiningSequenceTail(
        aFrag->Get2b() + aPos + 1, aFrag->GetLength() - (aPos + 1));
  }

  if (justifyStyle == StyleTextJustify::InterCharacter) {
    return true;
  } else if (justifyStyle == StyleTextJustify::InterWord) {
    return false;
  }

  // text-justify: auto
  if (ch < 0x2150u) {
    return false;
  }
  if (aLangIsCJ) {
    if (  // Number Forms, Arrows, Mathematical Operators
        (0x2150u <= ch && ch <= 0x22ffu) ||
        // Enclosed Alphanumerics
        (0x2460u <= ch && ch <= 0x24ffu) ||
        // Block Elements, Geometric Shapes, Miscellaneous Symbols, Dingbats
        (0x2580u <= ch && ch <= 0x27bfu) ||
        // Supplemental Arrows-A, Braille Patterns, Supplemental Arrows-B,
        // Miscellaneous Mathematical Symbols-B,
        // Supplemental Mathematical Operators, Miscellaneous Symbols and Arrows
        (0x27f0u <= ch && ch <= 0x2bffu) ||
        // CJK Radicals Supplement, CJK Radicals Supplement, Ideographic
        // Description Characters, CJK Symbols and Punctuation, Hiragana,
        // Katakana, Bopomofo
        (0x2e80u <= ch && ch <= 0x312fu) ||
        // Kanbun, Bopomofo Extended, Katakana Phonetic Extensions,
        // Enclosed CJK Letters and Months, CJK Compatibility,
        // CJK Unified Ideographs Extension A, Yijing Hexagram Symbols,
        // CJK Unified Ideographs, Yi Syllables, Yi Radicals
        (0x3190u <= ch && ch <= 0xabffu) ||
        // CJK Compatibility Ideographs
        (0xf900u <= ch && ch <= 0xfaffu) ||
        // Halfwidth and Fullwidth Forms (a part)
        (0xff5eu <= ch && ch <= 0xff9fu)) {
      return true;
    }
    if (NS_IS_HIGH_SURROGATE(ch)) {
      if (char32_t u = aFrag->ScalarValueAt(AssertedCast<uint32_t>(aPos))) {
        // CJK Unified Ideographs Extension B,
        // CJK Unified Ideographs Extension C,
        // CJK Unified Ideographs Extension D,
        // CJK Compatibility Ideographs Supplement
        if (0x20000u <= u && u <= 0x2ffffu) {
          return true;
        }
      }
    }
  }
  return false;
}

void nsTextFrame::ClearMetrics(ReflowOutput& aMetrics) {
  aMetrics.ClearSize();
  aMetrics.SetBlockStartAscent(0);
  mAscent = 0;

  AddStateBits(TEXT_NO_RENDERED_GLYPHS);
}

static int32_t FindChar(const nsTextFragment* frag, int32_t aOffset,
                        int32_t aLength, char16_t ch) {
  int32_t i = 0;
  if (frag->Is2b()) {
    const char16_t* str = frag->Get2b() + aOffset;
    for (; i < aLength; ++i) {
      if (*str == ch) {
        return i + aOffset;
      }
      ++str;
    }
  } else {
    if (uint16_t(ch) <= 0xFF) {
      const char* str = frag->Get1b() + aOffset;
      const void* p = memchr(str, ch, aLength);
      if (p) {
        return (static_cast<const char*>(p) - str) + aOffset;
      }
    }
  }
  return -1;
}

static bool IsChineseOrJapanese(const nsTextFrame* aFrame) {
  if (aFrame->ShouldSuppressLineBreak()) {
    // Always treat ruby as CJ language so that those characters can
    // be expanded properly even when surrounded by other language.
    return true;
  }

  nsAtom* language = aFrame->StyleFont()->mLanguage;
  if (!language) {
    return false;
  }
  return nsStyleUtil::MatchesLanguagePrefix(language, u"ja") ||
         nsStyleUtil::MatchesLanguagePrefix(language, u"zh");
}

#ifdef DEBUG
static bool IsInBounds(const gfxSkipCharsIterator& aStart,
                       int32_t aContentLength, gfxTextRun::Range aRange) {
  if (aStart.GetSkippedOffset() > aRange.start) {
    return false;
  }
  if (aContentLength == INT32_MAX) {
    return true;
  }
  gfxSkipCharsIterator iter(aStart);
  iter.AdvanceOriginal(aContentLength);
  return iter.GetSkippedOffset() >= aRange.end;
}
#endif

nsTextFrame::PropertyProvider::PropertyProvider(
    gfxTextRun* aTextRun, const nsStyleText* aTextStyle,
    const nsTextFragment* aFrag, nsTextFrame* aFrame,
    const gfxSkipCharsIterator& aStart, int32_t aLength,
    nsIFrame* aLineContainer, nscoord aOffsetFromBlockOriginForTabs,
    nsTextFrame::TextRunType aWhichTextRun)
    : mTextRun(aTextRun),
      mFontGroup(nullptr),
      mTextStyle(aTextStyle),
      mFrag(aFrag),
      mLineContainer(aLineContainer),
      mFrame(aFrame),
      mStart(aStart),
      mTempIterator(aStart),
      mTabWidths(nullptr),
      mTabWidthsAnalyzedLimit(0),
      mLength(aLength),
      mWordSpacing(WordSpacing(aFrame, mTextRun, *aTextStyle)),
      mLetterSpacing(LetterSpacing(aFrame, *aTextStyle)),
      mMinTabAdvance(-1.0),
      mHyphenWidth(-1),
      mOffsetFromBlockOriginForTabs(aOffsetFromBlockOriginForTabs),
      mJustificationArrayStart(0),
      mReflowing(true),
      mWhichTextRun(aWhichTextRun) {
  NS_ASSERTION(mStart.IsInitialized(), "Start not initialized?");
}

nsTextFrame::PropertyProvider::PropertyProvider(
    nsTextFrame* aFrame, const gfxSkipCharsIterator& aStart,
    nsTextFrame::TextRunType aWhichTextRun, nsFontMetrics* aFontMetrics)
    : mTextRun(aFrame->GetTextRun(aWhichTextRun)),
      mFontGroup(nullptr),
      mFontMetrics(aFontMetrics),
      mTextStyle(aFrame->StyleText()),
      mFrag(aFrame->TextFragment()),
      mLineContainer(nullptr),
      mFrame(aFrame),
      mStart(aStart),
      mTempIterator(aStart),
      mTabWidths(nullptr),
      mTabWidthsAnalyzedLimit(0),
      mLength(aFrame->GetContentLength()),
      mWordSpacing(WordSpacing(aFrame, mTextRun, *mTextStyle)),
      mLetterSpacing(LetterSpacing(aFrame, *mTextStyle)),
      mMinTabAdvance(-1.0),
      mHyphenWidth(-1),
      mOffsetFromBlockOriginForTabs(0),
      mJustificationArrayStart(0),
      mReflowing(false),
      mWhichTextRun(aWhichTextRun) {
  NS_ASSERTION(mTextRun, "Textrun not initialized!");
}

gfx::ShapedTextFlags nsTextFrame::PropertyProvider::GetShapedTextFlags() const {
  return nsLayoutUtils::GetTextRunOrientFlagsForStyle(mFrame->Style());
}

already_AddRefed<DrawTarget> nsTextFrame::PropertyProvider::GetDrawTarget()
    const {
  return CreateReferenceDrawTarget(GetFrame());
}

gfxFloat nsTextFrame::PropertyProvider::MinTabAdvance() const {
  if (mMinTabAdvance < 0.0) {
    mMinTabAdvance = GetMinTabAdvanceAppUnits(mTextRun);
  }
  return mMinTabAdvance;
}

/**
 * Finds the offset of the first character of the cluster containing aPos
 */
static void FindClusterStart(const gfxTextRun* aTextRun, int32_t aOriginalStart,
                             gfxSkipCharsIterator* aPos) {
  while (aPos->GetOriginalOffset() > aOriginalStart) {
    if (aPos->IsOriginalCharSkipped() ||
        aTextRun->IsClusterStart(aPos->GetSkippedOffset())) {
      break;
    }
    aPos->AdvanceOriginal(-1);
  }
}

/**
 * Finds the offset of the last character of the cluster containing aPos.
 * If aAllowSplitLigature is false, we also check for a ligature-group
 * start.
 */
static void FindClusterEnd(const gfxTextRun* aTextRun, int32_t aOriginalEnd,
                           gfxSkipCharsIterator* aPos,
                           bool aAllowSplitLigature = true) {
  MOZ_ASSERT(aPos->GetOriginalOffset() < aOriginalEnd,
             "character outside string");

  aPos->AdvanceOriginal(1);
  while (aPos->GetOriginalOffset() < aOriginalEnd) {
    if (aPos->IsOriginalCharSkipped() ||
        (aTextRun->IsClusterStart(aPos->GetSkippedOffset()) &&
         (aAllowSplitLigature ||
          aTextRun->IsLigatureGroupStart(aPos->GetSkippedOffset())))) {
      break;
    }
    aPos->AdvanceOriginal(1);
  }
  aPos->AdvanceOriginal(-1);
}

JustificationInfo nsTextFrame::PropertyProvider::ComputeJustification(
    Range aRange, nsTArray<JustificationAssignment>* aAssignments) {
  JustificationInfo info;

  // Horizontal-in-vertical frame is orthogonal to the line, so it
  // doesn't actually include any justification opportunity inside.
  // The spec says such frame should be treated as a U+FFFC. Since we
  // do not insert justification opportunities on the sides of that
  // character, the sides of this frame are not justifiable either.
  if (mFrame->Style()->IsTextCombined()) {
    return info;
  }

  bool isCJ = IsChineseOrJapanese(mFrame);
  nsSkipCharsRunIterator run(
      mStart, nsSkipCharsRunIterator::LENGTH_INCLUDES_SKIPPED, aRange.Length());
  run.SetOriginalOffset(aRange.start);
  mJustificationArrayStart = run.GetSkippedOffset();

  nsTArray<JustificationAssignment> assignments;
  assignments.SetCapacity(aRange.Length());
  while (run.NextRun()) {
    uint32_t originalOffset = run.GetOriginalOffset();
    uint32_t skippedOffset = run.GetSkippedOffset();
    uint32_t length = run.GetRunLength();
    assignments.SetLength(skippedOffset + length - mJustificationArrayStart);

    gfxSkipCharsIterator iter = run.GetPos();
    for (uint32_t i = 0; i < length; ++i) {
      uint32_t offset = originalOffset + i;
      if (!IsJustifiableCharacter(mTextStyle, mFrag, offset, isCJ)) {
        continue;
      }

      iter.SetOriginalOffset(offset);

      FindClusterStart(mTextRun, originalOffset, &iter);
      uint32_t firstCharOffset = iter.GetSkippedOffset();
      uint32_t firstChar = firstCharOffset > mJustificationArrayStart
                               ? firstCharOffset - mJustificationArrayStart
                               : 0;
      if (!firstChar) {
        info.mIsStartJustifiable = true;
      } else {
        auto& assign = assignments[firstChar];
        auto& prevAssign = assignments[firstChar - 1];
        if (prevAssign.mGapsAtEnd) {
          prevAssign.mGapsAtEnd = 1;
          assign.mGapsAtStart = 1;
        } else {
          assign.mGapsAtStart = 2;
          info.mInnerOpportunities++;
        }
      }

      FindClusterEnd(mTextRun, originalOffset + length, &iter);
      uint32_t lastChar = iter.GetSkippedOffset() - mJustificationArrayStart;
      // Assign the two gaps temporary to the last char. If the next cluster is
      // justifiable as well, one of the gaps will be removed by code above.
      assignments[lastChar].mGapsAtEnd = 2;
      info.mInnerOpportunities++;

      // Skip the whole cluster
      i = iter.GetOriginalOffset() - originalOffset;
    }
  }

  if (!assignments.IsEmpty() && assignments.LastElement().mGapsAtEnd) {
    // We counted the expansion opportunity after the last character,
    // but it is not an inner opportunity.
    MOZ_ASSERT(info.mInnerOpportunities > 0);
    info.mInnerOpportunities--;
    info.mIsEndJustifiable = true;
  }

  if (aAssignments) {
    *aAssignments = std::move(assignments);
  }
  return info;
}

// aStart, aLength in transformed string offsets
void nsTextFrame::PropertyProvider::GetSpacing(Range aRange,
                                               Spacing* aSpacing) const {
  GetSpacingInternal(
      aRange, aSpacing,
      !(mTextRun->GetFlags2() & nsTextFrameUtils::Flags::HasTab));
}

static bool CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset,
                               bool aNewlineIsSignificant) {
  if (aOffset + 1 >= aTextRun->GetLength()) {
    return true;
  }
  const auto* g = aTextRun->GetCharacterGlyphs();
  return g[aOffset + 1].IsClusterStart() &&
         g[aOffset + 1].IsLigatureGroupStart() &&
         !g[aOffset].CharIsFormattingControl() && !g[aOffset].CharIsTab() &&
         !(aNewlineIsSignificant && g[aOffset].CharIsNewline());
}

static gfxFloat ComputeTabWidthAppUnits(const nsIFrame* aFrame) {
  const auto& tabSize = aFrame->StyleText()->mTabSize;
  if (tabSize.IsLength()) {
    nscoord w = tabSize.length._0.ToAppUnits();
    MOZ_ASSERT(w >= 0);
    return w;
  }

  MOZ_ASSERT(tabSize.IsNumber());
  gfxFloat spaces = tabSize.number._0;
  MOZ_ASSERT(spaces >= 0);

  const nsIFrame* cb = aFrame->GetContainingBlock(0, aFrame->StyleDisplay());
  const auto* styleText = cb->StyleText();

  // Round the space width when converting to appunits the same way textruns do.
  RefPtr<nsFontMetrics> fm = nsLayoutUtils::GetFontMetricsForFrame(cb, 1.0f);
  bool vertical = cb->GetWritingMode().IsCentralBaseline();
  nscoord spaceWidth = nscoord(NS_round(
      GetFirstFontMetrics(fm->GetThebesFontGroup(), vertical).spaceWidth *
      cb->PresContext()->AppUnitsPerDevPixel()));
  return spaces * (spaceWidth + styleText->mLetterSpacing.ToAppUnits() +
                   styleText->mWordSpacing.Resolve(spaceWidth));
}

void nsTextFrame::PropertyProvider::GetSpacingInternal(Range aRange,
                                                       Spacing* aSpacing,
                                                       bool aIgnoreTabs) const {
  MOZ_ASSERT(IsInBounds(mStart, mLength, aRange), "Range out of bounds");

  uint32_t index;
  for (index = 0; index < aRange.Length(); ++index) {
    aSpacing[index].mBefore = 0.0;
    aSpacing[index].mAfter = 0.0;
  }

  if (mFrame->Style()->IsTextCombined()) {
    return;
  }

  // Find our offset into the original+transformed string
  gfxSkipCharsIterator start(mStart);
  start.SetSkippedOffset(aRange.start);

  // First, compute the word and letter spacing
  if (mWordSpacing || mLetterSpacing) {
    // Iterate over non-skipped characters
    nsSkipCharsRunIterator run(
        start, nsSkipCharsRunIterator::LENGTH_UNSKIPPED_ONLY, aRange.Length());
    bool newlineIsSignificant = mTextStyle->NewlineIsSignificant(mFrame);
    while (run.NextRun()) {
      uint32_t runOffsetInSubstring = run.GetSkippedOffset() - aRange.start;
      gfxSkipCharsIterator iter = run.GetPos();
      for (int32_t i = 0; i < run.GetRunLength(); ++i) {
        if (CanAddSpacingAfter(mTextRun, run.GetSkippedOffset() + i,
                               newlineIsSignificant)) {
          // End of a cluster, not in a ligature: put letter-spacing after it
          aSpacing[runOffsetInSubstring + i].mAfter += mLetterSpacing;
        }
        if (IsCSSWordSpacingSpace(mFrag, i + run.GetOriginalOffset(), mFrame,
                                  mTextStyle)) {
          // It kinda sucks, but space characters can be part of clusters,
          // and even still be whitespace (I think!)
          iter.SetSkippedOffset(run.GetSkippedOffset() + i);
          FindClusterEnd(mTextRun, run.GetOriginalOffset() + run.GetRunLength(),
                         &iter);
          uint32_t runOffset = iter.GetSkippedOffset() - aRange.start;
          aSpacing[runOffset].mAfter += mWordSpacing;
        }
      }
    }
  }

  // Now add tab spacing, if there is any
  if (!aIgnoreTabs) {
    gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame);
    if (tabWidth > 0) {
      CalcTabWidths(aRange, tabWidth);
      if (mTabWidths) {
        mTabWidths->ApplySpacing(aSpacing,
                                 aRange.start - mStart.GetSkippedOffset(),
                                 aRange.Length());
      }
    }
  }

  // Now add in justification spacing
  if (mJustificationSpacings.Length() > 0) {
    // If there is any spaces trimmed at the end, aStart + aLength may
    // be larger than the flags array. When that happens, we can simply
    // ignore those spaces.
    auto arrayEnd = mJustificationArrayStart +
                    static_cast<uint32_t>(mJustificationSpacings.Length());
    auto end = std::min(aRange.end, arrayEnd);
    MOZ_ASSERT(aRange.start >= mJustificationArrayStart);
    for (auto i = aRange.start; i < end; i++) {
      const auto& spacing =
          mJustificationSpacings[i - mJustificationArrayStart];
      uint32_t offset = i - aRange.start;
      aSpacing[offset].mBefore += spacing.mBefore;
      aSpacing[offset].mAfter += spacing.mAfter;
    }
  }
}

// aX and the result are in whole appunits.
static gfxFloat AdvanceToNextTab(gfxFloat aX, gfxFloat aTabWidth,
                                 gfxFloat aMinAdvance) {
  // Advance aX to the next multiple of aTabWidth. We must advance
  // by at least aMinAdvance.
  gfxFloat nextPos = aX + aMinAdvance;
  return aTabWidth > 0.0 ? ceil(nextPos / aTabWidth) * aTabWidth : nextPos;
}

void nsTextFrame::PropertyProvider::CalcTabWidths(Range aRange,
                                                  gfxFloat aTabWidth) const {
  MOZ_ASSERT(aTabWidth > 0);

  if (!mTabWidths) {
    if (mReflowing && !mLineContainer) {
      // Intrinsic width computation does its own tab processing. We
      // just don't do anything here.
      return;
    }
    if (!mReflowing) {
      mTabWidths = mFrame->GetProperty(TabWidthProperty());
#ifdef DEBUG
      // If we're not reflowing, we should have already computed the
      // tab widths; check that they're available as far as the last
      // tab character present (if any)
      for (uint32_t i = aRange.end; i > aRange.start; --i) {
        if (mTextRun->CharIsTab(i - 1)) {
          uint32_t startOffset = mStart.GetSkippedOffset();
          NS_ASSERTION(mTabWidths && mTabWidths->mLimit + startOffset >= i,
                       "Precomputed tab widths are missing!");
          break;
        }
      }
#endif
      return;
    }
  }

  uint32_t startOffset = mStart.GetSkippedOffset();
  MOZ_ASSERT(aRange.start >= startOffset, "wrong start offset");
  MOZ_ASSERT(aRange.end <= startOffset + mLength, "beyond the end");
  uint32_t tabsEnd =
      (mTabWidths ? mTabWidths->mLimit : mTabWidthsAnalyzedLimit) + startOffset;
  if (tabsEnd < aRange.end) {
    NS_ASSERTION(mReflowing,
                 "We need precomputed tab widths, but don't have enough.");

    for (uint32_t i = tabsEnd; i < aRange.end; ++i) {
      Spacing spacing;
      GetSpacingInternal(Range(i, i + 1), &spacing, true);
      mOffsetFromBlockOriginForTabs += spacing.mBefore;

      if (!mTextRun->CharIsTab(i)) {
        if (mTextRun->IsClusterStart(i)) {
          uint32_t clusterEnd = i + 1;
          while (clusterEnd < mTextRun->GetLength() &&
                 !mTextRun->IsClusterStart(clusterEnd)) {
            ++clusterEnd;
          }
          mOffsetFromBlockOriginForTabs +=
              mTextRun->GetAdvanceWidth(Range(i, clusterEnd), nullptr);
        }
      } else {
        if (!mTabWidths) {
          mTabWidths = new TabWidthStore(mFrame->GetContentOffset());
          mFrame->SetProperty(TabWidthProperty(), mTabWidths);
        }
        double nextTab = AdvanceToNextTab(mOffsetFromBlockOriginForTabs,
                                          aTabWidth, MinTabAdvance());
        mTabWidths->mWidths.AppendElement(
            TabWidth(i - startOffset,
                     NSToIntRound(nextTab - mOffsetFromBlockOriginForTabs)));
        mOffsetFromBlockOriginForTabs = nextTab;
      }

      mOffsetFromBlockOriginForTabs += spacing.mAfter;
    }

    if (mTabWidths) {
      mTabWidths->mLimit = aRange.end - startOffset;
    }
  }

  if (!mTabWidths) {
    // Delete any stale property that may be left on the frame
    mFrame->RemoveProperty(TabWidthProperty());
    mTabWidthsAnalyzedLimit =
        std::max(mTabWidthsAnalyzedLimit, aRange.end - startOffset);
  }
}

gfxFloat nsTextFrame::PropertyProvider::GetHyphenWidth() const {
  if (mHyphenWidth < 0) {
    const auto& hyphenateChar = mTextStyle->mHyphenateCharacter;
    if (hyphenateChar.IsAuto()) {
      mHyphenWidth = GetFontGroup()->GetHyphenWidth(this);
    } else {
      RefPtr<gfxTextRun> hyphRun = GetHyphenTextRun(mFrame, nullptr);
      mHyphenWidth = hyphRun ? hyphRun->GetAdvanceWidth() : 0;
    }
  }
  return mHyphenWidth + mLetterSpacing;
}

static inline bool IS_HYPHEN(char16_t u) {
  return u == char16_t('-') ||  // HYPHEN-MINUS
         u == 0x058A ||         // ARMENIAN HYPHEN
         u == 0x2010 ||         // HYPHEN
         u == 0x2012 ||         // FIGURE DASH
         u == 0x2013;           // EN DASH
}

void nsTextFrame::PropertyProvider::GetHyphenationBreaks(
    Range aRange, HyphenType* aBreakBefore) const {
  MOZ_ASSERT(IsInBounds(mStart, mLength, aRange), "Range out of bounds");
  MOZ_ASSERT(mLength != INT32_MAX, "Can't call this with undefined length");

  if (!mTextStyle->WhiteSpaceCanWrap(mFrame) ||
      mTextStyle->mHyphens == StyleHyphens::None) {
    memset(aBreakBefore, static_cast<uint8_t>(HyphenType::None),
           aRange.Length() * sizeof(HyphenType));
    return;
  }

  // Iterate through the original-string character runs
  nsSkipCharsRunIterator run(
      mStart, nsSkipCharsRunIterator::LENGTH_UNSKIPPED_ONLY, aRange.Length());
  run.SetSkippedOffset(aRange.start);
  // We need to visit skipped characters so that we can detect SHY
  run.SetVisitSkipped();

  int32_t prevTrailingCharOffset = run.GetPos().GetOriginalOffset() - 1;
  bool allowHyphenBreakBeforeNextChar =
      prevTrailingCharOffset >= mStart.GetOriginalOffset() &&
      prevTrailingCharOffset < mStart.GetOriginalOffset() + mLength &&
      mFrag->CharAt(AssertedCast<uint32_t>(prevTrailingCharOffset)) == CH_SHY;

  while (run.NextRun()) {
    NS_ASSERTION(run.GetRunLength() > 0, "Shouldn't return zero-length runs");
    if (run.IsSkipped()) {
      // Check if there's a soft hyphen which would let us hyphenate before
      // the next non-skipped character. Don't look at soft hyphens followed
      // by other skipped characters, we won't use them.
      allowHyphenBreakBeforeNextChar =
          mFrag->CharAt(AssertedCast<uint32_t>(
              run.GetOriginalOffset() + run.GetRunLength() - 1)) == CH_SHY;
    } else {
      int32_t runOffsetInSubstring = run.GetSkippedOffset() - aRange.start;
      memset(aBreakBefore + runOffsetInSubstring,
             static_cast<uint8_t>(HyphenType::None),
             run.GetRunLength() * sizeof(HyphenType));
      // Don't allow hyphen breaks at the start of the line
      aBreakBefore[runOffsetInSubstring] =
          allowHyphenBreakBeforeNextChar &&
                  (!mFrame->HasAnyStateBits(TEXT_START_OF_LINE) ||
                   run.GetSkippedOffset() > mStart.GetSkippedOffset())
              ? HyphenType::Soft
              : HyphenType::None;
      allowHyphenBreakBeforeNextChar = false;
    }
  }

  if (mTextStyle->mHyphens == StyleHyphens::Auto) {
    gfxSkipCharsIterator skipIter(mStart);
    for (uint32_t i = 0; i < aRange.Length(); ++i) {
      if (IS_HYPHEN(mFrag->CharAt(AssertedCast<uint32_t>(
              skipIter.ConvertSkippedToOriginal(aRange.start + i))))) {
        if (i < aRange.Length() - 1) {
          aBreakBefore[i + 1] = HyphenType::Explicit;
        }
        continue;
      }

      if (mTextRun->CanHyphenateBefore(aRange.start + i) &&
          aBreakBefore[i] == HyphenType::None) {
        aBreakBefore[i] = HyphenType::AutoWithoutManualInSameWord;
      }
    }
  }
}

void nsTextFrame::PropertyProvider::InitializeForDisplay(bool aTrimAfter) {
  nsTextFrame::TrimmedOffsets trimmed = mFrame->GetTrimmedOffsets(
      mFrag, (aTrimAfter ? nsTextFrame::TrimmedOffsetFlags::Default
                         : nsTextFrame::TrimmedOffsetFlags::NoTrimAfter));
  mStart.SetOriginalOffset(trimmed.mStart);
  mLength = trimmed.mLength;
  SetupJustificationSpacing(true);
}

void nsTextFrame::PropertyProvider::InitializeForMeasure() {
  nsTextFrame::TrimmedOffsets trimmed = mFrame->GetTrimmedOffsets(
      mFrag, nsTextFrame::TrimmedOffsetFlags::NotPostReflow);
  mStart.SetOriginalOffset(trimmed.mStart);
  mLength = trimmed.mLength;
  SetupJustificationSpacing(false);
}

void nsTextFrame::PropertyProvider::SetupJustificationSpacing(
    bool aPostReflow) {
  MOZ_ASSERT(mLength != INT32_MAX, "Can't call this with undefined length");

  if (!mFrame->HasAnyStateBits(TEXT_JUSTIFICATION_ENABLED)) {
    return;
  }

  gfxSkipCharsIterator start(mStart), end(mStart);
  // We can't just use our mLength here; when InitializeForDisplay is
  // called with false for aTrimAfter, we still shouldn't be assigning
  // justification space to any trailing whitespace.
  nsTextFrame::TrimmedOffsets trimmed = mFrame->GetTrimmedOffsets(
      mFrag, (aPostReflow ? nsTextFrame::TrimmedOffsetFlags::Default
                          : nsTextFrame::TrimmedOffsetFlags::NotPostReflow));
  end.AdvanceOriginal(trimmed.mLength);
  gfxSkipCharsIterator realEnd(end);

  Range range(uint32_t(start.GetOriginalOffset()),
              uint32_t(end.GetOriginalOffset()));
  nsTArray<JustificationAssignment> assignments;
  JustificationInfo info = ComputeJustification(range, &assignments);

  auto assign = mFrame->GetJustificationAssignment();
  auto totalGaps = JustificationUtils::CountGaps(info, assign);
  if (!totalGaps || assignments.IsEmpty()) {
    // Nothing to do, nothing is justifiable and we shouldn't have any
    // justification space assigned
    return;
  }

  // Remember that textrun measurements are in the run's orientation,
  // so its advance "width" is actually a height in vertical writing modes,
  // corresponding to the inline-direction of the frame.
  gfxFloat naturalWidth = mTextRun->GetAdvanceWidth(
      Range(mStart.GetSkippedOffset(), realEnd.GetSkippedOffset()), this);
  if (mFrame->HasAnyStateBits(TEXT_HYPHEN_BREAK)) {
    naturalWidth += GetHyphenWidth();
  }
  nscoord totalSpacing = mFrame->ISize() - naturalWidth;
  if (totalSpacing <= 0) {
    // No space available
    return;
  }

  assignments[0].mGapsAtStart = assign.mGapsAtStart;
  assignments.LastElement().mGapsAtEnd = assign.mGapsAtEnd;

  MOZ_ASSERT(mJustificationSpacings.IsEmpty());
  JustificationApplicationState state(totalGaps, totalSpacing);
  mJustificationSpacings.SetCapacity(assignments.Length());
  for (const JustificationAssignment& assign : assignments) {
    Spacing* spacing = mJustificationSpacings.AppendElement();
    spacing->mBefore = state.Consume(assign.mGapsAtStart);
    spacing->mAfter = state.Consume(assign.mGapsAtEnd);
  }
}

void nsTextFrame::PropertyProvider::InitFontGroupAndFontMetrics() const {
  if (!mFontMetrics) {
    if (mWhichTextRun == nsTextFrame::eInflated) {
      if (!mFrame->InflatedFontMetrics()) {
        float inflation = mFrame->GetFontSizeInflation();
        mFontMetrics = nsLayoutUtils::GetFontMetricsForFrame(mFrame, inflation);
        mFrame->SetInflatedFontMetrics(mFontMetrics);
      } else {
        mFontMetrics = mFrame->InflatedFontMetrics();
      }
    } else {
      mFontMetrics = nsLayoutUtils::GetFontMetricsForFrame(mFrame, 1.0f);
    }
  }
  mFontGroup = mFontMetrics->GetThebesFontGroup();
}

//----------------------------------------------------------------------

static nscolor EnsureDifferentColors(nscolor colorA, nscolor colorB) {
  if (colorA == colorB) {
    nscolor res;
    res = NS_RGB(NS_GET_R(colorA) ^ 0xff, NS_GET_G(colorA) ^ 0xff,
                 NS_GET_B(colorA) ^ 0xff);
    return res;
  }
  return colorA;
}

//-----------------------------------------------------------------------------

nsTextPaintStyle::nsTextPaintStyle(nsTextFrame* aFrame)
    : mFrame(aFrame),
      mPresContext(aFrame->PresContext()),
      mInitCommonColors(false),
      mInitSelectionColorsAndShadow(false),
      mResolveColors(true),
      mSelectionTextColor(NS_RGBA(0, 0, 0, 0)),
      mSelectionBGColor(NS_RGBA(0, 0, 0, 0)),
      mSufficientContrast(0),
      mFrameBackgroundColor(NS_RGBA(0, 0, 0, 0)),
      mSystemFieldForegroundColor(NS_RGBA(0, 0, 0, 0)),
      mSystemFieldBackgroundColor(NS_RGBA(0, 0, 0, 0)) {
  for (uint32_t i = 0; i < ArrayLength(mSelectionStyle); i++)
    mSelectionStyle[i].mInit = false;
}

bool nsTextPaintStyle::EnsureSufficientContrast(nscolor* aForeColor,
                                                nscolor* aBackColor) {
  InitCommonColors();

  const bool sameAsForeground = *aForeColor == NS_SAME_AS_FOREGROUND_COLOR;
  if (sameAsForeground) {
    *aForeColor = GetTextColor();
  }

  // If the combination of selection background color and frame background color
  // has sufficient contrast, don't exchange the selection colors.
  //
  // Note we use a different threshold here: mSufficientContrast is for contrast
  // between text and background colors, but since we're diffing two
  // backgrounds, we don't need that much contrast.  We match the heuristic from
  // NS_SUFFICIENT_LUMINOSITY_DIFFERENCE_BG and use 20% of mSufficientContrast.
  const int32_t minLuminosityDifferenceForBackground = mSufficientContrast / 5;
  const int32_t backLuminosityDifference =
      NS_LUMINOSITY_DIFFERENCE(*aBackColor, mFrameBackgroundColor);
  if (backLuminosityDifference >= minLuminosityDifferenceForBackground) {
    return false;
  }

  // Otherwise, we should use the higher-contrast color for the selection
  // background color.
  //
  // For NS_SAME_AS_FOREGROUND_COLOR we only do this if the background is
  // totally indistinguishable, that is, if the luminosity difference is 0.
  if (sameAsForeground && backLuminosityDifference) {
    return false;
  }

  int32_t foreLuminosityDifference =
      NS_LUMINOSITY_DIFFERENCE(*aForeColor, mFrameBackgroundColor);
  if (backLuminosityDifference < foreLuminosityDifference) {
    std::swap(*aForeColor, *aBackColor);
    // Ensure foreground color is opaque to guarantee contrast.
    *aForeColor = NS_RGB(NS_GET_R(*aForeColor), NS_GET_G(*aForeColor),
                         NS_GET_B(*aForeColor));
    return true;
  }
  return false;
}

nscolor nsTextPaintStyle::GetTextColor() {
  if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
    if (!mResolveColors) {
      return NS_SAME_AS_FOREGROUND_COLOR;
    }

    const nsStyleSVG* style = mFrame->StyleSVG();
    switch (style->mFill.kind.tag) {
      case StyleSVGPaintKind::Tag::None:
        return NS_RGBA(0, 0, 0, 0);
      case StyleSVGPaintKind::Tag::Color:
        return nsLayoutUtils::GetColor(mFrame, &nsStyleSVG::mFill);
      default:
        NS_ERROR("cannot resolve SVG paint to nscolor");
        return NS_RGBA(0, 0, 0, 255);
    }
  }

  return nsLayoutUtils::GetColor(mFrame, &nsStyleText::mWebkitTextFillColor);
}

bool nsTextPaintStyle::GetSelectionColors(nscolor* aForeColor,
                                          nscolor* aBackColor) {
  NS_ASSERTION(aForeColor, "aForeColor is null");
  NS_ASSERTION(aBackColor, "aBackColor is null");

  if (!InitSelectionColorsAndShadow()) {
    return false;
  }

  *aForeColor = mSelectionTextColor;
  *aBackColor = mSelectionBGColor;
  return true;
}

void nsTextPaintStyle::GetHighlightColors(nscolor* aForeColor,
                                          nscolor* aBackColor) {
  NS_ASSERTION(aForeColor, "aForeColor is null");
  NS_ASSERTION(aBackColor, "aBackColor is null");

  const nsFrameSelection* frameSelection = mFrame->GetConstFrameSelection();
  const Selection* selection =
      frameSelection->GetSelection(SelectionType::eFind);
  const SelectionCustomColors* customColors = nullptr;
  if (selection) {
    customColors = selection->GetCustomColors();
  }

  if (!customColors) {
    nscolor backColor = LookAndFeel::Color(
        LookAndFeel::ColorID::TextHighlightBackground, mFrame);
    nscolor foreColor = LookAndFeel::Color(
        LookAndFeel::ColorID::TextHighlightForeground, mFrame);
    EnsureSufficientContrast(&foreColor, &backColor);
    *aForeColor = foreColor;
    *aBackColor = backColor;
    return;
  }

  if (customColors->mForegroundColor && customColors->mBackgroundColor) {
    nscolor foreColor = *customColors->mForegroundColor;
    nscolor backColor = *customColors->mBackgroundColor;

    if (EnsureSufficientContrast(&foreColor, &backColor) &&
        customColors->mAltForegroundColor &&
        customColors->mAltBackgroundColor) {
      foreColor = *customColors->mAltForegroundColor;
      backColor = *customColors->mAltBackgroundColor;
    }

    *aForeColor = foreColor;
    *aBackColor = backColor;
    return;
  }

  InitCommonColors();

  if (customColors->mBackgroundColor) {
    // !mForegroundColor means "currentColor"; the current color of the text.
    nscolor foreColor = GetTextColor();
    nscolor backColor = *customColors->mBackgroundColor;

    int32_t luminosityDifference =
        NS_LUMINOSITY_DIFFERENCE(foreColor, backColor);

    if (mSufficientContrast > luminosityDifference &&
        customColors->mAltBackgroundColor) {
      int32_t altLuminosityDifference = NS_LUMINOSITY_DIFFERENCE(
          foreColor, *customColors->mAltBackgroundColor);

      if (luminosityDifference < altLuminosityDifference) {
        backColor = *customColors->mAltBackgroundColor;
      }
    }

    *aForeColor = foreColor;
    *aBackColor = backColor;
    return;
  }

  if (customColors->mForegroundColor) {
    nscolor foreColor = *customColors->mForegroundColor;
    // !mBackgroundColor means "transparent"; the current color of the
    // background.

    int32_t luminosityDifference =
        NS_LUMINOSITY_DIFFERENCE(foreColor, mFrameBackgroundColor);

    if (mSufficientContrast > luminosityDifference &&
        customColors->mAltForegroundColor) {
      int32_t altLuminosityDifference = NS_LUMINOSITY_DIFFERENCE(
          *customColors->mForegroundColor, mFrameBackgroundColor);

      if (luminosityDifference < altLuminosityDifference) {
        foreColor = *customColors->mAltForegroundColor;
      }
    }

    *aForeColor = foreColor;
    *aBackColor = NS_TRANSPARENT;
    return;
  }

  // There are neither mForegroundColor nor mBackgroundColor.
  *aForeColor = GetTextColor();
  *aBackColor = NS_TRANSPARENT;
}

void nsTextPaintStyle::GetURLSecondaryColor(nscolor* aForeColor) {
  NS_ASSERTION(aForeColor, "aForeColor is null");

  nscolor textColor = GetTextColor();
  textColor = NS_RGBA(NS_GET_R(textColor), NS_GET_G(textColor),
                      NS_GET_B(textColor), (uint8_t)(255 * 0.5f));
  // Don't use true alpha color for readability.
  InitCommonColors();
  *aForeColor = NS_ComposeColors(mFrameBackgroundColor, textColor);
}

void nsTextPaintStyle::GetIMESelectionColors(int32_t aIndex,
                                             nscolor* aForeColor,
                                             nscolor* aBackColor) {
  NS_ASSERTION(aForeColor, "aForeColor is null");
  NS_ASSERTION(aBackColor, "aBackColor is null");
  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");

  nsSelectionStyle* selectionStyle = GetSelectionStyle(aIndex);
  *aForeColor = selectionStyle->mTextColor;
  *aBackColor = selectionStyle->mBGColor;
}

bool nsTextPaintStyle::GetSelectionUnderlineForPaint(int32_t aIndex,
                                                     nscolor* aLineColor,
                                                     float* aRelativeSize,
                                                     uint8_t* aStyle) {
  NS_ASSERTION(aLineColor, "aLineColor is null");
  NS_ASSERTION(aRelativeSize, "aRelativeSize is null");
  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");

  nsSelectionStyle* selectionStyle = GetSelectionStyle(aIndex);
  if (selectionStyle->mUnderlineStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE ||
      selectionStyle->mUnderlineColor == NS_TRANSPARENT ||
      selectionStyle->mUnderlineRelativeSize <= 0.0f)
    return false;

  *aLineColor = selectionStyle->mUnderlineColor;
  *aRelativeSize = selectionStyle->mUnderlineRelativeSize;
  *aStyle = selectionStyle->mUnderlineStyle;
  return true;
}

void nsTextPaintStyle::InitCommonColors() {
  if (mInitCommonColors) {
    return;
  }

  auto bgColor = nsCSSRendering::FindEffectiveBackgroundColor(mFrame);
  mFrameBackgroundColor = bgColor.mColor;

  mSystemFieldForegroundColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Fieldtext, mFrame);
  mSystemFieldBackgroundColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Field, mFrame);

  if (bgColor.mIsThemed) {
    // Assume a native widget has sufficient contrast always
    mSufficientContrast = 0;
    mInitCommonColors = true;
    return;
  }

  nscolor defaultWindowBackgroundColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Window, mFrame);
  nscolor selectionTextColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Highlighttext, mFrame);
  nscolor selectionBGColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Highlight, mFrame);

  mSufficientContrast = std::min(
      std::min(NS_SUFFICIENT_LUMINOSITY_DIFFERENCE,
               NS_LUMINOSITY_DIFFERENCE(selectionTextColor, selectionBGColor)),
      NS_LUMINOSITY_DIFFERENCE(defaultWindowBackgroundColor, selectionBGColor));

  mInitCommonColors = true;
}

nscolor nsTextPaintStyle::GetSystemFieldForegroundColor() {
  InitCommonColors();
  return mSystemFieldForegroundColor;
}

nscolor nsTextPaintStyle::GetSystemFieldBackgroundColor() {
  InitCommonColors();
  return mSystemFieldBackgroundColor;
}

bool nsTextPaintStyle::InitSelectionColorsAndShadow() {
  if (mInitSelectionColorsAndShadow) {
    return true;
  }

  int16_t selectionFlags;
  const int16_t selectionStatus = mFrame->GetSelectionStatus(&selectionFlags);
  if (!(selectionFlags & nsISelectionDisplay::DISPLAY_TEXT) ||
      selectionStatus < nsISelectionController::SELECTION_ON) {
    // Not displaying the normal selection.
    // We're not caching this fact, so every call to GetSelectionColors
    // will come through here. We could avoid this, but it's not really worth
    // it.
    return false;
  }

  mInitSelectionColorsAndShadow = true;

  // Use ::selection pseudo class if applicable.
  if (RefPtr<ComputedStyle> style =
          mFrame->ComputeSelectionStyle(selectionStatus)) {
    mSelectionBGColor =
        style->GetVisitedDependentColor(&nsStyleBackground::mBackgroundColor);
    mSelectionTextColor =
        style->GetVisitedDependentColor(&nsStyleText::mWebkitTextFillColor);
    mSelectionPseudoStyle = std::move(style);
    return true;
  }

  mSelectionTextColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Highlighttext, mFrame);

  nscolor selectionBGColor =
      LookAndFeel::Color(LookAndFeel::ColorID::Highlight, mFrame);

  switch (selectionStatus) {
    case nsISelectionController::SELECTION_ATTENTION: {
      mSelectionTextColor = LookAndFeel::Color(
          LookAndFeel::ColorID::TextSelectAttentionForeground, mFrame);
      mSelectionBGColor = LookAndFeel::Color(
          LookAndFeel::ColorID::TextSelectAttentionBackground, mFrame);
      mSelectionBGColor =
          EnsureDifferentColors(mSelectionBGColor, selectionBGColor);
      break;
    }
    case nsISelectionController::SELECTION_ON: {
      mSelectionBGColor = selectionBGColor;
      break;
    }
    default: {
      mSelectionBGColor = LookAndFeel::Color(
          LookAndFeel::ColorID::TextSelectDisabledBackground, mFrame);
      mSelectionBGColor =
          EnsureDifferentColors(mSelectionBGColor, selectionBGColor);
      break;
    }
  }

  if (mResolveColors) {
    EnsureSufficientContrast(&mSelectionTextColor, &mSelectionBGColor);
  }
  return true;
}

nsTextPaintStyle::nsSelectionStyle* nsTextPaintStyle::GetSelectionStyle(
    int32_t aIndex) {
  InitSelectionStyle(aIndex);
  return &mSelectionStyle[aIndex];
}

struct StyleIDs {
  LookAndFeel::ColorID mForeground, mBackground, mLine;
  LookAndFeel::IntID mLineStyle;
  LookAndFeel::FloatID mLineRelativeSize;
};
static StyleIDs SelectionStyleIDs[] = {
    {LookAndFeel::ColorID::IMERawInputForeground,
     LookAndFeel::ColorID::IMERawInputBackground,
     LookAndFeel::ColorID::IMERawInputUnderline,
     LookAndFeel::IntID::IMERawInputUnderlineStyle,
     LookAndFeel::FloatID::IMEUnderlineRelativeSize},
    {LookAndFeel::ColorID::IMESelectedRawTextForeground,
     LookAndFeel::ColorID::IMESelectedRawTextBackground,
     LookAndFeel::ColorID::IMESelectedRawTextUnderline,
     LookAndFeel::IntID::IMESelectedRawTextUnderlineStyle,
     LookAndFeel::FloatID::IMEUnderlineRelativeSize},
    {LookAndFeel::ColorID::IMEConvertedTextForeground,
     LookAndFeel::ColorID::IMEConvertedTextBackground,
     LookAndFeel::ColorID::IMEConvertedTextUnderline,
     LookAndFeel::IntID::IMEConvertedTextUnderlineStyle,
     LookAndFeel::FloatID::IMEUnderlineRelativeSize},
    {LookAndFeel::ColorID::IMESelectedConvertedTextForeground,
     LookAndFeel::ColorID::IMESelectedConvertedTextBackground,
     LookAndFeel::ColorID::IMESelectedConvertedTextUnderline,
     LookAndFeel::IntID::IMESelectedConvertedTextUnderline,
     LookAndFeel::FloatID::IMEUnderlineRelativeSize},
    {LookAndFeel::ColorID::End, LookAndFeel::ColorID::End,
     LookAndFeel::ColorID::SpellCheckerUnderline,
     LookAndFeel::IntID::SpellCheckerUnderlineStyle,
     LookAndFeel::FloatID::SpellCheckerUnderlineRelativeSize}};

void nsTextPaintStyle::InitSelectionStyle(int32_t aIndex) {
  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "aIndex is invalid");
  nsSelectionStyle* selectionStyle = &mSelectionStyle[aIndex];
  if (selectionStyle->mInit) {
    return;
  }

  StyleIDs* styleIDs = &SelectionStyleIDs[aIndex];

  nscolor foreColor, backColor;
  if (styleIDs->mForeground == LookAndFeel::ColorID::End) {
    foreColor = NS_SAME_AS_FOREGROUND_COLOR;
  } else {
    foreColor = LookAndFeel::Color(styleIDs->mForeground, mFrame);
  }
  if (styleIDs->mBackground == LookAndFeel::ColorID::End) {
    backColor = NS_TRANSPARENT;
  } else {
    backColor = LookAndFeel::Color(styleIDs->mBackground, mFrame);
  }

  // Convert special color to actual color
  NS_ASSERTION(foreColor != NS_TRANSPARENT,
               "foreColor cannot be NS_TRANSPARENT");
  NS_ASSERTION(backColor != NS_SAME_AS_FOREGROUND_COLOR,
               "backColor cannot be NS_SAME_AS_FOREGROUND_COLOR");
  NS_ASSERTION(backColor != NS_40PERCENT_FOREGROUND_COLOR,
               "backColor cannot be NS_40PERCENT_FOREGROUND_COLOR");

  if (mResolveColors) {
    foreColor = GetResolvedForeColor(foreColor, GetTextColor(), backColor);

    if (NS_GET_A(backColor) > 0) {
      EnsureSufficientContrast(&foreColor, &backColor);
    }
  }

  nscolor lineColor;
  float relativeSize;
  uint8_t lineStyle;
  GetSelectionUnderline(mFrame, aIndex, &lineColor, &relativeSize, &lineStyle);

  if (mResolveColors) {
    lineColor = GetResolvedForeColor(lineColor, foreColor, backColor);
  }

  selectionStyle->mTextColor = foreColor;
  selectionStyle->mBGColor = backColor;
  selectionStyle->mUnderlineColor = lineColor;
  selectionStyle->mUnderlineStyle = lineStyle;
  selectionStyle->mUnderlineRelativeSize = relativeSize;
  selectionStyle->mInit = true;
}

/* static */
bool nsTextPaintStyle::GetSelectionUnderline(nsIFrame* aFrame, int32_t aIndex,
                                             nscolor* aLineColor,
                                             float* aRelativeSize,
                                             uint8_t* aStyle) {
  NS_ASSERTION(aFrame, "aFrame is null");
  NS_ASSERTION(aRelativeSize, "aRelativeSize is null");
  NS_ASSERTION(aStyle, "aStyle is null");
  NS_ASSERTION(aIndex >= 0 && aIndex < 5, "Index out of range");

  StyleIDs& styleID = SelectionStyleIDs[aIndex];

  nscolor color = LookAndFeel::Color(styleID.mLine, aFrame);
  int32_t style = LookAndFeel::GetInt(styleID.mLineStyle);
  if (style > NS_STYLE_TEXT_DECORATION_STYLE_MAX) {
    NS_ERROR("Invalid underline style value is specified");
    style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
  }
  float size = LookAndFeel::GetFloat(styleID.mLineRelativeSize);

  NS_ASSERTION(size, "selection underline relative size must be larger than 0");

  if (aLineColor) {
    *aLineColor = color;
  }
  *aRelativeSize = size;
  *aStyle = style;

  return style != NS_STYLE_TEXT_DECORATION_STYLE_NONE &&
         color != NS_TRANSPARENT && size > 0.0f;
}

bool nsTextPaintStyle::GetSelectionShadow(
    Span<const StyleSimpleShadow>* aShadows) {
  if (!InitSelectionColorsAndShadow()) {
    return false;
  }

  if (mSelectionPseudoStyle) {
    *aShadows = mSelectionPseudoStyle->StyleText()->mTextShadow.AsSpan();
    return true;
  }

  return false;
}

inline nscolor Get40PercentColor(nscolor aForeColor, nscolor aBackColor) {
  nscolor foreColor = NS_RGBA(NS_GET_R(aForeColor), NS_GET_G(aForeColor),
                              NS_GET_B(aForeColor), (uint8_t)(255 * 0.4f));
  // Don't use true alpha color for readability.
  return NS_ComposeColors(aBackColor, foreColor);
}

nscolor nsTextPaintStyle::GetResolvedForeColor(nscolor aColor,
                                               nscolor aDefaultForeColor,
                                               nscolor aBackColor) {
  if (aColor == NS_SAME_AS_FOREGROUND_COLOR) {
    return aDefaultForeColor;
  }

  if (aColor != NS_40PERCENT_FOREGROUND_COLOR) {
    return aColor;
  }

  // Get actual background color
  nscolor actualBGColor = aBackColor;
  if (actualBGColor == NS_TRANSPARENT) {
    InitCommonColors();
    actualBGColor = mFrameBackgroundColor;
  }
  return Get40PercentColor(aDefaultForeColor, actualBGColor);
}

//-----------------------------------------------------------------------------

#ifdef ACCESSIBILITY
a11y::AccType nsTextFrame::AccessibleType() {
  if (IsEmpty()) {
    RenderedText text =
        GetRenderedText(0, UINT32_MAX, TextOffsetType::OffsetsInContentText,
                        TrailingWhitespace::DontTrim);
    if (text.mString.IsEmpty()) {
      return a11y::eNoType;
    }
  }

  return a11y::eTextLeafType;
}
#endif

//-----------------------------------------------------------------------------
void nsTextFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
                       nsIFrame* aPrevInFlow) {
  NS_ASSERTION(!aPrevInFlow, "Can't be a continuation!");
  MOZ_ASSERT(aContent->IsText(), "Bogus content!");

  // Remove any NewlineOffsetProperty or InFlowContentLengthProperty since they
  // might be invalid if the content was modified while there was no frame
  if (aContent->HasFlag(NS_HAS_NEWLINE_PROPERTY)) {
    aContent->RemoveProperty(nsGkAtoms::newline);
    aContent->UnsetFlags(NS_HAS_NEWLINE_PROPERTY);
  }
  if (aContent->HasFlag(NS_HAS_FLOWLENGTH_PROPERTY)) {
    aContent->RemoveProperty(nsGkAtoms::flowlength);
    aContent->UnsetFlags(NS_HAS_FLOWLENGTH_PROPERTY);
  }

  // Since our content has a frame now, this flag is no longer needed.
  aContent->UnsetFlags(NS_CREATE_FRAME_IF_NON_WHITESPACE);

  // We're not a continuing frame.
  // mContentOffset = 0; not necessary since we get zeroed out at init
  nsIFrame::Init(aContent, aParent, aPrevInFlow);
}

void nsTextFrame::ClearFrameOffsetCache() {
  // See if we need to remove ourselves from the offset cache
  if (HasAnyStateBits(TEXT_IN_OFFSET_CACHE)) {
    nsIFrame* primaryFrame = mContent->GetPrimaryFrame();
    if (primaryFrame) {
      // The primary frame might be null here.  For example,
      // nsLineBox::DeleteLineList just destroys the frames in order, which
      // means that the primary frame is already dead if we're a continuing text
      // frame, in which case, all of its properties are gone, and we don't need
      // to worry about deleting this property here.
      primaryFrame->RemoveProperty(OffsetToFrameProperty());
    }
    RemoveStateBits(TEXT_IN_OFFSET_CACHE);
  }
}

void nsTextFrame::DestroyFrom(nsIFrame* aDestructRoot,
                              PostDestroyData& aPostDestroyData) {
  ClearFrameOffsetCache();

  // We might want to clear NS_CREATE_FRAME_IF_NON_WHITESPACE or
  // NS_REFRAME_IF_WHITESPACE on mContent here, since our parent frame
  // type might be changing.  Not clear whether it's worth it.
  ClearTextRuns();
  if (mNextContinuation) {
    mNextContinuation->SetPrevInFlow(nullptr);
  }
  // Let the base class destroy the frame
  nsIFrame::DestroyFrom(aDestructRoot, aPostDestroyData);
}

nsTArray<nsTextFrame*>* nsTextFrame::GetContinuations() {
  MOZ_ASSERT(NS_IsMainThread());
  // Only for use on the primary frame, which has no prev-continuation.
  MOZ_ASSERT(!GetPrevContinuation());
  if (!mNextContinuation) {
    return nullptr;
  }
  if (mHasContinuationsProperty) {
    return GetProperty(ContinuationsProperty());
  }
  size_t count = 0;
  for (nsIFrame* f = this; f; f = f->GetNextContinuation()) {
    ++count;
  }
  auto* continuations = new nsTArray<nsTextFrame*>;
  if (continuations->SetCapacity(count, fallible)) {
    for (nsTextFrame* f = this; f;
         f = static_cast<nsTextFrame*>(f->GetNextContinuation())) {
      continuations->AppendElement(f);
    }
  } else {
    delete continuations;
    continuations = nullptr;
  }
  AddProperty(ContinuationsProperty(), continuations);
  mHasContinuationsProperty = true;
  return continuations;
}

class nsContinuingTextFrame final : public nsTextFrame {
 public:
  NS_DECL_FRAMEARENA_HELPERS(nsContinuingTextFrame)

  friend nsIFrame* NS_NewContinuingTextFrame(mozilla::PresShell* aPresShell,
                                             ComputedStyle* aStyle);

  void Init(nsIContent* aContent, nsContainerFrame* aParent,
            nsIFrame* aPrevInFlow) final;

  void DestroyFrom(nsIFrame* aDestructRoot,
                   PostDestroyData& aPostDestroyData) final;

  nsTextFrame* GetPrevContinuation() const final { return mPrevContinuation; }

  void SetPrevContinuation(nsIFrame* aPrevContinuation) final {
    NS_ASSERTION(!aPrevContinuation || Type() == aPrevContinuation->Type(),
                 "setting a prev continuation with incorrect type!");
    NS_ASSERTION(
        !nsSplittableFrame::IsInPrevContinuationChain(aPrevContinuation, this),
        "creating a loop in continuation chain!");
    mPrevContinuation = static_cast<nsTextFrame*>(aPrevContinuation);
    RemoveStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
    nsTextFrame* prevFirst = mFirstContinuation;
    if (mPrevContinuation) {
      mFirstContinuation = mPrevContinuation->FirstContinuation();
      if (mFirstContinuation) {
        mFirstContinuation->ClearCachedContinuations();
      }
    } else {
      mFirstContinuation = nullptr;
    }
    if (mFirstContinuation != prevFirst) {
      if (prevFirst) {
        prevFirst->ClearCachedContinuations();
      }
      auto* f = static_cast<nsContinuingTextFrame*>(mNextContinuation);
      while (f) {
        f->mFirstContinuation = mFirstContinuation;
        f = static_cast<nsContinuingTextFrame*>(f->mNextContinuation);
      }
    }
  }

  nsTextFrame* GetPrevInFlow() const final {
    return HasAnyStateBits(NS_FRAME_IS_FLUID_CONTINUATION) ? mPrevContinuation
                                                           : nullptr;
  }

  void SetPrevInFlow(nsIFrame* aPrevInFlow) final {
    NS_ASSERTION(!aPrevInFlow || Type() == aPrevInFlow->Type(),
                 "setting a prev in flow with incorrect type!");
    NS_ASSERTION(
        !nsSplittableFrame::IsInPrevContinuationChain(aPrevInFlow, this),
        "creating a loop in continuation chain!");
    mPrevContinuation = static_cast<nsTextFrame*>(aPrevInFlow);
    AddStateBits(NS_FRAME_IS_FLUID_CONTINUATION);
    nsTextFrame* prevFirst = mFirstContinuation;
    if (mPrevContinuation) {
      mFirstContinuation = mPrevContinuation->FirstContinuation();
      if (mFirstContinuation) {
        mFirstContinuation->ClearCachedContinuations();
      }
    } else {
      mFirstContinuation = nullptr;
    }
    if (mFirstContinuation != prevFirst) {
      if (prevFirst) {
        prevFirst->ClearCachedContinuations();
      }
      auto* f = static_cast<nsContinuingTextFrame*>(mNextContinuation);
      while (f) {
        f->mFirstContinuation = mFirstContinuation;
        f = static_cast<nsContinuingTextFrame*>(f->mNextContinuation);
      }
    }
  }

  nsIFrame* FirstInFlow() const final;
  nsTextFrame* FirstContinuation() const final {
#if DEBUG
    // If we have a prev-continuation pointer, then our first-continuation
    // must be the same as that frame's.
    if (mPrevContinuation) {
      // If there's a prev-prev, then we can safely cast mPrevContinuation to
      // an nsContinuingTextFrame and access its mFirstContinuation pointer
      // directly, to avoid recursively calling FirstContinuation(), leading
      // to exponentially-slow behavior in the assertion.
      if (mPrevContinuation->GetPrevContinuation()) {
        auto* prev = static_cast<nsContinuingTextFrame*>(mPrevContinuation);
        MOZ_ASSERT(mFirstContinuation == prev->mFirstContinuation);
      } else {
        MOZ_ASSERT(mFirstContinuation ==
                   mPrevContinuation->FirstContinuation());
      }
    } else {
      MOZ_ASSERT(!mFirstContinuation);
    }
#endif
    return mFirstContinuation;
  };

  void AddInlineMinISize(gfxContext* aRenderingContext,
                         InlineMinISizeData* aData) final;
  void AddInlinePrefISize(gfxContext* aRenderingContext,
                          InlinePrefISizeData* aData) final;

 protected:
  explicit nsContinuingTextFrame(ComputedStyle* aStyle,
                                 nsPresContext* aPresContext)
      : nsTextFrame(aStyle, aPresContext, kClassID) {}

  nsTextFrame* mPrevContinuation;
  nsTextFrame* mFirstContinuation = nullptr;
};

void nsContinuingTextFrame::Init(nsIContent* aContent,
                                 nsContainerFrame* aParent,
                                 nsIFrame* aPrevInFlow) {
  NS_ASSERTION(aPrevInFlow, "Must be a continuation!");

  // Hook the frame into the flow
  nsTextFrame* prev = static_cast<nsTextFrame*>(aPrevInFlow);
  nsTextFrame* nextContinuation = prev->GetNextContinuation();
  SetPrevInFlow(aPrevInFlow);
  aPrevInFlow->SetNextInFlow(this);

  // NOTE: bypassing nsTextFrame::Init!!!
  nsIFrame::Init(aContent, aParent, aPrevInFlow);

  mContentOffset = prev->GetContentOffset() + prev->GetContentLengthHint();
  NS_ASSERTION(mContentOffset < int32_t(aContent->GetText()->GetLength()),
               "Creating ContinuingTextFrame, but there is no more content");
  if (prev->Style() != Style()) {
    // We're taking part of prev's text, and its style may be different
    // so clear its textrun which may no longer be valid (and don't set ours)
    prev->ClearTextRuns();
  } else {
    float inflation = prev->GetFontSizeInflation();
    SetFontSizeInflation(inflation);
    mTextRun = prev->GetTextRun(nsTextFrame::eInflated);
    if (inflation != 1.0f) {
      gfxTextRun* uninflatedTextRun =
          prev->GetTextRun(nsTextFrame::eNotInflated);
      if (uninflatedTextRun) {
        SetTextRun(uninflatedTextRun, nsTextFrame::eNotInflated, 1.0f);
      }
    }
  }
  if (aPrevInFlow->HasAnyStateBits(NS_FRAME_IS_BIDI)) {
    FrameBidiData bidiData = aPrevInFlow->GetBidiData();
    bidiData.precedingControl = kBidiLevelNone;
    SetProperty(BidiDataProperty(), bidiData);

    if (nextContinuation) {
      SetNextContinuation(nextContinuation);
      nextContinuation->SetPrevContinuation(this);
      // Adjust next-continuations' content offset as needed.
      while (nextContinuation &&
             nextContinuation->GetContentOffset() < mContentOffset) {
#ifdef DEBUG
        FrameBidiData nextBidiData = nextContinuation->GetBidiData();
        NS_ASSERTION(bidiData.embeddingLevel == nextBidiData.embeddingLevel &&
                         bidiData.baseLevel == nextBidiData.baseLevel,
                     "stealing text from different type of BIDI continuation");
        MOZ_ASSERT(nextBidiData.precedingControl == kBidiLevelNone,
                   "There shouldn't be any virtual bidi formatting character "
                   "between continuations");
#endif
        nextContinuation->mContentOffset = mContentOffset;
        nextContinuation = nextContinuation->GetNextContinuation();
      }
    }
    AddStateBits(NS_FRAME_IS_BIDI);
  }  // prev frame is bidi
}

void nsContinuingTextFrame::DestroyFrom(nsIFrame* aDestructRoot,
                                        PostDestroyData& aPostDestroyData) {
  ClearFrameOffsetCache();

  // The text associated with this frame will become associated with our
  // prev-continuation. If that means the text has changed style, then
  // we need to wipe out the text run for the text.
  // Note that mPrevContinuation can be null if we're destroying the whole
  // frame chain from the start to the end.
  // If this frame is mentioned in the userData for a textrun (say
  // because there's a direction change at the start of this frame), then
  // we have to clear the textrun because we're going away and the
  // textrun had better not keep a dangling reference to us.
  if (IsInTextRunUserData() ||
      (mPrevContinuation && mPrevContinuation->Style() != Style())) {
    ClearTextRuns();
    // Clear the previous continuation's text run also, so that it can rebuild
    // the text run to include our text.
    if (mPrevContinuation) {
      mPrevContinuation->ClearTextRuns();
    }
  }
  nsSplittableFrame::RemoveFromFlow(this);
  // Let the base class destroy the frame
  nsIFrame::DestroyFrom(aDestructRoot, aPostDestroyData);
}

nsIFrame* nsContinuingTextFrame::FirstInFlow() const {
  // Can't cast to |nsContinuingTextFrame*| because the first one isn't.
  nsIFrame *firstInFlow,
      *previous = const_cast<nsIFrame*>(static_cast<const nsIFrame*>(this));
  do {
    firstInFlow = previous;
    previous = firstInFlow->GetPrevInFlow();
  } while (previous);
  MOZ_ASSERT(firstInFlow, "post-condition failed");
  return firstInFlow;
}

// XXX Do we want to do all the work for the first-in-flow or do the
// work for each part?  (Be careful of first-letter / first-line, though,
// especially first-line!)  Doing all the work on the first-in-flow has
// the advantage of avoiding the potential for incremental reflow bugs,
// but depends on our maintining the frame tree in reasonable ways even
// for edge cases (block-within-inline splits, nextBidi, etc.)

// XXX We really need to make :first-letter happen during frame
// construction.

// Needed for text frames in XUL.
/* virtual */
nscoord nsTextFrame::GetMinISize(gfxContext* aRenderingContext) {
  return nsLayoutUtils::MinISizeFromInline(this, aRenderingContext);
}

// Needed for text frames in XUL.
/* virtual */
nscoord nsTextFrame::GetPrefISize(gfxContext* aRenderingContext) {
  return nsLayoutUtils::PrefISizeFromInline(this, aRenderingContext);
}

/* virtual */
void nsContinuingTextFrame::AddInlineMinISize(gfxContext* aRenderingContext,
                                              InlineMinISizeData* aData) {
  // Do nothing, since the first-in-flow accounts for everything.
}

/* virtual */
void nsContinuingTextFrame::AddInlinePrefISize(gfxContext* aRenderingContext,
                                               InlinePrefISizeData* aData) {
  // Do nothing, since the first-in-flow accounts for everything.
}

//----------------------------------------------------------------------

#if defined(DEBUG_rbs) || defined(DEBUG_bzbarsky)
static void VerifyNotDirty(nsFrameState state) {
  bool isZero = state & NS_FRAME_FIRST_REFLOW;
  bool isDirty = state & NS_FRAME_IS_DIRTY;
  if (!isZero && isDirty) {
    NS_WARNING("internal offsets may be out-of-sync");
  }
}
#  define DEBUG_VERIFY_NOT_DIRTY(state) VerifyNotDirty(state)
#else
#  define DEBUG_VERIFY_NOT_DIRTY(state)
#endif

nsIFrame* NS_NewTextFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
  return new (aPresShell) nsTextFrame(aStyle, aPresShell->GetPresContext());
}

NS_IMPL_FRAMEARENA_HELPERS(nsTextFrame)

nsIFrame* NS_NewContinuingTextFrame(PresShell* aPresShell,
                                    ComputedStyle* aStyle) {
  return new (aPresShell)
      nsContinuingTextFrame(aStyle, aPresShell->GetPresContext());
}

NS_IMPL_FRAMEARENA_HELPERS(nsContinuingTextFrame)

nsTextFrame::~nsTextFrame() = default;

Maybe<nsIFrame::Cursor> nsTextFrame::GetCursor(const nsPoint& aPoint) {
  StyleCursorKind kind = StyleUI()->Cursor().keyword;
  if (kind == StyleCursorKind::Auto) {
    if (!IsSelectable(nullptr)) {
      kind = StyleCursorKind::Default;
    } else {
      kind = GetWritingMode().IsVertical() ? StyleCursorKind::VerticalText
                                           : StyleCursorKind::Text;
    }
  }
  return Some(Cursor{kind, AllowCustomCursorImage::Yes});
}

nsTextFrame* nsTextFrame::LastInFlow() const {
  nsTextFrame* lastInFlow = const_cast<nsTextFrame*>(this);
  while (lastInFlow->GetNextInFlow()) {
    lastInFlow = lastInFlow->GetNextInFlow();
  }
  MOZ_ASSERT(lastInFlow, "post-condition failed");
  return lastInFlow;
}

nsTextFrame* nsTextFrame::LastContinuation() const {
  nsTextFrame* lastContinuation = const_cast<nsTextFrame*>(this);
  while (lastContinuation->mNextContinuation) {
    lastContinuation = lastContinuation->mNextContinuation;
  }
  MOZ_ASSERT(lastContinuation, "post-condition failed");
  return lastContinuation;
}

bool nsTextFrame::ShouldSuppressLineBreak() const {
  // If the parent frame of the text frame is ruby content box, it must
  // suppress line break inside. This check is necessary, because when
  // a whitespace is only contained by pseudo ruby frames, its style
  // context won't have SuppressLineBreak bit set.
  if (mozilla::RubyUtils::IsRubyContentBox(GetParent()->Type())) {
    return true;
  }
  return Style()->ShouldSuppressLineBreak();
}

void nsTextFrame::InvalidateFrame(uint32_t aDisplayItemKey,
                                  bool aRebuildDisplayItems) {
  InvalidateSelectionState();

  if (SVGUtils::IsInSVGTextSubtree(this)) {
    nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
        GetParent(), LayoutFrameType::SVGText);
    svgTextFrame->InvalidateFrame();
    return;
  }
  nsIFrame::InvalidateFrame(aDisplayItemKey, aRebuildDisplayItems);
}

void nsTextFrame::InvalidateFrameWithRect(const nsRect& aRect,
                                          uint32_t aDisplayItemKey,
                                          bool aRebuildDisplayItems) {
  InvalidateSelectionState();

  if (SVGUtils::IsInSVGTextSubtree(this)) {
    nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
        GetParent(), LayoutFrameType::SVGText);
    svgTextFrame->InvalidateFrame();
    return;
  }
  nsIFrame::InvalidateFrameWithRect(aRect, aDisplayItemKey,
                                    aRebuildDisplayItems);
}

gfxTextRun* nsTextFrame::GetUninflatedTextRun() const {
  return GetProperty(UninflatedTextRunProperty());
}

void nsTextFrame::SetInflatedFontMetrics(nsFontMetrics* aFontMetrics) {
  mFontMetrics = aFontMetrics;
}

void nsTextFrame::SetTextRun(gfxTextRun* aTextRun, TextRunType aWhichTextRun,
                             float aInflation) {
  NS_ASSERTION(aTextRun, "must have text run");

  // Our inflated text run is always stored in mTextRun.  In the cases
  // where our current inflation is not 1.0, however, we store two text
  // runs, and the uninflated one goes in a frame property.  We never
  // store a single text run in both.
  if (aWhichTextRun == eInflated) {
    if (HasFontSizeInflation() && aInflation == 1.0f) {
      // FIXME: Probably shouldn't do this within each SetTextRun
      // method, but it doesn't hurt.
      ClearTextRun(nullptr, nsTextFrame::eNotInflated);
    }
    SetFontSizeInflation(aInflation);
  } else {
    MOZ_ASSERT(aInflation == 1.0f, "unexpected inflation");
    if (HasFontSizeInflation()) {
      // Setting the property will not automatically increment the textrun's
      // reference count, so we need to do it here.
      aTextRun->AddRef();
      SetProperty(UninflatedTextRunProperty(), aTextRun);
      return;
    }
    // fall through to setting mTextRun
  }

  mTextRun = aTextRun;

  // FIXME: Add assertions testing the relationship between
  // GetFontSizeInflation() and whether we have an uninflated text run
  // (but be aware that text runs can go away).
}

bool nsTextFrame::RemoveTextRun(gfxTextRun* aTextRun) {
  if (aTextRun == mTextRun) {
    mTextRun = nullptr;
    mFontMetrics = nullptr;
    return true;
  }
  if (HasAnyStateBits(TEXT_HAS_FONT_INFLATION) &&
      GetProperty(UninflatedTextRunProperty()) == aTextRun) {
    RemoveProperty(UninflatedTextRunProperty());
    return true;
  }
  return false;
}

void nsTextFrame::ClearTextRun(nsTextFrame* aStartContinuation,
                               TextRunType aWhichTextRun) {
  RefPtr<gfxTextRun> textRun = GetTextRun(aWhichTextRun);
  if (!textRun) {
    return;
  }

  if (aWhichTextRun == nsTextFrame::eInflated) {
    mFontMetrics = nullptr;
  }

  DebugOnly<bool> checkmTextrun = textRun == mTextRun;
  UnhookTextRunFromFrames(textRun, aStartContinuation);
  MOZ_ASSERT(checkmTextrun ? !mTextRun
                           : !GetProperty(UninflatedTextRunProperty()));
}

void nsTextFrame::DisconnectTextRuns() {
  MOZ_ASSERT(!IsInTextRunUserData(),
             "Textrun mentions this frame in its user data so we can't just "
             "disconnect");
  mTextRun = nullptr;
  if (HasAnyStateBits(TEXT_HAS_FONT_INFLATION)) {
    RemoveProperty(UninflatedTextRunProperty());
  }
}

void nsTextFrame::NotifyNativeAnonymousTextnodeChange(uint32_t aOldLength) {
  MOZ_ASSERT(mContent->IsInNativeAnonymousSubtree());

  MarkIntrinsicISizesDirty();

  // This is to avoid making a new Reflow request in CharacterDataChanged:
  for (nsTextFrame* f = this; f; f = f->GetNextContinuation()) {
    f->MarkSubtreeDirty();
    f->mReflowRequestedForCharDataChange = true;
  }

  // Pretend that all the text changed.
  CharacterDataChangeInfo info;
  info.mAppend = false;
  info.mChangeStart = 0;
  info.mChangeEnd = aOldLength;
  info.mReplaceLength = GetContent()->TextLength();
  CharacterDataChanged(info);
}

nsresult nsTextFrame::CharacterDataChanged(
    const CharacterDataChangeInfo& aInfo) {
  if (mContent->HasFlag(NS_HAS_NEWLINE_PROPERTY)) {
    mContent->RemoveProperty(nsGkAtoms::newline);
    mContent->UnsetFlags(NS_HAS_NEWLINE_PROPERTY);
  }
  if (mContent->HasFlag(NS_HAS_FLOWLENGTH_PROPERTY)) {
    mContent->RemoveProperty(nsGkAtoms::flowlength);
    mContent->UnsetFlags(NS_HAS_FLOWLENGTH_PROPERTY);
  }

  // Find the first frame whose text has changed. Frames that are entirely
  // before the text change are completely unaffected.
  nsTextFrame* next;
  nsTextFrame* textFrame = this;
  while (true) {
    next = textFrame->GetNextContinuation();
    if (!next || next->GetContentOffset() > int32_t(aInfo.mChangeStart)) {
      break;
    }
    textFrame = next;
  }

  int32_t endOfChangedText = aInfo.mChangeStart + aInfo.mReplaceLength;

  // Parent of the last frame that we passed to FrameNeedsReflow (or noticed
  // had already received an earlier FrameNeedsReflow call).
  // (For subsequent frames with this same parent, we can just set their
  // dirty bit without bothering to call FrameNeedsReflow again.)
  nsIFrame* lastDirtiedFrameParent = nullptr;

  mozilla::PresShell* presShell = PresContext()->GetPresShell();
  do {
    // textFrame contained deleted text (or the insertion point,
    // if this was a pure insertion).
    textFrame->RemoveStateBits(TEXT_WHITESPACE_FLAGS);
    textFrame->ClearTextRuns();

    nsIFrame* parentOfTextFrame = textFrame->GetParent();
    bool areAncestorsAwareOfReflowRequest = false;
    if (lastDirtiedFrameParent == parentOfTextFrame) {
      // An earlier iteration of this loop already called
      // FrameNeedsReflow for a sibling of |textFrame|.
      areAncestorsAwareOfReflowRequest = true;
    } else {
      lastDirtiedFrameParent = parentOfTextFrame;
    }

    if (textFrame->mReflowRequestedForCharDataChange) {
      // We already requested a reflow for this frame; nothing to do.
      MOZ_ASSERT(textFrame->HasAnyStateBits(NS_FRAME_IS_DIRTY),
                 "mReflowRequestedForCharDataChange should only be set "
                 "on dirty frames");
    } else {
      // Make sure textFrame is queued up for a reflow.  Also set a flag so we
      // don't waste time doing this again in repeated calls to this method.
      textFrame->mReflowRequestedForCharDataChange = true;
      if (!areAncestorsAwareOfReflowRequest) {
        // Ask the parent frame to reflow me.
        presShell->FrameNeedsReflow(textFrame, IntrinsicDirty::StyleChange,
                                    NS_FRAME_IS_DIRTY);
      } else {
        // We already called FrameNeedsReflow on behalf of an earlier sibling,
        // so we can just mark this frame as dirty and don't need to bother
        // telling its ancestors.
        // Note: if the parent is a block, we're cheating here because we should
        // be marking our line dirty, but we're not. nsTextFrame::SetLength will
        // do that when it gets called during reflow.
        textFrame->MarkSubtreeDirty();
      }
    }
    textFrame->InvalidateFrame();

    // Below, frames that start after the deleted text will be adjusted so that
    // their offsets move with the trailing unchanged text. If this change
    // deletes more text than it inserts, those frame offsets will decrease.
    // We need to maintain the invariant that mContentOffset is non-decreasing
    // along the continuation chain. So we need to ensure that frames that
    // started in the deleted text are all still starting before the
    // unchanged text.
    if (textFrame->mContentOffset > endOfChangedText) {
      textFrame->mContentOffset = endOfChangedText;
    }

    textFrame = textFrame->GetNextContinuation();
  } while (textFrame &&
           textFrame->GetContentOffset() < int32_t(aInfo.mChangeEnd));

  // This is how much the length of the string changed by --- i.e.,
  // how much the trailing unchanged text moved.
  int32_t sizeChange =
      aInfo.mChangeStart + aInfo.mReplaceLength - aInfo.mChangeEnd;

  if (sizeChange) {
    // Fix the offsets of the text frames that start in the trailing
    // unchanged text.
    while (textFrame) {
      textFrame->mContentOffset += sizeChange;
      // XXX we could rescue some text runs by adjusting their user data
      // to reflect the change in DOM offsets
      textFrame->ClearTextRuns();
      textFrame = textFrame->GetNextContinuation();
    }
  }

  return NS_OK;
}

NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(TextCombineScaleFactorProperty, float)

float nsTextFrame::GetTextCombineScaleFactor(nsTextFrame* aFrame) {
  float factor = aFrame->GetProperty(TextCombineScaleFactorProperty());
  return factor ? factor : 1.0f;
}

void nsTextFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
                                   const nsDisplayListSet& aLists) {
  if (!IsVisibleForPainting()) {
    return;
  }

  DO_GLOBAL_REFLOW_COUNT_DSP("nsTextFrame");

  const nsStyleText* st = StyleText();
  bool isTextTransparent =
      NS_GET_A(st->mWebkitTextFillColor.CalcColor(this)) == 0 &&
      NS_GET_A(st->mWebkitTextStrokeColor.CalcColor(this)) == 0;
  if ((HasAnyStateBits(TEXT_NO_RENDERED_GLYPHS) ||
       (isTextTransparent && !StyleText()->HasTextShadow())) &&
      aBuilder->IsForPainting() && !SVGUtils::IsInSVGTextSubtree(this)) {
    if (!IsSelected()) {
      TextDecorations textDecs;
      GetTextDecorations(PresContext(), eResolvedColors, textDecs);
      if (!textDecs.HasDecorationLines()) {
        if (auto* currentPresContext = aBuilder->CurrentPresContext()) {
          currentPresContext->SetBuiltInvisibleText();
        }
        return;
      }
    }
  }

  aLists.Content()->AppendNewToTop<nsDisplayText>(aBuilder, this);
}

UniquePtr<SelectionDetails> nsTextFrame::GetSelectionDetails() {
  const nsFrameSelection* frameSelection = GetConstFrameSelection();
  if (frameSelection->IsInTableSelectionMode()) {
    return nullptr;
  }
  UniquePtr<SelectionDetails> details = frameSelection->LookUpSelection(
      mContent, GetContentOffset(), GetContentLength(), false);
  for (SelectionDetails* sd = details.get(); sd; sd = sd->mNext.get()) {
    sd->mStart += mContentOffset;
    sd->mEnd += mContentOffset;
  }
  return details;
}

static void PaintSelectionBackground(
    DrawTarget& aDrawTarget, nscolor aColor, const LayoutDeviceRect& aDirtyRect,
    const LayoutDeviceRect& aRect, nsTextFrame::DrawPathCallbacks* aCallbacks) {
  Rect rect = aRect.Intersect(aDirtyRect).ToUnknownRect();
  MaybeSnapToDevicePixels(rect, aDrawTarget);

  if (aCallbacks) {
    aCallbacks->NotifySelectionBackgroundNeedsFill(rect, aColor, aDrawTarget);
  } else {
    ColorPattern color(ToDeviceColor(aColor));
    aDrawTarget.FillRect(rect, color);
  }
}

// Attempt to get the LineBaselineOffset property of aChildFrame
// If not set, calculate this value for all child frames of aBlockFrame
static nscoord LazyGetLineBaselineOffset(nsIFrame* aChildFrame,
                                         nsBlockFrame* aBlockFrame) {
  bool offsetFound;
  nscoord offset =
      aChildFrame->GetProperty(nsIFrame::LineBaselineOffset(), &offsetFound);

  if (!offsetFound) {
    for (const auto& line : aBlockFrame->Lines()) {
      if (line.IsInline()) {
        int32_t n = line.GetChildCount();
        nscoord lineBaseline = line.BStart() + line.GetLogicalAscent();
        for (auto* lineFrame = line.mFirstChild; n > 0;
             lineFrame = lineFrame->GetNextSibling(), --n) {
          offset = lineBaseline - lineFrame->GetNormalPosition().y;
          lineFrame->SetProperty(nsIFrame::LineBaselineOffset(), offset);
        }
      }
    }
    return aChildFrame->GetProperty(nsIFrame::LineBaselineOffset(),
                                    &offsetFound);
  } else {
    return offset;
  }
}

static bool IsUnderlineRight(const ComputedStyle& aStyle) {
  // Check for 'left' or 'right' explicitly specified in the property;
  // if neither is there, we use auto positioning based on lang.
  const auto position = aStyle.StyleText()->mTextUnderlinePosition;
  if (position.IsLeft()) {
    return false;
  }
  if (position.IsRight()) {
    return true;
  }
  // If neither 'left' nor 'right' was specified, check the language.
  nsAtom* langAtom = aStyle.StyleFont()->mLanguage;
  if (!langAtom) {
    return false;
  }
  nsDependentAtomString langStr(langAtom);
  return (StringBeginsWith(langStr, u"ja"_ns) ||
          StringBeginsWith(langStr, u"ko"_ns)) &&
         (langStr.Length() == 2 || langStr[2] == '-');
}

void nsTextFrame::GetTextDecorations(
    nsPresContext* aPresContext,
    nsTextFrame::TextDecorationColorResolution aColorResolution,
    nsTextFrame::TextDecorations& aDecorations) {
  const nsCompatibility compatMode = aPresContext->CompatibilityMode();

  bool useOverride = false;
  nscolor overrideColor = NS_RGBA(0, 0, 0, 0);

  bool nearestBlockFound = false;
  // Use writing mode of parent frame for orthogonal text frame to work.
  // See comment in nsTextFrame::DrawTextRunAndDecorations.
  WritingMode wm = GetParent()->GetWritingMode();
  bool vertical = wm.IsVertical();

  nscoord ascent = GetLogicalBaseline(wm);
  // physicalBlockStartOffset represents the offset from our baseline
  // to f's physical block start, which is top in horizontal writing
  // mode, and left in vertical writing modes, in our coordinate space.
  // This physical block start is logical block start in most cases,
  // but for vertical-rl, it is logical block end, and consequently in
  // that case, it starts from the descent instead of ascent.
  nscoord physicalBlockStartOffset =
      wm.IsVerticalRL() ? GetSize().width - ascent : ascent;
  // baselineOffset represents the offset from our baseline to f's baseline or
  // the nearest block's baseline, in our coordinate space, whichever is closest
  // during the particular iteration
  nscoord baselineOffset = 0;

  for (nsIFrame *f = this, *fChild = nullptr; f;
       fChild = f, f = nsLayoutUtils::GetParentOrPlaceholderFor(f)) {
    ComputedStyle* const context = f->Style();
    if (!context->HasTextDecorationLines()) {
      break;
    }

    if (context->GetPseudoType() == PseudoStyleType::marker &&
        (context->StyleList()->mListStylePosition ==
             NS_STYLE_LIST_STYLE_POSITION_OUTSIDE ||
         !context->StyleDisplay()->IsInlineOutsideStyle())) {
      // Outside ::marker pseudos, and inside markers that aren't inlines, don't
      // have text decorations.
      break;
    }

    const nsStyleTextReset* const styleTextReset = context->StyleTextReset();
    const StyleTextDecorationLine textDecorations =
        styleTextReset->mTextDecorationLine;

    if (!useOverride &&
        (StyleTextDecorationLine::COLOR_OVERRIDE & textDecorations)) {
      // This handles the <a href="blah.html"><font color="green">La
      // la la</font></a> case. The link underline should be green.
      useOverride = true;
      overrideColor =
          nsLayoutUtils::GetColor(f, &nsStyleTextReset::mTextDecorationColor);
    }

    nsBlockFrame* fBlock = do_QueryFrame(f);
    const bool firstBlock = !nearestBlockFound && fBlock;

    // Not updating positions once we hit a parent block is equivalent to
    // the CSS 2.1 spec that blocks should propagate decorations down to their
    // children (albeit the style should be preserved)
    // However, if we're vertically aligned within a block, then we need to
    // recover the correct baseline from the line by querying the FrameProperty
    // that should be set (see nsLineLayout::VerticalAlignLine).
    if (firstBlock) {
      // At this point, fChild can't be null since TextFrames can't be blocks
      Maybe<StyleVerticalAlignKeyword> verticalAlign =
          fChild->VerticalAlignEnum();
      if (verticalAlign != Some(StyleVerticalAlignKeyword::Baseline)) {
        // Since offset is the offset in the child's coordinate space, we have
        // to undo the accumulation to bring the transform out of the block's
        // coordinate space
        const nscoord lineBaselineOffset =
            LazyGetLineBaselineOffset(fChild, fBlock);

        baselineOffset = physicalBlockStartOffset - lineBaselineOffset -
                         (vertical ? fChild->GetNormalPosition().x
                                   : fChild->GetNormalPosition().y);
      }
    } else if (!nearestBlockFound) {
      // offset here is the offset from f's baseline to f's top/left
      // boundary. It's descent for vertical-rl, and ascent otherwise.
      nscoord offset = wm.IsVerticalRL()
                           ? f->GetSize().width - f->GetLogicalBaseline(wm)
                           : f->GetLogicalBaseline(wm);
      baselineOffset = physicalBlockStartOffset - offset;
    }

    nearestBlockFound = nearestBlockFound || firstBlock;
    physicalBlockStartOffset +=
        vertical ? f->GetNormalPosition().x : f->GetNormalPosition().y;

    const uint8_t style = styleTextReset->mTextDecorationStyle;
    if (textDecorations) {
      nscolor color;
      if (useOverride) {
        color = overrideColor;
      } else if (SVGUtils::IsInSVGTextSubtree(this)) {
        // XXX We might want to do something with text-decoration-color when
        //     painting SVG text, but it's not clear what we should do.  We
        //     at least need SVG text decorations to paint with 'fill' if
        //     text-decoration-color has its initial value currentColor.
        //     We could choose to interpret currentColor as "currentFill"
        //     for SVG text, and have e.g. text-decoration-color:red to
        //     override the fill paint of the decoration.
        color = aColorResolution == eResolvedColors
                    ? nsLayoutUtils::GetColor(f, &nsStyleSVG::mFill)
                    : NS_SAME_AS_FOREGROUND_COLOR;
      } else {
        color =
            nsLayoutUtils::GetColor(f, &nsStyleTextReset::mTextDecorationColor);
      }

      bool swapUnderlineAndOverline =
          wm.IsCentralBaseline() && IsUnderlineRight(*context);
      const auto kUnderline = swapUnderlineAndOverline
                                  ? StyleTextDecorationLine::OVERLINE
                                  : StyleTextDecorationLine::UNDERLINE;
      const auto kOverline = swapUnderlineAndOverline
                                 ? StyleTextDecorationLine::UNDERLINE
                                 : StyleTextDecorationLine::OVERLINE;

      const nsStyleText* const styleText = context->StyleText();
      if (textDecorations & kUnderline) {
        aDecorations.mUnderlines.AppendElement(nsTextFrame::LineDecoration(
            f, baselineOffset, styleText->mTextUnderlinePosition,
            styleText->mTextUnderlineOffset,
            styleTextReset->mTextDecorationThickness, color, style));
      }
      if (textDecorations & kOverline) {
        aDecorations.mOverlines.AppendElement(nsTextFrame::LineDecoration(
            f, baselineOffset, styleText->mTextUnderlinePosition,
            styleText->mTextUnderlineOffset,
            styleTextReset->mTextDecorationThickness, color, style));
      }
      if (textDecorations & StyleTextDecorationLine::LINE_THROUGH) {
        aDecorations.mStrikes.AppendElement(nsTextFrame::LineDecoration(
            f, baselineOffset, styleText->mTextUnderlinePosition,
            styleText->mTextUnderlineOffset,
            styleTextReset->mTextDecorationThickness, color, style));
      }
    }

    // In all modes, if we're on an inline-block/table/grid/flex (or
    // -moz-inline-box), we're done.
    // If we're on a ruby frame other than ruby text container, we
    // should continue.
    mozilla::StyleDisplay display = f->GetDisplay();
    if (!nsStyleDisplay::IsInlineFlow(display) &&
        (!nsStyleDisplay::IsRubyDisplayType(display) ||
         display == mozilla::StyleDisplay::RubyTextContainer) &&
        nsStyleDisplay::IsDisplayTypeInlineOutside(display)) {
      break;
    }

    // In quirks mode, if we're on an HTML table element, we're done.
    if (compatMode == eCompatibility_NavQuirks &&
        f->GetContent()->IsHTMLElement(nsGkAtoms::table)) {
      break;
    }

    // If we're on an absolutely-positioned element or a floating
    // element, we're done.
    if (f->IsFloating() || f->IsAbsolutelyPositioned()) {
      break;
    }

    // If we're an outer <svg> element, which is classified as an atomic
    // inline-level element, we're done.
    if (f->IsSVGOuterSVGFrame()) {
      break;
    }
  }
}

static float GetInflationForTextDecorations(nsIFrame* aFrame,
                                            nscoord aInflationMinFontSize) {
  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
    auto container =
        nsLayoutUtils::GetClosestFrameOfType(aFrame, LayoutFrameType::SVGText);
    MOZ_ASSERT(container);
    return static_cast<SVGTextFrame*>(container)->GetFontSizeScaleFactor();
  }
  return nsLayoutUtils::FontSizeInflationInner(aFrame, aInflationMinFontSize);
}

struct EmphasisMarkInfo {
  RefPtr<gfxTextRun> textRun;
  gfxFloat advance;
  gfxFloat baselineOffset;
};

NS_DECLARE_FRAME_PROPERTY_DELETABLE(EmphasisMarkProperty, EmphasisMarkInfo)

static void ComputeTextEmphasisStyleString(const StyleTextEmphasisStyle& aStyle,
                                           nsAString& aOut) {
  MOZ_ASSERT(!aStyle.IsNone());
  if (aStyle.IsString()) {
    nsDependentCSubstring string = aStyle.AsString().AsString();
    AppendUTF8toUTF16(string, aOut);
    return;
  }
  const auto& keyword = aStyle.AsKeyword();
  const bool fill = keyword.fill == StyleTextEmphasisFillMode::Filled;
  switch (keyword.shape) {
    case StyleTextEmphasisShapeKeyword::Dot:
      return aOut.AppendLiteral(fill ? u"\u2022" : u"\u25e6");
    case StyleTextEmphasisShapeKeyword::Circle:
      return aOut.AppendLiteral(fill ? u"\u25cf" : u"\u25cb");
    case StyleTextEmphasisShapeKeyword::DoubleCircle:
      return aOut.AppendLiteral(fill ? u"\u25c9" : u"\u25ce");
    case StyleTextEmphasisShapeKeyword::Triangle:
      return aOut.AppendLiteral(fill ? u"\u25b2" : u"\u25b3");
    case StyleTextEmphasisShapeKeyword::Sesame:
      return aOut.AppendLiteral(fill ? u"\ufe45" : u"\ufe46");
    default:
      MOZ_ASSERT_UNREACHABLE("Unknown emphasis style shape");
  }
}

static already_AddRefed<gfxTextRun> GenerateTextRunForEmphasisMarks(
    nsTextFrame* aFrame, gfxFontGroup* aFontGroup,
    ComputedStyle* aComputedStyle, const nsStyleText* aStyleText) {
  nsAutoString string;
  ComputeTextEmphasisStyleString(aStyleText->mTextEmphasisStyle, string);

  RefPtr<DrawTarget> dt = CreateReferenceDrawTarget(aFrame);
  auto appUnitsPerDevUnit = aFrame->PresContext()->AppUnitsPerDevPixel();
  gfx::ShapedTextFlags flags =
      nsLayoutUtils::GetTextRunOrientFlagsForStyle(aComputedStyle);
  if (flags == gfx::ShapedTextFlags::TEXT_ORIENT_VERTICAL_MIXED) {
    // The emphasis marks should always be rendered upright per spec.
    flags = gfx::ShapedTextFlags::TEXT_ORIENT_VERTICAL_UPRIGHT;
  }
  return aFontGroup->MakeTextRun<char16_t>(string.get(), string.Length(), dt,
                                           appUnitsPerDevUnit, flags,
                                           nsTextFrameUtils::Flags(), nullptr);
}

static nsRubyFrame* FindFurthestInlineRubyAncestor(nsTextFrame* aFrame) {
  nsRubyFrame* rubyFrame = nullptr;
  for (nsIFrame* frame = aFrame->GetParent();
       frame && frame->IsFrameOfType(nsIFrame::eLineParticipant);
       frame = frame->GetParent()) {
    if (frame->IsRubyFrame()) {
      rubyFrame = static_cast<nsRubyFrame*>(frame);
    }
  }
  return rubyFrame;
}

nsRect nsTextFrame::UpdateTextEmphasis(WritingMode aWM,
                                       PropertyProvider& aProvider) {
  const nsStyleText* styleText = StyleText();
  if (!styleText->HasEffectiveTextEmphasis()) {
    RemoveProperty(EmphasisMarkProperty());
    return nsRect();
  }

  ComputedStyle* computedStyle = Style();
  bool isTextCombined = computedStyle->IsTextCombined();
  if (isTextCombined) {
    computedStyle = GetParent()->Style();
  }
  RefPtr<nsFontMetrics> fm = nsLayoutUtils::GetFontMetricsOfEmphasisMarks(
      computedStyle, PresContext(), GetFontSizeInflation());
  EmphasisMarkInfo* info = new EmphasisMarkInfo;
  info->textRun = GenerateTextRunForEmphasisMarks(
      this, fm->GetThebesFontGroup(), computedStyle, styleText);
  info->advance = info->textRun->GetAdvanceWidth();

  // Calculate the baseline offset
  LogicalSide side = styleText->TextEmphasisSide(aWM);
  LogicalSize frameSize = GetLogicalSize(aWM);
  // The overflow rect is inflated in the inline direction by half
  // advance of the emphasis mark on each side, so that even if a mark
  // is drawn for a zero-width character, it won't be clipped.
  LogicalRect overflowRect(aWM, -info->advance / 2,
                           /* BStart to be computed below */ 0,
                           frameSize.ISize(aWM) + info->advance,
                           fm->MaxAscent() + fm->MaxDescent());
  RefPtr<nsFontMetrics> baseFontMetrics =
      isTextCombined
          ? nsLayoutUtils::GetInflatedFontMetricsForFrame(GetParent())
          : do_AddRef(aProvider.GetFontMetrics());
  // When the writing mode is vertical-lr the line is inverted, and thus
  // the ascent and descent are swapped.
  nscoord absOffset = (side == eLogicalSideBStart) != aWM.IsLineInverted()
                          ? baseFontMetrics->MaxAscent() + fm->MaxDescent()
                          : baseFontMetrics->MaxDescent() + fm->MaxAscent();
  RubyBlockLeadings leadings;
  if (nsRubyFrame* ruby = FindFurthestInlineRubyAncestor(this)) {
    leadings = ruby->GetBlockLeadings();
  }
  if (side == eLogicalSideBStart) {
    info->baselineOffset = -absOffset - leadings.mStart;
    overflowRect.BStart(aWM) = -overflowRect.BSize(aWM) - leadings.mStart;
  } else {
    MOZ_ASSERT(side == eLogicalSideBEnd);
    info->baselineOffset = absOffset + leadings.mEnd;
    overflowRect.BStart(aWM) = frameSize.BSize(aWM) + leadings.mEnd;
  }
  // If text combined, fix the gap between the text frame and its parent.
  if (isTextCombined) {
    nscoord gap = (baseFontMetrics->MaxHeight() - frameSize.BSize(aWM)) / 2;
    overflowRect.BStart(aWM) += gap * (side == eLogicalSideBStart ? -1 : 1);
  }

  SetProperty(EmphasisMarkProperty(), info);
  return overflowRect.GetPhysicalRect(aWM, frameSize.GetPhysicalSize(aWM));
}

// helper function for implementing text-decoration-thickness
// https://drafts.csswg.org/css-text-decor-4/#text-decoration-width-property
// Returns the thickness in device pixels.
static gfxFloat ComputeDecorationLineThickness(
    const StyleTextDecorationLength& aThickness, const gfxFloat aAutoValue,
    const gfxFont::Metrics& aFontMetrics, const gfxFloat aAppUnitsPerDevPixel,
    const nsIFrame* aFrame) {
  if (aThickness.IsAuto()) {
    return aAutoValue;
  }

  if (aThickness.IsFromFont()) {
    return aFontMetrics.underlineSize;
  }
  auto em = [&] { return aFrame->StyleFont()->mSize.ToAppUnits(); };
  return aThickness.AsLengthPercentage().Resolve(em) / aAppUnitsPerDevPixel;
}

// Helper function for implementing text-underline-offset and -position
// https://drafts.csswg.org/css-text-decor-4/#underline-offset
// Returns the offset in device pixels.
static gfxFloat ComputeDecorationLineOffset(
    StyleTextDecorationLine aLineType,
    const StyleTextUnderlinePosition& aPosition,
    const LengthPercentageOrAuto& aOffset, const gfxFont::Metrics& aFontMetrics,
    const gfxFloat aAppUnitsPerDevPixel, const nsIFrame* aFrame,
    bool aIsCentralBaseline, bool aSwappedUnderline) {
  // Em value to use if we need to resolve a percentage length.
  auto em = [&] { return aFrame->StyleFont()->mSize.ToAppUnits(); };
  // If we're in vertical-upright typographic mode, we need to compute the
  // offset of the decoration line from the default central baseline.
  if (aIsCentralBaseline) {
    // Line-through simply goes at the (central) baseline.
    if (aLineType == StyleTextDecorationLine::LINE_THROUGH) {
      return 0;
    }

    // Compute "zero position" for the under- or overline.
    gfxFloat zeroPos = 0.5 * aFontMetrics.emHeight;

    // aOffset applies to underline only; for overline (or offset:auto) we use
    // a somewhat arbitrary offset of half the font's (horziontal-mode) value
    // for underline-offset, to get a little bit of separation between glyph
    // edges and the line in typical cases.
    // If we have swapped under-/overlines for text-underline-position:right,
    // we need to take account of this to determine which decoration lines are
    // "real" underlines which should respect the text-underline-* values.
    bool isUnderline =
        (aLineType == StyleTextDecorationLine::UNDERLINE) != aSwappedUnderline;
    gfxFloat offset =
        isUnderline && !aOffset.IsAuto()
            ? aOffset.AsLengthPercentage().Resolve(em) / aAppUnitsPerDevPixel
            : aFontMetrics.underlineOffset * -0.5;

    // Direction of the decoration line's offset from the central baseline.
    gfxFloat dir = aLineType == StyleTextDecorationLine::OVERLINE ? 1.0 : -1.0;
    return dir * (zeroPos + offset);
  }

  // Compute line offset for horizontal typographic mode.
  if (aLineType == StyleTextDecorationLine::UNDERLINE) {
    if (aPosition.IsFromFont()) {
      gfxFloat zeroPos = aFontMetrics.underlineOffset;
      gfxFloat offset =
          aOffset.IsAuto()
              ? 0
              : aOffset.AsLengthPercentage().Resolve(em) / aAppUnitsPerDevPixel;
      return zeroPos - offset;
    }

    if (aPosition.IsUnder()) {
      gfxFloat zeroPos = -aFontMetrics.maxDescent;
      gfxFloat offset =
          aOffset.IsAuto()
              ? -0.5 * aFontMetrics.underlineOffset
              : aOffset.AsLengthPercentage().Resolve(em) / aAppUnitsPerDevPixel;
      return zeroPos - offset;
    }

    // text-underline-position must be 'auto', so zero position is the
    // baseline and 'auto' offset will apply the font's underline-offset.
    //
    // If offset is `auto`, we clamp the offset (in horizontal typographic mode)
    // to a minimum of 1/16 em (equivalent to 1px at font-size 16px) to mitigate
    // skip-ink issues with fonts that leave the underlineOffset field as zero.
    MOZ_ASSERT(aPosition.IsAuto());
    return aOffset.IsAuto() ? std::min(aFontMetrics.underlineOffset,
                                       -aFontMetrics.emHeight / 16.0)
                            : -aOffset.AsLengthPercentage().Resolve(em) /
                                  aAppUnitsPerDevPixel;
  }

  if (aLineType == StyleTextDecorationLine::OVERLINE) {
    return aFontMetrics.maxAscent;
  }

  if (aLineType == StyleTextDecorationLine::LINE_THROUGH) {
    return aFontMetrics.strikeoutOffset;
  }

  MOZ_ASSERT_UNREACHABLE("unknown decoration line type");
  return 0;
}

void nsTextFrame::UnionAdditionalOverflow(nsPresContext* aPresContext,
                                          nsIFrame* aBlock,
                                          PropertyProvider& aProvider,
                                          nsRect* aInkOverflowRect,
                                          bool aIncludeTextDecorations,
                                          bool aIncludeShadows) {
  const WritingMode wm = GetWritingMode();
  bool verticalRun = mTextRun->IsVertical();
  const gfxFloat appUnitsPerDevUnit = aPresContext->AppUnitsPerDevPixel();

  if (IsFloatingFirstLetterChild()) {
    bool inverted = wm.IsLineInverted();
    // The underline/overline drawable area must be contained in the overflow
    // rect when this is in floating first letter frame at *both* modes.
    // In this case, aBlock is the ::first-letter frame.
    uint8_t decorationStyle =
        aBlock->Style()->StyleTextReset()->mTextDecorationStyle;
    // If the style is none, let's include decoration line rect as solid style
    // since changing the style from none to solid/dotted/dashed doesn't cause
    // reflow.
    if (decorationStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
      decorationStyle = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
    }
    nsCSSRendering::DecorationRectParams params;

    bool useVerticalMetrics = verticalRun && mTextRun->UseCenterBaseline();
    nsFontMetrics* fontMetrics = aProvider.GetFontMetrics();
    RefPtr<gfxFont> font =
        fontMetrics->GetThebesFontGroup()->GetFirstValidFont();
    const gfxFont::Metrics& metrics =
        font->GetMetrics(useVerticalMetrics ? nsFontMetrics::eVertical
                                            : nsFontMetrics::eHorizontal);

    params.defaultLineThickness = metrics.underlineSize;
    params.lineSize.height = ComputeDecorationLineThickness(
        aBlock->Style()->StyleTextReset()->mTextDecorationThickness,
        params.defaultLineThickness, metrics, appUnitsPerDevUnit, this);

    const auto* styleText = aBlock->StyleText();
    bool swapUnderline =
        wm.IsCentralBaseline() && IsUnderlineRight(*aBlock->Style());
    params.offset = ComputeDecorationLineOffset(
        StyleTextDecorationLine::UNDERLINE, styleText->mTextUnderlinePosition,
        styleText->mTextUnderlineOffset, metrics, appUnitsPerDevUnit, this,
        wm.IsCentralBaseline(), swapUnderline);

    nscoord maxAscent =
        inverted ? fontMetrics->MaxDescent() : fontMetrics->MaxAscent();

    Float gfxWidth =
        (verticalRun ? aInkOverflowRect->height : aInkOverflowRect->width) /
        appUnitsPerDevUnit;
    params.lineSize.width = gfxWidth;
    params.ascent = gfxFloat(mAscent) / appUnitsPerDevUnit;
    params.style = decorationStyle;
    params.vertical = verticalRun;
    params.sidewaysLeft = mTextRun->IsSidewaysLeft();
    params.decoration = StyleTextDecorationLine::UNDERLINE;
    nsRect underlineRect =
        nsCSSRendering::GetTextDecorationRect(aPresContext, params);

    // TODO(jfkthame):
    // Should we actually be calling ComputeDecorationLineOffset again here?
    params.offset = maxAscent / appUnitsPerDevUnit;
    params.decoration = StyleTextDecorationLine::OVERLINE;
    nsRect overlineRect =
        nsCSSRendering::GetTextDecorationRect(aPresContext, params);

    aInkOverflowRect->UnionRect(*aInkOverflowRect, underlineRect);
    aInkOverflowRect->UnionRect(*aInkOverflowRect, overlineRect);

    // XXX If strikeoutSize is much thicker than the underlineSize, it may
    //     cause overflowing from the overflow rect.  However, such case
    //     isn't realistic, we don't need to compute it now.
  }
  if (aIncludeTextDecorations) {
    // Use writing mode of parent frame for orthogonal text frame to
    // work. See comment in nsTextFrame::DrawTextRunAndDecorations.
    WritingMode parentWM = GetParent()->GetWritingMode();
    bool verticalDec = parentWM.IsVertical();
    bool useVerticalMetrics =
        verticalDec != verticalRun
            ? verticalDec
            : verticalRun && mTextRun->UseCenterBaseline();

    // Since CSS 2.1 requires that text-decoration defined on ancestors maintain
    // style and position, they can be drawn at virtually any y-offset, so
    // maxima and minima are required to reliably generate the rectangle for
    // them
    TextDecorations textDecs;
    GetTextDecorations(aPresContext, eResolvedColors, textDecs);
    if (textDecs.HasDecorationLines()) {
      nscoord inflationMinFontSize =
          nsLayoutUtils::InflationMinFontSizeFor(aBlock);

      const nscoord measure = verticalDec ? GetSize().height : GetSize().width;
      gfxFloat gfxWidth = measure / appUnitsPerDevUnit;
      gfxFloat ascent =
          gfxFloat(GetLogicalBaseline(parentWM)) / appUnitsPerDevUnit;
      nscoord frameBStart = 0;
      if (parentWM.IsVerticalRL()) {
        frameBStart = GetSize().width;
        ascent = -ascent;
      }

      nsCSSRendering::DecorationRectParams params;
      params.lineSize = Size(gfxWidth, 0);
      params.ascent = ascent;
      params.vertical = verticalDec;
      params.sidewaysLeft = mTextRun->IsSidewaysLeft();

      nscoord topOrLeft(nscoord_MAX), bottomOrRight(nscoord_MIN);
      typedef gfxFont::Metrics Metrics;
      auto accumulateDecorationRect =
          [&](const LineDecoration& dec, gfxFloat Metrics::*lineSize,
              mozilla::StyleTextDecorationLine lineType) {
            params.style = dec.mStyle;
            // If the style is solid, let's include decoration line rect of
            // solid style since changing the style from none to
            // solid/dotted/dashed doesn't cause reflow.
            if (params.style == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
              params.style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
            }

            float inflation = GetInflationForTextDecorations(
                dec.mFrame, inflationMinFontSize);
            const Metrics metrics =
                GetFirstFontMetrics(GetFontGroupForFrame(dec.mFrame, inflation),
                                    useVerticalMetrics);

            params.defaultLineThickness = metrics.*lineSize;
            params.lineSize.height = ComputeDecorationLineThickness(
                dec.mTextDecorationThickness, params.defaultLineThickness,
                metrics, appUnitsPerDevUnit, this);

            bool swapUnderline =
                parentWM.IsCentralBaseline() && IsUnderlineRight(*Style());
            params.offset = ComputeDecorationLineOffset(
                lineType, dec.mTextUnderlinePosition, dec.mTextUnderlineOffset,
                metrics, appUnitsPerDevUnit, this, parentWM.IsCentralBaseline(),
                swapUnderline);

            const nsRect decorationRect =
                nsCSSRendering::GetTextDecorationRect(aPresContext, params) +
                (verticalDec ? nsPoint(frameBStart - dec.mBaselineOffset, 0)
                             : nsPoint(0, -dec.mBaselineOffset));

            if (verticalDec) {
              topOrLeft = std::min(decorationRect.x, topOrLeft);
              bottomOrRight = std::max(decorationRect.XMost(), bottomOrRight);
            } else {
              topOrLeft = std::min(decorationRect.y, topOrLeft);
              bottomOrRight = std::max(decorationRect.YMost(), bottomOrRight);
            }
          };

      // Below we loop through all text decorations and compute the rectangle
      // containing all of them, in this frame's coordinate space
      params.decoration = StyleTextDecorationLine::UNDERLINE;
      for (const LineDecoration& dec : textDecs.mUnderlines) {
        accumulateDecorationRect(dec, &Metrics::underlineSize,
                                 params.decoration);
      }
      params.decoration = StyleTextDecorationLine::OVERLINE;
      for (const LineDecoration& dec : textDecs.mOverlines) {
        accumulateDecorationRect(dec, &Metrics::underlineSize,
                                 params.decoration);
      }
      params.decoration = StyleTextDecorationLine::LINE_THROUGH;
      for (const LineDecoration& dec : textDecs.mStrikes) {
        accumulateDecorationRect(dec, &Metrics::strikeoutSize,
                                 params.decoration);
      }

      aInkOverflowRect->UnionRect(
          *aInkOverflowRect,
          verticalDec
              ? nsRect(topOrLeft, 0, bottomOrRight - topOrLeft, measure)
              : nsRect(0, topOrLeft, measure, bottomOrRight - topOrLeft));
    }

    aInkOverflowRect->UnionRect(*aInkOverflowRect,
                                UpdateTextEmphasis(parentWM, aProvider));
  }

  // text-stroke overflows: add half of text-stroke-width on all sides
  nscoord textStrokeWidth = StyleText()->mWebkitTextStrokeWidth;
  if (textStrokeWidth > 0) {
    // Inflate rect by stroke-width/2; we add an extra pixel to allow for
    // antialiasing, rounding errors, etc.
    nsRect strokeRect = *aInkOverflowRect;
    strokeRect.Inflate(textStrokeWidth / 2 + appUnitsPerDevUnit);
    aInkOverflowRect->UnionRect(*aInkOverflowRect, strokeRect);
  }

  // Text-shadow overflows
  if (aIncludeShadows) {
    nsRect shadowRect =
        nsLayoutUtils::GetTextShadowRectsUnion(*aInkOverflowRect, this);
    aInkOverflowRect->UnionRect(*aInkOverflowRect, shadowRect);
  }

  // When this frame is not selected, the text-decoration area must be in
  // frame bounds.
  if (!IsSelected() ||
      !CombineSelectionUnderlineRect(aPresContext, *aInkOverflowRect))
    return;
  AddStateBits(TEXT_SELECTION_UNDERLINE_OVERFLOWED);
}

gfxFloat nsTextFrame::ComputeDescentLimitForSelectionUnderline(
    nsPresContext* aPresContext, const gfxFont::Metrics& aFontMetrics) {
  gfxFloat app = aPresContext->AppUnitsPerDevPixel();
  nscoord lineHeightApp =
      ReflowInput::CalcLineHeight(GetContent(), Style(), PresContext(),
                                  NS_UNCONSTRAINEDSIZE, GetFontSizeInflation());
  gfxFloat lineHeight = gfxFloat(lineHeightApp) / app;
  if (lineHeight <= aFontMetrics.maxHeight) {
    return aFontMetrics.maxDescent;
  }
  return aFontMetrics.maxDescent + (lineHeight - aFontMetrics.maxHeight) / 2;
}

// Make sure this stays in sync with DrawSelectionDecorations below
static const SelectionTypeMask kSelectionTypesWithDecorations =
    ToSelectionTypeMask(SelectionType::eSpellCheck) |
    ToSelectionTypeMask(SelectionType::eURLStrikeout) |
    ToSelectionTypeMask(SelectionType::eIMERawClause) |
    ToSelectionTypeMask(SelectionType::eIMESelectedRawClause) |
    ToSelectionTypeMask(SelectionType::eIMEConvertedClause) |
    ToSelectionTypeMask(SelectionType::eIMESelectedClause);

/* static */
gfxFloat nsTextFrame::ComputeSelectionUnderlineHeight(
    nsPresContext* aPresContext, const gfxFont::Metrics& aFontMetrics,
    SelectionType aSelectionType) {
  switch (aSelectionType) {
    case SelectionType::eIMERawClause:
    case SelectionType::eIMESelectedRawClause:
    case SelectionType::eIMEConvertedClause:
    case SelectionType::eIMESelectedClause:
      return aFontMetrics.underlineSize;
    case SelectionType::eSpellCheck: {
      // The thickness of the spellchecker underline shouldn't honor the font
      // metrics.  It should be constant pixels value which is decided from the
      // default font size.  Note that if the actual font size is smaller than
      // the default font size, we should use the actual font size because the
      // computed value from the default font size can be too thick for the
      // current font size.
      Length defaultFontSize =
          aPresContext->Document()
              ->GetFontPrefsForLang(nullptr)
              ->GetDefaultFont(StyleGenericFontFamily::None)
              ->size;
      int32_t zoomedFontSize = aPresContext->CSSPixelsToDevPixels(
          nsStyleFont::ZoomText(*aPresContext->Document(), defaultFontSize)
              .ToCSSPixels());
      gfxFloat fontSize =
          std::min(gfxFloat(zoomedFontSize), aFontMetrics.emHeight);
      fontSize = std::max(fontSize, 1.0);
      return ceil(fontSize / 20);
    }
    default:
      NS_WARNING("Requested underline style is not valid");
      return aFontMetrics.underlineSize;
  }
}

enum class DecorationType { Normal, Selection };
struct nsTextFrame::PaintDecorationLineParams
    : nsCSSRendering::DecorationRectParams {
  gfxContext* context = nullptr;
  LayoutDeviceRect dirtyRect;
  Point pt;
  const nscolor* overrideColor = nullptr;
  nscolor color = NS_RGBA(0, 0, 0, 0);
  gfxFloat icoordInFrame = 0.0f;
  gfxFloat baselineOffset = 0.0f;
  DecorationType decorationType = DecorationType::Normal;
  DrawPathCallbacks* callbacks = nullptr;
};

void nsTextFrame::PaintDecorationLine(
    const PaintDecorationLineParams& aParams) {
  nsCSSRendering::PaintDecorationLineParams params;
  static_cast<nsCSSRendering::DecorationRectParams&>(params) = aParams;
  params.dirtyRect = aParams.dirtyRect.ToUnknownRect();
  params.pt = aParams.pt;
  params.color = aParams.overrideColor ? *aParams.overrideColor : aParams.color;
  params.icoordInFrame = Float(aParams.icoordInFrame);
  params.baselineOffset = Float(aParams.baselineOffset);
  if (aParams.callbacks) {
    Rect path = nsCSSRendering::DecorationLineToPath(params);
    if (aParams.decorationType == DecorationType::Normal) {
      aParams.callbacks->PaintDecorationLine(path, params.color);
    } else {
      aParams.callbacks->PaintSelectionDecorationLine(path, params.color);
    }
  } else {
    nsCSSRendering::PaintDecorationLine(this, *aParams.context->GetDrawTarget(),
                                        params);
  }
}

static uint8_t ToStyleLineStyle(const TextRangeStyle& aStyle) {
  switch (aStyle.mLineStyle) {
    case TextRangeStyle::LineStyle::None:
      return NS_STYLE_TEXT_DECORATION_STYLE_NONE;
    case TextRangeStyle::LineStyle::Solid:
      return NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
    case TextRangeStyle::LineStyle::Dotted:
      return NS_STYLE_TEXT_DECORATION_STYLE_DOTTED;
    case TextRangeStyle::LineStyle::Dashed:
      return NS_STYLE_TEXT_DECORATION_STYLE_DASHED;
    case TextRangeStyle::LineStyle::Double:
      return NS_STYLE_TEXT_DECORATION_STYLE_DOUBLE;
    case TextRangeStyle::LineStyle::Wavy:
      return NS_STYLE_TEXT_DECORATION_STYLE_WAVY;
  }
  MOZ_ASSERT_UNREACHABLE("Invalid line style");
  return NS_STYLE_TEXT_DECORATION_STYLE_NONE;
}

/**
 * This, plus kSelectionTypesWithDecorations, encapsulates all knowledge
 * about drawing text decoration for selections.
 */
void nsTextFrame::DrawSelectionDecorations(
    gfxContext* aContext, const LayoutDeviceRect& aDirtyRect,
    SelectionType aSelectionType, nsTextPaintStyle& aTextPaintStyle,
    const TextRangeStyle& aRangeStyle, const Point& aPt,
    gfxFloat aICoordInFrame, gfxFloat aWidth, gfxFloat aAscent,
    const gfxFont::Metrics& aFontMetrics, DrawPathCallbacks* aCallbacks,
    bool aVertical, StyleTextDecorationLine aDecoration) {
  PaintDecorationLineParams params;
  params.context = aContext;
  params.dirtyRect = aDirtyRect;
  params.pt = aPt;
  params.lineSize.width = aWidth;
  params.ascent = aAscent;
  params.decoration = aDecoration;
  params.decorationType = DecorationType::Selection;
  params.callbacks = aCallbacks;
  params.vertical = aVertical;
  params.sidewaysLeft = mTextRun->IsSidewaysLeft();
  params.descentLimit = ComputeDescentLimitForSelectionUnderline(
      aTextPaintStyle.PresContext(), aFontMetrics);

  float relativeSize;
  const auto& decThickness = StyleTextReset()->mTextDecorationThickness;
  const gfxFloat appUnitsPerDevPixel =
      aTextPaintStyle.PresContext()->AppUnitsPerDevPixel();

  const WritingMode wm = GetWritingMode();
  switch (aSelectionType) {
    case SelectionType::eIMERawClause:
    case SelectionType::eIMESelectedRawClause:
    case SelectionType::eIMEConvertedClause:
    case SelectionType::eIMESelectedClause:
    case SelectionType::eSpellCheck: {
      int32_t index = nsTextPaintStyle::GetUnderlineStyleIndexForSelectionType(
          aSelectionType);
      bool weDefineSelectionUnderline =
          aTextPaintStyle.GetSelectionUnderlineForPaint(
              index, &params.color, &relativeSize, &params.style);
      params.defaultLineThickness = ComputeSelectionUnderlineHeight(
          aTextPaintStyle.PresContext(), aFontMetrics, aSelectionType);
      params.lineSize.height = ComputeDecorationLineThickness(
          decThickness, params.defaultLineThickness, aFontMetrics,
          appUnitsPerDevPixel, this);

      bool swapUnderline = wm.IsCentralBaseline() && IsUnderlineRight(*Style());
      const auto* styleText = StyleText();
      params.offset = ComputeDecorationLineOffset(
          aDecoration, styleText->mTextUnderlinePosition,
          styleText->mTextUnderlineOffset, aFontMetrics, appUnitsPerDevPixel,
          this, wm.IsCentralBaseline(), swapUnderline);

      bool isIMEType = aSelectionType != SelectionType::eSpellCheck;

      if (isIMEType) {
        // IME decoration lines should not be drawn on the both ends, i.e., we
        // need to cut both edges of the decoration lines.  Because same style
        // IME selections can adjoin, but the users need to be able to know
        // where are the boundaries of the selections.
        //
        //  X: underline
        //
        //     IME selection #1        IME selection #2      IME selection #3
        //  |                     |                      |
        //  | XXXXXXXXXXXXXXXXXXX | XXXXXXXXXXXXXXXXXXXX | XXXXXXXXXXXXXXXXXXX
        //  +---------------------+----------------------+--------------------
        //   ^                   ^ ^                    ^ ^
        //  gap                  gap                    gap
        params.pt.x += 1.0;
        params.lineSize.width -= 2.0;
      }
      if (isIMEType && aRangeStyle.IsDefined()) {
        // If IME defines the style, that should override our definition.
        if (aRangeStyle.IsLineStyleDefined()) {
          if (aRangeStyle.mLineStyle == TextRangeStyle::LineStyle::None) {
            return;
          }
          params.style = ToStyleLineStyle(aRangeStyle);
          relativeSize = aRangeStyle.mIsBoldLine ? 2.0f : 1.0f;
        } else if (!weDefineSelectionUnderline) {
          // There is no underline style definition.
          return;
        }
        // If underline color is defined and that doesn't depend on the
        // foreground color, we should use the color directly.
        if (aRangeStyle.IsUnderlineColorDefined() &&
            (!aRangeStyle.IsForegroundColorDefined() ||
             aRangeStyle.mUnderlineColor != aRangeStyle.mForegroundColor)) {
          params.color = aRangeStyle.mUnderlineColor;
        }
        // If foreground color or background color is defined, the both colors
        // are computed by GetSelectionTextColors().  Then, we should use its
        // foreground color always.  The color should have sufficient contrast
        // with the background color.
        else if (aRangeStyle.IsForegroundColorDefined() ||
                 aRangeStyle.IsBackgroundColorDefined()) {
          nscolor bg;
          GetSelectionTextColors(aSelectionType, aTextPaintStyle, aRangeStyle,
                                 &params.color, &bg);
        }
        // Otherwise, use the foreground color of the frame.
        else {
          params.color = aTextPaintStyle.GetTextColor();
        }
      } else if (!weDefineSelectionUnderline) {
        // IME doesn't specify the selection style and we don't define selection
        // underline.
        return;
      }
      break;
    }
    case SelectionType::eURLStrikeout: {
      nscoord inflationMinFontSize =
          nsLayoutUtils::InflationMinFontSizeFor(this);
      float inflation =
          GetInflationForTextDecorations(this, inflationMinFontSize);
      const gfxFont::Metrics metrics =
          GetFirstFontMetrics(GetFontGroupForFrame(this, inflation), aVertical);

      relativeSize = 2.0f;
      aTextPaintStyle.GetURLSecondaryColor(&params.color);
      params.style = NS_STYLE_TEXT_DECORATION_STYLE_SOLID;
      params.defaultLineThickness = metrics.strikeoutSize;
      params.lineSize.height = ComputeDecorationLineThickness(
          decThickness, params.defaultLineThickness, metrics,
          appUnitsPerDevPixel, this);
      // TODO(jfkthame): ComputeDecorationLineOffset? check vertical mode!
      params.offset = metrics.strikeoutOffset + 0.5;
      params.decoration = StyleTextDecorationLine::LINE_THROUGH;
      break;
    }
    default:
      NS_WARNING("Requested selection decorations when there aren't any");
      return;
  }
  params.lineSize.height *= relativeSize;
  params.defaultLineThickness *= relativeSize;
  params.icoordInFrame =
      (aVertical ? params.pt.y - aPt.y : params.pt.x - aPt.x) + aICoordInFrame;
  PaintDecorationLine(params);
}

/* static */
bool nsTextFrame::GetSelectionTextColors(SelectionType aSelectionType,
                                         nsTextPaintStyle& aTextPaintStyle,
                                         const TextRangeStyle& aRangeStyle,
                                         nscolor* aForeground,
                                         nscolor* aBackground) {
  switch (aSelectionType) {
    case SelectionType::eNormal:
      return aTextPaintStyle.GetSelectionColors(aForeground, aBackground);
    case SelectionType::eFind:
      aTextPaintStyle.GetHighlightColors(aForeground, aBackground);
      return true;
    case SelectionType::eURLSecondary:
      aTextPaintStyle.GetURLSecondaryColor(aForeground);
      *aBackground = NS_RGBA(0, 0, 0, 0);
      return true;
    case SelectionType::eIMERawClause:
    case SelectionType::eIMESelectedRawClause:
    case SelectionType::eIMEConvertedClause:
    case SelectionType::eIMESelectedClause:
      if (aRangeStyle.IsDefined()) {
        if (!aRangeStyle.IsForegroundColorDefined() &&
            !aRangeStyle.IsBackgroundColorDefined()) {
          *aForeground = aTextPaintStyle.GetTextColor();
          *aBackground = NS_RGBA(0, 0, 0, 0);
          return false;
        }
        if (aRangeStyle.IsForegroundColorDefined()) {
          *aForeground = aRangeStyle.mForegroundColor;
          if (aRangeStyle.IsBackgroundColorDefined()) {
            *aBackground = aRangeStyle.mBackgroundColor;
          } else {
            // If foreground color is defined but background color isn't
            // defined, we can guess that IME must expect that the background
            // color is system's default field background color.
            *aBackground = aTextPaintStyle.GetSystemFieldBackgroundColor();
          }
        } else {  // aRangeStyle.IsBackgroundColorDefined() is true
          *aBackground = aRangeStyle.mBackgroundColor;
          // If background color is defined but foreground color isn't defined,
          // we can assume that IME must expect that the foreground color is
          // same as system's field text color.
          *aForeground = aTextPaintStyle.GetSystemFieldForegroundColor();
        }
        return true;
      }
      aTextPaintStyle.GetIMESelectionColors(
          nsTextPaintStyle::GetUnderlineStyleIndexForSelectionType(
              aSelectionType),
          aForeground, aBackground);
      return true;
    default:
      *aForeground = aTextPaintStyle.GetTextColor();
      *aBackground = NS_RGBA(0, 0, 0, 0);
      return false;
  }
}

/**
 * This sets *aShadows to the appropriate shadows, if any, for the given
 * type of selection.
 * If text-shadow was not specified, *aShadows is left untouched.
 */
static void GetSelectionTextShadow(nsIFrame* aFrame,
                                   SelectionType aSelectionType,
                                   nsTextPaintStyle& aTextPaintStyle,
                                   Span<const StyleSimpleShadow>* aShadows) {
  if (aSelectionType != SelectionType::eNormal) {
    return;
  }
  aTextPaintStyle.GetSelectionShadow(aShadows);
}

/**
 * This class lets us iterate over chunks of text in a uniform selection state,
 * observing cluster boundaries, in content order, maintaining the current
 * x-offset as we go, and telling whether the text chunk has a hyphen after
 * it or not. The caller is responsible for actually computing the advance
 * width of each chunk.
 */
class SelectionIterator {
  typedef nsTextFrame::PropertyProvider PropertyProvider;

 public:
  /**
   * aStart and aLength are in the original string. aSelectionDetails is
   * according to the original string.
   * @param aXOffset the offset from the origin of the frame to the start
   * of the text (the left baseline origin for LTR, the right baseline origin
   * for RTL)
   */
  SelectionIterator(SelectionDetails** aSelectionDetails,
                    gfxTextRun::Range aRange, PropertyProvider& aProvider,
                    gfxTextRun* aTextRun, gfxFloat aXOffset);

  /**
   * Returns the next segment of uniformly selected (or not) text.
   * @param aXOffset the offset from the origin of the frame to the start
   * of the text (the left baseline origin for LTR, the right baseline origin
   * for RTL)
   * @param aRange the transformed string range of the text for this segment
   * @param aHyphenWidth if a hyphen is to be rendered after the text, the
   * width of the hyphen, otherwise zero
   * @param aSelectionType the selection type for this segment
   * @param aStyle the selection style for this segment
   * @return false if there are no more segments
   */
  bool GetNextSegment(gfxFloat* aXOffset, gfxTextRun::Range* aRange,
                      gfxFloat* aHyphenWidth, SelectionType* aSelectionType,
                      TextRangeStyle* aStyle);
  void UpdateWithAdvance(gfxFloat aAdvance) {
    mXOffset += aAdvance * mTextRun->GetDirection();
  }

 private:
  SelectionDetails** mSelectionDetails;
  PropertyProvider& mProvider;
  RefPtr<gfxTextRun> mTextRun;
  gfxSkipCharsIterator mIterator;
  gfxTextRun::Range mOriginalRange;
  gfxFloat mXOffset;
};

SelectionIterator::SelectionIterator(SelectionDetails** aSelectionDetails,
                                     gfxTextRun::Range aRange,
                                     PropertyProvider& aProvider,
                                     gfxTextRun* aTextRun, gfxFloat aXOffset)
    : mSelectionDetails(aSelectionDetails),
      mProvider(aProvider),
      mTextRun(aTextRun),
      mIterator(aProvider.GetStart()),
      mOriginalRange(aRange),
      mXOffset(aXOffset) {
  mIterator.SetOriginalOffset(aRange.start);
}

bool SelectionIterator::GetNextSegment(gfxFloat* aXOffset,
                                       gfxTextRun::Range* aRange,
                                       gfxFloat* aHyphenWidth,
                                       SelectionType* aSelectionType,
                                       TextRangeStyle* aStyle) {
  if (mIterator.GetOriginalOffset() >= int32_t(mOriginalRange.end))
    return false;

  // save offset into transformed string now
  uint32_t runOffset = mIterator.GetSkippedOffset();

  uint32_t index = mIterator.GetOriginalOffset() - mOriginalRange.start;
  SelectionDetails* sdptr = mSelectionDetails[index];
  SelectionType selectionType =
      sdptr ? sdptr->mSelectionType : SelectionType::eNone;
  TextRangeStyle style;
  if (sdptr) {
    style = sdptr->mTextRangeStyle;
  }
  for (++index; index < mOriginalRange.Length(); ++index) {
    if (sdptr != mSelectionDetails[index]) {
      break;
    }
  }
  mIterator.SetOriginalOffset(index + mOriginalRange.start);

  // Advance to the next cluster boundary
  while (mIterator.GetOriginalOffset() < int32_t(mOriginalRange.end) &&
         !mIterator.IsOriginalCharSkipped() &&
         !mTextRun->IsClusterStart(mIterator.GetSkippedOffset())) {
    mIterator.AdvanceOriginal(1);
  }

  bool haveHyphenBreak =
      mProvider.GetFrame()->HasAnyStateBits(TEXT_HYPHEN_BREAK);
  aRange->start = runOffset;
  aRange->end = mIterator.GetSkippedOffset();
  *aXOffset = mXOffset;
  *aHyphenWidth = 0;
  if (mIterator.GetOriginalOffset() == int32_t(mOriginalRange.end) &&
      haveHyphenBreak) {
    *aHyphenWidth = mProvider.GetHyphenWidth();
  }
  *aSelectionType = selectionType;
  *aStyle = style;
  return true;
}

static void AddHyphenToMetrics(nsTextFrame* aTextFrame, bool aIsRightToLeft,
                               gfxTextRun::Metrics* aMetrics,
                               gfxFont::BoundingBoxType aBoundingBoxType,
                               DrawTarget* aDrawTarget) {
  // Fix up metrics to include hyphen
  RefPtr<gfxTextRun> hyphenTextRun = GetHyphenTextRun(aTextFrame, aDrawTarget);
  if (!hyphenTextRun) {
    return;
  }

  gfxTextRun::Metrics hyphenMetrics =
      hyphenTextRun->MeasureText(aBoundingBoxType, aDrawTarget);
  if (aTextFrame->GetWritingMode().IsLineInverted()) {
    hyphenMetrics.mBoundingBox.y = -hyphenMetrics.mBoundingBox.YMost();
  }
  aMetrics->CombineWith(hyphenMetrics, aIsRightToLeft);
}

void nsTextFrame::PaintOneShadow(const PaintShadowParams& aParams,
                                 const StyleSimpleShadow& aShadowDetails,
                                 gfxRect& aBoundingBox, uint32_t aBlurFlags) {
  AUTO_PROFILER_LABEL("nsTextFrame::PaintOneShadow", GRAPHICS);

  nsPoint shadowOffset(aShadowDetails.horizontal.ToAppUnits(),
                       aShadowDetails.vertical.ToAppUnits());
  nscoord blurRadius = std::max(aShadowDetails.blur.ToAppUnits(), 0);

  nscolor shadowColor = aShadowDetails.color.CalcColor(aParams.foregroundColor);

  if (auto* textDrawer = aParams.context->GetTextDrawer()) {
    wr::Shadow wrShadow;

    wrShadow.offset = {PresContext()->AppUnitsToFloatDevPixels(shadowOffset.x),
                       PresContext()->AppUnitsToFloatDevPixels(shadowOffset.y)};

    wrShadow.blur_radius = PresContext()->AppUnitsToFloatDevPixels(blurRadius);
    wrShadow.color = wr::ToColorF(ToDeviceColor(shadowColor));

    bool inflate = true;
    textDrawer->AppendShadow(wrShadow, inflate);
    return;
  }

  // This rect is the box which is equivalent to where the shadow will be
  // painted. The origin of aBoundingBox is the text baseline left, so we must
  // translate it by that much in order to make the origin the top-left corner
  // of the text bounding box. Note that aLeftSideOffset is line-left, so
  // actually means top offset in vertical writing modes.
  gfxRect shadowGfxRect;
  WritingMode wm = GetWritingMode();
  if (wm.IsVertical()) {
    shadowGfxRect = aBoundingBox;
    if (wm.IsVerticalRL()) {
      // for vertical-RL, reverse direction of x-coords of bounding box
      shadowGfxRect.x = -shadowGfxRect.XMost();
    }
    shadowGfxRect += gfxPoint(aParams.textBaselinePt.x,
                              aParams.framePt.y + aParams.leftSideOffset);
  } else {
    shadowGfxRect =
        aBoundingBox + gfxPoint(aParams.framePt.x + aParams.leftSideOffset,
                                aParams.textBaselinePt.y);
  }
  Point shadowGfxOffset(shadowOffset.x, shadowOffset.y);
  shadowGfxRect += gfxPoint(shadowGfxOffset.x, shadowOffset.y);

  nsRect shadowRect(NSToCoordRound(shadowGfxRect.X()),
                    NSToCoordRound(shadowGfxRect.Y()),
                    NSToCoordRound(shadowGfxRect.Width()),
                    NSToCoordRound(shadowGfxRect.Height()));

  nsContextBoxBlur contextBoxBlur;
  const auto A2D = PresContext()->AppUnitsPerDevPixel();
  gfxContext* shadowContext =
      contextBoxBlur.Init(shadowRect, 0, blurRadius, A2D, aParams.context,
                          LayoutDevicePixel::ToAppUnits(aParams.dirtyRect, A2D),
                          nullptr, aBlurFlags);
  if (!shadowContext) {
    return;
  }

  aParams.context->Save();
  aParams.context->SetColor(sRGBColor::FromABGR(shadowColor));

  // Draw the text onto our alpha-only surface to capture the alpha values.
  // Remember that the box blur context has a device offset on it, so we don't
  // need to translate any coordinates to fit on the surface.
  gfxFloat advanceWidth;
  nsTextPaintStyle textPaintStyle(this);
  DrawTextParams params(shadowContext);
  params.advanceWidth = &advanceWidth;
  params.dirtyRect = aParams.dirtyRect;
  params.framePt = aParams.framePt + shadowGfxOffset;
  params.provider = aParams.provider;
  params.textStyle = &textPaintStyle;
  params.textColor =
      aParams.context == shadowContext ? shadowColor : NS_RGB(0, 0, 0);
  params.clipEdges = aParams.clipEdges;
  params.drawSoftHyphen = HasAnyStateBits(TEXT_HYPHEN_BREAK);
  // Multi-color shadow is not allowed, so we use the same color of the text
  // color.
  params.decorationOverrideColor = &params.textColor;
  params.fontPalette = StyleFont()->GetFontPaletteAtom();
  params.paletteValueSet = PresContext()->GetFontPaletteValueSet();

  DrawText(aParams.range, aParams.textBaselinePt + shadowGfxOffset, params);

  contextBoxBlur.DoPaint();
  aParams.context->Restore();
}

// Paints selection backgrounds and text in the correct colors. Also computes
// aAllTypes, the union of all selection types that are applying to this text.
bool nsTextFrame::PaintTextWithSelectionColors(
    const PaintTextSelectionParams& aParams,
    const UniquePtr<SelectionDetails>& aDetails,
    SelectionTypeMask* aAllSelectionTypeMask, const ClipEdges& aClipEdges) {
  const gfxTextRun::Range& contentRange = aParams.contentRange;

  // Figure out which selections control the colors to use for each character.
  // Note: prevailingSelectionsBuffer is keeping extra raw pointers to
  // uniquely-owned resources, but it's safe because it's temporary and the
  // resources are owned by the caller. Therefore, they'll outlive this object.
  AutoTArray<SelectionDetails*, BIG_TEXT_NODE_SIZE> prevailingSelectionsBuffer;
  SelectionDetails** prevailingSelections =
      prevailingSelectionsBuffer.AppendElements(contentRange.Length(),
                                                fallible);
  if (!prevailingSelections) {
    return false;
  }

  SelectionTypeMask allSelectionTypeMask = 0;
  for (uint32_t i = 0; i < contentRange.Length(); ++i) {
    prevailingSelections[i] = nullptr;
  }

  bool anyBackgrounds = false;
  for (SelectionDetails* sdptr = aDetails.get(); sdptr;
       sdptr = sdptr->mNext.get()) {
    int32_t start = std::max(0, sdptr->mStart - int32_t(contentRange.start));
    int32_t end = std::min(int32_t(contentRange.Length()),
                           sdptr->mEnd - int32_t(contentRange.start));
    SelectionType selectionType = sdptr->mSelectionType;
    if (start < end) {
      allSelectionTypeMask |= ToSelectionTypeMask(selectionType);
      // Ignore selections that don't set colors
      nscolor foreground, background;
      if (GetSelectionTextColors(selectionType, *aParams.textPaintStyle,
                                 sdptr->mTextRangeStyle, &foreground,
                                 &background)) {
        if (NS_GET_A(background) > 0) {
          anyBackgrounds = true;
        }
        for (int32_t i = start; i < end; ++i) {
          // Favour normal selection over IME selections
          if (!prevailingSelections[i] ||
              selectionType < prevailingSelections[i]->mSelectionType) {
            prevailingSelections[i] = sdptr;
          }
        }
      }
    }
  }
  *aAllSelectionTypeMask = allSelectionTypeMask;

  if (!allSelectionTypeMask) {
    // Nothing is selected in the given text range. XXX can this still occur?
    return false;
  }

  bool vertical = mTextRun->IsVertical();
  const gfxFloat startIOffset =
      vertical ? aParams.textBaselinePt.y - aParams.framePt.y
               : aParams.textBaselinePt.x - aParams.framePt.x;
  gfxFloat iOffset, hyphenWidth;
  Range range;  // in transformed string
  TextRangeStyle rangeStyle;
  // Draw background colors

  auto* textDrawer = aParams.context->GetTextDrawer();

  if (anyBackgrounds && !aParams.IsGenerateTextMask()) {
    int32_t appUnitsPerDevPixel =
        aParams.textPaintStyle->PresContext()->AppUnitsPerDevPixel();
    SelectionIterator iterator(prevailingSelections, contentRange,
                               *aParams.provider, mTextRun, startIOffset);
    SelectionType selectionType;
    while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
                                   &selectionType, &rangeStyle)) {
      nscolor foreground, background;
      GetSelectionTextColors(selectionType, *aParams.textPaintStyle, rangeStyle,
                             &foreground, &background);
      // Draw background color
      gfxFloat advance =
          hyphenWidth + mTextRun->GetAdvanceWidth(range, aParams.provider);
      if (NS_GET_A(background) > 0) {
        nsRect bgRect;
        gfxFloat offs = iOffset - (mTextRun->IsInlineReversed() ? advance : 0);
        if (vertical) {
          bgRect = nsRect(aParams.framePt.x, aParams.framePt.y + offs,
                          GetSize().width, advance);
        } else {
          bgRect = nsRect(aParams.framePt.x + offs, aParams.framePt.y, advance,
                          GetSize().height);
        }

        LayoutDeviceRect selectionRect =
            LayoutDeviceRect::FromAppUnits(bgRect, appUnitsPerDevPixel);

        if (textDrawer) {
          textDrawer->AppendSelectionRect(selectionRect,
                                          ToDeviceColor(background));
        } else {
          PaintSelectionBackground(*aParams.context->GetDrawTarget(),
                                   background, aParams.dirtyRect, selectionRect,
                                   aParams.callbacks);
        }
      }
      iterator.UpdateWithAdvance(advance);
    }
  }

  gfxFloat advance;
  DrawTextParams params(aParams.context);
  params.dirtyRect = aParams.dirtyRect;
  params.framePt = aParams.framePt;
  params.provider = aParams.provider;
  params.textStyle = aParams.textPaintStyle;
  params.clipEdges = &aClipEdges;
  params.advanceWidth = &advance;
  params.callbacks = aParams.callbacks;
  params.glyphRange = aParams.glyphRange;
  params.fontPalette = StyleFont()->GetFontPaletteAtom();
  params.paletteValueSet = PresContext()->GetFontPaletteValueSet();

  PaintShadowParams shadowParams(aParams);
  shadowParams.provider = aParams.provider;
  shadowParams.clipEdges = &aClipEdges;

  // Draw text
  const nsStyleText* textStyle = StyleText();
  SelectionIterator iterator(prevailingSelections, contentRange,
                             *aParams.provider, mTextRun, startIOffset);
  SelectionType selectionType;
  while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth, &selectionType,
                                 &rangeStyle)) {
    nscolor foreground, background;
    if (aParams.IsGenerateTextMask()) {
      foreground = NS_RGBA(0, 0, 0, 255);
    } else {
      GetSelectionTextColors(selectionType, *aParams.textPaintStyle, rangeStyle,
                             &foreground, &background);
    }

    gfx::Point textBaselinePt =
        vertical
            ? gfx::Point(aParams.textBaselinePt.x, aParams.framePt.y + iOffset)
            : gfx::Point(aParams.framePt.x + iOffset, aParams.textBaselinePt.y);

    // Determine what shadow, if any, to draw - either from textStyle
    // or from the ::-moz-selection pseudo-class if specified there
    Span<const StyleSimpleShadow> shadows = textStyle->mTextShadow.AsSpan();
    GetSelectionTextShadow(this, selectionType, *aParams.textPaintStyle,
                           &shadows);
    if (!shadows.IsEmpty()) {
      nscoord startEdge = iOffset;
      if (mTextRun->IsInlineReversed()) {
        startEdge -=
            hyphenWidth + mTextRun->GetAdvanceWidth(range, aParams.provider);
      }
      shadowParams.range = range;
      shadowParams.textBaselinePt = textBaselinePt;
      shadowParams.foregroundColor = foreground;
      shadowParams.leftSideOffset = startEdge;
      PaintShadows(shadows, shadowParams);
    }

    // Draw text segment
    params.textColor = foreground;
    params.textStrokeColor = aParams.textPaintStyle->GetWebkitTextStrokeColor();
    params.textStrokeWidth = aParams.textPaintStyle->GetWebkitTextStrokeWidth();
    params.drawSoftHyphen = hyphenWidth > 0;
    DrawText(range, textBaselinePt, params);
    advance += hyphenWidth;
    iterator.UpdateWithAdvance(advance);
  }
  return true;
}

void nsTextFrame::PaintTextSelectionDecorations(
    const PaintTextSelectionParams& aParams,
    const UniquePtr<SelectionDetails>& aDetails, SelectionType aSelectionType) {
  // Hide text decorations if we're currently hiding @font-face fallback text
  if (aParams.provider->GetFontGroup()->ShouldSkipDrawing()) {
    return;
  }

  // Figure out which characters will be decorated for this selection.
  // Note: selectedCharsBuffer is keeping extra raw pointers to
  // uniquely-owned resources, but it's safe because it's temporary and the
  // resources are owned by the caller. Therefore, they'll outlive this object.
  const gfxTextRun::Range& contentRange = aParams.contentRange;
  AutoTArray<SelectionDetails*, BIG_TEXT_NODE_SIZE> selectedCharsBuffer;
  SelectionDetails** selectedChars =
      selectedCharsBuffer.AppendElements(contentRange.Length(), fallible);
  if (!selectedChars) {
    return;
  }
  for (uint32_t i = 0; i < contentRange.Length(); ++i) {
    selectedChars[i] = nullptr;
  }

  for (SelectionDetails* sdptr = aDetails.get(); sdptr;
       sdptr = sdptr->mNext.get()) {
    if (sdptr->mSelectionType == aSelectionType) {
      int32_t start = std::max(0, sdptr->mStart - int32_t(contentRange.start));
      int32_t end = std::min(int32_t(contentRange.Length()),
                             sdptr->mEnd - int32_t(contentRange.start));
      for (int32_t i = start; i < end; ++i) {
        selectedChars[i] = sdptr;
      }
    }
  }

  RefPtr<gfxFont> firstFont =
      aParams.provider->GetFontGroup()->GetFirstValidFont();
  bool verticalRun = mTextRun->IsVertical();
  bool useVerticalMetrics = verticalRun && mTextRun->UseCenterBaseline();
  bool rightUnderline = useVerticalMetrics && IsUnderlineRight(*Style());
  const auto kDecoration = rightUnderline ? StyleTextDecorationLine::OVERLINE
                                          : StyleTextDecorationLine::UNDERLINE;
  gfxFont::Metrics decorationMetrics(
      firstFont->GetMetrics(useVerticalMetrics ? nsFontMetrics::eVertical
                                               : nsFontMetrics::eHorizontal));
  decorationMetrics.underlineOffset =
      aParams.provider->GetFontGroup()->GetUnderlineOffset();

  gfxFloat startIOffset = verticalRun
                              ? aParams.textBaselinePt.y - aParams.framePt.y
                              : aParams.textBaselinePt.x - aParams.framePt.x;
  SelectionIterator iterator(selectedChars, contentRange, *aParams.provider,
                             mTextRun, startIOffset);
  gfxFloat iOffset, hyphenWidth;
  Range range;
  int32_t app = aParams.textPaintStyle->PresContext()->AppUnitsPerDevPixel();
  // XXX aTextBaselinePt is in AppUnits, shouldn't it be nsFloatPoint?
  Point pt;
  if (verticalRun) {
    pt.x = (aParams.textBaselinePt.x - mAscent) / app;
  } else {
    pt.y = (aParams.textBaselinePt.y - mAscent) / app;
  }
  SelectionType nextSelectionType;
  TextRangeStyle selectedStyle;

  while (iterator.GetNextSegment(&iOffset, &range, &hyphenWidth,
                                 &nextSelectionType, &selectedStyle)) {
    gfxFloat advance =
        hyphenWidth + mTextRun->GetAdvanceWidth(range, aParams.provider);
    if (nextSelectionType == aSelectionType) {
      if (verticalRun) {
        pt.y = (aParams.framePt.y + iOffset -
                (mTextRun->IsInlineReversed() ? advance : 0)) /
               app;
      } else {
        pt.x = (aParams.framePt.x + iOffset -
                (mTextRun->IsInlineReversed() ? advance : 0)) /
               app;
      }
      gfxFloat width = Abs(advance) / app;
      gfxFloat xInFrame = pt.x - (aParams.framePt.x / app);
      DrawSelectionDecorations(aParams.context, aParams.dirtyRect,
                               aSelectionType, *aParams.textPaintStyle,
                               selectedStyle, pt, xInFrame, width,
                               mAscent / app, decorationMetrics,
                               aParams.callbacks, verticalRun, kDecoration);
    }
    iterator.UpdateWithAdvance(advance);
  }
}

bool nsTextFrame::PaintTextWithSelection(
    const PaintTextSelectionParams& aParams, const ClipEdges& aClipEdges) {
  NS_ASSERTION(GetContent()->IsMaybeSelected(), "wrong paint path");

  UniquePtr<SelectionDetails> details = GetSelectionDetails();
  if (!details) {
    return false;
  }

  SelectionTypeMask allSelectionTypeMask;
  if (!PaintTextWithSelectionColors(aParams, details, &allSelectionTypeMask,
                                    aClipEdges)) {
    return false;
  }
  // Iterate through just the selection rawSelectionTypes that paint decorations
  // and paint decorations for any that actually occur in this frame. Paint
  // higher-numbered selection rawSelectionTypes below lower-numered ones on the
  // general principal that lower-numbered selections are higher priority.
  allSelectionTypeMask &= kSelectionTypesWithDecorations;
  MOZ_ASSERT(kPresentSelectionTypes[0] == SelectionType::eNormal,
             "The following for loop assumes that the first item of "
             "kPresentSelectionTypes is SelectionType::eNormal");
  for (size_t i = ArrayLength(kPresentSelectionTypes) - 1; i >= 1; --i) {
    SelectionType selectionType = kPresentSelectionTypes[i];
    if (ToSelectionTypeMask(selectionType) & allSelectionTypeMask) {
      // There is some selection of this selectionType. Try to paint its
      // decorations (there might not be any for this type but that's OK,
      // PaintTextSelectionDecorations will exit early).
      PaintTextSelectionDecorations(aParams, details, selectionType);
    }
  }

  return true;
}

void nsTextFrame::DrawEmphasisMarks(gfxContext* aContext, WritingMode aWM,
                                    const gfx::Point& aTextBaselinePt,
                                    const gfx::Point& aFramePt, Range aRange,
                                    const nscolor* aDecorationOverrideColor,
                                    PropertyProvider* aProvider) {
  const EmphasisMarkInfo* info = GetProperty(EmphasisMarkProperty());
  if (!info) {
    return;
  }

  bool isTextCombined = Style()->IsTextCombined();
  if (isTextCombined && !aWM.IsVertical()) {
    // XXX This only happens when the parent is display:contents with an
    // orthogonal writing mode. This should be rare, and don't have use
    // cases, so we don't care. It is non-trivial to implement a sane
    // behavior for that case: if you treat the text as not combined,
    // the marks would spread wider than the text (which is rendered as
    // combined); if you try to draw a single mark, selecting part of
    // the text could dynamically create multiple new marks.
    NS_WARNING("Give up on combined text with horizontal wm");
    return;
  }
  nscolor color =
      aDecorationOverrideColor
          ? *aDecorationOverrideColor
          : nsLayoutUtils::GetColor(this, &nsStyleText::mTextEmphasisColor);
  aContext->SetColor(sRGBColor::FromABGR(color));
  gfx::Point pt;
  if (!isTextCombined) {
    pt = aTextBaselinePt;
  } else {
    MOZ_ASSERT(aWM.IsVertical());
    pt = aFramePt;
    if (aWM.IsVerticalRL()) {
      pt.x += GetSize().width - GetLogicalBaseline(aWM);
    } else {
      pt.x += GetLogicalBaseline(aWM);
    }
  }
  if (!aWM.IsVertical()) {
    pt.y += info->baselineOffset;
  } else {
    if (aWM.IsVerticalRL()) {
      pt.x -= info->baselineOffset;
    } else {
      pt.x += info->baselineOffset;
    }
  }
  if (!isTextCombined) {
    mTextRun->DrawEmphasisMarks(aContext, info->textRun.get(), info->advance,
                                pt, aRange, aProvider);
  } else {
    pt.y += (GetSize().height - info->advance) / 2;
    gfxTextRun::DrawParams params(aContext);
    info->textRun->Draw(Range(info->textRun.get()), pt, params);
  }
}

nscolor nsTextFrame::GetCaretColorAt(int32_t aOffset) {
  MOZ_ASSERT(aOffset >= 0, "aOffset must be positive");

  nscolor result = nsIFrame::GetCaretColorAt(aOffset);
  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);
  int32_t contentOffset = provider.GetStart().GetOriginalOffset();
  int32_t contentLength = provider.GetOriginalLength();
  MOZ_ASSERT(
      aOffset >= contentOffset && aOffset <= contentOffset + contentLength,
      "aOffset must be in the frame's range");

  int32_t offsetInFrame = aOffset - contentOffset;
  if (offsetInFrame < 0 || offsetInFrame >= contentLength) {
    return result;
  }

  bool isSolidTextColor = true;
  if (SVGUtils::IsInSVGTextSubtree(this)) {
    const nsStyleSVG* style = StyleSVG();
    if (!style->mFill.kind.IsNone() && !style->mFill.kind.IsColor()) {
      isSolidTextColor = false;
    }
  }

  nsTextPaintStyle textPaintStyle(this);
  textPaintStyle.SetResolveColors(isSolidTextColor);
  UniquePtr<SelectionDetails> details = GetSelectionDetails();
  SelectionType selectionType = SelectionType::eNone;
  for (SelectionDetails* sdptr = details.get(); sdptr;
       sdptr = sdptr->mNext.get()) {
    int32_t start = std::max(0, sdptr->mStart - contentOffset);
    int32_t end = std::min(contentLength, sdptr->mEnd - contentOffset);
    if (start <= offsetInFrame && offsetInFrame < end &&
        (selectionType == SelectionType::eNone ||
         sdptr->mSelectionType < selectionType)) {
      nscolor foreground, background;
      if (GetSelectionTextColors(sdptr->mSelectionType, textPaintStyle,
                                 sdptr->mTextRangeStyle, &foreground,
                                 &background)) {
        if (!isSolidTextColor && NS_IS_SELECTION_SPECIAL_COLOR(foreground)) {
          result = NS_RGBA(0, 0, 0, 255);
        } else {
          result = foreground;
        }
        selectionType = sdptr->mSelectionType;
      }
    }
  }

  return result;
}

static gfxTextRun::Range ComputeTransformedRange(
    nsTextFrame::PropertyProvider& aProvider) {
  gfxSkipCharsIterator iter(aProvider.GetStart());
  uint32_t start = iter.GetSkippedOffset();
  iter.AdvanceOriginal(aProvider.GetOriginalLength());
  return gfxTextRun::Range(start, iter.GetSkippedOffset());
}

bool nsTextFrame::MeasureCharClippedText(nscoord aVisIStartEdge,
                                         nscoord aVisIEndEdge,
                                         nscoord* aSnappedStartEdge,
                                         nscoord* aSnappedEndEdge) {
  // We need a *reference* rendering context (not one that might have a
  // transform), so we don't have a rendering context argument.
  // XXX get the block and line passed to us somehow! This is slow!
  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return false;
  }

  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);
  // Trim trailing whitespace
  provider.InitializeForDisplay(true);

  Range range = ComputeTransformedRange(provider);
  uint32_t startOffset = range.start;
  uint32_t maxLength = range.Length();
  return MeasureCharClippedText(provider, aVisIStartEdge, aVisIEndEdge,
                                &startOffset, &maxLength, aSnappedStartEdge,
                                aSnappedEndEdge);
}

static uint32_t GetClusterLength(const gfxTextRun* aTextRun,
                                 uint32_t aStartOffset, uint32_t aMaxLength,
                                 bool aIsRTL) {
  uint32_t clusterLength = aIsRTL ? 0 : 1;
  while (clusterLength < aMaxLength) {
    if (aTextRun->IsClusterStart(aStartOffset + clusterLength)) {
      if (aIsRTL) {
        ++clusterLength;
      }
      break;
    }
    ++clusterLength;
  }
  return clusterLength;
}

bool nsTextFrame::MeasureCharClippedText(
    PropertyProvider& aProvider, nscoord aVisIStartEdge, nscoord aVisIEndEdge,
    uint32_t* aStartOffset, uint32_t* aMaxLength, nscoord* aSnappedStartEdge,
    nscoord* aSnappedEndEdge) {
  *aSnappedStartEdge = 0;
  *aSnappedEndEdge = 0;
  if (aVisIStartEdge <= 0 && aVisIEndEdge <= 0) {
    return true;
  }

  uint32_t offset = *aStartOffset;
  uint32_t maxLength = *aMaxLength;
  const nscoord frameISize = ISize();
  const bool rtl = mTextRun->IsRightToLeft();
  gfxFloat advanceWidth = 0;
  const nscoord startEdge = rtl ? aVisIEndEdge : aVisIStartEdge;
  if (startEdge > 0) {
    const gfxFloat maxAdvance = gfxFloat(startEdge);
    while (maxLength > 0) {
      uint32_t clusterLength =
          GetClusterLength(mTextRun, offset, maxLength, rtl);
      advanceWidth += mTextRun->GetAdvanceWidth(
          Range(offset, offset + clusterLength), &aProvider);
      maxLength -= clusterLength;
      offset += clusterLength;
      if (advanceWidth >= maxAdvance) {
        break;
      }
    }
    nscoord* snappedStartEdge = rtl ? aSnappedEndEdge : aSnappedStartEdge;
    *snappedStartEdge = NSToCoordFloor(advanceWidth);
    *aStartOffset = offset;
  }

  const nscoord endEdge = rtl ? aVisIStartEdge : aVisIEndEdge;
  if (endEdge > 0) {
    const gfxFloat maxAdvance = gfxFloat(frameISize - endEdge);
    while (maxLength > 0) {
      uint32_t clusterLength =
          GetClusterLength(mTextRun, offset, maxLength, rtl);
      gfxFloat nextAdvance =
          advanceWidth + mTextRun->GetAdvanceWidth(
                             Range(offset, offset + clusterLength), &aProvider);
      if (nextAdvance > maxAdvance) {
        break;
      }
      // This cluster fits, include it.
      advanceWidth = nextAdvance;
      maxLength -= clusterLength;
      offset += clusterLength;
    }
    maxLength = offset - *aStartOffset;
    nscoord* snappedEndEdge = rtl ? aSnappedStartEdge : aSnappedEndEdge;
    *snappedEndEdge = NSToCoordFloor(gfxFloat(frameISize) - advanceWidth);
  }
  *aMaxLength = maxLength;
  return maxLength != 0;
}

void nsTextFrame::PaintShadows(Span<const StyleSimpleShadow> aShadows,
                               const PaintShadowParams& aParams) {
  if (aShadows.IsEmpty()) {
    return;
  }

  gfxTextRun::Metrics shadowMetrics = mTextRun->MeasureText(
      aParams.range, gfxFont::LOOSE_INK_EXTENTS, nullptr, aParams.provider);
  if (GetWritingMode().IsLineInverted()) {
    std::swap(shadowMetrics.mAscent, shadowMetrics.mDescent);
    shadowMetrics.mBoundingBox.y = -shadowMetrics.mBoundingBox.YMost();
  }
  if (HasAnyStateBits(TEXT_HYPHEN_BREAK)) {
    AddHyphenToMetrics(this, mTextRun->IsRightToLeft(), &shadowMetrics,
                       gfxFont::LOOSE_INK_EXTENTS,
                       aParams.context->GetDrawTarget());
  }
  // Add bounds of text decorations
  gfxRect decorationRect(0, -shadowMetrics.mAscent, shadowMetrics.mAdvanceWidth,
                         shadowMetrics.mAscent + shadowMetrics.mDescent);
  shadowMetrics.mBoundingBox.UnionRect(shadowMetrics.mBoundingBox,
                                       decorationRect);

  // If the textrun uses any color or SVG fonts, we need to force use of a mask
  // for shadow rendering even if blur radius is zero.
  // Force disable hardware acceleration for text shadows since it's usually
  // more expensive than just doing it on the CPU.
  uint32_t blurFlags = nsContextBoxBlur::DISABLE_HARDWARE_ACCELERATION_BLUR;
  uint32_t numGlyphRuns;
  const gfxTextRun::GlyphRun* run = mTextRun->GetGlyphRuns(&numGlyphRuns);
  while (numGlyphRuns-- > 0) {
    if (run->mFont->AlwaysNeedsMaskForShadow()) {
      blurFlags |= nsContextBoxBlur::FORCE_MASK;
      break;
    }
    run++;
  }

  if (mTextRun->IsVertical()) {
    std::swap(shadowMetrics.mBoundingBox.x, shadowMetrics.mBoundingBox.y);
    std::swap(shadowMetrics.mBoundingBox.width,
              shadowMetrics.mBoundingBox.height);
  }

  for (const auto& shadow : Reversed(aShadows)) {
    PaintOneShadow(aParams, shadow, shadowMetrics.mBoundingBox, blurFlags);
  }
}

void nsTextFrame::PaintText(const PaintTextParams& aParams,
                            const nscoord aVisIStartEdge,
                            const nscoord aVisIEndEdge,
                            const nsPoint& aToReferenceFrame,
                            const bool aIsSelected,
                            float aOpacity /* = 1.0f */) {
  // Don't pass in the rendering context here, because we need a
  // *reference* context and rendering context might have some transform
  // in it
  // XXX get the block and line passed to us somehow! This is slow!
  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return;
  }

  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);

  // Trim trailing whitespace, unless we're painting a selection highlight,
  // which should include trailing spaces if present (bug 1146754).
  provider.InitializeForDisplay(!aIsSelected);

  const bool reversed = mTextRun->IsInlineReversed();
  const bool verticalRun = mTextRun->IsVertical();
  WritingMode wm = GetWritingMode();
  const float frameWidth = GetSize().width;
  const float frameHeight = GetSize().height;
  gfx::Point textBaselinePt;
  if (verticalRun) {
    if (wm.IsVerticalLR()) {
      textBaselinePt.x = nsLayoutUtils::GetSnappedBaselineX(
          this, aParams.context, nscoord(aParams.framePt.x), mAscent);
    } else {
      textBaselinePt.x = nsLayoutUtils::GetSnappedBaselineX(
          this, aParams.context, nscoord(aParams.framePt.x) + frameWidth,
          -mAscent);
    }
    textBaselinePt.y = reversed ? aParams.framePt.y.value + frameHeight
                                : aParams.framePt.y.value;
  } else {
    textBaselinePt =
        gfx::Point(reversed ? aParams.framePt.x.value + frameWidth
                            : aParams.framePt.x.value,
                   nsLayoutUtils::GetSnappedBaselineY(
                       this, aParams.context, aParams.framePt.y, mAscent));
  }
  Range range = ComputeTransformedRange(provider);
  uint32_t startOffset = range.start;
  uint32_t maxLength = range.Length();
  nscoord snappedStartEdge, snappedEndEdge;
  if (!MeasureCharClippedText(provider, aVisIStartEdge, aVisIEndEdge,
                              &startOffset, &maxLength, &snappedStartEdge,
                              &snappedEndEdge)) {
    return;
  }
  if (verticalRun) {
    textBaselinePt.y += reversed ? -snappedEndEdge : snappedStartEdge;
  } else {
    textBaselinePt.x += reversed ? -snappedEndEdge : snappedStartEdge;
  }
  const ClipEdges clipEdges(this, aToReferenceFrame, snappedStartEdge,
                            snappedEndEdge);
  nsTextPaintStyle textPaintStyle(this);
  textPaintStyle.SetResolveColors(!aParams.callbacks);

  // Fork off to the (slower) paint-with-selection path if necessary.
  if (aIsSelected) {
    MOZ_ASSERT(aOpacity == 1.0f, "We don't support opacity with selections!");
    gfxSkipCharsIterator tmp(provider.GetStart());
    Range contentRange(
        uint32_t(tmp.ConvertSkippedToOriginal(startOffset)),
        uint32_t(tmp.ConvertSkippedToOriginal(startOffset + maxLength)));
    PaintTextSelectionParams params(aParams);
    params.textBaselinePt = textBaselinePt;
    params.provider = &provider;
    params.contentRange = contentRange;
    params.textPaintStyle = &textPaintStyle;
    params.glyphRange = range;
    if (PaintTextWithSelection(params, clipEdges)) {
      return;
    }
  }

  nscolor foregroundColor = aParams.IsGenerateTextMask()
                                ? NS_RGBA(0, 0, 0, 255)
                                : textPaintStyle.GetTextColor();
  if (aOpacity != 1.0f) {
    gfx::sRGBColor gfxColor = gfx::sRGBColor::FromABGR(foregroundColor);
    gfxColor.a *= aOpacity;
    foregroundColor = gfxColor.ToABGR();
  }

  nscolor textStrokeColor = aParams.IsGenerateTextMask()
                                ? NS_RGBA(0, 0, 0, 255)
                                : textPaintStyle.GetWebkitTextStrokeColor();
  if (aOpacity != 1.0f) {
    gfx::sRGBColor gfxColor = gfx::sRGBColor::FromABGR(textStrokeColor);
    gfxColor.a *= aOpacity;
    textStrokeColor = gfxColor.ToABGR();
  }

  range = Range(startOffset, startOffset + maxLength);
  if (!aParams.callbacks && aParams.IsPaintText()) {
    const nsStyleText* textStyle = StyleText();
    PaintShadowParams shadowParams(aParams);
    shadowParams.range = range;
    shadowParams.textBaselinePt = textBaselinePt;
    shadowParams.leftSideOffset = snappedStartEdge;
    shadowParams.provider = &provider;
    shadowParams.foregroundColor = foregroundColor;
    shadowParams.clipEdges = &clipEdges;
    PaintShadows(textStyle->mTextShadow.AsSpan(), shadowParams);
  }

  gfxFloat advanceWidth;
  DrawTextParams params(aParams.context);
  params.dirtyRect = aParams.dirtyRect;
  params.framePt = aParams.framePt;
  params.provider = &provider;
  params.advanceWidth = &advanceWidth;
  params.textStyle = &textPaintStyle;
  params.textColor = foregroundColor;
  params.textStrokeColor = textStrokeColor;
  params.textStrokeWidth = textPaintStyle.GetWebkitTextStrokeWidth();
  params.clipEdges = &clipEdges;
  params.drawSoftHyphen = HasAnyStateBits(TEXT_HYPHEN_BREAK);
  params.contextPaint = aParams.contextPaint;
  params.callbacks = aParams.callbacks;
  params.glyphRange = range;
  params.fontPalette = StyleFont()->GetFontPaletteAtom();
  params.paletteValueSet = PresContext()->GetFontPaletteValueSet();

  DrawText(range, textBaselinePt, params);
}

static void DrawTextRun(const gfxTextRun* aTextRun,
                        const gfx::Point& aTextBaselinePt,
                        gfxTextRun::Range aRange,
                        const nsTextFrame::DrawTextRunParams& aParams,
                        nsTextFrame* aFrame) {
  gfxTextRun::DrawParams params(aParams.context);
  params.provider = aParams.provider;
  params.advanceWidth = aParams.advanceWidth;
  params.contextPaint = aParams.contextPaint;
  params.fontPalette = aParams.fontPalette;
  params.paletteValueSet = aParams.paletteValueSet;
  params.callbacks = aParams.callbacks;
  if (aParams.callbacks) {
    aParams.callbacks->NotifyBeforeText(aParams.textColor);
    params.drawMode = DrawMode::GLYPH_PATH;
    aTextRun->Draw(aRange, aTextBaselinePt, params);
    aParams.callbacks->NotifyAfterText();
  } else {
    auto* textDrawer = aParams.context->GetTextDrawer();
    if (NS_GET_A(aParams.textColor) != 0 || textDrawer ||
        aParams.textStrokeWidth == 0.0f) {
      aParams.context->SetColor(sRGBColor::FromABGR(aParams.textColor));
    } else {
      params.drawMode = DrawMode::GLYPH_STROKE;
    }

    if ((NS_GET_A(aParams.textStrokeColor) != 0 || textDrawer) &&
        aParams.textStrokeWidth != 0.0f) {
      if (textDrawer) {
        textDrawer->FoundUnsupportedFeature();
        return;
      }
      params.drawMode |= DrawMode::GLYPH_STROKE;

      // Check the paint-order property; if we find stroke before fill,
      // then change mode to GLYPH_STROKE_UNDERNEATH.
      uint32_t paintOrder = aFrame->StyleSVG()->mPaintOrder;
      while (paintOrder) {
        auto component = StylePaintOrder(paintOrder & kPaintOrderMask);
        switch (component) {
          case StylePaintOrder::Fill:
            // Just break the loop, no need to check further
            paintOrder = 0;
            break;
          case StylePaintOrder::Stroke:
            params.drawMode |= DrawMode::GLYPH_STROKE_UNDERNEATH;
            paintOrder = 0;
            break;
          default:
            MOZ_FALLTHROUGH_ASSERT("Unknown paint-order variant, how?");
          case StylePaintOrder::Markers:
          case StylePaintOrder::Normal:
            break;
        }
        paintOrder >>= kPaintOrderShift;
      }

      // Use ROUND joins as they are less likely to produce ugly artifacts
      // when stroking glyphs with sharp angles (see bug 1546985).
      StrokeOptions strokeOpts(aParams.textStrokeWidth, JoinStyle::ROUND);
      params.textStrokeColor = aParams.textStrokeColor;
      params.strokeOpts = &strokeOpts;
      aTextRun->Draw(aRange, aTextBaselinePt, params);
    } else {
      aTextRun->Draw(aRange, aTextBaselinePt, params);
    }
  }
}

void nsTextFrame::DrawTextRun(Range aRange, const gfx::Point& aTextBaselinePt,
                              const DrawTextRunParams& aParams) {
  MOZ_ASSERT(aParams.advanceWidth, "Must provide advanceWidth");

  ::DrawTextRun(mTextRun, aTextBaselinePt, aRange, aParams, this);

  if (aParams.drawSoftHyphen) {
    // Don't use ctx as the context, because we need a reference context here,
    // ctx may be transformed.
    DrawTextRunParams params = aParams;
    params.provider = nullptr;
    params.advanceWidth = nullptr;
    RefPtr<gfxTextRun> hyphenTextRun = GetHyphenTextRun(this, nullptr);
    if (hyphenTextRun) {
      gfx::Point p(aTextBaselinePt);
      bool vertical = GetWritingMode().IsVertical();
      // For right-to-left text runs, the soft-hyphen is positioned at the left
      // of the text.
      float shift = mTextRun->GetDirection() * (*aParams.advanceWidth);
      if (vertical) {
        p.y += shift;
      } else {
        p.x += shift;
      }
      ::DrawTextRun(hyphenTextRun.get(), p, Range(hyphenTextRun.get()), params,
                    this);
    }
  }
}

void nsTextFrame::DrawTextRunAndDecorations(
    Range aRange, const gfx::Point& aTextBaselinePt,
    const DrawTextParams& aParams, const TextDecorations& aDecorations) {
  const gfxFloat app = aParams.textStyle->PresContext()->AppUnitsPerDevPixel();
  // Writing mode of parent frame is used because the text frame may
  // be orthogonal to its parent when text-combine-upright is used or
  // its parent has "display: contents", and in those cases, we want
  // to draw the decoration lines according to parents' direction
  // rather than ours.
  const WritingMode wm = GetParent()->GetWritingMode();
  bool verticalDec = wm.IsVertical();
  bool verticalRun = mTextRun->IsVertical();
  // If the text run and the decoration is orthogonal, we choose the
  // metrics for decoration so that decoration line won't be broken.
  bool useVerticalMetrics = verticalDec != verticalRun
                                ? verticalDec
                                : verticalRun && mTextRun->UseCenterBaseline();

  // XXX aFramePt is in AppUnits, shouldn't it be nsFloatPoint?
  nscoord x = NSToCoordRound(aParams.framePt.x);
  nscoord y = NSToCoordRound(aParams.framePt.y);

  // 'measure' here is textrun-relative, so for a horizontal run it's the
  // width, while for a vertical run it's the height of the decoration
  const nsSize frameSize = GetSize();
  nscoord measure = verticalDec ? frameSize.height : frameSize.width;

  if (verticalDec) {
    aParams.clipEdges->Intersect(&y, &measure);
  } else {
    aParams.clipEdges->Intersect(&x, &measure);
  }

  // decSize is a textrun-relative size, so its 'width' field is actually
  // the run-relative measure, and 'height' will be the line thickness
  gfxFloat ascent = gfxFloat(GetLogicalBaseline(wm)) / app;
  // The starting edge of the frame in block direction
  gfxFloat frameBStart = verticalDec ? aParams.framePt.x : aParams.framePt.y;

  // In vertical-rl mode, block coordinates are measured from the
  // right, so we need to adjust here.
  if (wm.IsVerticalRL()) {
    frameBStart += frameSize.width;
    ascent = -ascent;
  }

  nscoord inflationMinFontSize = nsLayoutUtils::InflationMinFontSizeFor(this);

  PaintDecorationLineParams params;
  params.context = aParams.context;
  params.dirtyRect = aParams.dirtyRect;
  params.overrideColor = aParams.decorationOverrideColor;
  params.callbacks = aParams.callbacks;
  params.glyphRange = aParams.glyphRange;
  params.provider = aParams.provider;
  // pt is the physical point where the decoration is to be drawn,
  // relative to the frame; one of its coordinates will be updated below.
  params.pt = Point(x / app, y / app);
  Float& bCoord = verticalDec ? params.pt.x.value : params.pt.y.value;
  params.lineSize = Size(measure / app, 0);
  params.ascent = ascent;
  params.vertical = verticalDec;
  params.sidewaysLeft = mTextRun->IsSidewaysLeft();

  // The matrix of the context may have been altered for text-combine-
  // upright. However, we want to draw decoration lines unscaled, thus
  // we need to revert the scaling here.
  gfxContextMatrixAutoSaveRestore scaledRestorer;
  if (Style()->IsTextCombined()) {
    float scaleFactor = GetTextCombineScaleFactor(this);
    if (scaleFactor != 1.0f) {
      scaledRestorer.SetContext(aParams.context);
      gfxMatrix unscaled = aParams.context->CurrentMatrixDouble();
      gfxPoint pt(x / app, y / app);
      unscaled.PreTranslate(pt)
          .PreScale(1.0f / scaleFactor, 1.0f)
          .PreTranslate(-pt);
      aParams.context->SetMatrixDouble(unscaled);
    }
  }

  typedef gfxFont::Metrics Metrics;
  auto paintDecorationLine = [&](const LineDecoration& dec,
                                 gfxFloat Metrics::*lineSize,
                                 StyleTextDecorationLine lineType) {
    if (dec.mStyle == NS_STYLE_TEXT_DECORATION_STYLE_NONE) {
      return;
    }

    float inflation =
        GetInflationForTextDecorations(dec.mFrame, inflationMinFontSize);
    const Metrics metrics = GetFirstFontMetrics(
        GetFontGroupForFrame(dec.mFrame, inflation), useVerticalMetrics);

    bCoord = (frameBStart - dec.mBaselineOffset) / app;

    params.color = dec.mColor;
    params.baselineOffset = dec.mBaselineOffset / app;
    params.defaultLineThickness = metrics.*lineSize;
    params.lineSize.height = ComputeDecorationLineThickness(
        dec.mTextDecorationThickness, params.defaultLineThickness, metrics, app,
        dec.mFrame);

    bool swapUnderline = wm.IsCentralBaseline() && IsUnderlineRight(*Style());
    params.offset = ComputeDecorationLineOffset(
        lineType, dec.mTextUnderlinePosition, dec.mTextUnderlineOffset, metrics,
        app, dec.mFrame, wm.IsCentralBaseline(), swapUnderline);

    params.style = dec.mStyle;
    PaintDecorationLine(params);
  };

  // We create a clip region in order to draw the decoration lines only in the
  // range of the text. Restricting the draw area prevents the decoration lines
  // to be drawn multiple times when a part of the text is selected.

  // We skip clipping for the following cases:
  // - drawing the whole text
  // - having different orientation of the text and the writing-mode, such as
  //   "text-combine-upright" (Bug 1408825)
  bool skipClipping =
      aRange.Length() == mTextRun->GetLength() || verticalDec != verticalRun;

  gfxRect clipRect;
  if (!skipClipping) {
    // Get the inline-size according to the specified range.
    gfxFloat clipLength = mTextRun->GetAdvanceWidth(aRange, aParams.provider);
    nsRect visualRect = InkOverflowRect();

    const bool isInlineReversed = mTextRun->IsInlineReversed();
    if (verticalDec) {
      clipRect.x = aParams.framePt.x + visualRect.x;
      clipRect.y = isInlineReversed ? aTextBaselinePt.y.value - clipLength
                                    : aTextBaselinePt.y.value;
      clipRect.width = visualRect.width;
      clipRect.height = clipLength;
    } else {
      clipRect.x = isInlineReversed ? aTextBaselinePt.x.value - clipLength
                                    : aTextBaselinePt.x.value;
      clipRect.y = aParams.framePt.y + visualRect.y;
      clipRect.width = clipLength;
      clipRect.height = visualRect.height;
    }

    clipRect.Scale(1 / app);
    clipRect.Round();
    params.context->Clip(clipRect);
  }

  // Underlines
  params.decoration = StyleTextDecorationLine::UNDERLINE;
  for (const LineDecoration& dec : Reversed(aDecorations.mUnderlines)) {
    paintDecorationLine(dec, &Metrics::underlineSize, params.decoration);
  }

  // Overlines
  params.decoration = StyleTextDecorationLine::OVERLINE;
  for (const LineDecoration& dec : Reversed(aDecorations.mOverlines)) {
    paintDecorationLine(dec, &Metrics::underlineSize, params.decoration);
  }

  // Some glyphs and emphasis marks may extend outside the region, so we reset
  // the clip region here. For an example, italic glyphs.
  if (!skipClipping) {
    params.context->PopClip();
  }

  {
    gfxContextMatrixAutoSaveRestore unscaledRestorer;
    if (scaledRestorer.HasMatrix()) {
      unscaledRestorer.SetContext(aParams.context);
      aParams.context->SetMatrix(scaledRestorer.Matrix());
    }

    // CSS 2.1 mandates that text be painted after over/underlines,
    // and *then* line-throughs
    DrawTextRun(aRange, aTextBaselinePt, aParams);
  }

  // Emphasis marks
  DrawEmphasisMarks(aParams.context, wm, aTextBaselinePt, aParams.framePt,
                    aRange, aParams.decorationOverrideColor, aParams.provider);

  // Re-apply the clip region when the line-through is being drawn.
  if (!skipClipping) {
    params.context->Clip(clipRect);
  }

  // Line-throughs
  params.decoration = StyleTextDecorationLine::LINE_THROUGH;
  for (const LineDecoration& dec : Reversed(aDecorations.mStrikes)) {
    paintDecorationLine(dec, &Metrics::strikeoutSize, params.decoration);
  }

  if (!skipClipping) {
    params.context->PopClip();
  }
}

void nsTextFrame::DrawText(Range aRange, const gfx::Point& aTextBaselinePt,
                           const DrawTextParams& aParams) {
  TextDecorations decorations;
  GetTextDecorations(aParams.textStyle->PresContext(),
                     aParams.callbacks ? eUnresolvedColors : eResolvedColors,
                     decorations);

  // Hide text decorations if we're currently hiding @font-face fallback text
  const bool drawDecorations =
      !aParams.provider->GetFontGroup()->ShouldSkipDrawing() &&
      (decorations.HasDecorationLines() ||
       StyleText()->HasEffectiveTextEmphasis());
  if (drawDecorations) {
    DrawTextRunAndDecorations(aRange, aTextBaselinePt, aParams, decorations);
  } else {
    DrawTextRun(aRange, aTextBaselinePt, aParams);
  }

  if (auto* textDrawer = aParams.context->GetTextDrawer()) {
    textDrawer->TerminateShadows();
  }
}

NS_DECLARE_FRAME_PROPERTY_DELETABLE(WebRenderTextBounds, nsRect)

nsRect nsTextFrame::WebRenderBounds() {
  nsRect* cachedBounds = GetProperty(WebRenderTextBounds());
  if (!cachedBounds) {
    OverflowAreas overflowAreas;
    ComputeCustomOverflowInternal(overflowAreas, false);
    cachedBounds = new nsRect();
    *cachedBounds = overflowAreas.InkOverflow();
    SetProperty(WebRenderTextBounds(), cachedBounds);
  }
  return *cachedBounds;
}

int16_t nsTextFrame::GetSelectionStatus(int16_t* aSelectionFlags) {
  // get the selection controller
  nsCOMPtr<nsISelectionController> selectionController;
  nsresult rv = GetSelectionController(PresContext(),
                                       getter_AddRefs(selectionController));
  if (NS_FAILED(rv) || !selectionController)
    return nsISelectionController::SELECTION_OFF;

  selectionController->GetSelectionFlags(aSelectionFlags);

  int16_t selectionValue;
  selectionController->GetDisplaySelection(&selectionValue);

  return selectionValue;
}

bool nsTextFrame::IsEntirelyWhitespace() const {
  const nsTextFragment& text = mContent->AsText()->TextFragment();
  for (uint32_t index = 0; index < text.GetLength(); ++index) {
    const char16_t ch = text.CharAt(index);
    if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == 0xa0) {
      continue;
    }
    return false;
  }
  return true;
}

/**
 * Compute the longest prefix of text whose width is <= aWidth. Return
 * the length of the prefix. Also returns the width of the prefix in aFitWidth.
 */
static uint32_t CountCharsFit(const gfxTextRun* aTextRun,
                              gfxTextRun::Range aRange, gfxFloat aWidth,
                              nsTextFrame::PropertyProvider* aProvider,
                              gfxFloat* aFitWidth) {
  uint32_t last = 0;
  gfxFloat width = 0;
  for (uint32_t i = 1; i <= aRange.Length(); ++i) {
    if (i == aRange.Length() || aTextRun->IsClusterStart(aRange.start + i)) {
      gfxTextRun::Range range(aRange.start + last, aRange.start + i);
      gfxFloat nextWidth = width + aTextRun->GetAdvanceWidth(range, aProvider);
      if (nextWidth > aWidth) {
        break;
      }
      last = i;
      width = nextWidth;
    }
  }
  *aFitWidth = width;
  return last;
}

nsIFrame::ContentOffsets nsTextFrame::CalcContentOffsetsFromFramePoint(
    const nsPoint& aPoint) {
  return GetCharacterOffsetAtFramePointInternal(aPoint, true);
}

nsIFrame::ContentOffsets nsTextFrame::GetCharacterOffsetAtFramePoint(
    const nsPoint& aPoint) {
  return GetCharacterOffsetAtFramePointInternal(aPoint, false);
}

nsIFrame::ContentOffsets nsTextFrame::GetCharacterOffsetAtFramePointInternal(
    const nsPoint& aPoint, bool aForInsertionPoint) {
  ContentOffsets offsets;

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return offsets;
  }

  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);
  // Trim leading but not trailing whitespace if possible
  provider.InitializeForDisplay(false);
  gfxFloat width =
      mTextRun->IsVertical()
          ? (mTextRun->IsInlineReversed() ? mRect.height - aPoint.y : aPoint.y)
          : (mTextRun->IsInlineReversed() ? mRect.width - aPoint.x : aPoint.x);
  if (Style()->IsTextCombined()) {
    width /= GetTextCombineScaleFactor(this);
  }
  gfxFloat fitWidth;
  Range skippedRange = ComputeTransformedRange(provider);

  uint32_t charsFit =
      CountCharsFit(mTextRun, skippedRange, width, &provider, &fitWidth);

  int32_t selectedOffset;
  if (charsFit < skippedRange.Length()) {
    // charsFit characters fitted, but no more could fit. See if we're
    // more than halfway through the cluster.. If we are, choose the next
    // cluster.
    gfxSkipCharsIterator extraCluster(provider.GetStart());
    extraCluster.AdvanceSkipped(charsFit);

    bool allowSplitLigature = true;  // Allow selection of partial ligature...

    // ...but don't let selection/insertion-point split two Regional Indicator
    // chars that are ligated in the textrun to form a single flag symbol.
    uint32_t offs = extraCluster.GetOriginalOffset();
    const nsTextFragment* frag = TextFragment();
    if (frag->IsHighSurrogateFollowedByLowSurrogateAt(offs) &&
        gfxFontUtils::IsRegionalIndicator(frag->ScalarValueAt(offs))) {
      allowSplitLigature = false;
      if (extraCluster.GetSkippedOffset() > 1 &&
          !mTextRun->IsLigatureGroupStart(extraCluster.GetSkippedOffset())) {
        // CountCharsFit() left us in the middle of the flag; back up over the
        // first character of the ligature, and adjust fitWidth accordingly.
        extraCluster.AdvanceSkipped(-2);  // it's a surrogate pair: 2 code units
        fitWidth -= mTextRun->GetAdvanceWidth(
            Range(extraCluster.GetSkippedOffset(),
                  extraCluster.GetSkippedOffset() + 2),
            &provider);
      }
    }

    gfxSkipCharsIterator extraClusterLastChar(extraCluster);
    FindClusterEnd(
        mTextRun,
        provider.GetStart().GetOriginalOffset() + provider.GetOriginalLength(),
        &extraClusterLastChar, allowSplitLigature);
    PropertyProvider::Spacing spacing;
    Range extraClusterRange(extraCluster.GetSkippedOffset(),
                            extraClusterLastChar.GetSkippedOffset() + 1);
    gfxFloat charWidth =
        mTextRun->GetAdvanceWidth(extraClusterRange, &provider, &spacing);
    charWidth -= spacing.mBefore + spacing.mAfter;
    selectedOffset = !aForInsertionPoint ||
                             width <= fitWidth + spacing.mBefore + charWidth / 2
                         ? extraCluster.GetOriginalOffset()
                         : extraClusterLastChar.GetOriginalOffset() + 1;
  } else {
    // All characters fitted, we're at (or beyond) the end of the text.
    // XXX This could be some pathological situation where negative spacing
    // caused characters to move backwards. We can't really handle that
    // in the current frame system because frames can't have negative
    // intrinsic widths.
    selectedOffset =
        provider.GetStart().GetOriginalOffset() + provider.GetOriginalLength();
    // If we're at the end of a preformatted line which has a terminating
    // linefeed, we want to reduce the offset by one to make sure that the
    // selection is placed before the linefeed character.
    if (HasSignificantTerminalNewline()) {
      --selectedOffset;
    }
  }

  offsets.content = GetContent();
  offsets.offset = offsets.secondaryOffset = selectedOffset;
  offsets.associate = mContentOffset == offsets.offset ? CARET_ASSOCIATE_AFTER
                                                       : CARET_ASSOCIATE_BEFORE;
  return offsets;
}

bool nsTextFrame::CombineSelectionUnderlineRect(nsPresContext* aPresContext,
                                                nsRect& aRect) {
  if (aRect.IsEmpty()) {
    return false;
  }

  nsRect givenRect = aRect;

  gfxFontGroup* fontGroup = GetInflatedFontGroupForFrame(this);
  RefPtr<gfxFont> firstFont = fontGroup->GetFirstValidFont();
  WritingMode wm = GetWritingMode();
  bool verticalRun = wm.IsVertical();
  bool useVerticalMetrics = verticalRun && !wm.IsSideways();
  const gfxFont::Metrics& metrics =
      firstFont->GetMetrics(useVerticalMetrics ? nsFontMetrics::eVertical
                                               : nsFontMetrics::eHorizontal);

  nsCSSRendering::DecorationRectParams params;
  params.ascent = aPresContext->AppUnitsToGfxUnits(mAscent);

  params.offset = fontGroup->GetUnderlineOffset();

  TextDecorations textDecs;
  GetTextDecorations(aPresContext, eResolvedColors, textDecs);

  params.descentLimit =
      ComputeDescentLimitForSelectionUnderline(aPresContext, metrics);
  params.vertical = verticalRun;

  EnsureTextRun(nsTextFrame::eInflated);
  params.sidewaysLeft = mTextRun ? mTextRun->IsSidewaysLeft() : false;

  UniquePtr<SelectionDetails> details = GetSelectionDetails();
  for (SelectionDetails* sd = details.get(); sd; sd = sd->mNext.get()) {
    if (sd->mStart == sd->mEnd ||
        sd->mSelectionType == SelectionType::eInvalid ||
        !(ToSelectionTypeMask(sd->mSelectionType) &
          kSelectionTypesWithDecorations) ||
        // URL strikeout does not use underline.
        sd->mSelectionType == SelectionType::eURLStrikeout) {
      continue;
    }

    float relativeSize;
    int32_t index = nsTextPaintStyle::GetUnderlineStyleIndexForSelectionType(
        sd->mSelectionType);
    if (sd->mSelectionType == SelectionType::eSpellCheck) {
      if (!nsTextPaintStyle::GetSelectionUnderline(
              this, index, nullptr, &relativeSize, &params.style)) {
        continue;
      }
    } else {
      // IME selections
      TextRangeStyle& rangeStyle = sd->mTextRangeStyle;
      if (rangeStyle.IsDefined()) {
        if (!rangeStyle.IsLineStyleDefined() ||
            rangeStyle.mLineStyle == TextRangeStyle::LineStyle::None) {
          continue;
        }
        params.style = ToStyleLineStyle(rangeStyle);
        relativeSize = rangeStyle.mIsBoldLine ? 2.0f : 1.0f;
      } else if (!nsTextPaintStyle::GetSelectionUnderline(
                     this, index, nullptr, &relativeSize, &params.style)) {
        continue;
      }
    }
    nsRect decorationArea;

    const auto& decThickness = StyleTextReset()->mTextDecorationThickness;
    params.lineSize.width = aPresContext->AppUnitsToGfxUnits(aRect.width);
    params.defaultLineThickness = ComputeSelectionUnderlineHeight(
        aPresContext, metrics, sd->mSelectionType);

    params.lineSize.height = ComputeDecorationLineThickness(
        decThickness, params.defaultLineThickness, metrics,
        aPresContext->AppUnitsPerDevPixel(), this);

    bool swapUnderline = wm.IsCentralBaseline() && IsUnderlineRight(*Style());
    const auto* styleText = StyleText();
    params.offset = ComputeDecorationLineOffset(
        textDecs.HasUnderline() ? StyleTextDecorationLine::UNDERLINE
                                : StyleTextDecorationLine::OVERLINE,
        styleText->mTextUnderlinePosition, styleText->mTextUnderlineOffset,
        metrics, aPresContext->AppUnitsPerDevPixel(), this,
        wm.IsCentralBaseline(), swapUnderline);

    relativeSize = std::max(relativeSize, 1.0f);
    params.lineSize.height *= relativeSize;
    params.defaultLineThickness *= relativeSize;
    decorationArea =
        nsCSSRendering::GetTextDecorationRect(aPresContext, params);
    aRect.UnionRect(aRect, decorationArea);
  }

  return !aRect.IsEmpty() && !givenRect.Contains(aRect);
}

bool nsTextFrame::IsFrameSelected() const {
  NS_ASSERTION(!GetContent() || GetContent()->IsMaybeSelected(),
               "use the public IsSelected() instead");
  if (mIsSelected == nsTextFrame::SelectionState::Unknown) {
    const bool isSelected =
        GetContent()->IsSelected(GetContentOffset(), GetContentEnd());
    mIsSelected = isSelected ? nsTextFrame::SelectionState::Selected
                             : nsTextFrame::SelectionState::NotSelected;
  } else {
#ifdef DEBUG
    // Assert that the selection caching works.
    const bool isReallySelected =
        GetContent()->IsSelected(GetContentOffset(), GetContentEnd());
    NS_ASSERTION((mIsSelected == nsTextFrame::SelectionState::Selected) ==
                     isReallySelected,
                 "Should have called InvalidateSelectionState()");
#endif
  }

  return mIsSelected == nsTextFrame::SelectionState::Selected;
}

nsTextFrame* nsTextFrame::FindContinuationForOffset(int32_t aOffset) {
  // Use a continuations array to accelerate finding the first continuation
  // of interest, if possible.
  MOZ_ASSERT(!GetPrevContinuation(), "should be called on the primary frame");
  auto* continuations = GetContinuations();
  nsTextFrame* f = this;
  if (continuations) {
    size_t index;
    if (BinarySearchIf(
            *continuations, 0, continuations->Length(),
            [=](nsTextFrame* aFrame) -> int {
              return aOffset - aFrame->GetContentOffset();
            },
            &index)) {
      f = (*continuations)[index];
    } else {
      f = (*continuations)[index ? index - 1 : 0];
    }
  }

  while (f && f->GetContentEnd() <= aOffset) {
    f = f->GetNextContinuation();
  }

  return f;
}

void nsTextFrame::SelectionStateChanged(uint32_t aStart, uint32_t aEnd,
                                        bool aSelected,
                                        SelectionType aSelectionType) {
  NS_ASSERTION(!GetPrevContinuation(),
               "Should only be called for primary frame");
  DEBUG_VERIFY_NOT_DIRTY(mState);

  InvalidateSelectionState();

  // Selection is collapsed, which can't affect text frame rendering
  if (aStart == aEnd) {
    return;
  }

  nsTextFrame* f = FindContinuationForOffset(aStart);

  nsPresContext* presContext = PresContext();
  while (f && f->GetContentOffset() < int32_t(aEnd)) {
    // We may need to reflow to recompute the overflow area for
    // spellchecking or IME underline if their underline is thicker than
    // the normal decoration line.
    if (ToSelectionTypeMask(aSelectionType) & kSelectionTypesWithDecorations) {
      bool didHaveOverflowingSelection =
          f->HasAnyStateBits(TEXT_SELECTION_UNDERLINE_OVERFLOWED);
      nsRect r(nsPoint(0, 0), GetSize());
      if (didHaveOverflowingSelection ||
          (aSelected && f->CombineSelectionUnderlineRect(presContext, r))) {
        presContext->PresShell()->FrameNeedsReflow(
            f, IntrinsicDirty::StyleChange, NS_FRAME_IS_DIRTY);
      }
    }
    // Selection might change anything. Invalidate the overflow area.
    f->InvalidateFrame();

    f = f->GetNextContinuation();
  }
}

void nsTextFrame::UpdateIteratorFromOffset(const PropertyProvider& aProperties,
                                           int32_t& aInOffset,
                                           gfxSkipCharsIterator& aIter) {
  if (aInOffset < GetContentOffset()) {
    NS_WARNING("offset before this frame's content");
    aInOffset = GetContentOffset();
  } else if (aInOffset > GetContentEnd()) {
    NS_WARNING("offset after this frame's content");
    aInOffset = GetContentEnd();
  }

  int32_t trimmedOffset = aProperties.GetStart().GetOriginalOffset();
  int32_t trimmedEnd = trimmedOffset + aProperties.GetOriginalLength();
  aInOffset = std::max(aInOffset, trimmedOffset);
  aInOffset = std::min(aInOffset, trimmedEnd);

  aIter.SetOriginalOffset(aInOffset);

  if (aInOffset < trimmedEnd && !aIter.IsOriginalCharSkipped() &&
      !mTextRun->IsClusterStart(aIter.GetSkippedOffset())) {
    // Called for non-cluster boundary
    FindClusterStart(mTextRun, trimmedOffset, &aIter);
  }
}

nsPoint nsTextFrame::GetPointFromIterator(const gfxSkipCharsIterator& aIter,
                                          PropertyProvider& aProperties) {
  Range range(aProperties.GetStart().GetSkippedOffset(),
              aIter.GetSkippedOffset());
  gfxFloat advance = mTextRun->GetAdvanceWidth(range, &aProperties);
  nscoord iSize = NSToCoordCeilClamped(advance);
  nsPoint point;

  if (mTextRun->IsVertical()) {
    point.x = 0;
    if (mTextRun->IsInlineReversed()) {
      point.y = mRect.height - iSize;
    } else {
      point.y = iSize;
    }
  } else {
    point.y = 0;
    if (mTextRun->IsInlineReversed()) {
      point.x = mRect.width - iSize;
    } else {
      point.x = iSize;
    }
    if (Style()->IsTextCombined()) {
      point.x *= GetTextCombineScaleFactor(this);
    }
  }
  return point;
}

nsresult nsTextFrame::GetPointFromOffset(int32_t inOffset, nsPoint* outPoint) {
  if (!outPoint) {
    return NS_ERROR_NULL_POINTER;
  }

  DEBUG_VERIFY_NOT_DIRTY(mState);
  if (mState & NS_FRAME_IS_DIRTY) {
    return NS_ERROR_UNEXPECTED;
  }

  if (GetContentLength() <= 0) {
    outPoint->x = 0;
    outPoint->y = 0;
    return NS_OK;
  }

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return NS_ERROR_FAILURE;
  }

  PropertyProvider properties(this, iter, nsTextFrame::eInflated, mFontMetrics);
  // Don't trim trailing whitespace, we want the caret to appear in the right
  // place if it's positioned there
  properties.InitializeForDisplay(false);

  UpdateIteratorFromOffset(properties, inOffset, iter);

  *outPoint = GetPointFromIterator(iter, properties);

  return NS_OK;
}

nsresult nsTextFrame::GetCharacterRectsInRange(int32_t aInOffset,
                                               int32_t aLength,
                                               nsTArray<nsRect>& aRects) {
  DEBUG_VERIFY_NOT_DIRTY(mState);
  if (mState & NS_FRAME_IS_DIRTY) {
    return NS_ERROR_UNEXPECTED;
  }

  if (GetContentLength() <= 0) {
    return NS_OK;
  }

  if (!mTextRun) {
    return NS_ERROR_FAILURE;
  }

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  PropertyProvider properties(this, iter, nsTextFrame::eInflated, mFontMetrics);
  // Don't trim trailing whitespace, we want the caret to appear in the right
  // place if it's positioned there
  properties.InitializeForDisplay(false);

  UpdateIteratorFromOffset(properties, aInOffset, iter);

  const int32_t kContentEnd = GetContentEnd();
  const int32_t kEndOffset = std::min(aInOffset + aLength, kContentEnd);
  while (aInOffset < kEndOffset) {
    if (!iter.IsOriginalCharSkipped() &&
        !mTextRun->IsClusterStart(iter.GetSkippedOffset())) {
      FindClusterStart(mTextRun,
                       properties.GetStart().GetOriginalOffset() +
                           properties.GetOriginalLength(),
                       &iter);
    }

    nsPoint point = GetPointFromIterator(iter, properties);
    nsRect rect;
    rect.x = point.x;
    rect.y = point.y;

    nscoord iSize = 0;
    if (aInOffset < kContentEnd) {
      gfxSkipCharsIterator nextIter(iter);
      nextIter.AdvanceOriginal(1);
      if (!nextIter.IsOriginalCharSkipped() &&
          !mTextRun->IsClusterStart(nextIter.GetSkippedOffset()) &&
          nextIter.GetOriginalOffset() < kContentEnd) {
        FindClusterEnd(mTextRun, kContentEnd, &nextIter);
      }

      gfxFloat advance = mTextRun->GetAdvanceWidth(
          Range(iter.GetSkippedOffset(), nextIter.GetSkippedOffset()),
          &properties);
      iSize = NSToCoordCeilClamped(advance);
    }

    if (mTextRun->IsVertical()) {
      rect.width = mRect.width;
      rect.height = iSize;
      if (mTextRun->IsInlineReversed()) {
        // The iterator above returns a point with the origin at the
        // bottom left instead of the top left. Move the origin to the top left
        // by subtracting the character's height.
        rect.y -= rect.height;
      }
    } else {
      rect.width = iSize;
      rect.height = mRect.height;
      if (Style()->IsTextCombined()) {
        rect.width *= GetTextCombineScaleFactor(this);
      }
      if (mTextRun->IsInlineReversed()) {
        // The iterator above returns a point with the origin at the
        // top right instead of the top left. Move the origin to the top left by
        // subtracting the character's width. This is intentionally done after
        // GetTextCombineScaleFactor() so we use the final, scaled width.
        rect.x -= rect.width;
      }
    }
    aRects.AppendElement(rect);
    aInOffset++;
    // Don't advance iter if we've reached the end
    if (aInOffset < kEndOffset) {
      iter.AdvanceOriginal(1);
    }
  }

  return NS_OK;
}

nsresult nsTextFrame::GetChildFrameContainingOffset(int32_t aContentOffset,
                                                    bool aHint,
                                                    int32_t* aOutOffset,
                                                    nsIFrame** aOutFrame) {
  DEBUG_VERIFY_NOT_DIRTY(mState);
#if 0  // XXXrbs disable due to bug 310227
  if (mState & NS_FRAME_IS_DIRTY)
    return NS_ERROR_UNEXPECTED;
#endif

  NS_ASSERTION(aOutOffset && aOutFrame, "Bad out parameters");
  NS_ASSERTION(aContentOffset >= 0,
               "Negative content offset, existing code was very broken!");
  nsIFrame* primaryFrame = mContent->GetPrimaryFrame();
  if (this != primaryFrame) {
    // This call needs to happen on the primary frame
    return primaryFrame->GetChildFrameContainingOffset(aContentOffset, aHint,
                                                       aOutOffset, aOutFrame);
  }

  nsTextFrame* f = this;
  int32_t offset = mContentOffset;

  // Try to look up the offset to frame property
  nsTextFrame* cachedFrame = GetProperty(OffsetToFrameProperty());

  if (cachedFrame) {
    f = cachedFrame;
    offset = f->GetContentOffset();

    f->RemoveStateBits(TEXT_IN_OFFSET_CACHE);
  }

  if ((aContentOffset >= offset) && (aHint || aContentOffset != offset)) {
    while (true) {
      nsTextFrame* next = f->GetNextContinuation();
      if (!next || aContentOffset < next->GetContentOffset()) {
        break;
      }
      if (aContentOffset == next->GetContentOffset()) {
        if (aHint) {
          f = next;
          if (f->GetContentLength() == 0) {
            continue;  // use the last of the empty frames with this offset
          }
        }
        break;
      }
      f = next;
    }
  } else {
    while (true) {
      nsTextFrame* prev = f->GetPrevContinuation();
      if (!prev || aContentOffset > f->GetContentOffset()) {
        break;
      }
      if (aContentOffset == f->GetContentOffset()) {
        if (!aHint) {
          f = prev;
          if (f->GetContentLength() == 0) {
            continue;  // use the first of the empty frames with this offset
          }
        }
        break;
      }
      f = prev;
    }
  }

  *aOutOffset = aContentOffset - f->GetContentOffset();
  *aOutFrame = f;

  // cache the frame we found
  SetProperty(OffsetToFrameProperty(), f);
  f->AddStateBits(TEXT_IN_OFFSET_CACHE);

  return NS_OK;
}

nsIFrame::FrameSearchResult nsTextFrame::PeekOffsetNoAmount(bool aForward,
                                                            int32_t* aOffset) {
  NS_ASSERTION(aOffset && *aOffset <= GetContentLength(),
               "aOffset out of range");

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return CONTINUE_EMPTY;
  }

  TrimmedOffsets trimmed = GetTrimmedOffsets(TextFragment());
  // Check whether there are nonskipped characters in the trimmmed range
  return (iter.ConvertOriginalToSkipped(trimmed.GetEnd()) >
          iter.ConvertOriginalToSkipped(trimmed.mStart))
             ? FOUND
             : CONTINUE;
}

/**
 * This class iterates through the clusters before or after the given
 * aPosition (which is a content offset). You can test each cluster
 * to see if it's whitespace (as far as selection/caret movement is concerned),
 * or punctuation, or if there is a word break before the cluster. ("Before"
 * is interpreted according to aDirection, so if aDirection is -1, "before"
 * means actually *after* the cluster content.)
 */
class MOZ_STACK_CLASS ClusterIterator {
 public:
  ClusterIterator(nsTextFrame* aTextFrame, int32_t aPosition,
                  int32_t aDirection, nsString& aContext,
                  bool aTrimSpaces = true);

  bool NextCluster();
  bool IsInlineWhitespace() const;
  bool IsNewline() const;
  bool IsPunctuation() const;
  bool HaveWordBreakBefore() const { return mHaveWordBreak; }

  // Get the charIndex that corresponds to the "before" side of the current
  // character, according to the direction of iteration: so for a forward
  // iterator, this is simply mCharIndex, while for a reverse iterator it will
  // be mCharIndex + <number of code units in the character>.
  int32_t GetBeforeOffset() const {
    MOZ_ASSERT(mCharIndex >= 0);
    return mDirection < 0 ? GetAfterInternal() : mCharIndex;
  }
  // Get the charIndex that corresponds to the "before" side of the current
  // character, according to the direction of iteration: the opposite side
  // to what GetBeforeOffset returns.
  int32_t GetAfterOffset() const {
    MOZ_ASSERT(mCharIndex >= 0);
    return mDirection > 0 ? GetAfterInternal() : mCharIndex;
  }

 private:
  // Helper for Get{After,Before}Offset; returns the charIndex after the
  // current position in the text, accounting for surrogate pairs.
  int32_t GetAfterInternal() const;

  gfxSkipCharsIterator mIterator;
  // Usually, mFrag is pointer to `dom::CharacterData::mText`.  However, if
  // we're in a password field, this points `mMaskedFrag`.
  const nsTextFragment* mFrag;
  // If we're in a password field, this is initialized with mask characters.
  nsTextFragment mMaskedFrag;
  nsTextFrame* mTextFrame;
  int32_t mDirection;  // +1 or -1, or 0 to indicate failure
  int32_t mCharIndex;
  nsTextFrame::TrimmedOffsets mTrimmed;
  nsTArray<bool> mWordBreaks;
  bool mHaveWordBreak;
};

static bool IsAcceptableCaretPosition(const gfxSkipCharsIterator& aIter,
                                      bool aRespectClusters,
                                      const gfxTextRun* aTextRun,
                                      nsTextFrame* aFrame) {
  if (aIter.IsOriginalCharSkipped()) {
    return false;
  }
  uint32_t index = aIter.GetSkippedOffset();
  if (aRespectClusters && !aTextRun->IsClusterStart(index)) {
    return false;
  }
  if (index > 0) {
    // Check whether the proposed position is in between the two halves of a
    // surrogate pair, before a Variation Selector character, or within a
    // ligated emoji sequence; if so, this is not a valid character boundary.
    // (In the case where we are respecting clusters, we won't actually get
    // this far because the low surrogate is also marked as non-clusterStart
    // so we'll return FALSE above.)
    const uint32_t offs = AssertedCast<uint32_t>(aIter.GetOriginalOffset());
    const nsTextFragment* frag = aFrame->TextFragment();
    const char16_t ch = frag->CharAt(offs);

    if (gfxFontUtils::IsVarSelector(ch) ||
        frag->IsLowSurrogateFollowingHighSurrogateAt(offs) ||
        (!aTextRun->IsLigatureGroupStart(index) &&
         (unicode::GetEmojiPresentation(ch) == unicode::EmojiDefault ||
          (unicode::GetEmojiPresentation(ch) == unicode::TextDefault &&
           offs + 1 < frag->GetLength() &&
           frag->CharAt(offs + 1) == gfxFontUtils::kUnicodeVS16)))) {
      return false;
    }

    // If the proposed position is before a high surrogate, we need to decode
    // the surrogate pair (if valid) and check the resulting character.
    if (NS_IS_HIGH_SURROGATE(ch)) {
      if (const char32_t ucs4 = frag->ScalarValueAt(offs)) {
        // If the character is a (Plane-14) variation selector,
        // or an emoji character that is ligated with the previous
        // character (i.e. part of a Regional-Indicator flag pair,
        // or an emoji-ZWJ sequence), this is not a valid boundary.
        if (gfxFontUtils::IsVarSelector(ucs4) ||
            (!aTextRun->IsLigatureGroupStart(index) &&
             unicode::GetEmojiPresentation(ucs4) == unicode::EmojiDefault)) {
          return false;
        }
      }
    }
  }
  return true;
}

nsIFrame::FrameSearchResult nsTextFrame::PeekOffsetCharacter(
    bool aForward, int32_t* aOffset, PeekOffsetCharacterOptions aOptions) {
  int32_t contentLength = GetContentLength();
  NS_ASSERTION(aOffset && *aOffset <= contentLength, "aOffset out of range");

  if (!aOptions.mIgnoreUserStyleAll) {
    StyleUserSelect selectStyle;
    Unused << IsSelectable(&selectStyle);
    if (selectStyle == StyleUserSelect::All) {
      return CONTINUE_UNSELECTABLE;
    }
  }

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return CONTINUE_EMPTY;
  }

  TrimmedOffsets trimmed =
      GetTrimmedOffsets(TextFragment(), TrimmedOffsetFlags::NoTrimAfter);

  // A negative offset means "end of frame".
  int32_t startOffset =
      GetContentOffset() + (*aOffset < 0 ? contentLength : *aOffset);

  if (!aForward) {
    // If at the beginning of the line, look at the previous continuation
    for (int32_t i = std::min(trimmed.GetEnd(), startOffset) - 1;
         i >= trimmed.mStart; --i) {
      iter.SetOriginalOffset(i);
      if (IsAcceptableCaretPosition(iter, aOptions.mRespectClusters, mTextRun,
                                    this)) {
        *aOffset = i - mContentOffset;
        return FOUND;
      }
    }
    *aOffset = 0;
  } else {
    // If we're at the end of a line, look at the next continuation
    iter.SetOriginalOffset(startOffset);
    if (startOffset <= trimmed.GetEnd() &&
        !(startOffset < trimmed.GetEnd() &&
          StyleText()->NewlineIsSignificant(this) &&
          iter.GetSkippedOffset() < mTextRun->GetLength() &&
          mTextRun->CharIsNewline(iter.GetSkippedOffset()))) {
      for (int32_t i = startOffset + 1; i <= trimmed.GetEnd(); ++i) {
        iter.SetOriginalOffset(i);
        if (i == trimmed.GetEnd() ||
            IsAcceptableCaretPosition(iter, aOptions.mRespectClusters, mTextRun,
                                      this)) {
          *aOffset = i - mContentOffset;
          return FOUND;
        }
      }
    }
    *aOffset = contentLength;
  }

  return CONTINUE;
}

bool ClusterIterator::IsInlineWhitespace() const {
  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
  return IsSelectionInlineWhitespace(mFrag, mCharIndex);
}

bool ClusterIterator::IsNewline() const {
  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
  return IsSelectionNewline(mFrag, mCharIndex);
}

bool ClusterIterator::IsPunctuation() const {
  NS_ASSERTION(mCharIndex >= 0, "No cluster selected");
  // Return true for all Punctuation categories (Unicode general category P?),
  // and also for Symbol categories (S?) except for Modifier Symbol, which is
  // kept together with any adjacent letter/number. (Bug 1066756)
  const char16_t ch = mFrag->CharAt(AssertedCast<uint32_t>(mCharIndex));
  const uint8_t cat = unicode::GetGeneralCategory(ch);
  switch (cat) {
    case HB_UNICODE_GENERAL_CATEGORY_CONNECT_PUNCTUATION: /* Pc */
      if (ch == '_' && !StaticPrefs::layout_word_select_stop_at_underscore()) {
        return false;
      }
      [[fallthrough]];
    case HB_UNICODE_GENERAL_CATEGORY_DASH_PUNCTUATION:    /* Pd */
    case HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION:   /* Pe */
    case HB_UNICODE_GENERAL_CATEGORY_FINAL_PUNCTUATION:   /* Pf */
    case HB_UNICODE_GENERAL_CATEGORY_INITIAL_PUNCTUATION: /* Pi */
    case HB_UNICODE_GENERAL_CATEGORY_OTHER_PUNCTUATION:   /* Po */
    case HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION:    /* Ps */
    case HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL:     /* Sc */
    // Deliberately omitted:
    // case HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL:     /* Sk */
    case HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL:  /* Sm */
    case HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL: /* So */
      return true;
    default:
      return false;
  }
}

int32_t ClusterIterator::GetAfterInternal() const {
  if (mFrag->IsHighSurrogateFollowedByLowSurrogateAt(
          AssertedCast<uint32_t>(mCharIndex))) {
    return mCharIndex + 2;
  }
  return mCharIndex + 1;
}

bool ClusterIterator::NextCluster() {
  if (!mDirection) {
    return false;
  }
  const gfxTextRun* textRun = mTextFrame->GetTextRun(nsTextFrame::eInflated);

  mHaveWordBreak = false;
  while (true) {
    bool keepGoing = false;
    if (mDirection > 0) {
      if (mIterator.GetOriginalOffset() >= mTrimmed.GetEnd()) {
        return false;
      }
      keepGoing = mIterator.IsOriginalCharSkipped() ||
                  mIterator.GetOriginalOffset() < mTrimmed.mStart ||
                  !textRun->IsClusterStart(mIterator.GetSkippedOffset());
      mCharIndex = mIterator.GetOriginalOffset();
      mIterator.AdvanceOriginal(1);
    } else {
      if (mIterator.GetOriginalOffset() <= mTrimmed.mStart) {
        // Trimming can skip backward word breakers, see bug 1667138
        return mHaveWordBreak;
      }
      mIterator.AdvanceOriginal(-1);
      keepGoing = mIterator.IsOriginalCharSkipped() ||
                  mIterator.GetOriginalOffset() >= mTrimmed.GetEnd() ||
                  !textRun->IsClusterStart(mIterator.GetSkippedOffset());
      mCharIndex = mIterator.GetOriginalOffset();
    }

    if (mWordBreaks[GetBeforeOffset() - mTextFrame->GetContentOffset()]) {
      mHaveWordBreak = true;
    }
    if (!keepGoing) {
      return true;
    }
  }
}

ClusterIterator::ClusterIterator(nsTextFrame* aTextFrame, int32_t aPosition,
                                 int32_t aDirection, nsString& aContext,
                                 bool aTrimSpaces)
    : mIterator(aTextFrame->EnsureTextRun(nsTextFrame::eInflated)),
      mTextFrame(aTextFrame),
      mDirection(aDirection),
      mCharIndex(-1),
      mHaveWordBreak(false) {
  gfxTextRun* textRun = aTextFrame->GetTextRun(nsTextFrame::eInflated);
  if (!textRun) {
    mDirection = 0;  // signal failure
    return;
  }

  mFrag = aTextFrame->TextFragment();
  // If we're in a password field, some characters may be masked.  In such
  // case, we need to treat each masked character is a mask character since
  // we shouldn't expose word boundary which is hidden by the masking.
  if (aTextFrame->GetContent() && mFrag->GetLength() > 0 &&
      aTextFrame->GetContent()->HasFlag(NS_MAYBE_MASKED) &&
      (textRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed)) {
    const char16_t kPasswordMask = TextEditor::PasswordMask();
    const nsTransformedTextRun* transformedTextRun =
        static_cast<const nsTransformedTextRun*>(textRun);
    // Use nsString and not nsAutoString so that we get a nsStringBuffer which
    // can be just AddRefed in `mMaskedFrag`.
    nsString maskedText;
    maskedText.SetCapacity(mFrag->GetLength());
    for (uint32_t i = 0; i < mFrag->GetLength(); ++i) {
      mIterator.SetOriginalOffset(i);
      uint32_t skippedOffset = mIterator.GetSkippedOffset();
      if (mFrag->IsHighSurrogateFollowedByLowSurrogateAt(i)) {
        if (transformedTextRun->mStyles[skippedOffset]->mMaskPassword) {
          maskedText.Append(kPasswordMask);
          maskedText.Append(kPasswordMask);
        } else {
          maskedText.Append(mFrag->CharAt(i));
          maskedText.Append(mFrag->CharAt(i + 1));
        }
        ++i;
      } else {
        maskedText.Append(
            transformedTextRun->mStyles[skippedOffset]->mMaskPassword
                ? kPasswordMask
                : mFrag->CharAt(i));
      }
    }
    mMaskedFrag.SetTo(maskedText, mFrag->IsBidi(), true);
    mFrag = &mMaskedFrag;
  }

  mIterator.SetOriginalOffset(aPosition);
  mTrimmed = aTextFrame->GetTrimmedOffsets(
      mFrag, aTrimSpaces ? nsTextFrame::TrimmedOffsetFlags::Default
                         : nsTextFrame::TrimmedOffsetFlags::NoTrimAfter |
                               nsTextFrame::TrimmedOffsetFlags::NoTrimBefore);

  const uint32_t textOffset =
      AssertedCast<uint32_t>(aTextFrame->GetContentOffset());
  const uint32_t textLen =
      AssertedCast<uint32_t>(aTextFrame->GetContentLength());

  // Allocate an extra element to record the word break at the end of the line
  // or text run in mWordBreak[textLen].
  mWordBreaks.AppendElements(textLen + 1);
  PodZero(mWordBreaks.Elements(), textLen + 1);
  uint32_t textStart;
  if (aDirection > 0) {
    if (aContext.IsEmpty()) {
      // No previous context, so it must be the start of a line or text run
      mWordBreaks[0] = true;
    }
    textStart = aContext.Length();
    mFrag->AppendTo(aContext, textOffset, textLen);
  } else {
    if (aContext.IsEmpty()) {
      // No following context, so it must be the end of a line or text run
      mWordBreaks[textLen] = true;
    }
    textStart = 0;
    nsAutoString str;
    mFrag->AppendTo(str, textOffset, textLen);
    aContext.Insert(str, 0);
  }

  const uint32_t textEnd = textStart + textLen;
  intl::WordBreakIteratorUtf16 wordBreakIter(aContext);
  Maybe<uint32_t> nextBreak =
      wordBreakIter.Seek(textStart > 0 ? textStart - 1 : textStart);
  while (nextBreak && *nextBreak <= textEnd) {
    mWordBreaks[*nextBreak - textStart] = true;
    nextBreak = wordBreakIter.Next();
  }

  MOZ_ASSERT(textEnd != aContext.Length() || mWordBreaks[textLen],
             "There should be a word break at the end of a line or text run!");
}

nsIFrame::FrameSearchResult nsTextFrame::PeekOffsetWord(
    bool aForward, bool aWordSelectEatSpace, bool aIsKeyboardSelect,
    int32_t* aOffset, PeekWordState* aState, bool aTrimSpaces) {
  int32_t contentLength = GetContentLength();
  NS_ASSERTION(aOffset && *aOffset <= contentLength, "aOffset out of range");

  StyleUserSelect selectStyle;
  Unused << IsSelectable(&selectStyle);
  if (selectStyle == StyleUserSelect::All) {
    return CONTINUE_UNSELECTABLE;
  }

  int32_t offset =
      GetContentOffset() + (*aOffset < 0 ? contentLength : *aOffset);
  ClusterIterator cIter(this, offset, aForward ? 1 : -1, aState->mContext,
                        aTrimSpaces);

  if (!cIter.NextCluster()) {
    return CONTINUE_EMPTY;
  }

  do {
    bool isPunctuation = cIter.IsPunctuation();
    bool isInlineWhitespace = cIter.IsInlineWhitespace();
    bool isWhitespace = isInlineWhitespace || cIter.IsNewline();
    bool isWordBreakBefore = cIter.HaveWordBreakBefore();
    if (!isWhitespace || isInlineWhitespace) {
      aState->SetSawInlineCharacter();
    }
    if (aWordSelectEatSpace == isWhitespace && !aState->mSawBeforeType) {
      aState->SetSawBeforeType();
      aState->Update(isPunctuation, isWhitespace);
      continue;
    }
    // See if we can break before the current cluster
    if (!aState->mAtStart) {
      bool canBreak;
      if (isPunctuation != aState->mLastCharWasPunctuation) {
        canBreak = BreakWordBetweenPunctuation(aState, aForward, isPunctuation,
                                               isWhitespace, aIsKeyboardSelect);
      } else if (!aState->mLastCharWasWhitespace && !isWhitespace &&
                 !isPunctuation && isWordBreakBefore) {
        // if both the previous and the current character are not white
        // space but this can be word break before, we don't need to eat
        // a white space in this case. This case happens in some languages
        // that their words are not separated by white spaces. E.g.,
        // Japanese and Chinese.
        canBreak = true;
      } else {
        canBreak = isWordBreakBefore && aState->mSawBeforeType &&
                   (aWordSelectEatSpace != isWhitespace);
      }
      if (canBreak) {
        *aOffset = cIter.GetBeforeOffset() - mContentOffset;
        return FOUND;
      }
    }
    aState->Update(isPunctuation, isWhitespace);
  } while (cIter.NextCluster());

  *aOffset = cIter.GetAfterOffset() - mContentOffset;
  return CONTINUE;
}

bool nsTextFrame::HasVisibleText() {
  // Text in the range is visible if there is at least one character in the
  // range that is not skipped and is mapped by this frame (which is the primary
  // frame) or one of its continuations.
  for (nsTextFrame* f = this; f; f = f->GetNextContinuation()) {
    int32_t dummyOffset = 0;
    if (f->PeekOffsetNoAmount(true, &dummyOffset) == FOUND) {
      return true;
    }
  }
  return false;
}

std::pair<int32_t, int32_t> nsTextFrame::GetOffsets() const {
  return std::make_pair(GetContentOffset(), GetContentEnd());
}

static int32_t FindEndOfPunctuationRun(const nsTextFragment* aFrag,
                                       const gfxTextRun* aTextRun,
                                       gfxSkipCharsIterator* aIter,
                                       int32_t aOffset, int32_t aStart,
                                       int32_t aEnd) {
  int32_t i;

  for (i = aStart; i < aEnd - aOffset; ++i) {
    if (nsContentUtils::IsFirstLetterPunctuation(
            aFrag->ScalarValueAt(AssertedCast<uint32_t>(aOffset + i)))) {
      aIter->SetOriginalOffset(aOffset + i);
      FindClusterEnd(aTextRun, aEnd, aIter);
      i = aIter->GetOriginalOffset() - aOffset;
    } else {
      break;
    }
  }
  return i;
}

/**
 * Returns true if this text frame completes the first-letter, false
 * if it does not contain a true "letter".
 * If returns true, then it also updates aLength to cover just the first-letter
 * text.
 *
 * XXX :first-letter should be handled during frame construction
 * (and it has a good bit in common with nextBidi)
 *
 * @param aLength an in/out parameter: on entry contains the maximum length to
 * return, on exit returns length of the first-letter fragment (which may
 * include leading and trailing punctuation, for example)
 */
static bool FindFirstLetterRange(const nsTextFragment* aFrag,
                                 const nsAtom* aLang,
                                 const gfxTextRun* aTextRun, int32_t aOffset,
                                 const gfxSkipCharsIterator& aIter,
                                 int32_t* aLength) {
  int32_t i;
  int32_t length = *aLength;
  int32_t endOffset = aOffset + length;
  gfxSkipCharsIterator iter(aIter);

  // Currently the only language-specific special case we handle here is the
  // Dutch "IJ" digraph.
  auto LangTagIsDutch = [](const nsAtom* aLang) -> bool {
    if (!aLang) {
      return false;
    }
    if (aLang == nsGkAtoms::nl) {
      return true;
    }
    // We don't need to fully parse as a Locale; just check the initial subtag.
    nsDependentAtomString langStr(aLang);
    int32_t index = langStr.FindChar('-');
    if (index > 0) {
      langStr.Truncate(index);
      return langStr.EqualsLiteral("nl");
    }
    return false;
  };

  // skip leading whitespace, then consume clusters that start with punctuation
  i = FindEndOfPunctuationRun(
      aFrag, aTextRun, &iter, aOffset,
      GetTrimmableWhitespaceCount(aFrag, aOffset, length, 1), endOffset);
  if (i == length) {
    return false;
  }

  // If the next character is not a letter, number or symbol, there is no
  // first-letter.
  // Return true so that we don't go on looking, but set aLength to 0.
  const char32_t usv =
      aFrag->ScalarValueAt(AssertedCast<uint32_t>(aOffset + i));
  if (!nsContentUtils::IsAlphanumericOrSymbol(usv)) {
    *aLength = 0;
    return true;
  }

  // consume another cluster (the actual first letter)

  // For complex scripts such as Indic and SEAsian, where first-letter
  // should extend to entire orthographic "syllable" clusters, we don't
  // want to allow this to split a ligature.
  bool allowSplitLigature;
  bool usesIndicHalfForms = false;

  typedef intl::Script Script;
  Script script = intl::UnicodeProperties::GetScriptCode(usv);
  switch (script) {
    default:
      allowSplitLigature = true;
      break;

    // Don't break regional-indicator ligatures.
    case Script::COMMON:
      allowSplitLigature = !gfxFontUtils::IsRegionalIndicator(usv);
      break;

    // For now, lacking any definitive specification of when to apply this
    // behavior, we'll base the decision on the HarfBuzz shaping engine
    // used for each script: those that are handled by the Indic, Tibetan,
    // Myanmar and SEAsian shapers will apply the "don't split ligatures"
    // rule.

    // Indic
    case Script::BENGALI:
    case Script::DEVANAGARI:
    case Script::GUJARATI:
      usesIndicHalfForms = true;
      [[fallthrough]];

    case Script::GURMUKHI:
    case Script::KANNADA:
    case Script::MALAYALAM:
    case Script::ORIYA:
    case Script::TAMIL:
    case Script::TELUGU:
    case Script::SINHALA:
    case Script::BALINESE:
    case Script::LEPCHA:
    case Script::REJANG:
    case Script::SUNDANESE:
    case Script::JAVANESE:
    case Script::KAITHI:
    case Script::MEETEI_MAYEK:
    case Script::CHAKMA:
    case Script::SHARADA:
    case Script::TAKRI:
    case Script::KHMER:

    // Tibetan
    case Script::TIBETAN:

    // Myanmar
    case Script::MYANMAR:

    // Other SEAsian
    case Script::BUGINESE:
    case Script::NEW_TAI_LUE:
    case Script::CHAM:
    case Script::TAI_THAM:

      // What about Thai/Lao - any special handling needed?
      // Should we special-case Arabic lam-alef?

      allowSplitLigature = false;
      break;
  }

  iter.SetOriginalOffset(aOffset + i);
  FindClusterEnd(aTextRun, endOffset, &iter, allowSplitLigature);

  i = iter.GetOriginalOffset() - aOffset;

  // Heuristic for Indic scripts that like to form conjuncts:
  // If we ended at a virama that is ligated with the preceding character
  // (e.g. creating a half-form), then don't stop here; include the next
  // cluster as well so that we don't break a conjunct.
  //
  // Unfortunately this cannot distinguish between a letter+virama that ligate
  // to create a half-form (in which case we have a conjunct that should not
  // be broken) and a letter+virama that ligate purely for presentational
  // reasons to position the (visible) virama component (in which case breaking
  // after the virama would be acceptable). So results may be imperfect,
  // depending how the font has chosen to implement visible viramas.
  if (usesIndicHalfForms) {
    while (i + 1 < length &&
           !aTextRun->IsLigatureGroupStart(iter.GetSkippedOffset())) {
      char32_t c = aFrag->ScalarValueAt(AssertedCast<uint32_t>(aOffset + i));
      if (intl::UnicodeProperties::GetCombiningClass(c) ==
          HB_UNICODE_COMBINING_CLASS_VIRAMA) {
        iter.AdvanceOriginal(1);
        FindClusterEnd(aTextRun, endOffset, &iter, allowSplitLigature);
        i = iter.GetOriginalOffset() - aOffset;
      } else {
        break;
      }
    }
  }

  if (i + 1 == length) {
    return true;
  }

  // Check for Dutch "ij" digraph special case.
  if (script == Script::LATIN && LangTagIsDutch(aLang)) {
    if (ToLowerCase(aFrag->CharAt(AssertedCast<uint32_t>(aOffset + i))) ==
            'i' &&
        ToLowerCase(aFrag->CharAt(AssertedCast<uint32_t>(aOffset + i + 1))) ==
            'j') {
      iter.SetOriginalOffset(aOffset + i + 1);
      FindClusterEnd(aTextRun, endOffset, &iter, allowSplitLigature);
      i = iter.GetOriginalOffset() - aOffset;
      if (i + 1 == length) {
        return true;
      }
    }
  }

  // consume clusters that start with punctuation
  i = FindEndOfPunctuationRun(aFrag, aTextRun, &iter, aOffset, i + 1,
                              endOffset);
  if (i < length) {
    *aLength = i;
  }
  return true;
}

static uint32_t FindStartAfterSkippingWhitespace(
    nsTextFrame::PropertyProvider* aProvider,
    nsIFrame::InlineIntrinsicISizeData* aData, const nsStyleText* aTextStyle,
    gfxSkipCharsIterator* aIterator, uint32_t aFlowEndInTextRun) {
  if (aData->mSkipWhitespace) {
    while (aIterator->GetSkippedOffset() < aFlowEndInTextRun &&
           IsTrimmableSpace(aProvider->GetFragment(),
                            aIterator->GetOriginalOffset(), aTextStyle)) {
      aIterator->AdvanceOriginal(1);
    }
  }
  return aIterator->GetSkippedOffset();
}

float nsTextFrame::GetFontSizeInflation() const {
  if (!HasFontSizeInflation()) {
    return 1.0f;
  }
  return GetProperty(FontSizeInflationProperty());
}

void nsTextFrame::SetFontSizeInflation(float aInflation) {
  if (aInflation == 1.0f) {
    if (HasFontSizeInflation()) {
      RemoveStateBits(TEXT_HAS_FONT_INFLATION);
      RemoveProperty(FontSizeInflationProperty());
    }
    return;
  }

  AddStateBits(TEXT_HAS_FONT_INFLATION);
  SetProperty(FontSizeInflationProperty(), aInflation);
}

/* virtual */
void nsTextFrame::MarkIntrinsicISizesDirty() {
  ClearTextRuns();
  nsIFrame::MarkIntrinsicISizesDirty();
}

// XXX this doesn't handle characters shaped by line endings. We need to
// temporarily override the "current line ending" settings.
void nsTextFrame::AddInlineMinISizeForFlow(gfxContext* aRenderingContext,
                                           nsIFrame::InlineMinISizeData* aData,
                                           TextRunType aTextRunType) {
  uint32_t flowEndInTextRun;
  gfxSkipCharsIterator iter =
      EnsureTextRun(aTextRunType, aRenderingContext->GetDrawTarget(),
                    aData->LineContainer(), aData->mLine, &flowEndInTextRun);
  gfxTextRun* textRun = GetTextRun(aTextRunType);
  if (!textRun) {
    return;
  }

  // Pass null for the line container. This will disable tab spacing, but that's
  // OK since we can't really handle tabs for intrinsic sizing anyway.
  const nsStyleText* textStyle = StyleText();
  const nsTextFragment* frag = TextFragment();

  // If we're hyphenating, the PropertyProvider needs the actual length;
  // otherwise we can just pass INT32_MAX to mean "all the text"
  int32_t len = INT32_MAX;
  bool hyphenating = frag->GetLength() > 0 &&
                     (textStyle->mHyphens == StyleHyphens::Auto ||
                      (textStyle->mHyphens == StyleHyphens::Manual &&
                       !!(textRun->GetFlags() &
                          gfx::ShapedTextFlags::TEXT_ENABLE_HYPHEN_BREAKS)));
  if (hyphenating) {
    gfxSkipCharsIterator tmp(iter);
    len = std::min<int32_t>(GetContentOffset() + GetInFlowContentLength(),
                            tmp.ConvertSkippedToOriginal(flowEndInTextRun)) -
          iter.GetOriginalOffset();
  }
  PropertyProvider provider(textRun, textStyle, frag, this, iter, len, nullptr,
                            0, aTextRunType);

  bool collapseWhitespace = !textStyle->WhiteSpaceIsSignificant();
  bool preformatNewlines = textStyle->NewlineIsSignificant(this);
  bool preformatTabs = textStyle->WhiteSpaceIsSignificant();
  bool whitespaceCanHang = textStyle->WhiteSpaceCanHangOrVisuallyCollapse();
  gfxFloat tabWidth = -1;
  uint32_t start = FindStartAfterSkippingWhitespace(&provider, aData, textStyle,
                                                    &iter, flowEndInTextRun);

  // text-combine-upright frame is constantly 1em on inline-axis.
  if (Style()->IsTextCombined()) {
    if (start < flowEndInTextRun && textRun->CanBreakLineBefore(start)) {
      aData->OptionallyBreak();
    }
    aData->mCurrentLine += provider.GetFontMetrics()->EmHeight();
    aData->mTrailingWhitespace = 0;
    return;
  }

  if (textStyle->EffectiveOverflowWrap() == StyleOverflowWrap::Anywhere &&
      textStyle->WordCanWrap(this)) {
    aData->OptionallyBreak();
    aData->mCurrentLine +=
        textRun->GetMinAdvanceWidth(Range(start, flowEndInTextRun));
    aData->mTrailingWhitespace = 0;
    aData->mAtStartOfLine = false;
    aData->OptionallyBreak();
    return;
  }

  AutoTArray<gfxTextRun::HyphenType, BIG_TEXT_NODE_SIZE> hyphBuffer;
  if (hyphenating) {
    if (hyphBuffer.AppendElements(flowEndInTextRun - start, fallible)) {
      provider.GetHyphenationBreaks(Range(start, flowEndInTextRun),
                                    hyphBuffer.Elements());
    } else {
      hyphenating = false;
    }
  }

  for (uint32_t i = start, wordStart = start; i <= flowEndInTextRun; ++i) {
    bool preformattedNewline = false;
    bool preformattedTab = false;
    if (i < flowEndInTextRun) {
      // XXXldb Shouldn't we be including the newline as part of the
      // segment that it ends rather than part of the segment that it
      // starts?
      preformattedNewline = preformatNewlines && textRun->CharIsNewline(i);
      preformattedTab = preformatTabs && textRun->CharIsTab(i);
      if (!textRun->CanBreakLineBefore(i) && !preformattedNewline &&
          !preformattedTab &&
          (!hyphenating ||
           !gfxTextRun::IsOptionalHyphenBreak(hyphBuffer[i - start]))) {
        // we can't break here (and it's not the end of the flow)
        continue;
      }
    }

    if (i > wordStart) {
      nscoord width = NSToCoordCeilClamped(
          textRun->GetAdvanceWidth(Range(wordStart, i), &provider));
      width = std::max(0, width);
      aData->mCurrentLine = NSCoordSaturatingAdd(aData->mCurrentLine, width);
      aData->mAtStartOfLine = false;

      if (collapseWhitespace || whitespaceCanHang) {
        uint32_t trimStart = GetEndOfTrimmedText(frag, textStyle, wordStart, i,
                                                 &iter, whitespaceCanHang);
        if (trimStart == start) {
          // This is *all* trimmable whitespace, so whatever trailingWhitespace
          // we saw previously is still trailing...
          aData->mTrailingWhitespace += width;
        } else {
          // Some non-whitespace so the old trailingWhitespace is no longer
          // trailing
          nscoord wsWidth = NSToCoordCeilClamped(
              textRun->GetAdvanceWidth(Range(trimStart, i), &provider));
          aData->mTrailingWhitespace = std::max(0, wsWidth);
        }
      } else {
        aData->mTrailingWhitespace = 0;
      }
    }

    if (preformattedTab) {
      PropertyProvider::Spacing spacing;
      provider.GetSpacing(Range(i, i + 1), &spacing);
      aData->mCurrentLine += nscoord(spacing.mBefore);
      if (tabWidth < 0) {
        tabWidth = ComputeTabWidthAppUnits(this);
      }
      gfxFloat afterTab = AdvanceToNextTab(aData->mCurrentLine, tabWidth,
                                           provider.MinTabAdvance());
      aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
      wordStart = i + 1;
    } else if (i < flowEndInTextRun ||
               (i == textRun->GetLength() &&
                (textRun->GetFlags2() &
                 nsTextFrameUtils::Flags::HasTrailingBreak))) {
      if (preformattedNewline) {
        aData->ForceBreak();
      } else if (i < flowEndInTextRun && hyphenating &&
                 gfxTextRun::IsOptionalHyphenBreak(hyphBuffer[i - start])) {
        aData->OptionallyBreak(NSToCoordRound(provider.GetHyphenWidth()));
      } else {
        aData->OptionallyBreak();
      }
      if (aData->mSkipWhitespace) {
        iter.SetSkippedOffset(i);
        wordStart = FindStartAfterSkippingWhitespace(
            &provider, aData, textStyle, &iter, flowEndInTextRun);
      } else {
        wordStart = i;
      }
    }
  }

  if (start < flowEndInTextRun) {
    // Check if we have collapsible whitespace at the end
    aData->mSkipWhitespace = IsTrimmableSpace(
        provider.GetFragment(),
        iter.ConvertSkippedToOriginal(flowEndInTextRun - 1), textStyle);
  }
}

bool nsTextFrame::IsCurrentFontInflation(float aInflation) const {
  return fabsf(aInflation - GetFontSizeInflation()) < 1e-6;
}

// XXX Need to do something here to avoid incremental reflow bugs due to
// first-line and first-letter changing min-width
/* virtual */
void nsTextFrame::AddInlineMinISize(gfxContext* aRenderingContext,
                                    nsIFrame::InlineMinISizeData* aData) {
  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
  TextRunType trtype = (inflation == 1.0f) ? eNotInflated : eInflated;

  if (trtype == eInflated && !IsCurrentFontInflation(inflation)) {
    // FIXME: Ideally, if we already have a text run, we'd move it to be
    // the uninflated text run.
    ClearTextRun(nullptr, nsTextFrame::eInflated);
    mFontMetrics = nullptr;
  }

  nsTextFrame* f;
  const gfxTextRun* lastTextRun = nullptr;
  // nsContinuingTextFrame does nothing for AddInlineMinISize; all text frames
  // in the flow are handled right here.
  for (f = this; f; f = f->GetNextContinuation()) {
    // f->GetTextRun(nsTextFrame::eNotInflated) could be null if we
    // haven't set up textruns yet for f.  Except in OOM situations,
    // lastTextRun will only be null for the first text frame.
    if (f == this || f->GetTextRun(trtype) != lastTextRun) {
      nsIFrame* lc;
      if (aData->LineContainer() &&
          aData->LineContainer() != (lc = FindLineContainer(f))) {
        NS_ASSERTION(f != this,
                     "wrong InlineMinISizeData container"
                     " for first continuation");
        aData->mLine = nullptr;
        aData->SetLineContainer(lc);
      }

      // This will process all the text frames that share the same textrun as f.
      f->AddInlineMinISizeForFlow(aRenderingContext, aData, trtype);
      lastTextRun = f->GetTextRun(trtype);
    }
  }
}

// XXX this doesn't handle characters shaped by line endings. We need to
// temporarily override the "current line ending" settings.
void nsTextFrame::AddInlinePrefISizeForFlow(
    gfxContext* aRenderingContext, nsIFrame::InlinePrefISizeData* aData,
    TextRunType aTextRunType) {
  uint32_t flowEndInTextRun;
  gfxSkipCharsIterator iter =
      EnsureTextRun(aTextRunType, aRenderingContext->GetDrawTarget(),
                    aData->LineContainer(), aData->mLine, &flowEndInTextRun);
  gfxTextRun* textRun = GetTextRun(aTextRunType);
  if (!textRun) {
    return;
  }

  // Pass null for the line container. This will disable tab spacing, but that's
  // OK since we can't really handle tabs for intrinsic sizing anyway.

  const nsStyleText* textStyle = StyleText();
  const nsTextFragment* frag = TextFragment();
  PropertyProvider provider(textRun, textStyle, frag, this, iter, INT32_MAX,
                            nullptr, 0, aTextRunType);

  // text-combine-upright frame is constantly 1em on inline-axis.
  if (Style()->IsTextCombined()) {
    aData->mCurrentLine += provider.GetFontMetrics()->EmHeight();
    aData->mTrailingWhitespace = 0;
    aData->mLineIsEmpty = false;
    return;
  }

  bool collapseWhitespace = !textStyle->WhiteSpaceIsSignificant();
  bool preformatNewlines = textStyle->NewlineIsSignificant(this);
  bool preformatTabs = textStyle->TabIsSignificant();
  gfxFloat tabWidth = -1;
  uint32_t start = FindStartAfterSkippingWhitespace(&provider, aData, textStyle,
                                                    &iter, flowEndInTextRun);

  // XXX Should we consider hyphenation here?
  // If newlines and tabs aren't preformatted, nothing to do inside
  // the loop so make i skip to the end
  uint32_t loopStart =
      (preformatNewlines || preformatTabs) ? start : flowEndInTextRun;
  for (uint32_t i = loopStart, lineStart = start; i <= flowEndInTextRun; ++i) {
    bool preformattedNewline = false;
    bool preformattedTab = false;
    if (i < flowEndInTextRun) {
      // XXXldb Shouldn't we be including the newline as part of the
      // segment that it ends rather than part of the segment that it
      // starts?
      NS_ASSERTION(preformatNewlines || preformatTabs,
                   "We can't be here unless newlines are "
                   "hard breaks or there are tabs");
      preformattedNewline = preformatNewlines && textRun->CharIsNewline(i);
      preformattedTab = preformatTabs && textRun->CharIsTab(i);
      if (!preformattedNewline && !preformattedTab) {
        // we needn't break here (and it's not the end of the flow)
        continue;
      }
    }

    if (i > lineStart) {
      nscoord width = NSToCoordCeilClamped(
          textRun->GetAdvanceWidth(Range(lineStart, i), &provider));
      width = std::max(0, width);
      aData->mCurrentLine = NSCoordSaturatingAdd(aData->mCurrentLine, width);
      aData->mLineIsEmpty = false;

      if (collapseWhitespace) {
        uint32_t trimStart =
            GetEndOfTrimmedText(frag, textStyle, lineStart, i, &iter);
        if (trimStart == start) {
          // This is *all* trimmable whitespace, so whatever trailingWhitespace
          // we saw previously is still trailing...
          aData->mTrailingWhitespace += width;
        } else {
          // Some non-whitespace so the old trailingWhitespace is no longer
          // trailing
          nscoord wsWidth = NSToCoordCeilClamped(
              textRun->GetAdvanceWidth(Range(trimStart, i), &provider));
          aData->mTrailingWhitespace = std::max(0, wsWidth);
        }
      } else {
        aData->mTrailingWhitespace = 0;
      }
    }

    if (preformattedTab) {
      PropertyProvider::Spacing spacing;
      provider.GetSpacing(Range(i, i + 1), &spacing);
      aData->mCurrentLine += nscoord(spacing.mBefore);
      if (tabWidth < 0) {
        tabWidth = ComputeTabWidthAppUnits(this);
      }
      gfxFloat afterTab = AdvanceToNextTab(aData->mCurrentLine, tabWidth,
                                           provider.MinTabAdvance());
      aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
      aData->mLineIsEmpty = false;
      lineStart = i + 1;
    } else if (preformattedNewline) {
      aData->ForceBreak();
      lineStart = i;
    }
  }

  // Check if we have collapsible whitespace at the end
  if (start < flowEndInTextRun) {
    aData->mSkipWhitespace = IsTrimmableSpace(
        provider.GetFragment(),
        iter.ConvertSkippedToOriginal(flowEndInTextRun - 1), textStyle);
  }
}

// XXX Need to do something here to avoid incremental reflow bugs due to
// first-line and first-letter changing pref-width
/* virtual */
void nsTextFrame::AddInlinePrefISize(gfxContext* aRenderingContext,
                                     nsIFrame::InlinePrefISizeData* aData) {
  float inflation = nsLayoutUtils::FontSizeInflationFor(this);
  TextRunType trtype = (inflation == 1.0f) ? eNotInflated : eInflated;

  if (trtype == eInflated && !IsCurrentFontInflation(inflation)) {
    // FIXME: Ideally, if we already have a text run, we'd move it to be
    // the uninflated text run.
    ClearTextRun(nullptr, nsTextFrame::eInflated);
    mFontMetrics = nullptr;
  }

  nsTextFrame* f;
  const gfxTextRun* lastTextRun = nullptr;
  // nsContinuingTextFrame does nothing for AddInlineMinISize; all text frames
  // in the flow are handled right here.
  for (f = this; f; f = f->GetNextContinuation()) {
    // f->GetTextRun(nsTextFrame::eNotInflated) could be null if we
    // haven't set up textruns yet for f.  Except in OOM situations,
    // lastTextRun will only be null for the first text frame.
    if (f == this || f->GetTextRun(trtype) != lastTextRun) {
      nsIFrame* lc;
      if (aData->LineContainer() &&
          aData->LineContainer() != (lc = FindLineContainer(f))) {
        NS_ASSERTION(f != this,
                     "wrong InlinePrefISizeData container"
                     " for first continuation");
        aData->mLine = nullptr;
        aData->SetLineContainer(lc);
      }

      // This will process all the text frames that share the same textrun as f.
      f->AddInlinePrefISizeForFlow(aRenderingContext, aData, trtype);
      lastTextRun = f->GetTextRun(trtype);
    }
  }
}

/* virtual */
nsIFrame::SizeComputationResult nsTextFrame::ComputeSize(
    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
    nscoord aAvailableISize, const LogicalSize& aMargin,
    const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
    ComputeSizeFlags aFlags) {
  // Inlines and text don't compute size before reflow.
  return {LogicalSize(aWM, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE),
          AspectRatioUsage::None};
}

static nsRect RoundOut(const gfxRect& aRect) {
  nsRect r;
  r.x = NSToCoordFloor(aRect.X());
  r.y = NSToCoordFloor(aRect.Y());
  r.width = NSToCoordCeil(aRect.XMost()) - r.x;
  r.height = NSToCoordCeil(aRect.YMost()) - r.y;
  return r;
}

nsRect nsTextFrame::ComputeTightBounds(DrawTarget* aDrawTarget) const {
  if (Style()->HasTextDecorationLines() || HasAnyStateBits(TEXT_HYPHEN_BREAK)) {
    // This is conservative, but OK.
    return InkOverflowRect();
  }

  gfxSkipCharsIterator iter =
      const_cast<nsTextFrame*>(this)->EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return nsRect();
  }

  PropertyProvider provider(const_cast<nsTextFrame*>(this), iter,
                            nsTextFrame::eInflated, mFontMetrics);
  // Trim trailing whitespace
  provider.InitializeForDisplay(true);

  gfxTextRun::Metrics metrics = mTextRun->MeasureText(
      ComputeTransformedRange(provider), gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS,
      aDrawTarget, &provider);
  if (GetWritingMode().IsLineInverted()) {
    metrics.mBoundingBox.y = -metrics.mBoundingBox.YMost();
  }
  // mAscent should be the same as metrics.mAscent, but it's what we use to
  // paint so that's the one we'll use.
  nsRect boundingBox = RoundOut(metrics.mBoundingBox);
  boundingBox += nsPoint(0, mAscent);
  if (mTextRun->IsVertical()) {
    // Swap line-relative textMetrics dimensions to physical coordinates.
    std::swap(boundingBox.x, boundingBox.y);
    std::swap(boundingBox.width, boundingBox.height);
  }
  return boundingBox;
}

/* virtual */
nsresult nsTextFrame::GetPrefWidthTightBounds(gfxContext* aContext, nscoord* aX,
                                              nscoord* aXMost) {
  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return NS_ERROR_FAILURE;
  }

  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);
  provider.InitializeForMeasure();

  gfxTextRun::Metrics metrics = mTextRun->MeasureText(
      ComputeTransformedRange(provider), gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS,
      aContext->GetDrawTarget(), &provider);
  // Round it like nsTextFrame::ComputeTightBounds() to ensure consistency.
  *aX = NSToCoordFloor(metrics.mBoundingBox.x);
  *aXMost = NSToCoordCeil(metrics.mBoundingBox.XMost());

  return NS_OK;
}

static bool HasSoftHyphenBefore(const nsTextFragment* aFrag,
                                const gfxTextRun* aTextRun,
                                int32_t aStartOffset,
                                const gfxSkipCharsIterator& aIter) {
  if (aIter.GetSkippedOffset() < aTextRun->GetLength() &&
      aTextRun->CanHyphenateBefore(aIter.GetSkippedOffset())) {
    return true;
  }
  if (!(aTextRun->GetFlags2() & nsTextFrameUtils::Flags::HasShy)) {
    return false;
  }
  gfxSkipCharsIterator iter = aIter;
  while (iter.GetOriginalOffset() > aStartOffset) {
    iter.AdvanceOriginal(-1);
    if (!iter.IsOriginalCharSkipped()) {
      break;
    }
    if (aFrag->CharAt(AssertedCast<uint32_t>(iter.GetOriginalOffset())) ==
        CH_SHY) {
      return true;
    }
  }
  return false;
}

/**
 * Removes all frames from aFrame up to (but not including) aFirstToNotRemove,
 * because their text has all been taken and reflowed by earlier frames.
 */
static void RemoveEmptyInFlows(nsTextFrame* aFrame,
                               nsTextFrame* aFirstToNotRemove) {
  MOZ_ASSERT(aFrame != aFirstToNotRemove, "This will go very badly");
  // We have to be careful here, because some RemoveFrame implementations
  // remove and destroy not only the passed-in frame but also all its following
  // in-flows (and sometimes all its following continuations in general).  So
  // we remove |f| and everything up to but not including firstToNotRemove from
  // the flow first, to make sure that only the things we want destroyed are
  // destroyed.

  // This sadly duplicates some of the logic from
  // nsSplittableFrame::RemoveFromFlow.  We can get away with not duplicating
  // all of it, because we know that the prev-continuation links of
  // firstToNotRemove and f are fluid, and non-null.
  NS_ASSERTION(aFirstToNotRemove->GetPrevContinuation() ==
                       aFirstToNotRemove->GetPrevInFlow() &&
                   aFirstToNotRemove->GetPrevInFlow() != nullptr,
               "aFirstToNotRemove should have a fluid prev continuation");
  NS_ASSERTION(aFrame->GetPrevContinuation() == aFrame->GetPrevInFlow() &&
                   aFrame->GetPrevInFlow() != nullptr,
               "aFrame should have a fluid prev continuation");

  nsTextFrame* prevContinuation = aFrame->GetPrevContinuation();
  nsTextFrame* lastRemoved = aFirstToNotRemove->GetPrevContinuation();

  for (nsTextFrame* f = aFrame; f != aFirstToNotRemove;
       f = f->GetNextContinuation()) {
    // f is going to be destroyed soon, after it is unlinked from the
    // continuation chain. If its textrun is going to be destroyed we need to
    // do it now, before we unlink the frames to remove from the flow,
    // because DestroyFrom calls ClearTextRuns() and that will start at the
    // first frame with the text run and walk the continuations.
    if (f->IsInTextRunUserData()) {
      f->ClearTextRuns();
    } else {
      f->DisconnectTextRuns();
    }
  }

  prevContinuation->SetNextInFlow(aFirstToNotRemove);
  aFirstToNotRemove->SetPrevInFlow(prevContinuation);

  // **Note: it is important here that we clear the Next link from lastRemoved
  // BEFORE clearing the Prev link from aFrame, because SetPrevInFlow() will
  // follow the Next pointers, wiping out the cached mFirstContinuation field
  // from each following frame in the list. We need this to stop when it
  // reaches lastRemoved!
  lastRemoved->SetNextInFlow(nullptr);
  aFrame->SetPrevInFlow(nullptr);

  nsContainerFrame* parent = aFrame->GetParent();
  nsBlockFrame* parentBlock = do_QueryFrame(parent);
  if (parentBlock) {
    // Manually call DoRemoveFrame so we can tell it that we're
    // removing empty frames; this will keep it from blowing away
    // text runs.
    parentBlock->DoRemoveFrame(aFrame, nsBlockFrame::FRAMES_ARE_EMPTY);
  } else {
    // Just remove it normally; use FrameChildListID::NoReflowPrincipal to avoid
    // posting new reflows.
    parent->RemoveFrame(FrameChildListID::NoReflowPrincipal, aFrame);
  }
}

void nsTextFrame::SetLength(int32_t aLength, nsLineLayout* aLineLayout,
                            uint32_t aSetLengthFlags) {
  mContentLengthHint = aLength;
  int32_t end = GetContentOffset() + aLength;
  nsTextFrame* f = GetNextInFlow();
  if (!f) {
    return;
  }

  // If our end offset is moving, then even if frames are not being pushed or
  // pulled, content is moving to or from the next line and the next line
  // must be reflowed.
  // If the next-continuation is dirty, then we should dirty the next line now
  // because we may have skipped doing it if we dirtied it in
  // CharacterDataChanged. This is ugly but teaching FrameNeedsReflow
  // and ChildIsDirty to handle a range of frames would be worse.
  if (aLineLayout &&
      (end != f->mContentOffset || f->HasAnyStateBits(NS_FRAME_IS_DIRTY))) {
    aLineLayout->SetDirtyNextLine();
  }

  if (end < f->mContentOffset) {
    // Our frame is shrinking. Give the text to our next in flow.
    if (aLineLayout && HasSignificantTerminalNewline() &&
        !GetParent()->IsLetterFrame() &&
        (aSetLengthFlags & ALLOW_FRAME_CREATION_AND_DESTRUCTION)) {
      // Whatever text we hand to our next-in-flow will end up in a frame all of
      // its own, since it ends in a forced linebreak.  Might as well just put
      // it in a separate frame now.  This is important to prevent text run
      // churn; if we did not do that, then we'd likely end up rebuilding
      // textruns for all our following continuations.
      // We skip this optimization when the parent is a first-letter frame
      // because it doesn't deal well with more than one child frame.
      // We also skip this optimization if we were called during bidi
      // resolution, so as not to create a new frame which doesn't appear in
      // the bidi resolver's list of frames
      nsIFrame* newFrame =
          PresShell()->FrameConstructor()->CreateContinuingFrame(this,
                                                                 GetParent());
      nsTextFrame* next = static_cast<nsTextFrame*>(newFrame);
      GetParent()->InsertFrames(FrameChildListID::NoReflowPrincipal, this,
                                aLineLayout->GetLine(),
                                nsFrameList(next, next));
      f = next;
    }

    f->mContentOffset = end;
    if (f->GetTextRun(nsTextFrame::eInflated) != mTextRun) {
      ClearTextRuns();
      f->ClearTextRuns();
    }
    return;
  }
  // Our frame is growing. Take text from our in-flow(s).
  // We can take text from frames in lines beyond just the next line.
  // We don't dirty those lines. That's OK, because when we reflow
  // our empty next-in-flow, it will take text from its next-in-flow and
  // dirty that line.

  // Note that in the process we may end up removing some frames from
  // the flow if they end up empty.
  nsTextFrame* framesToRemove = nullptr;
  while (f && f->mContentOffset < end) {
    f->mContentOffset = end;
    if (f->GetTextRun(nsTextFrame::eInflated) != mTextRun) {
      ClearTextRuns();
      f->ClearTextRuns();
    }
    nsTextFrame* next = f->GetNextInFlow();
    // Note: the "f->GetNextSibling() == next" check below is to restrict
    // this optimization to the case where they are on the same child list.
    // Otherwise we might remove the only child of a nsFirstLetterFrame
    // for example and it can't handle that.  See bug 597627 for details.
    if (next && next->mContentOffset <= end && f->GetNextSibling() == next &&
        (aSetLengthFlags & ALLOW_FRAME_CREATION_AND_DESTRUCTION)) {
      // |f| is now empty.  We may as well remove it, instead of copying all
      // the text from |next| into it instead; the latter leads to use
      // rebuilding textruns for all following continuations.
      // We skip this optimization if we were called during bidi resolution,
      // since the bidi resolver may try to handle the destroyed frame later
      // and crash
      if (!framesToRemove) {
        // Remember that we have to remove this frame.
        framesToRemove = f;
      }
    } else if (framesToRemove) {
      RemoveEmptyInFlows(framesToRemove, f);
      framesToRemove = nullptr;
    }
    f = next;
  }

  MOZ_ASSERT(!framesToRemove || (f && f->mContentOffset == end),
             "How did we exit the loop if we null out framesToRemove if "
             "!next || next->mContentOffset > end ?");

  if (framesToRemove) {
    // We are guaranteed that we exited the loop with f not null, per the
    // postcondition above
    RemoveEmptyInFlows(framesToRemove, f);
  }

#ifdef DEBUG
  f = this;
  int32_t iterations = 0;
  while (f && iterations < 10) {
    f->GetContentLength();  // Assert if negative length
    f = f->GetNextContinuation();
    ++iterations;
  }
  f = this;
  iterations = 0;
  while (f && iterations < 10) {
    f->GetContentLength();  // Assert if negative length
    f = f->GetPrevContinuation();
    ++iterations;
  }
#endif
}

bool nsTextFrame::IsFloatingFirstLetterChild() const {
  nsIFrame* frame = GetParent();
  return frame && frame->IsFloating() && frame->IsLetterFrame();
}

bool nsTextFrame::IsInitialLetterChild() const {
  nsIFrame* frame = GetParent();
  return frame && frame->StyleTextReset()->mInitialLetterSize != 0.0f &&
         frame->IsLetterFrame();
}

struct NewlineProperty {
  int32_t mStartOffset;
  // The offset of the first \n after mStartOffset, or -1 if there is none
  int32_t mNewlineOffset;
};

void nsTextFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                         const ReflowInput& aReflowInput,
                         nsReflowStatus& aStatus) {
  MarkInReflow();
  DO_GLOBAL_REFLOW_COUNT("nsTextFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");

  InvalidateSelectionState();

  // XXX If there's no line layout, we shouldn't even have created this
  // frame. This may happen if, for example, this is text inside a table
  // but not inside a cell. For now, just don't reflow.
  if (!aReflowInput.mLineLayout) {
    ClearMetrics(aMetrics);
    return;
  }

  ReflowText(*aReflowInput.mLineLayout, aReflowInput.AvailableWidth(),
             aReflowInput.mRenderingContext->GetDrawTarget(), aMetrics,
             aStatus);
}

#ifdef ACCESSIBILITY
/**
 * Notifies accessibility about text reflow. Used by nsTextFrame::ReflowText.
 */
class MOZ_STACK_CLASS ReflowTextA11yNotifier {
 public:
  ReflowTextA11yNotifier(nsPresContext* aPresContext, nsIContent* aContent)
      : mContent(aContent), mPresContext(aPresContext) {}
  ~ReflowTextA11yNotifier() {
    if (nsAccessibilityService* accService =
            PresShell::GetAccessibilityService()) {
      accService->UpdateText(mPresContext->PresShell(), mContent);
    }
  }

 private:
  ReflowTextA11yNotifier();
  ReflowTextA11yNotifier(const ReflowTextA11yNotifier&);
  ReflowTextA11yNotifier& operator=(const ReflowTextA11yNotifier&);

  nsIContent* mContent;
  nsPresContext* mPresContext;
};
#endif

void nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
                             DrawTarget* aDrawTarget, ReflowOutput& aMetrics,
                             nsReflowStatus& aStatus) {
  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");

#ifdef NOISY_REFLOW
  ListTag(stdout);
  printf(": BeginReflow: availableWidth=%d\n", aAvailableWidth);
#endif

  nsPresContext* presContext = PresContext();

#ifdef ACCESSIBILITY
  // Schedule the update of accessible tree since rendered text might be
  // changed.
  if (StyleVisibility()->IsVisible()) {
    ReflowTextA11yNotifier(presContext, mContent);
  }
#endif

  /////////////////////////////////////////////////////////////////////
  // Set up flags and clear out state
  /////////////////////////////////////////////////////////////////////

  // Clear out the reflow input flags in mState. We also clear the whitespace
  // flags because this can change whether the frame maps whitespace-only text
  // or not. We also clear the flag that tracks whether we had a pending
  // reflow request from CharacterDataChanged (since we're reflowing now).
  RemoveStateBits(TEXT_REFLOW_FLAGS | TEXT_WHITESPACE_FLAGS);
  mReflowRequestedForCharDataChange = false;
  RemoveProperty(WebRenderTextBounds());

  // Discard cached continuations array that will be invalidated by the reflow.
  if (nsTextFrame* first = FirstContinuation()) {
    first->ClearCachedContinuations();
  }

  // Temporarily map all possible content while we construct our new textrun.
  // so that when doing reflow our styles prevail over any part of the
  // textrun we look at. Note that next-in-flows may be mapping the same
  // content; gfxTextRun construction logic will ensure that we take priority.
  int32_t maxContentLength = GetInFlowContentLength();

  InvalidateSelectionState();

  // We don't need to reflow if there is no content.
  if (!maxContentLength) {
    ClearMetrics(aMetrics);
    return;
  }

#ifdef NOISY_BIDI
  printf("Reflowed textframe\n");
#endif

  const nsStyleText* textStyle = StyleText();

  bool atStartOfLine = aLineLayout.LineAtStart();
  if (atStartOfLine) {
    AddStateBits(TEXT_START_OF_LINE);
  }

  uint32_t flowEndInTextRun;
  nsIFrame* lineContainer = aLineLayout.LineContainerFrame();
  const nsTextFragment* frag = TextFragment();

  // DOM offsets of the text range we need to measure, after trimming
  // whitespace, restricting to first-letter, and restricting preformatted text
  // to nearest newline
  int32_t length = maxContentLength;
  int32_t offset = GetContentOffset();

  // Restrict preformatted text to the nearest newline
  int32_t newLineOffset = -1;  // this will be -1 or a content offset
  int32_t contentNewLineOffset = -1;
  // Pointer to the nsGkAtoms::newline set on this frame's element
  NewlineProperty* cachedNewlineOffset = nullptr;
  if (textStyle->NewlineIsSignificant(this)) {
    cachedNewlineOffset = mContent->HasFlag(NS_HAS_NEWLINE_PROPERTY)
                              ? static_cast<NewlineProperty*>(
                                    mContent->GetProperty(nsGkAtoms::newline))
                              : nullptr;
    if (cachedNewlineOffset && cachedNewlineOffset->mStartOffset <= offset &&
        (cachedNewlineOffset->mNewlineOffset == -1 ||
         cachedNewlineOffset->mNewlineOffset >= offset)) {
      contentNewLineOffset = cachedNewlineOffset->mNewlineOffset;
    } else {
      contentNewLineOffset =
          FindChar(frag, offset, GetContent()->TextLength() - offset, '\n');
    }
    if (contentNewLineOffset < offset + length) {
      /*
        The new line offset could be outside this frame if the frame has been
        split by bidi resolution. In that case we won't use it in this reflow
        (newLineOffset will remain -1), but we will still cache it in mContent
      */
      newLineOffset = contentNewLineOffset;
    }
    if (newLineOffset >= 0) {
      length = newLineOffset + 1 - offset;
    }
  }
  if ((atStartOfLine && !textStyle->WhiteSpaceIsSignificant()) ||
      HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
    // Skip leading whitespace. Make sure we don't skip a 'pre-line'
    // newline if there is one.
    int32_t skipLength = newLineOffset >= 0 ? length - 1 : length;
    int32_t whitespaceCount =
        GetTrimmableWhitespaceCount(frag, offset, skipLength, 1);
    if (whitespaceCount) {
      offset += whitespaceCount;
      length -= whitespaceCount;
      // Make sure this frame maps the trimmable whitespace.
      if (MOZ_UNLIKELY(offset > GetContentEnd())) {
        SetLength(offset - GetContentOffset(), &aLineLayout,
                  ALLOW_FRAME_CREATION_AND_DESTRUCTION);
      }
    }
  }

  // If trimming whitespace left us with nothing to do, return early.
  if (length == 0) {
    ClearMetrics(aMetrics);
    return;
  }

  bool completedFirstLetter = false;
  // Layout dependent styles are a problem because we need to reconstruct
  // the gfxTextRun based on our layout.
  if (aLineLayout.GetInFirstLetter() || aLineLayout.GetInFirstLine()) {
    SetLength(maxContentLength, &aLineLayout,
              ALLOW_FRAME_CREATION_AND_DESTRUCTION);

    if (aLineLayout.GetInFirstLetter()) {
      // floating first-letter boundaries are significant in textrun
      // construction, so clear the textrun out every time we hit a first-letter
      // and have changed our length (which controls the first-letter boundary)
      ClearTextRuns();
      // Find the length of the first-letter. We need a textrun for this.
      // REVIEW: maybe-bogus inflation should be ok (fixed below)
      gfxSkipCharsIterator iter =
          EnsureTextRun(nsTextFrame::eInflated, aDrawTarget, lineContainer,
                        aLineLayout.GetLine(), &flowEndInTextRun);

      if (mTextRun) {
        int32_t firstLetterLength = length;
        if (aLineLayout.GetFirstLetterStyleOK()) {
          // We only pass a language code to FindFirstLetterRange if it was
          // explicit in the content.
          const nsStyleFont* styleFont = StyleFont();
          const nsAtom* lang = styleFont->mExplicitLanguage
                                   ? styleFont->mLanguage.get()
                                   : nullptr;
          completedFirstLetter = FindFirstLetterRange(
              frag, lang, mTextRun, offset, iter, &firstLetterLength);
          if (newLineOffset >= 0) {
            // Don't allow a preformatted newline to be part of a first-letter.
            firstLetterLength = std::min(firstLetterLength, length - 1);
            if (length == 1) {
              // There is no text to be consumed by the first-letter before the
              // preformatted newline. Note that the first letter is therefore
              // complete (FindFirstLetterRange will have returned false).
              completedFirstLetter = true;
            }
          }
        } else {
          // We're in a first-letter frame's first in flow, so if there
          // was a first-letter, we'd be it. However, for one reason
          // or another (e.g., preformatted line break before this text),
          // we're not actually supposed to have first-letter style. So
          // just make a zero-length first-letter.
          firstLetterLength = 0;
          completedFirstLetter = true;
        }
        length = firstLetterLength;
        if (length) {
          AddStateBits(TEXT_FIRST_LETTER);
        }
        // Change this frame's length to the first-letter length right now
        // so that when we rebuild the textrun it will be built with the
        // right first-letter boundary
        SetLength(offset + length - GetContentOffset(), &aLineLayout,
                  ALLOW_FRAME_CREATION_AND_DESTRUCTION);
        // Ensure that the textrun will be rebuilt
        ClearTextRuns();
      }
    }
  }

  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);

  if (!IsCurrentFontInflation(fontSizeInflation)) {
    // FIXME: Ideally, if we already have a text run, we'd move it to be
    // the uninflated text run.
    ClearTextRun(nullptr, nsTextFrame::eInflated);
    mFontMetrics = nullptr;
  }

  gfxSkipCharsIterator iter =
      EnsureTextRun(nsTextFrame::eInflated, aDrawTarget, lineContainer,
                    aLineLayout.GetLine(), &flowEndInTextRun);

  NS_ASSERTION(IsCurrentFontInflation(fontSizeInflation),
               "EnsureTextRun should have set font size inflation");

  if (mTextRun && iter.GetOriginalEnd() < offset + length) {
    // The textrun does not map enough text for this frame. This can happen
    // when the textrun was ended in the middle of a text node because a
    // preformatted newline was encountered, and prev-in-flow frames have
    // consumed all the text of the textrun. We need a new textrun.
    ClearTextRuns();
    iter = EnsureTextRun(nsTextFrame::eInflated, aDrawTarget, lineContainer,
                         aLineLayout.GetLine(), &flowEndInTextRun);
  }

  if (!mTextRun) {
    ClearMetrics(aMetrics);
    return;
  }

  NS_ASSERTION(gfxSkipCharsIterator(iter).ConvertOriginalToSkipped(
                   offset + length) <= mTextRun->GetLength(),
               "Text run does not map enough text for our reflow");

  /////////////////////////////////////////////////////////////////////
  // See how much text should belong to this text frame, and measure it
  /////////////////////////////////////////////////////////////////////

  iter.SetOriginalOffset(offset);
  nscoord xOffsetForTabs =
      (mTextRun->GetFlags2() & nsTextFrameUtils::Flags::HasTab)
          ? (aLineLayout.GetCurrentFrameInlineDistanceFromBlock() -
             lineContainer->GetUsedBorderAndPadding().left)
          : -1;
  PropertyProvider provider(mTextRun, textStyle, frag, this, iter, length,
                            lineContainer, xOffsetForTabs,
                            nsTextFrame::eInflated);

  uint32_t transformedOffset = provider.GetStart().GetSkippedOffset();

  // The metrics for the text go in here
  gfxTextRun::Metrics textMetrics;
  gfxFont::BoundingBoxType boundingBoxType =
      IsFloatingFirstLetterChild() || IsInitialLetterChild()
          ? gfxFont::TIGHT_HINTED_OUTLINE_EXTENTS
          : gfxFont::LOOSE_INK_EXTENTS;

  int32_t limitLength = length;
  int32_t forceBreak = aLineLayout.GetForcedBreakPosition(this);
  bool forceBreakAfter = false;
  if (forceBreak >= length) {
    forceBreakAfter = forceBreak == length;
    // The break is not within the text considered for this textframe.
    forceBreak = -1;
  }
  if (forceBreak >= 0) {
    limitLength = forceBreak;
  }
  // This is the heart of text reflow right here! We don't know where
  // to break, so we need to see how much text fits in the available width.
  uint32_t transformedLength;
  if (offset + limitLength >= int32_t(frag->GetLength())) {
    NS_ASSERTION(offset + limitLength == int32_t(frag->GetLength()),
                 "Content offset/length out of bounds");
    NS_ASSERTION(flowEndInTextRun >= transformedOffset,
                 "Negative flow length?");
    transformedLength = flowEndInTextRun - transformedOffset;
  } else {
    // we're not looking at all the content, so we need to compute the
    // length of the transformed substring we're looking at
    gfxSkipCharsIterator iter(provider.GetStart());
    iter.SetOriginalOffset(offset + limitLength);
    transformedLength = iter.GetSkippedOffset() - transformedOffset;
  }
  uint32_t transformedLastBreak = 0;
  bool usedHyphenation;
  gfxFloat trimmedWidth = 0;
  gfxFloat availWidth = aAvailableWidth;
  if (Style()->IsTextCombined()) {
    // If text-combine-upright is 'all', we would compress whatever long
    // text into ~1em width, so there is no limited on the avail width.
    availWidth = std::numeric_limits<gfxFloat>::infinity();
  }
  bool canTrimTrailingWhitespace = !textStyle->WhiteSpaceIsSignificant() ||
                                   HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML);

  bool isBreakSpaces = textStyle->mWhiteSpace == StyleWhiteSpace::BreakSpaces;
  // allow whitespace to overflow the container
  bool whitespaceCanHang = textStyle->WhiteSpaceCanHangOrVisuallyCollapse();
  gfxBreakPriority breakPriority = aLineLayout.LastOptionalBreakPriority();
  gfxTextRun::SuppressBreak suppressBreak = gfxTextRun::eNoSuppressBreak;
  bool shouldSuppressLineBreak = ShouldSuppressLineBreak();
  if (shouldSuppressLineBreak) {
    suppressBreak = gfxTextRun::eSuppressAllBreaks;
  } else if (!aLineLayout.LineIsBreakable()) {
    suppressBreak = gfxTextRun::eSuppressInitialBreak;
  }
  uint32_t transformedCharsFit = mTextRun->BreakAndMeasureText(
      transformedOffset, transformedLength, HasAnyStateBits(TEXT_START_OF_LINE),
      availWidth, &provider, suppressBreak,
      canTrimTrailingWhitespace ? &trimmedWidth : nullptr, whitespaceCanHang,
      &textMetrics, boundingBoxType, aDrawTarget, &usedHyphenation,
      &transformedLastBreak, textStyle->WordCanWrap(this), isBreakSpaces,
      &breakPriority);
  if (!length && !textMetrics.mAscent && !textMetrics.mDescent) {
    // If we're measuring a zero-length piece of text, update
    // the height manually.
    nsFontMetrics* fm = provider.GetFontMetrics();
    if (fm) {
      textMetrics.mAscent = gfxFloat(fm->MaxAscent());
      textMetrics.mDescent = gfxFloat(fm->MaxDescent());
    }
  }
  if (GetWritingMode().IsLineInverted()) {
    std::swap(textMetrics.mAscent, textMetrics.mDescent);
    textMetrics.mBoundingBox.y = -textMetrics.mBoundingBox.YMost();
  }
  // The "end" iterator points to the first character after the string mapped
  // by this frame. Basically, its original-string offset is offset+charsFit
  // after we've computed charsFit.
  gfxSkipCharsIterator end(provider.GetEndHint());
  end.SetSkippedOffset(transformedOffset + transformedCharsFit);
  int32_t charsFit = end.GetOriginalOffset() - offset;
  if (offset + charsFit == newLineOffset) {
    // We broke before a trailing preformatted '\n'. The newline should
    // be assigned to this frame. Note that newLineOffset will be -1 if
    // there was no preformatted newline, so we wouldn't get here in that
    // case.
    ++charsFit;
  }
  // That might have taken us beyond our assigned content range (because
  // we might have advanced over some skipped chars that extend outside
  // this frame), so get back in.
  int32_t lastBreak = -1;
  if (charsFit >= limitLength) {
    charsFit = limitLength;
    if (transformedLastBreak != UINT32_MAX) {
      // lastBreak is needed.
      // This may set lastBreak greater than 'length', but that's OK
      lastBreak = end.ConvertSkippedToOriginal(transformedOffset +
                                               transformedLastBreak);
    }
    end.SetOriginalOffset(offset + charsFit);
    // If we were forced to fit, and the break position is after a soft hyphen,
    // note that this is a hyphenation break.
    if ((forceBreak >= 0 || forceBreakAfter) &&
        HasSoftHyphenBefore(frag, mTextRun, offset, end)) {
      usedHyphenation = true;
    }
  }
  if (usedHyphenation) {
    // Fix up metrics to include hyphen
    AddHyphenToMetrics(this, mTextRun->IsRightToLeft(), &textMetrics,
                       boundingBoxType, aDrawTarget);
    AddStateBits(TEXT_HYPHEN_BREAK | TEXT_HAS_NONCOLLAPSED_CHARACTERS);
  }
  if (textMetrics.mBoundingBox.IsEmpty()) {
    AddStateBits(TEXT_NO_RENDERED_GLYPHS);
  }

  gfxFloat trimmableWidth = 0;
  bool brokeText = forceBreak >= 0 || transformedCharsFit < transformedLength;
  if (canTrimTrailingWhitespace) {
    // Optimization: if we trimmed trailing whitespace, and we can be sure
    // this frame will be at the end of the line, then leave it trimmed off.
    // Otherwise we have to undo the trimming, in case we're not at the end of
    // the line. (If we actually do end up at the end of the line, we'll have
    // to trim it off again in TrimTrailingWhiteSpace, and we'd like to avoid
    // having to re-do it.)
    if (brokeText || HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
      // We're definitely going to break so our trailing whitespace should
      // definitely be trimmed. Record that we've already done it.
      AddStateBits(TEXT_TRIMMED_TRAILING_WHITESPACE);
    } else if (!HasAnyStateBits(TEXT_IS_IN_TOKEN_MATHML)) {
      // We might not be at the end of the line. (Note that even if this frame
      // ends in breakable whitespace, it might not be at the end of the line
      // because it might be followed by breakable, but preformatted,
      // whitespace.) Undo the trimming.
      textMetrics.mAdvanceWidth += trimmedWidth;
      trimmableWidth = trimmedWidth;
      if (mTextRun->IsRightToLeft()) {
        // Space comes before text, so the bounding box is moved to the
        // right by trimmdWidth
        textMetrics.mBoundingBox.MoveBy(gfxPoint(trimmedWidth, 0));
      }
    }
  }

  if (!brokeText && lastBreak >= 0) {
    // Since everything fit and no break was forced,
    // record the last break opportunity
    NS_ASSERTION(textMetrics.mAdvanceWidth - trimmableWidth <= availWidth,
                 "If the text doesn't fit, and we have a break opportunity, "
                 "why didn't MeasureText use it?");
    MOZ_ASSERT(lastBreak >= offset, "Strange break position");
    aLineLayout.NotifyOptionalBreakPosition(this, lastBreak - offset, true,
                                            breakPriority);
  }

  int32_t contentLength = offset + charsFit - GetContentOffset();

  /////////////////////////////////////////////////////////////////////
  // Compute output metrics
  /////////////////////////////////////////////////////////////////////

  // first-letter frames should use the tight bounding box metrics for
  // ascent/descent for good drop-cap effects
  if (HasAnyStateBits(TEXT_FIRST_LETTER)) {
    textMetrics.mAscent =
        std::max(gfxFloat(0.0), -textMetrics.mBoundingBox.Y());
    textMetrics.mDescent =
        std::max(gfxFloat(0.0), textMetrics.mBoundingBox.YMost());
  }

  // Setup metrics for caller
  // Disallow negative widths
  WritingMode wm = GetWritingMode();
  LogicalSize finalSize(wm);
  finalSize.ISize(wm) =
      NSToCoordCeilClamped(std::max(gfxFloat(0.0), textMetrics.mAdvanceWidth));

  if (transformedCharsFit == 0 && !usedHyphenation) {
    aMetrics.SetBlockStartAscent(0);
    finalSize.BSize(wm) = 0;
  } else if (boundingBoxType != gfxFont::LOOSE_INK_EXTENTS) {
    // Use actual text metrics for floating first letter frame.
    aMetrics.SetBlockStartAscent(NSToCoordCeil(textMetrics.mAscent));
    finalSize.BSize(wm) =
        aMetrics.BlockStartAscent() + NSToCoordCeil(textMetrics.mDescent);
  } else {
    // Otherwise, ascent should contain the overline drawable area.
    // And also descent should contain the underline drawable area.
    // nsFontMetrics::GetMaxAscent/GetMaxDescent contains them.
    nsFontMetrics* fm = provider.GetFontMetrics();
    nscoord fontAscent =
        wm.IsLineInverted() ? fm->MaxDescent() : fm->MaxAscent();
    nscoord fontDescent =
        wm.IsLineInverted() ? fm->MaxAscent() : fm->MaxDescent();
    aMetrics.SetBlockStartAscent(
        std::max(NSToCoordCeil(textMetrics.mAscent), fontAscent));
    nscoord descent =
        std::max(NSToCoordCeil(textMetrics.mDescent), fontDescent);
    finalSize.BSize(wm) = aMetrics.BlockStartAscent() + descent;
  }
  if (Style()->IsTextCombined()) {
    nsFontMetrics* fm = provider.GetFontMetrics();
    gfxFloat width = finalSize.ISize(wm);
    gfxFloat em = fm->EmHeight();
    // Compress the characters in horizontal axis if necessary.
    if (width <= em) {
      RemoveProperty(TextCombineScaleFactorProperty());
    } else {
      SetProperty(TextCombineScaleFactorProperty(), em / width);
      finalSize.ISize(wm) = em;
    }
    // Make the characters be in an 1em square.
    if (finalSize.BSize(wm) != em) {
      aMetrics.SetBlockStartAscent(aMetrics.BlockStartAscent() +
                                   (em - finalSize.BSize(wm)) / 2);
      finalSize.BSize(wm) = em;
    }
  }
  aMetrics.SetSize(wm, finalSize);

  NS_ASSERTION(aMetrics.BlockStartAscent() >= 0, "Negative ascent???");
  NS_ASSERTION(
      (Style()->IsTextCombined() ? aMetrics.ISize(aMetrics.GetWritingMode())
                                 : aMetrics.BSize(aMetrics.GetWritingMode())) -
              aMetrics.BlockStartAscent() >=
          0,
      "Negative descent???");

  mAscent = aMetrics.BlockStartAscent();

  // Handle text that runs outside its normal bounds.
  nsRect boundingBox = RoundOut(textMetrics.mBoundingBox);
  if (mTextRun->IsVertical()) {
    // Swap line-relative textMetrics dimensions to physical coordinates.
    std::swap(boundingBox.x, boundingBox.y);
    std::swap(boundingBox.width, boundingBox.height);
    if (GetWritingMode().IsVerticalRL()) {
      boundingBox.x = -boundingBox.XMost();
      boundingBox.x += aMetrics.Width() - mAscent;
    } else {
      boundingBox.x += mAscent;
    }
  } else {
    boundingBox.y += mAscent;
  }
  aMetrics.SetOverflowAreasToDesiredBounds();
  aMetrics.InkOverflow().UnionRect(aMetrics.InkOverflow(), boundingBox);

  // When we have text decorations, we don't need to compute their overflow now
  // because we're guaranteed to do it later
  // (see nsLineLayout::RelativePositionFrames)
  UnionAdditionalOverflow(presContext, aLineLayout.LineContainerFrame(),
                          provider, &aMetrics.InkOverflow(), false, true);

  /////////////////////////////////////////////////////////////////////
  // Clean up, update state
  /////////////////////////////////////////////////////////////////////

  // If all our characters are discarded or collapsed, then trimmable width
  // from the last textframe should be preserved. Otherwise the trimmable width
  // from this textframe overrides. (Currently in CSS trimmable width can be
  // at most one space so there's no way for trimmable width from a previous
  // frame to accumulate with trimmable width from this frame.)
  if (transformedCharsFit > 0) {
    aLineLayout.SetTrimmableISize(NSToCoordFloor(trimmableWidth));
    AddStateBits(TEXT_HAS_NONCOLLAPSED_CHARACTERS);
  }
  bool breakAfter = forceBreakAfter;
  if (!shouldSuppressLineBreak) {
    if (charsFit > 0 && charsFit == length &&
        textStyle->mHyphens != StyleHyphens::None &&
        HasSoftHyphenBefore(frag, mTextRun, offset, end)) {
      bool fits =
          textMetrics.mAdvanceWidth + provider.GetHyphenWidth() <= availWidth;
      // Record a potential break after final soft hyphen
      aLineLayout.NotifyOptionalBreakPosition(this, length, fits,
                                              gfxBreakPriority::eNormalBreak);
    }
    // length == 0 means either the text is empty or it's all collapsed away
    bool emptyTextAtStartOfLine = atStartOfLine && length == 0;
    if (!breakAfter && charsFit == length && !emptyTextAtStartOfLine &&
        transformedOffset + transformedLength == mTextRun->GetLength() &&
        (mTextRun->GetFlags2() & nsTextFrameUtils::Flags::HasTrailingBreak)) {
      // We placed all the text in the textrun and we have a break opportunity
      // at the end of the textrun. We need to record it because the following
      // content may not care about nsLineBreaker.

      // Note that because we didn't break, we can be sure that (thanks to the
      // code up above) textMetrics.mAdvanceWidth includes the width of any
      // trailing whitespace. So we need to subtract trimmableWidth here
      // because if we did break at this point, that much width would be
      // trimmed.
      if (textMetrics.mAdvanceWidth - trimmableWidth > availWidth) {
        breakAfter = true;
      } else {
        aLineLayout.NotifyOptionalBreakPosition(this, length, true,
                                                gfxBreakPriority::eNormalBreak);
      }
    }
  }

  // Compute reflow status
  if (contentLength != maxContentLength) {
    aStatus.SetIncomplete();
  }

  if (charsFit == 0 && length > 0 && !usedHyphenation) {
    // Couldn't place any text
    aStatus.SetInlineLineBreakBeforeAndReset();
  } else if (contentLength > 0 &&
             mContentOffset + contentLength - 1 == newLineOffset) {
    // Ends in \n
    aStatus.SetInlineLineBreakAfter();
    aLineLayout.SetLineEndsInBR(true);
  } else if (breakAfter) {
    aStatus.SetInlineLineBreakAfter();
  }
  if (completedFirstLetter) {
    aLineLayout.SetFirstLetterStyleOK(false);
    aStatus.SetFirstLetterComplete();
  }

  // Updated the cached NewlineProperty, or delete it.
  if (contentLength < maxContentLength &&
      textStyle->NewlineIsSignificant(this) &&
      (contentNewLineOffset < 0 ||
       mContentOffset + contentLength <= contentNewLineOffset)) {
    if (!cachedNewlineOffset) {
      cachedNewlineOffset = new NewlineProperty;
      if (NS_FAILED(mContent->SetProperty(
              nsGkAtoms::newline, cachedNewlineOffset,
              nsINode::DeleteProperty<NewlineProperty>))) {
        delete cachedNewlineOffset;
        cachedNewlineOffset = nullptr;
      }
      mContent->SetFlags(NS_HAS_NEWLINE_PROPERTY);
    }
    if (cachedNewlineOffset) {
      cachedNewlineOffset->mStartOffset = offset;
      cachedNewlineOffset->mNewlineOffset = contentNewLineOffset;
    }
  } else if (cachedNewlineOffset) {
    mContent->RemoveProperty(nsGkAtoms::newline);
    mContent->UnsetFlags(NS_HAS_NEWLINE_PROPERTY);
  }

  // Compute space and letter counts for justification, if required
  if (!textStyle->WhiteSpaceIsSignificant() &&
      (lineContainer->StyleText()->mTextAlign == StyleTextAlign::Justify ||
       lineContainer->StyleText()->mTextAlignLast ==
           StyleTextAlignLast::Justify ||
       shouldSuppressLineBreak) &&
      !SVGUtils::IsInSVGTextSubtree(lineContainer)) {
    AddStateBits(TEXT_JUSTIFICATION_ENABLED);
    Range range(uint32_t(offset), uint32_t(offset + charsFit));
    aLineLayout.SetJustificationInfo(provider.ComputeJustification(range));
  }

  SetLength(contentLength, &aLineLayout, ALLOW_FRAME_CREATION_AND_DESTRUCTION);

  InvalidateFrame();

#ifdef NOISY_REFLOW
  ListTag(stdout);
  printf(": desiredSize=%d,%d(b=%d) status=%x\n", aMetrics.Width(),
         aMetrics.Height(), aMetrics.BlockStartAscent(), aStatus);
#endif
}

/* virtual */
bool nsTextFrame::CanContinueTextRun() const {
  // We can continue a text run through a text frame
  return true;
}

nsTextFrame::TrimOutput nsTextFrame::TrimTrailingWhiteSpace(
    DrawTarget* aDrawTarget) {
  MOZ_ASSERT(!HasAnyStateBits(NS_FRAME_IS_DIRTY | NS_FRAME_FIRST_REFLOW),
             "frame should have been reflowed");

  TrimOutput result;
  result.mChanged = false;
  result.mDeltaWidth = 0;

  AddStateBits(TEXT_END_OF_LINE);

  if (!GetTextRun(nsTextFrame::eInflated)) {
    // If reflow didn't create a textrun, there must have been no content once
    // leading whitespace was trimmed, so nothing more to do here.
    return result;
  }

  int32_t contentLength = GetContentLength();
  if (!contentLength) {
    return result;
  }

  gfxSkipCharsIterator start =
      EnsureTextRun(nsTextFrame::eInflated, aDrawTarget);
  NS_ENSURE_TRUE(mTextRun, result);

  uint32_t trimmedStart = start.GetSkippedOffset();

  const nsTextFragment* frag = TextFragment();
  TrimmedOffsets trimmed = GetTrimmedOffsets(frag);
  gfxSkipCharsIterator trimmedEndIter = start;
  const nsStyleText* textStyle = StyleText();
  gfxFloat delta = 0;
  uint32_t trimmedEnd =
      trimmedEndIter.ConvertOriginalToSkipped(trimmed.GetEnd());

  if (!HasAnyStateBits(TEXT_TRIMMED_TRAILING_WHITESPACE) &&
      trimmed.GetEnd() < GetContentEnd()) {
    gfxSkipCharsIterator end = trimmedEndIter;
    uint32_t endOffset =
        end.ConvertOriginalToSkipped(GetContentOffset() + contentLength);
    if (trimmedEnd < endOffset) {
      // We can't be dealing with tabs here ... they wouldn't be trimmed. So
      // it's OK to pass null for the line container.
      PropertyProvider provider(mTextRun, textStyle, frag, this, start,
                                contentLength, nullptr, 0,
                                nsTextFrame::eInflated);
      delta =
          mTextRun->GetAdvanceWidth(Range(trimmedEnd, endOffset), &provider);
      result.mChanged = true;
    }
  }

  gfxFloat advanceDelta;
  mTextRun->SetLineBreaks(Range(trimmedStart, trimmedEnd),
                          HasAnyStateBits(TEXT_START_OF_LINE), true,
                          &advanceDelta);
  if (advanceDelta != 0) {
    result.mChanged = true;
  }

  // aDeltaWidth is *subtracted* from our width.
  // If advanceDelta is positive then setting the line break made us longer,
  // so aDeltaWidth could go negative.
  result.mDeltaWidth = NSToCoordFloor(delta - advanceDelta);
  // If aDeltaWidth goes negative, that means this frame might not actually fit
  // anymore!!! We need higher level line layout to recover somehow.
  // If it's because the frame has a soft hyphen that is now being displayed,
  // this should actually be OK, because our reflow recorded the break
  // opportunity that allowed the soft hyphen to be used, and we wouldn't
  // have recorded the opportunity unless the hyphen fit (or was the first
  // opportunity on the line).
  // Otherwise this can/ really only happen when we have glyphs with special
  // shapes at the end of lines, I think. Breaking inside a kerning pair won't
  // do it because that would mean we broke inside this textrun, and
  // BreakAndMeasureText should make sure the resulting shaped substring fits.
  // Maybe if we passed a maxTextLength? But that only happens at direction
  // changes (so we wouldn't kern across the boundary) or for first-letter
  // (which always fits because it starts the line!).
  NS_WARNING_ASSERTION(result.mDeltaWidth >= 0,
                       "Negative deltawidth, something odd is happening");

#ifdef NOISY_TRIM
  ListTag(stdout);
  printf(": trim => %d\n", result.mDeltaWidth);
#endif
  return result;
}

OverflowAreas nsTextFrame::RecomputeOverflow(nsIFrame* aBlockFrame,
                                             bool aIncludeShadows) {
  RemoveProperty(WebRenderTextBounds());

  nsRect bounds(nsPoint(0, 0), GetSize());
  OverflowAreas result(bounds, bounds);

  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  if (!mTextRun) {
    return result;
  }

  PropertyProvider provider(this, iter, nsTextFrame::eInflated, mFontMetrics);
  // Don't trim trailing space, in case we need to paint it as selected.
  provider.InitializeForDisplay(false);

  gfxTextRun::Metrics textMetrics =
      mTextRun->MeasureText(ComputeTransformedRange(provider),
                            gfxFont::LOOSE_INK_EXTENTS, nullptr, &provider);
  if (GetWritingMode().IsLineInverted()) {
    textMetrics.mBoundingBox.y = -textMetrics.mBoundingBox.YMost();
  }
  nsRect boundingBox = RoundOut(textMetrics.mBoundingBox);
  boundingBox += nsPoint(0, mAscent);
  if (mTextRun->IsVertical()) {
    // Swap line-relative textMetrics dimensions to physical coordinates.
    std::swap(boundingBox.x, boundingBox.y);
    std::swap(boundingBox.width, boundingBox.height);
  }
  nsRect& vis = result.InkOverflow();
  vis.UnionRect(vis, boundingBox);
  UnionAdditionalOverflow(PresContext(), aBlockFrame, provider, &vis, true,
                          aIncludeShadows);
  return result;
}

static void TransformChars(nsTextFrame* aFrame, const nsStyleText* aStyle,
                           const gfxTextRun* aTextRun, uint32_t aSkippedOffset,
                           const nsTextFragment* aFrag, int32_t aFragOffset,
                           int32_t aFragLen, nsAString& aOut) {
  nsAutoString fragString;
  char16_t* out;
  if (aStyle->mTextTransform.IsNone() && !NeedsToMaskPassword(aFrame)) {
    // No text-transform, so we can copy directly to the output string.
    aOut.SetLength(aOut.Length() + aFragLen);
    out = aOut.EndWriting() - aFragLen;
  } else {
    // Use a temporary string as source for the transform.
    fragString.SetLength(aFragLen);
    out = fragString.BeginWriting();
  }

  // Copy the text, with \n and \t replaced by <space> if appropriate.
  MOZ_ASSERT(aFragOffset >= 0);
  for (uint32_t i = 0; i < static_cast<uint32_t>(aFragLen); ++i) {
    char16_t ch = aFrag->CharAt(static_cast<uint32_t>(aFragOffset) + i);
    if ((ch == '\n' && !aStyle->NewlineIsSignificant(aFrame)) ||
        (ch == '\t' && !aStyle->TabIsSignificant())) {
      ch = ' ';
    }
    out[i] = ch;
  }

  if (!aStyle->mTextTransform.IsNone() || NeedsToMaskPassword(aFrame)) {
    MOZ_ASSERT(aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed);
    if (aTextRun->GetFlags2() & nsTextFrameUtils::Flags::IsTransformed) {
      // Apply text-transform according to style in the transformed run.
      auto transformedTextRun =
          static_cast<const nsTransformedTextRun*>(aTextRun);
      nsAutoString convertedString;
      AutoTArray<bool, 50> charsToMergeArray;
      AutoTArray<bool, 50> deletedCharsArray;
      nsCaseTransformTextRunFactory::TransformString(
          fragString, convertedString, /* aGlobalTransform = */ Nothing(),
          /* aCaseTransformsOnly = */ true, nullptr, charsToMergeArray,
          deletedCharsArray, transformedTextRun, aSkippedOffset);
      aOut.Append(convertedString);
    } else {
      // Should not happen (see assertion above), but as a fallback...
      aOut.Append(fragString);
    }
  }
}

static void LineStartsOrEndsAtHardLineBreak(nsTextFrame* aFrame,
                                            nsBlockFrame* aLineContainer,
                                            bool* aStartsAtHardBreak,
                                            bool* aEndsAtHardBreak) {
  bool foundValidLine;
  nsBlockInFlowLineIterator iter(aLineContainer, aFrame, &foundValidLine);
  if (!foundValidLine) {
    NS_ERROR("Invalid line!");
    *aStartsAtHardBreak = *aEndsAtHardBreak = true;
    return;
  }

  *aEndsAtHardBreak = !iter.GetLine()->IsLineWrapped();
  if (iter.Prev()) {
    *aStartsAtHardBreak = !iter.GetLine()->IsLineWrapped();
  } else {
    // Hit block boundary
    *aStartsAtHardBreak = true;
  }
}

nsIFrame::RenderedText nsTextFrame::GetRenderedText(
    uint32_t aStartOffset, uint32_t aEndOffset, TextOffsetType aOffsetType,
    TrailingWhitespace aTrimTrailingWhitespace) {
  MOZ_ASSERT(aStartOffset <= aEndOffset, "bogus offsets");
  MOZ_ASSERT(!GetPrevContinuation() ||
                 (aOffsetType == TextOffsetType::OffsetsInContentText &&
                  aStartOffset >= (uint32_t)GetContentOffset() &&
                  aEndOffset <= (uint32_t)GetContentEnd()),
             "Must be called on first-in-flow, or content offsets must be "
             "given and be within this frame.");

  // The handling of offsets could be more efficient...
  RenderedText result;
  nsBlockFrame* lineContainer = nullptr;
  nsTextFrame* textFrame;
  const nsTextFragment* textFrag = TextFragment();
  uint32_t offsetInRenderedString = 0;
  bool haveOffsets = false;

  for (textFrame = this; textFrame;
       textFrame = textFrame->GetNextContinuation()) {
    if (textFrame->HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
      // We don't trust dirty frames, especially when computing rendered text.
      break;
    }

    // Ensure the text run and grab the gfxSkipCharsIterator for it
    gfxSkipCharsIterator iter =
        textFrame->EnsureTextRun(nsTextFrame::eInflated);
    if (!textFrame->mTextRun) {
      break;
    }
    gfxSkipCharsIterator tmpIter = iter;

    // Check if the frame starts/ends at a hard line break, to determine
    // whether whitespace should be trimmed.
    bool startsAtHardBreak, endsAtHardBreak;
    if (!HasAnyStateBits(TEXT_START_OF_LINE | TEXT_END_OF_LINE)) {
      startsAtHardBreak = endsAtHardBreak = false;
    } else if (nsBlockFrame* thisLc =
                   do_QueryFrame(FindLineContainer(textFrame))) {
      if (thisLc != lineContainer) {
        // Setup line cursor when needed.
        lineContainer = thisLc;
        lineContainer->SetupLineCursorForQuery();
      }
      LineStartsOrEndsAtHardLineBreak(textFrame, lineContainer,
                                      &startsAtHardBreak, &endsAtHardBreak);
    } else {
      // Weird situation where we have a line layout without a block.
      // No soft breaks occur in this situation.
      startsAtHardBreak = endsAtHardBreak = true;
    }

    // Whether we need to trim whitespaces after the text frame.
    // TrimmedOffsetFlags::Default will allow trimming; we set NoTrim* flags
    // in the cases where this should not occur.
    TrimmedOffsetFlags trimFlags = TrimmedOffsetFlags::Default;
    if (!textFrame->IsAtEndOfLine() ||
        aTrimTrailingWhitespace != TrailingWhitespace::Trim ||
        !endsAtHardBreak) {
      trimFlags |= TrimmedOffsetFlags::NoTrimAfter;
    }

    // Whether to trim whitespaces before the text frame.
    if (!startsAtHardBreak) {
      trimFlags |= TrimmedOffsetFlags::NoTrimBefore;
    }

    TrimmedOffsets trimmedOffsets =
        textFrame->GetTrimmedOffsets(textFrag, trimFlags);
    bool trimmedSignificantNewline =
        trimmedOffsets.GetEnd() < GetContentEnd() &&
        HasSignificantTerminalNewline();
    uint32_t skippedToRenderedStringOffset =
        offsetInRenderedString -
        tmpIter.ConvertOriginalToSkipped(trimmedOffsets.mStart);
    uint32_t nextOffsetInRenderedString =
        tmpIter.ConvertOriginalToSkipped(trimmedOffsets.GetEnd()) +
        (trimmedSignificantNewline ? 1 : 0) + skippedToRenderedStringOffset;

    if (aOffsetType == TextOffsetType::OffsetsInRenderedText) {
      if (nextOffsetInRenderedString <= aStartOffset) {
        offsetInRenderedString = nextOffsetInRenderedString;
        continue;
      }
      if (!haveOffsets) {
        result.mOffsetWithinNodeText = tmpIter.ConvertSkippedToOriginal(
            aStartOffset - skippedToRenderedStringOffset);
        result.mOffsetWithinNodeRenderedText = aStartOffset;
        haveOffsets = true;
      }
      if (offsetInRenderedString >= aEndOffset) {
        break;
      }
    } else {
      if (uint32_t(textFrame->GetContentEnd()) <= aStartOffset) {
        offsetInRenderedString = nextOffsetInRenderedString;
        continue;
      }
      if (!haveOffsets) {
        result.mOffsetWithinNodeText = aStartOffset;
        // Skip trimmed space when computed the rendered text offset.
        int32_t clamped =
            std::max<int32_t>(aStartOffset, trimmedOffsets.mStart);
        result.mOffsetWithinNodeRenderedText =
            tmpIter.ConvertOriginalToSkipped(clamped) +
            skippedToRenderedStringOffset;
        MOZ_ASSERT(
            result.mOffsetWithinNodeRenderedText >= offsetInRenderedString &&
                result.mOffsetWithinNodeRenderedText <= INT32_MAX,
            "Bad offset within rendered text");
        haveOffsets = true;
      }
      if (uint32_t(textFrame->mContentOffset) >= aEndOffset) {
        break;
      }
    }

    int32_t startOffset;
    int32_t endOffset;
    if (aOffsetType == TextOffsetType::OffsetsInRenderedText) {
      startOffset = tmpIter.ConvertSkippedToOriginal(
          aStartOffset - skippedToRenderedStringOffset);
      endOffset = tmpIter.ConvertSkippedToOriginal(
          aEndOffset - skippedToRenderedStringOffset);
    } else {
      startOffset = aStartOffset;
      endOffset = std::min<uint32_t>(INT32_MAX, aEndOffset);
    }

    // If startOffset and/or endOffset are inside of trimmedOffsets' range,
    // then clamp the edges of trimmedOffsets accordingly.
    int32_t origTrimmedOffsetsEnd = trimmedOffsets.GetEnd();
    trimmedOffsets.mStart =
        std::max<uint32_t>(trimmedOffsets.mStart, startOffset);
    trimmedOffsets.mLength =
        std::min<uint32_t>(origTrimmedOffsetsEnd, endOffset) -
        trimmedOffsets.mStart;
    if (trimmedOffsets.mLength <= 0) {
      offsetInRenderedString = nextOffsetInRenderedString;
      continue;
    }

    const nsStyleText* textStyle = textFrame->StyleText();
    iter.SetOriginalOffset(trimmedOffsets.mStart);
    while (iter.GetOriginalOffset() < trimmedOffsets.GetEnd()) {
      int32_t runLength;
      bool isSkipped = iter.IsOriginalCharSkipped(&runLength);
      runLength = std::min(runLength,
                           trimmedOffsets.GetEnd() - iter.GetOriginalOffset());
      if (isSkipped) {
        MOZ_ASSERT(runLength >= 0);
        for (uint32_t i = 0; i < static_cast<uint32_t>(runLength); ++i) {
          const char16_t ch = textFrag->CharAt(
              AssertedCast<uint32_t>(iter.GetOriginalOffset() + i));
          if (ch == CH_SHY) {
            // We should preserve soft hyphens. They can't be transformed.
            result.mString.Append(ch);
          }
        }
      } else {
        TransformChars(textFrame, textStyle, textFrame->mTextRun,
                       iter.GetSkippedOffset(), textFrag,
                       iter.GetOriginalOffset(), runLength, result.mString);
      }
      iter.AdvanceOriginal(runLength);
    }

    if (trimmedSignificantNewline && GetContentEnd() <= endOffset) {
      // A significant newline was trimmed off (we must be
      // white-space:pre-line). Put it back.
      result.mString.Append('\n');
    }
    offsetInRenderedString = nextOffsetInRenderedString;
  }

  if (!haveOffsets) {
    result.mOffsetWithinNodeText = textFrag->GetLength();
    result.mOffsetWithinNodeRenderedText = offsetInRenderedString;
  }
  return result;
}

/* virtual */
bool nsTextFrame::IsEmpty() {
  NS_ASSERTION(!(mState & TEXT_IS_ONLY_WHITESPACE) ||
                   !(mState & TEXT_ISNOT_ONLY_WHITESPACE),
               "Invalid state");

  // XXXldb Should this check compatibility mode as well???
  const nsStyleText* textStyle = StyleText();
  if (textStyle->WhiteSpaceIsSignificant()) {
    // When WhiteSpaceIsSignificant styles are in effect, we only treat the
    // frame as empty if its content really is entirely *empty* (not just
    // whitespace), AND it is NOT editable or within an <input> element.
    // In these cases we consider that the whitespace-preserving style makes
    // the frame behave as non-empty so that its height doesn't become zero.
    return GetContentLength() == 0 && !GetContent()->IsEditable() &&
           !GetContent()->GetParent()->IsHTMLElement(nsGkAtoms::input);
  }

  if (mState & TEXT_ISNOT_ONLY_WHITESPACE) {
    return false;
  }

  if (mState & TEXT_IS_ONLY_WHITESPACE) {
    return true;
  }

  bool isEmpty =
      IsAllWhitespace(TextFragment(), textStyle->mWhiteSpace !=
                                          mozilla::StyleWhiteSpace::PreLine);
  AddStateBits(isEmpty ? TEXT_IS_ONLY_WHITESPACE : TEXT_ISNOT_ONLY_WHITESPACE);
  return isEmpty;
}

#ifdef DEBUG_FRAME_DUMP
// Translate the mapped content into a string that's printable
void nsTextFrame::ToCString(nsCString& aBuf) const {
  // Get the frames text content
  const nsTextFragment* frag = TextFragment();
  if (!frag) {
    return;
  }

  const int32_t length = GetContentEnd() - mContentOffset;
  if (length <= 0) {
    // Negative lengths are possible during invalidation.
    return;
  }

  // Limit the length to fragment length in case the text has not been reflowed.
  const uint32_t fragLength =
      std::min(frag->GetLength(), AssertedCast<uint32_t>(GetContentEnd()));

  uint32_t fragOffset = AssertedCast<uint32_t>(GetContentOffset());

  while (fragOffset < fragLength) {
    char16_t ch = frag->CharAt(fragOffset++);
    if (ch == '\r') {
      aBuf.AppendLiteral("\\r");
    } else if (ch == '\n') {
      aBuf.AppendLiteral("\\n");
    } else if (ch == '\t') {
      aBuf.AppendLiteral("\\t");
    } else if ((ch < ' ') || (ch >= 127)) {
      aBuf.Append(nsPrintfCString("\\u%04x", ch));
    } else {
      aBuf.Append(ch);
    }
  }
}

nsresult nsTextFrame::GetFrameName(nsAString& aResult) const {
  MakeFrameName(u"Text"_ns, aResult);
  nsAutoCString tmp;
  ToCString(tmp);
  tmp.SetLength(std::min<size_t>(tmp.Length(), 50u));
  aResult += u"\""_ns + NS_ConvertASCIItoUTF16(tmp) + u"\""_ns;
  return NS_OK;
}

void nsTextFrame::List(FILE* out, const char* aPrefix, ListFlags aFlags) const {
  nsCString str;
  ListGeneric(str, aPrefix, aFlags);

  str += nsPrintfCString(" [run=%p]", static_cast<void*>(mTextRun));

  // Output the first/last content offset and prev/next in flow info
  bool isComplete = uint32_t(GetContentEnd()) == GetContent()->TextLength();
  str += nsPrintfCString("[%d,%d,%c] ", GetContentOffset(), GetContentLength(),
                         isComplete ? 'T' : 'F');

  if (IsSelected()) {
    str += " SELECTED";
  }
  fprintf_stderr(out, "%s\n", str.get());
}

void nsTextFrame::ListTextRuns(FILE* out,
                               nsTHashSet<const void*>& aSeen) const {
  if (!mTextRun || aSeen.Contains(mTextRun)) {
    return;
  }
  aSeen.Insert(mTextRun);
  mTextRun->Dump(out);
}
#endif

void nsTextFrame::AdjustOffsetsForBidi(int32_t aStart, int32_t aEnd) {
  AddStateBits(NS_FRAME_IS_BIDI);
  if (mContent->HasFlag(NS_HAS_FLOWLENGTH_PROPERTY)) {
    mContent->RemoveProperty(nsGkAtoms::flowlength);
    mContent->UnsetFlags(NS_HAS_FLOWLENGTH_PROPERTY);
  }

  /*
   * After Bidi resolution we may need to reassign text runs.
   * This is called during bidi resolution from the block container, so we
   * shouldn't be holding a local reference to a textrun anywhere.
   */
  ClearTextRuns();

  nsTextFrame* prev = GetPrevContinuation();
  if (prev) {
    // the bidi resolver can be very evil when columns/pages are involved. Don't
    // let it violate our invariants.
    int32_t prevOffset = prev->GetContentOffset();
    aStart = std::max(aStart, prevOffset);
    aEnd = std::max(aEnd, prevOffset);
    prev->ClearTextRuns();
  }

  mContentOffset = aStart;
  SetLength(aEnd - aStart, nullptr, 0);
}

/**
 * @return true if this text frame ends with a newline character.  It should
 * return false if it is not a text frame.
 */
bool nsTextFrame::HasSignificantTerminalNewline() const {
  return ::HasTerminalNewline(this) && StyleText()->NewlineIsSignificant(this);
}

bool nsTextFrame::IsAtEndOfLine() const {
  return HasAnyStateBits(TEXT_END_OF_LINE);
}

nscoord nsTextFrame::GetLogicalBaseline(WritingMode aWM) const {
  if (!aWM.IsOrthogonalTo(GetWritingMode())) {
    return mAscent;
  }

  // When the text frame has a writing mode orthogonal to the desired
  // writing mode, return a baseline coincides its parent frame.
  nsIFrame* parent = GetParent();
  nsPoint position = GetNormalPosition();
  nscoord parentAscent = parent->GetLogicalBaseline(aWM);
  if (aWM.IsVerticalRL()) {
    nscoord parentDescent = parent->GetSize().width - parentAscent;
    nscoord descent = parentDescent - position.x;
    return GetSize().width - descent;
  }
  return parentAscent - (aWM.IsVertical() ? position.x : position.y);
}

bool nsTextFrame::HasAnyNoncollapsedCharacters() {
  gfxSkipCharsIterator iter = EnsureTextRun(nsTextFrame::eInflated);
  int32_t offset = GetContentOffset(), offsetEnd = GetContentEnd();
  int32_t skippedOffset = iter.ConvertOriginalToSkipped(offset);
  int32_t skippedOffsetEnd = iter.ConvertOriginalToSkipped(offsetEnd);
  return skippedOffset != skippedOffsetEnd;
}

bool nsTextFrame::ComputeCustomOverflow(OverflowAreas& aOverflowAreas) {
  return ComputeCustomOverflowInternal(aOverflowAreas, true);
}

bool nsTextFrame::ComputeCustomOverflowInternal(OverflowAreas& aOverflowAreas,
                                                bool aIncludeShadows) {
  if (HasAnyStateBits(NS_FRAME_FIRST_REFLOW)) {
    return true;
  }

  nsIFrame* decorationsBlock;
  if (IsFloatingFirstLetterChild()) {
    decorationsBlock = GetParent();
  } else {
    nsIFrame* f = this;
    for (;;) {
      nsBlockFrame* fBlock = do_QueryFrame(f);
      if (fBlock) {
        decorationsBlock = fBlock;
        break;
      }

      f = f->GetParent();
      if (!f) {
        NS_ERROR("Couldn't find any block ancestor (for text decorations)");
        return nsIFrame::ComputeCustomOverflow(aOverflowAreas);
      }
    }
  }

  aOverflowAreas = RecomputeOverflow(decorationsBlock, aIncludeShadows);
  return nsIFrame::ComputeCustomOverflow(aOverflowAreas);
}

NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(JustificationAssignmentProperty, int32_t)

void nsTextFrame::AssignJustificationGaps(
    const mozilla::JustificationAssignment& aAssign) {
  int32_t encoded = (aAssign.mGapsAtStart << 8) | aAssign.mGapsAtEnd;
  static_assert(sizeof(aAssign) == 1,
                "The encoding might be broken if JustificationAssignment "
                "is larger than 1 byte");
  SetProperty(JustificationAssignmentProperty(), encoded);
}

mozilla::JustificationAssignment nsTextFrame::GetJustificationAssignment()
    const {
  int32_t encoded = GetProperty(JustificationAssignmentProperty());
  mozilla::JustificationAssignment result;
  result.mGapsAtStart = encoded >> 8;
  result.mGapsAtEnd = encoded & 0xFF;
  return result;
}

uint32_t nsTextFrame::CountGraphemeClusters() const {
  const nsTextFragment* frag = TextFragment();
  MOZ_ASSERT(frag, "Text frame must have text fragment");
  nsAutoString content;
  frag->AppendTo(content, AssertedCast<uint32_t>(GetContentOffset()),
                 AssertedCast<uint32_t>(GetContentLength()));
  return unicode::CountGraphemeClusters(content);
}

bool nsTextFrame::HasNonSuppressedText() const {
  if (HasAnyStateBits(TEXT_ISNOT_ONLY_WHITESPACE |
                      // If we haven't reflowed yet, or are currently doing so,
                      // just return true because we can't be sure.
                      NS_FRAME_FIRST_REFLOW | NS_FRAME_IN_REFLOW)) {
    return true;
  }

  if (!GetTextRun(nsTextFrame::eInflated)) {
    return false;
  }

  TrimmedOffsets offsets =
      GetTrimmedOffsets(TextFragment(), TrimmedOffsetFlags::NoTrimAfter);
  return offsets.mLength != 0;
}