layout/generic/nsInlineFrame.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* rendering object for CSS display:inline objects */
   8
   9 #include "nsInlineFrame.h"
  10
  11 #include "gfxContext.h"
  12 #include "mozilla/ComputedStyle.h"
  13 #include "mozilla/Likely.h"
  14 #include "mozilla/PresShell.h"
  15 #include "mozilla/RestyleManager.h"
  16 #include "mozilla/ServoStyleSet.h"
  17 #include "mozilla/SVGTextFrame.h"
  18 #include "nsLineLayout.h"
  19 #include "nsBlockFrame.h"
  20 #include "nsLayoutUtils.h"
  21 #include "nsPlaceholderFrame.h"
  22 #include "nsGkAtoms.h"
  23 #include "nsPresContext.h"
  24 #include "nsPresContextInlines.h"
  25 #include "nsCSSAnonBoxes.h"
  26 #include "nsDisplayList.h"
  27 #include "nsStyleChangeList.h"
  28
  29 #ifdef DEBUG
  30 #  undef NOISY_PUSHING
  31 #endif
  32
  33 using namespace mozilla;
  34 using namespace mozilla::layout;
  35
  36 //////////////////////////////////////////////////////////////////////
  37
  38 // Basic nsInlineFrame methods
  39
  40 nsInlineFrame* NS_NewInlineFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
  41   return new (aPresShell) nsInlineFrame(aStyle, aPresShell->GetPresContext());
  42 }
  43
  44 NS_IMPL_FRAMEARENA_HELPERS(nsInlineFrame)
  45
  46 NS_QUERYFRAME_HEAD(nsInlineFrame)
  47   NS_QUERYFRAME_ENTRY(nsInlineFrame)
  48 NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
  49
  50 #ifdef DEBUG_FRAME_DUMP
  51 nsresult nsInlineFrame::GetFrameName(nsAString& aResult) const {
  52   return MakeFrameName(u"Inline"_ns, aResult);
  53 }
  54 #endif
  55
  56 void nsInlineFrame::InvalidateFrame(uint32_t aDisplayItemKey,
  57                                     bool aRebuildDisplayItems) {
  58   if (IsInSVGTextSubtree()) {
  59     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
  60         GetParent(), LayoutFrameType::SVGText);
  61     svgTextFrame->InvalidateFrame();
  62     return;
  63   }
  64   nsContainerFrame::InvalidateFrame(aDisplayItemKey, aRebuildDisplayItems);
  65 }
  66
  67 void nsInlineFrame::InvalidateFrameWithRect(const nsRect& aRect,
  68                                             uint32_t aDisplayItemKey,
  69                                             bool aRebuildDisplayItems) {
  70   if (IsInSVGTextSubtree()) {
  71     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
  72         GetParent(), LayoutFrameType::SVGText);
  73     svgTextFrame->InvalidateFrame();
  74     return;
  75   }
  76   nsContainerFrame::InvalidateFrameWithRect(aRect, aDisplayItemKey,
  77                                             aRebuildDisplayItems);
  78 }
  79
  80 static inline bool IsMarginZero(const LengthPercentageOrAuto& aLength) {
  81   return aLength.IsAuto() ||
  82          nsLayoutUtils::IsMarginZero(aLength.AsLengthPercentage());
  83 }
  84
  85 /* virtual */
  86 bool nsInlineFrame::IsSelfEmpty() {
  87 #if 0
  88   // I used to think inline frames worked this way, but it seems they
  89   // don't.  At least not in our codebase.
  90   if (GetPresContext()->CompatibilityMode() == eCompatibility_FullStandards) {
  91     return false;
  92   }
  93 #endif
  94   const nsStyleMargin* margin = StyleMargin();
  95   const nsStyleBorder* border = StyleBorder();
  96   const nsStylePadding* padding = StylePadding();
  97   // Block-start and -end ignored, since they shouldn't affect things, but this
  98   // doesn't really match with nsLineLayout.cpp's setting of
  99   // ZeroEffectiveSpanBox, anymore, so what should this really be?
 100   WritingMode wm = GetWritingMode();
 101   bool haveStart, haveEnd;
 102
 103   auto HaveSide = [&](mozilla::Side aSide) -> bool {
 104     return border->GetComputedBorderWidth(aSide) != 0 ||
 105            !nsLayoutUtils::IsPaddingZero(padding->mPadding.Get(aSide)) ||
 106            !IsMarginZero(margin->mMargin.Get(aSide));
 107   };
 108   // Initially set up haveStart and haveEnd in terms of visual (LTR/TTB)
 109   // coordinates; we'll exchange them later if bidi-RTL is in effect to
 110   // get logical start and end flags.
 111   if (wm.IsVertical()) {
 112     haveStart = HaveSide(eSideTop);
 113     haveEnd = HaveSide(eSideBottom);
 114   } else {
 115     haveStart = HaveSide(eSideLeft);
 116     haveEnd = HaveSide(eSideRight);
 117   }
 118   if (haveStart || haveEnd) {
 119     // We skip this block and return false for box-decoration-break:clone since
 120     // in that case all the continuations will have the border/padding/margin.
 121     if (HasAnyStateBits(NS_FRAME_PART_OF_IBSPLIT) &&
 122         StyleBorder()->mBoxDecorationBreak == StyleBoxDecorationBreak::Slice) {
 123       // When direction=rtl, we need to consider logical rather than visual
 124       // start and end, so swap the flags.
 125       if (wm.IsBidiRTL()) {
 126         std::swap(haveStart, haveEnd);
 127       }
 128       // For ib-split frames, ignore things we know we'll skip in GetSkipSides.
 129       // XXXbz should we be doing this for non-ib-split frames too, in a more
 130       // general way?
 131
 132       // Get the first continuation eagerly, as a performance optimization, to
 133       // avoid having to get it twice..
 134       nsIFrame* firstCont = FirstContinuation();
 135       return (!haveStart || firstCont->FrameIsNonFirstInIBSplit()) &&
 136              (!haveEnd || firstCont->FrameIsNonLastInIBSplit());
 137     }
 138     return false;
 139   }
 140   return true;
 141 }
 142
 143 bool nsInlineFrame::IsEmpty() {
 144   if (!IsSelfEmpty()) {
 145     return false;
 146   }
 147
 148   for (nsIFrame* kid : mFrames) {
 149     if (!kid->IsEmpty()) return false;
 150   }
 151
 152   return true;
 153 }
 154
 155 nsIFrame::FrameSearchResult nsInlineFrame::PeekOffsetCharacter(
 156     bool aForward, int32_t* aOffset, PeekOffsetCharacterOptions aOptions) {
 157   // Override the implementation in nsFrame, to skip empty inline frames
 158   NS_ASSERTION(aOffset && *aOffset <= 1, "aOffset out of range");
 159   int32_t startOffset = *aOffset;
 160   if (startOffset < 0) startOffset = 1;
 161   if (aForward == (startOffset == 0)) {
 162     // We're before the frame and moving forward, or after it and moving
 163     // backwards: skip to the other side, but keep going.
 164     *aOffset = 1 - startOffset;
 165   }
 166   return CONTINUE;
 167 }
 168
 169 void nsInlineFrame::Destroy(DestroyContext& aContext) {
 170   nsFrameList* overflowFrames = GetOverflowFrames();
 171   if (overflowFrames) {
 172     // Fixup the parent pointers for any child frames on the OverflowList.
 173     // nsIFrame::DestroyFrom depends on that to find the sticky scroll
 174     // container (an ancestor).
 175     overflowFrames->ApplySetParent(this);
 176   }
 177   nsContainerFrame::Destroy(aContext);
 178 }
 179
 180 void nsInlineFrame::StealFrame(nsIFrame* aChild) {
 181   if (MaybeStealOverflowContainerFrame(aChild)) {
 182     return;
 183   }
 184
 185   nsInlineFrame* parent = this;
 186   do {
 187     if (parent->mFrames.StartRemoveFrame(aChild)) {
 188       return;
 189     }
 190
 191     // We didn't find the child in our principal child list.
 192     // Maybe it's on the overflow list?
 193     nsFrameList* frameList = parent->GetOverflowFrames();
 194     if (frameList && frameList->ContinueRemoveFrame(aChild)) {
 195       if (frameList->IsEmpty()) {
 196         parent->DestroyOverflowList();
 197       }
 198       return;
 199     }
 200
 201     // Due to our "lazy reparenting" optimization 'aChild' might not actually
 202     // be on any of our child lists, but instead in one of our next-in-flows.
 203     parent = static_cast<nsInlineFrame*>(parent->GetNextInFlow());
 204   } while (parent);
 205
 206   MOZ_ASSERT_UNREACHABLE("nsInlineFrame::StealFrame: can't find aChild");
 207 }
 208
 209 void nsInlineFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
 210                                      const nsDisplayListSet& aLists) {
 211   BuildDisplayListForInline(aBuilder, aLists);
 212
 213   // The sole purpose of this is to trigger display of the selection
 214   // window for Named Anchors, which don't have any children and
 215   // normally don't have any size, but in Editor we use CSS to display
 216   // an image to represent this "hidden" element.
 217   if (!mFrames.FirstChild()) {
 218     DisplaySelectionOverlay(aBuilder, aLists.Content());
 219   }
 220 }
 221
 222 //////////////////////////////////////////////////////////////////////
 223 // Reflow methods
 224
 225 /* virtual */
 226 void nsInlineFrame::AddInlineMinISize(gfxContext* aRenderingContext,
 227                                       nsIFrame::InlineMinISizeData* aData) {
 228   DoInlineMinISize(aRenderingContext, aData);
 229 }
 230
 231 /* virtual */
 232 void nsInlineFrame::AddInlinePrefISize(gfxContext* aRenderingContext,
 233                                        nsIFrame::InlinePrefISizeData* aData) {
 234   DoInlinePrefISize(aRenderingContext, aData);
 235 }
 236
 237 /* virtual */
 238 nsIFrame::SizeComputationResult nsInlineFrame::ComputeSize(
 239     gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
 240     nscoord aAvailableISize, const LogicalSize& aMargin,
 241     const LogicalSize& aBorderPadding, const StyleSizeOverrides& aSizeOverrides,
 242     ComputeSizeFlags aFlags) {
 243   // Inlines and text don't compute size before reflow.
 244   return {LogicalSize(aWM, NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE),
 245           AspectRatioUsage::None};
 246 }
 247
 248 nsRect nsInlineFrame::ComputeTightBounds(DrawTarget* aDrawTarget) const {
 249   // be conservative
 250   if (Style()->HasTextDecorationLines()) {
 251     return InkOverflowRect();
 252   }
 253   return ComputeSimpleTightBounds(aDrawTarget);
 254 }
 255
 256 static void ReparentChildListStyle(nsPresContext* aPresContext,
 257                                    const nsFrameList::Slice& aFrames,
 258                                    nsIFrame* aParentFrame) {
 259   RestyleManager* restyleManager = aPresContext->RestyleManager();
 260
 261   for (nsIFrame* f : aFrames) {
 262     NS_ASSERTION(f->GetParent() == aParentFrame, "Bogus parentage");
 263     restyleManager->ReparentComputedStyleForFirstLine(f);
 264     nsLayoutUtils::MarkDescendantsDirty(f);
 265   }
 266 }
 267
 268 void nsInlineFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
 269                            const ReflowInput& aReflowInput,
 270                            nsReflowStatus& aStatus) {
 271   MarkInReflow();
 272   DO_GLOBAL_REFLOW_COUNT("nsInlineFrame");
 273   DISPLAY_REFLOW(aPresContext, this, aReflowInput, aMetrics, aStatus);
 274   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 275
 276   if (!aReflowInput.mLineLayout) {
 277     NS_ERROR("must have non-null aReflowInput.mLineLayout");
 278     return;
 279   }
 280   if (IsFrameTreeTooDeep(aReflowInput, aMetrics, aStatus)) {
 281     return;
 282   }
 283
 284   bool lazilySetParentPointer = false;
 285
 286   // Check for an overflow list with our prev-in-flow
 287   nsInlineFrame* prevInFlow = (nsInlineFrame*)GetPrevInFlow();
 288   if (prevInFlow) {
 289     AutoFrameListPtr prevOverflowFrames(aPresContext,
 290                                         prevInFlow->StealOverflowFrames());
 291     if (prevOverflowFrames) {
 292       // When pushing and pulling frames we need to check for whether any
 293       // views need to be reparented.
 294       nsContainerFrame::ReparentFrameViewList(*prevOverflowFrames, prevInFlow,
 295                                               this);
 296
 297       // Check if we should do the lazilySetParentPointer optimization.
 298       // Only do it in simple cases where we're being reflowed for the
 299       // first time, nothing (e.g. bidi resolution) has already given
 300       // us children, and there's no next-in-flow, so all our frames
 301       // will be taken from prevOverflowFrames.
 302       if (HasAnyStateBits(NS_FRAME_FIRST_REFLOW) && mFrames.IsEmpty() &&
 303           !GetNextInFlow()) {
 304         // If our child list is empty, just put the new frames into it.
 305         // Note that we don't set the parent pointer for the new frames. Instead
 306         // wait to do this until we actually reflow the frame. If the overflow
 307         // list contains thousands of frames this is a big performance issue
 308         // (see bug #5588)
 309         mFrames = std::move(*prevOverflowFrames);
 310         lazilySetParentPointer = true;
 311       } else {
 312         // Insert the new frames at the beginning of the child list
 313         // and set their parent pointer
 314         const nsFrameList::Slice& newFrames =
 315             mFrames.InsertFrames(this, nullptr, std::move(*prevOverflowFrames));
 316         // If our prev in flow was under the first continuation of a first-line
 317         // frame then we need to reparent the ComputedStyles to remove the
 318         // the special first-line styling. In the lazilySetParentPointer case
 319         // we reparent the ComputedStyles when we set their parents in
 320         // nsInlineFrame::ReflowFrames and nsInlineFrame::ReflowInlineFrame.
 321         if (aReflowInput.mLineLayout->GetInFirstLine()) {
 322           ReparentChildListStyle(aPresContext, newFrames, this);
 323         }
 324       }
 325     }
 326   }
 327
 328   // It's also possible that we have an overflow list for ourselves
 329 #ifdef DEBUG
 330   if (HasAnyStateBits(NS_FRAME_FIRST_REFLOW)) {
 331     // If it's our initial reflow, then we should not have an overflow list.
 332     // However, add an assertion in case we get reflowed more than once with
 333     // the initial reflow reason
 334     nsFrameList* overflowFrames = GetOverflowFrames();
 335     NS_ASSERTION(!overflowFrames || overflowFrames->IsEmpty(),
 336                  "overflow list is not empty for initial reflow");
 337   }
 338 #endif
 339   if (!HasAnyStateBits(NS_FRAME_FIRST_REFLOW)) {
 340     DrainSelfOverflowListInternal(aReflowInput.mLineLayout->GetInFirstLine());
 341   }
 342
 343   // Set our own reflow input (additional state above and beyond aReflowInput).
 344   InlineReflowInput irs;
 345   irs.mPrevFrame = nullptr;
 346   irs.mLineContainer = aReflowInput.mLineLayout->LineContainerFrame();
 347   irs.mLineLayout = aReflowInput.mLineLayout;
 348   irs.mNextInFlow = (nsInlineFrame*)GetNextInFlow();
 349   irs.mSetParentPointer = lazilySetParentPointer;
 350
 351   if (mFrames.IsEmpty()) {
 352     // Try to pull over one frame before starting so that we know
 353     // whether we have an anonymous block or not.
 354     Unused << PullOneFrame(aPresContext, irs);
 355   }
 356
 357   ReflowFrames(aPresContext, aReflowInput, irs, aMetrics, aStatus);
 358
 359   ReflowAbsoluteFrames(aPresContext, aMetrics, aReflowInput, aStatus);
 360
 361   // Note: the line layout code will properly compute our
 362   // overflow-rect state for us.
 363 }
 364
 365 nsresult nsInlineFrame::AttributeChanged(int32_t aNameSpaceID,
 366                                          nsAtom* aAttribute, int32_t aModType) {
 367   nsresult rv =
 368       nsContainerFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
 369
 370   if (NS_FAILED(rv)) {
 371     return rv;
 372   }
 373
 374   if (IsInSVGTextSubtree()) {
 375     SVGTextFrame* f = static_cast<SVGTextFrame*>(
 376         nsLayoutUtils::GetClosestFrameOfType(this, LayoutFrameType::SVGText));
 377     f->HandleAttributeChangeInDescendant(mContent->AsElement(), aNameSpaceID,
 378                                          aAttribute);
 379   }
 380
 381   return NS_OK;
 382 }
 383
 384 bool nsInlineFrame::DrainSelfOverflowListInternal(bool aInFirstLine) {
 385   AutoFrameListPtr overflowFrames(PresContext(), StealOverflowFrames());
 386   if (!overflowFrames || overflowFrames->IsEmpty()) {
 387     return false;
 388   }
 389
 390   // The frames on our own overflowlist may have been pushed by a
 391   // previous lazilySetParentPointer Reflow so we need to ensure the
 392   // correct parent pointer.  This is sometimes skipped by Reflow.
 393   nsIFrame* firstChild = overflowFrames->FirstChild();
 394   RestyleManager* restyleManager = PresContext()->RestyleManager();
 395   for (nsIFrame* f = firstChild; f; f = f->GetNextSibling()) {
 396     f->SetParent(this);
 397     if (MOZ_UNLIKELY(aInFirstLine)) {
 398       restyleManager->ReparentComputedStyleForFirstLine(f);
 399       nsLayoutUtils::MarkDescendantsDirty(f);
 400     }
 401   }
 402   mFrames.AppendFrames(nullptr, std::move(*overflowFrames));
 403   return true;
 404 }
 405
 406 /* virtual */
 407 bool nsInlineFrame::DrainSelfOverflowList() {
 408   nsIFrame* lineContainer = nsLayoutUtils::FindNearestBlockAncestor(this);
 409   // Add the eInFirstLine flag if we have a ::first-line ancestor frame.
 410   // No need to look further than the nearest line container though.
 411   bool inFirstLine = false;
 412   for (nsIFrame* p = GetParent(); p != lineContainer; p = p->GetParent()) {
 413     if (p->IsLineFrame()) {
 414       inFirstLine = true;
 415       break;
 416     }
 417   }
 418   return DrainSelfOverflowListInternal(inFirstLine);
 419 }
 420
 421 /* virtual */
 422 bool nsInlineFrame::CanContinueTextRun() const {
 423   // We can continue a text run through an inline frame
 424   return true;
 425 }
 426
 427 /* virtual */
 428 void nsInlineFrame::PullOverflowsFromPrevInFlow() {
 429   nsInlineFrame* prevInFlow = static_cast<nsInlineFrame*>(GetPrevInFlow());
 430   if (prevInFlow) {
 431     nsPresContext* presContext = PresContext();
 432     AutoFrameListPtr prevOverflowFrames(presContext,
 433                                         prevInFlow->StealOverflowFrames());
 434     if (prevOverflowFrames) {
 435       // Assume that our prev-in-flow has the same line container that we do.
 436       nsContainerFrame::ReparentFrameViewList(*prevOverflowFrames, prevInFlow,
 437                                               this);
 438       mFrames.InsertFrames(this, nullptr, std::move(*prevOverflowFrames));
 439     }
 440   }
 441 }
 442
 443 void nsInlineFrame::ReflowFrames(nsPresContext* aPresContext,
 444                                  const ReflowInput& aReflowInput,
 445                                  InlineReflowInput& irs, ReflowOutput& aMetrics,
 446                                  nsReflowStatus& aStatus) {
 447   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 448
 449   nsLineLayout* lineLayout = aReflowInput.mLineLayout;
 450   bool inFirstLine = aReflowInput.mLineLayout->GetInFirstLine();
 451   RestyleManager* restyleManager = aPresContext->RestyleManager();
 452   WritingMode frameWM = aReflowInput.GetWritingMode();
 453   WritingMode lineWM = aReflowInput.mLineLayout->mRootSpan->mWritingMode;
 454   LogicalMargin framePadding =
 455       aReflowInput.ComputedLogicalBorderPadding(frameWM);
 456   nscoord startEdge = 0;
 457   const bool boxDecorationBreakClone = MOZ_UNLIKELY(
 458       StyleBorder()->mBoxDecorationBreak == StyleBoxDecorationBreak::Clone);
 459   // Don't offset by our start borderpadding if we have a prev continuation or
 460   // if we're in a part of an {ib} split other than the first one. For
 461   // box-decoration-break:clone we always offset our start since all
 462   // continuations have border/padding.
 463   if ((!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) ||
 464       boxDecorationBreakClone) {
 465     startEdge = framePadding.IStart(frameWM);
 466   }
 467   nscoord availableISize = aReflowInput.AvailableISize();
 468   NS_ASSERTION(availableISize != NS_UNCONSTRAINEDSIZE,
 469                "should no longer use available widths");
 470   // Subtract off inline axis border+padding from availableISize
 471   availableISize -= startEdge;
 472   availableISize -= framePadding.IEnd(frameWM);
 473   lineLayout->BeginSpan(this, &aReflowInput, startEdge,
 474                         startEdge + availableISize, &mBaseline);
 475
 476   // First reflow our principal children.
 477   nsIFrame* frame = mFrames.FirstChild();
 478   bool done = false;
 479   while (frame) {
 480     // Check if we should lazily set the child frame's parent pointer.
 481     if (irs.mSetParentPointer) {
 482       nsIFrame* child = frame;
 483       do {
 484         child->SetParent(this);
 485         if (inFirstLine) {
 486           restyleManager->ReparentComputedStyleForFirstLine(child);
 487           nsLayoutUtils::MarkDescendantsDirty(child);
 488         }
 489         // We also need to do the same for |frame|'s next-in-flows that are in
 490         // the sibling list. Otherwise, if we reflow |frame| and it's complete
 491         // we'll crash when trying to delete its next-in-flow.
 492         // This scenario doesn't happen often, but it can happen.
 493         nsIFrame* nextSibling = child->GetNextSibling();
 494         child = child->GetNextInFlow();
 495         if (MOZ_UNLIKELY(child)) {
 496           while (child != nextSibling && nextSibling) {
 497             nextSibling = nextSibling->GetNextSibling();
 498           }
 499           if (!nextSibling) {
 500             child = nullptr;
 501           }
 502         }
 503         MOZ_ASSERT(!child || mFrames.ContainsFrame(child));
 504       } while (child);
 505
 506       // Fix the parent pointer for ::first-letter child frame next-in-flows,
 507       // so nsFirstLetterFrame::Reflow can destroy them safely (bug 401042).
 508       nsIFrame* realFrame = nsPlaceholderFrame::GetRealFrameFor(frame);
 509       if (realFrame->IsLetterFrame()) {
 510         nsIFrame* child = realFrame->PrincipalChildList().FirstChild();
 511         if (child) {
 512           NS_ASSERTION(child->IsTextFrame(), "unexpected frame type");
 513           nsIFrame* nextInFlow = child->GetNextInFlow();
 514           for (; nextInFlow; nextInFlow = nextInFlow->GetNextInFlow()) {
 515             NS_ASSERTION(nextInFlow->IsTextFrame(), "unexpected frame type");
 516             if (mFrames.ContainsFrame(nextInFlow)) {
 517               nextInFlow->SetParent(this);
 518               if (inFirstLine) {
 519                 restyleManager->ReparentComputedStyleForFirstLine(nextInFlow);
 520                 nsLayoutUtils::MarkDescendantsDirty(nextInFlow);
 521               }
 522             } else {
 523 #ifdef DEBUG
 524               // Once we find a next-in-flow that isn't ours none of the
 525               // remaining next-in-flows should be either.
 526               for (; nextInFlow; nextInFlow = nextInFlow->GetNextInFlow()) {
 527                 NS_ASSERTION(!mFrames.ContainsFrame(nextInFlow),
 528                              "unexpected letter frame flow");
 529               }
 530 #endif
 531               break;
 532             }
 533           }
 534         }
 535       }
 536     }
 537     MOZ_ASSERT(frame->GetParent() == this);
 538
 539     if (!done) {
 540       bool reflowingFirstLetter = lineLayout->GetFirstLetterStyleOK();
 541       ReflowInlineFrame(aPresContext, aReflowInput, irs, frame, aStatus);
 542       done = aStatus.IsInlineBreak() ||
 543              (!reflowingFirstLetter && aStatus.IsIncomplete());
 544       if (done) {
 545         if (!irs.mSetParentPointer) {
 546           break;
 547         }
 548         // Keep reparenting the remaining siblings, but don't reflow them.
 549         nsFrameList* pushedFrames = GetOverflowFrames();
 550         if (pushedFrames && pushedFrames->FirstChild() == frame) {
 551           // Don't bother if |frame| was pushed to our overflow list.
 552           break;
 553         }
 554       } else {
 555         irs.mPrevFrame = frame;
 556       }
 557     }
 558     frame = frame->GetNextSibling();
 559   }
 560
 561   // Attempt to pull frames from our next-in-flow until we can't
 562   if (!done && GetNextInFlow()) {
 563     while (true) {
 564       bool reflowingFirstLetter = lineLayout->GetFirstLetterStyleOK();
 565       if (!frame) {  // Could be non-null if we pulled a first-letter frame and
 566                      // it created a continuation, since we don't push those.
 567         frame = PullOneFrame(aPresContext, irs);
 568       }
 569 #ifdef NOISY_PUSHING
 570       printf("%p pulled up %p\n", this, frame);
 571 #endif
 572       if (!frame) {
 573         break;
 574       }
 575       ReflowInlineFrame(aPresContext, aReflowInput, irs, frame, aStatus);
 576       if (aStatus.IsInlineBreak() ||
 577           (!reflowingFirstLetter && aStatus.IsIncomplete())) {
 578         break;
 579       }
 580       irs.mPrevFrame = frame;
 581       frame = frame->GetNextSibling();
 582     }
 583   }
 584
 585   NS_ASSERTION(!aStatus.IsComplete() || !GetOverflowFrames(),
 586                "We can't be complete AND have overflow frames!");
 587
 588   // If after reflowing our children they take up no area then make
 589   // sure that we don't either.
 590   //
 591   // Note: CSS demands that empty inline elements still affect the
 592   // line-height calculations. However, continuations of an inline
 593   // that are empty we force to empty so that things like collapsed
 594   // whitespace in an inline element don't affect the line-height.
 595   aMetrics.ISize(lineWM) = lineLayout->EndSpan(this);
 596
 597   // Compute final width.
 598
 599   // XXX Note that that the padding start and end are in the frame's
 600   //     writing mode, but the metrics' inline-size is in the line's
 601   //     writing mode. This makes sense if the line and frame are both
 602   //     vertical or both horizontal, but what should happen with
 603   //     orthogonal inlines?
 604
 605   // Make sure to not include our start border and padding if we have a prev
 606   // continuation or if we're in a part of an {ib} split other than the first
 607   // one.  For box-decoration-break:clone we always include our start border
 608   // and padding since all continuations have them.
 609   if ((!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) ||
 610       boxDecorationBreakClone) {
 611     aMetrics.ISize(lineWM) += framePadding.IStart(frameWM);
 612   }
 613
 614   /*
 615    * We want to only apply the end border and padding if we're the last
 616    * continuation and either not in an {ib} split or the last part of it.  To
 617    * be the last continuation we have to be complete (so that we won't get a
 618    * next-in-flow) and have no non-fluid continuations on our continuation
 619    * chain.  For box-decoration-break:clone we always apply the end border and
 620    * padding since all continuations have them.
 621    */
 622   if ((aStatus.IsComplete() && !LastInFlow()->GetNextContinuation() &&
 623        !FrameIsNonLastInIBSplit()) ||
 624       boxDecorationBreakClone) {
 625     aMetrics.ISize(lineWM) += framePadding.IEnd(frameWM);
 626   }
 627
 628   nsLayoutUtils::SetBSizeFromFontMetrics(this, aMetrics, framePadding, lineWM,
 629                                          frameWM);
 630
 631   // For now our overflow area is zero. The real value will be
 632   // computed in |nsLineLayout::RelativePositionFrames|.
 633   aMetrics.mOverflowAreas.Clear();
 634
 635 #ifdef NOISY_FINAL_SIZE
 636   ListTag(stdout);
 637   printf(": metrics=%d,%d ascent=%d\n", aMetrics.Width(), aMetrics.Height(),
 638          aMetrics.BlockStartAscent());
 639 #endif
 640 }
 641
 642 // Returns whether there's any remaining frame to pull.
 643 /* static */
 644 bool nsInlineFrame::HasFramesToPull(nsInlineFrame* aNextInFlow) {
 645   while (aNextInFlow) {
 646     if (!aNextInFlow->mFrames.IsEmpty()) {
 647       return true;
 648     }
 649     if (const nsFrameList* overflow = aNextInFlow->GetOverflowFrames()) {
 650       if (!overflow->IsEmpty()) {
 651         return true;
 652       }
 653     }
 654     aNextInFlow = static_cast<nsInlineFrame*>(aNextInFlow->GetNextInFlow());
 655   }
 656   return false;
 657 }
 658
 659 void nsInlineFrame::ReflowInlineFrame(nsPresContext* aPresContext,
 660                                       const ReflowInput& aReflowInput,
 661                                       InlineReflowInput& irs, nsIFrame* aFrame,
 662                                       nsReflowStatus& aStatus) {
 663   nsLineLayout* lineLayout = aReflowInput.mLineLayout;
 664   bool reflowingFirstLetter = lineLayout->GetFirstLetterStyleOK();
 665   bool pushedFrame;
 666   aStatus.Reset();
 667   lineLayout->ReflowFrame(aFrame, aStatus, nullptr, pushedFrame);
 668
 669   if (aStatus.IsInlineBreakBefore()) {
 670     if (aFrame != mFrames.FirstChild()) {
 671       // Change break-before status into break-after since we have
 672       // already placed at least one child frame. This preserves the
 673       // break-type so that it can be propagated upward.
 674       StyleClear oldClearType = aStatus.FloatClearType();
 675       aStatus.Reset();
 676       aStatus.SetIncomplete();
 677       aStatus.SetInlineLineBreakAfter(oldClearType);
 678       PushFrames(aPresContext, aFrame, irs.mPrevFrame, irs);
 679     } else {
 680       // Preserve reflow status when breaking-before our first child
 681       // and propagate it upward without modification.
 682     }
 683     return;
 684   }
 685
 686   // Create a next-in-flow if needed.
 687   if (!aStatus.IsFullyComplete()) {
 688     CreateNextInFlow(aFrame);
 689   }
 690
 691   if (aStatus.IsInlineBreakAfter()) {
 692     nsIFrame* nextFrame = aFrame->GetNextSibling();
 693     if (nextFrame) {
 694       aStatus.SetIncomplete();
 695       PushFrames(aPresContext, nextFrame, aFrame, irs);
 696     } else {
 697       // We must return an incomplete status if there are more child
 698       // frames remaining in a next-in-flow that follows this frame.
 699       if (HasFramesToPull(static_cast<nsInlineFrame*>(GetNextInFlow()))) {
 700         aStatus.SetIncomplete();
 701       }
 702     }
 703     return;
 704   }
 705
 706   if (!aStatus.IsFullyComplete() && !reflowingFirstLetter) {
 707     nsIFrame* nextFrame = aFrame->GetNextSibling();
 708     if (nextFrame) {
 709       PushFrames(aPresContext, nextFrame, aFrame, irs);
 710     }
 711   }
 712 }
 713
 714 nsIFrame* nsInlineFrame::PullOneFrame(nsPresContext* aPresContext,
 715                                       InlineReflowInput& irs) {
 716   nsIFrame* frame = nullptr;
 717   nsInlineFrame* nextInFlow = irs.mNextInFlow;
 718
 719 #ifdef DEBUG
 720   bool willPull = HasFramesToPull(nextInFlow);
 721 #endif
 722
 723   while (nextInFlow) {
 724     frame = nextInFlow->mFrames.FirstChild();
 725     if (!frame) {
 726       // The nextInFlow's principal list has no frames, try its overflow list.
 727       nsFrameList* overflowFrames = nextInFlow->GetOverflowFrames();
 728       if (overflowFrames) {
 729         frame = overflowFrames->RemoveFirstChild();
 730         if (overflowFrames->IsEmpty()) {
 731           // We're stealing the only frame - delete the overflow list.
 732           nextInFlow->DestroyOverflowList();
 733         } else {
 734           // We leave the remaining frames on the overflow list (rather than
 735           // putting them on nextInFlow's principal list) so we don't have to
 736           // set up the parent for them.
 737         }
 738         // ReparentFloatsForInlineChild needs it to be on a child list -
 739         // we remove it again below.
 740         nextInFlow->mFrames = nsFrameList(frame, frame);
 741       }
 742     }
 743
 744     if (frame) {
 745       // If our block has no next continuation, then any floats belonging to
 746       // the pulled frame must belong to our block already. This check ensures
 747       // we do no extra work in the common non-vertical-breaking case.
 748       if (irs.mLineContainer && irs.mLineContainer->GetNextContinuation()) {
 749         // The blockChildren.ContainsFrame check performed by
 750         // ReparentFloatsForInlineChild will be fast because frame's ancestor
 751         // will be the first child of its containing block.
 752         ReparentFloatsForInlineChild(irs.mLineContainer, frame, false);
 753       }
 754       nextInFlow->mFrames.RemoveFirstChild();
 755       // nsFirstLineFrame::PullOneFrame calls ReparentComputedStyle.
 756
 757       mFrames.InsertFrame(this, irs.mPrevFrame, frame);
 758       if (irs.mLineLayout) {
 759         irs.mLineLayout->SetDirtyNextLine();
 760       }
 761       nsContainerFrame::ReparentFrameView(frame, nextInFlow, this);
 762       break;
 763     }
 764     nextInFlow = static_cast<nsInlineFrame*>(nextInFlow->GetNextInFlow());
 765     irs.mNextInFlow = nextInFlow;
 766   }
 767
 768   MOZ_ASSERT(!!frame == willPull);
 769   return frame;
 770 }
 771
 772 void nsInlineFrame::PushFrames(nsPresContext* aPresContext,
 773                                nsIFrame* aFromChild, nsIFrame* aPrevSibling,
 774                                InlineReflowInput& aState) {
 775 #ifdef NOISY_PUSHING
 776   printf("%p pushing aFromChild %p, disconnecting from prev sib %p\n", this,
 777          aFromChild, aPrevSibling);
 778 #endif
 779
 780   PushChildrenToOverflow(aFromChild, aPrevSibling);
 781   if (aState.mLineLayout) {
 782     aState.mLineLayout->SetDirtyNextLine();
 783   }
 784 }
 785
 786 //////////////////////////////////////////////////////////////////////
 787
 788 LogicalSides nsInlineFrame::GetLogicalSkipSides() const {
 789   LogicalSides skip(mWritingMode);
 790   if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
 791                    StyleBoxDecorationBreak::Clone)) {
 792     return skip;
 793   }
 794
 795   if (!IsFirst()) {
 796     nsInlineFrame* prev = (nsInlineFrame*)GetPrevContinuation();
 797     if (HasAnyStateBits(NS_INLINE_FRAME_BIDI_VISUAL_STATE_IS_SET) ||
 798         (prev && (prev->mRect.height || prev->mRect.width))) {
 799       // Prev continuation is not empty therefore we don't render our start
 800       // border edge.
 801       skip |= eLogicalSideBitsIStart;
 802     } else {
 803       // If the prev continuation is empty, then go ahead and let our start
 804       // edge border render.
 805     }
 806   }
 807   if (!IsLast()) {
 808     nsInlineFrame* next = (nsInlineFrame*)GetNextContinuation();
 809     if (HasAnyStateBits(NS_INLINE_FRAME_BIDI_VISUAL_STATE_IS_SET) ||
 810         (next && (next->mRect.height || next->mRect.width))) {
 811       // Next continuation is not empty therefore we don't render our end
 812       // border edge.
 813       skip |= eLogicalSideBitsIEnd;
 814     } else {
 815       // If the next continuation is empty, then go ahead and let our end
 816       // edge border render.
 817     }
 818   }
 819
 820   if (HasAnyStateBits(NS_FRAME_PART_OF_IBSPLIT)) {
 821     // All but the last part of an {ib} split should skip the "end" side (as
 822     // determined by this frame's direction) and all but the first part of such
 823     // a split should skip the "start" side.  But figuring out which part of
 824     // the split we are involves getting our first continuation, which might be
 825     // expensive.  So don't bother if we already have the relevant bits set.
 826     if (skip != LogicalSides(mWritingMode, eLogicalSideBitsIBoth)) {
 827       // We're missing one of the skip bits, so check whether we need to set it.
 828       // Only get the first continuation once, as an optimization.
 829       nsIFrame* firstContinuation = FirstContinuation();
 830       if (firstContinuation->FrameIsNonLastInIBSplit()) {
 831         skip |= eLogicalSideBitsIEnd;
 832       }
 833       if (firstContinuation->FrameIsNonFirstInIBSplit()) {
 834         skip |= eLogicalSideBitsIStart;
 835       }
 836     }
 837   }
 838
 839   return skip;
 840 }
 841
 842 Maybe<nscoord> nsInlineFrame::GetNaturalBaselineBOffset(
 843     WritingMode aWM, BaselineSharingGroup aBaselineGroup,
 844     BaselineExportContext) const {
 845   if (aBaselineGroup == BaselineSharingGroup::Last) {
 846     return Nothing{};
 847   }
 848   return Some(mBaseline);
 849 }
 850
 851 #ifdef ACCESSIBILITY
 852 a11y::AccType nsInlineFrame::AccessibleType() {
 853   // FIXME(emilio): This is broken, if the image has its default `display` value
 854   // overridden. Should be somewhere else.
 855   if (mContent->IsHTMLElement(
 856           nsGkAtoms::img))  // Create accessible for broken <img>
 857     return a11y::eHyperTextType;
 858
 859   return a11y::eNoType;
 860 }
 861 #endif
 862
 863 void nsInlineFrame::UpdateStyleOfOwnedAnonBoxesForIBSplit(
 864     ServoRestyleState& aRestyleState) {
 865   MOZ_ASSERT(HasAnyStateBits(NS_FRAME_OWNS_ANON_BOXES),
 866              "Why did we get called?");
 867   MOZ_ASSERT(HasAnyStateBits(NS_FRAME_PART_OF_IBSPLIT),
 868              "Why did we have the NS_FRAME_OWNS_ANON_BOXES bit set?");
 869   // Note: this assert _looks_ expensive, but it's cheap in all the cases when
 870   // it passes!
 871   MOZ_ASSERT(nsLayoutUtils::FirstContinuationOrIBSplitSibling(this) == this,
 872              "Only the primary frame of the inline in a block-inside-inline "
 873              "split should have NS_FRAME_OWNS_ANON_BOXES");
 874   MOZ_ASSERT(mContent->GetPrimaryFrame() == this,
 875              "We should be the primary frame for our element");
 876
 877   nsIFrame* blockFrame = GetProperty(nsIFrame::IBSplitSibling());
 878   MOZ_ASSERT(blockFrame, "Why did we have an IB split?");
 879
 880   // The later inlines need to get our style.
 881   ComputedStyle* ourStyle = Style();
 882
 883   // The anonymous block's style inherits from ours, and we already have our new
 884   // ComputedStyle.
 885   RefPtr<ComputedStyle> newContext =
 886       aRestyleState.StyleSet().ResolveInheritingAnonymousBoxStyle(
 887           PseudoStyleType::mozBlockInsideInlineWrapper, ourStyle);
 888
 889   // We're guaranteed that newContext only differs from the old ComputedStyle on
 890   // the block in things they might inherit from us.  And changehint processing
 891   // guarantees walking the continuation and ib-sibling chains, so our existing
 892   // changehint being in aChangeList is good enough.  So we don't need to touch
 893   // aChangeList at all here.
 894
 895   while (blockFrame) {
 896     MOZ_ASSERT(!blockFrame->GetPrevContinuation(),
 897                "Must be first continuation");
 898
 899     MOZ_ASSERT(blockFrame->Style()->GetPseudoType() ==
 900                    PseudoStyleType::mozBlockInsideInlineWrapper,
 901                "Unexpected kind of ComputedStyle");
 902
 903     for (nsIFrame* cont = blockFrame; cont;
 904          cont = cont->GetNextContinuation()) {
 905       cont->SetComputedStyle(newContext);
 906     }
 907
 908     nsIFrame* nextInline = blockFrame->GetProperty(nsIFrame::IBSplitSibling());
 909
 910     // This check is here due to bug 1431232.  Please remove it once
 911     // that bug is fixed.
 912     if (MOZ_UNLIKELY(!nextInline)) {
 913       break;
 914     }
 915
 916     MOZ_ASSERT(nextInline, "There is always a trailing inline in an IB split");
 917
 918     for (nsIFrame* cont = nextInline; cont;
 919          cont = cont->GetNextContinuation()) {
 920       cont->SetComputedStyle(ourStyle);
 921     }
 922     blockFrame = nextInline->GetProperty(nsIFrame::IBSplitSibling());
 923   }
 924 }
 925
 926 //////////////////////////////////////////////////////////////////////
 927
 928 // nsLineFrame implementation
 929
 930 nsFirstLineFrame* NS_NewFirstLineFrame(PresShell* aPresShell,
 931                                        ComputedStyle* aStyle) {
 932   return new (aPresShell)
 933       nsFirstLineFrame(aStyle, aPresShell->GetPresContext());
 934 }
 935
 936 NS_IMPL_FRAMEARENA_HELPERS(nsFirstLineFrame)
 937
 938 void nsFirstLineFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
 939                             nsIFrame* aPrevInFlow) {
 940   nsInlineFrame::Init(aContent, aParent, aPrevInFlow);
 941   if (!aPrevInFlow) {
 942     MOZ_ASSERT(Style()->GetPseudoType() == PseudoStyleType::firstLine);
 943     return;
 944   }
 945
 946   // This frame is a continuation - fixup the computed style if aPrevInFlow
 947   // is the first-in-flow (the only one with a ::first-line pseudo).
 948   if (aPrevInFlow->Style()->GetPseudoType() == PseudoStyleType::firstLine) {
 949     MOZ_ASSERT(FirstInFlow() == aPrevInFlow);
 950     // Create a new ComputedStyle that is a child of the parent
 951     // ComputedStyle thus removing the ::first-line style. This way
 952     // we behave as if an anonymous (unstyled) span was the child
 953     // of the parent frame.
 954     ComputedStyle* parentContext = aParent->Style();
 955     RefPtr<ComputedStyle> newSC =
 956         PresContext()->StyleSet()->ResolveInheritingAnonymousBoxStyle(
 957             PseudoStyleType::mozLineFrame, parentContext);
 958     SetComputedStyle(newSC);
 959   } else {
 960     MOZ_ASSERT(FirstInFlow() != aPrevInFlow);
 961     MOZ_ASSERT(aPrevInFlow->Style()->GetPseudoType() ==
 962                PseudoStyleType::mozLineFrame);
 963   }
 964 }
 965
 966 #ifdef DEBUG_FRAME_DUMP
 967 nsresult nsFirstLineFrame::GetFrameName(nsAString& aResult) const {
 968   return MakeFrameName(u"Line"_ns, aResult);
 969 }
 970 #endif
 971
 972 nsIFrame* nsFirstLineFrame::PullOneFrame(nsPresContext* aPresContext,
 973                                          InlineReflowInput& irs) {
 974   nsIFrame* frame = nsInlineFrame::PullOneFrame(aPresContext, irs);
 975   if (frame && !GetPrevInFlow()) {
 976     // We are a first-line frame. Fixup the child frames
 977     // style-context that we just pulled.
 978     NS_ASSERTION(frame->GetParent() == this, "Incorrect parent?");
 979     aPresContext->RestyleManager()->ReparentComputedStyleForFirstLine(frame);
 980     nsLayoutUtils::MarkDescendantsDirty(frame);
 981   }
 982   return frame;
 983 }
 984
 985 void nsFirstLineFrame::Reflow(nsPresContext* aPresContext,
 986                               ReflowOutput& aMetrics,
 987                               const ReflowInput& aReflowInput,
 988                               nsReflowStatus& aStatus) {
 989   MarkInReflow();
 990   MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
 991
 992   if (nullptr == aReflowInput.mLineLayout) {
 993     return;  // XXX does this happen? why?
 994   }
 995
 996   // Check for an overflow list with our prev-in-flow
 997   nsFirstLineFrame* prevInFlow = (nsFirstLineFrame*)GetPrevInFlow();
 998   if (prevInFlow) {
 999     AutoFrameListPtr prevOverflowFrames(aPresContext,
1000                                         prevInFlow->StealOverflowFrames());
1001     if (prevOverflowFrames) {
1002       // Reparent the new frames and their ComputedStyles.
1003       const nsFrameList::Slice& newFrames =
1004           mFrames.InsertFrames(this, nullptr, std::move(*prevOverflowFrames));
1005       ReparentChildListStyle(aPresContext, newFrames, this);
1006     }
1007   }
1008
1009   // It's also possible that we have an overflow list for ourselves.
1010   DrainSelfOverflowList();
1011
1012   // Set our own reflow input (additional state above and beyond aReflowInput).
1013   InlineReflowInput irs;
1014   irs.mPrevFrame = nullptr;
1015   irs.mLineContainer = aReflowInput.mLineLayout->LineContainerFrame();
1016   irs.mLineLayout = aReflowInput.mLineLayout;
1017   irs.mNextInFlow = (nsInlineFrame*)GetNextInFlow();
1018
1019   bool wasEmpty = mFrames.IsEmpty();
1020   if (wasEmpty) {
1021     // Try to pull over one frame before starting so that we know
1022     // whether we have an anonymous block or not.
1023     PullOneFrame(aPresContext, irs);
1024   }
1025
1026   if (nullptr == GetPrevInFlow()) {
1027     // XXX This is pretty sick, but what we do here is to pull-up, in
1028     // advance, all of the next-in-flows children. We re-resolve their
1029     // style while we are at at it so that when we reflow they have
1030     // the right style.
1031     //
1032     // All of this is so that text-runs reflow properly.
1033     irs.mPrevFrame = mFrames.LastChild();
1034     for (;;) {
1035       nsIFrame* frame = PullOneFrame(aPresContext, irs);
1036       if (!frame) {
1037         break;
1038       }
1039       irs.mPrevFrame = frame;
1040     }
1041     irs.mPrevFrame = nullptr;
1042   }
1043
1044   NS_ASSERTION(!aReflowInput.mLineLayout->GetInFirstLine(),
1045                "Nested first-line frames? BOGUS");
1046   aReflowInput.mLineLayout->SetInFirstLine(true);
1047   ReflowFrames(aPresContext, aReflowInput, irs, aMetrics, aStatus);
1048   aReflowInput.mLineLayout->SetInFirstLine(false);
1049
1050   ReflowAbsoluteFrames(aPresContext, aMetrics, aReflowInput, aStatus);
1051
1052   // Note: the line layout code will properly compute our overflow state for us
1053 }
1054
1055 /* virtual */
1056 void nsFirstLineFrame::PullOverflowsFromPrevInFlow() {
1057   nsFirstLineFrame* prevInFlow =
1058       static_cast<nsFirstLineFrame*>(GetPrevInFlow());
1059   if (prevInFlow) {
1060     nsPresContext* presContext = PresContext();
1061     AutoFrameListPtr prevOverflowFrames(presContext,
1062                                         prevInFlow->StealOverflowFrames());
1063     if (prevOverflowFrames) {
1064       // Assume that our prev-in-flow has the same line container that we do.
1065       const nsFrameList::Slice& newFrames =
1066           mFrames.InsertFrames(this, nullptr, std::move(*prevOverflowFrames));
1067       ReparentChildListStyle(presContext, newFrames, this);
1068     }
1069   }
1070 }
1071
1072 /* virtual */
1073 bool nsFirstLineFrame::DrainSelfOverflowList() {
1074   AutoFrameListPtr overflowFrames(PresContext(), StealOverflowFrames());
1075   if (overflowFrames) {
1076     bool result = !overflowFrames->IsEmpty();
1077     const nsFrameList::Slice& newFrames =
1078         mFrames.AppendFrames(nullptr, std::move(*overflowFrames));
1079     ReparentChildListStyle(PresContext(), newFrames, this);
1080     return result;
1081   }
1082   return false;
1083 }