layout/generic/nsFontInflationData.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 /* Per-block-formatting-context manager of font size inflation for pan and zoom
   8  * UI. */
   9
  10 #include "nsFontInflationData.h"
  11 #include "FrameProperties.h"
  12 #include "nsTextControlFrame.h"
  13 #include "nsListControlFrame.h"
  14 #include "nsComboboxControlFrame.h"
  15 #include "mozilla/dom/Text.h"  // for inline nsINode::AsText() definition
  16 #include "mozilla/PresShell.h"
  17 #include "mozilla/ReflowInput.h"
  18 #include "nsTextFrameUtils.h"
  19
  20 using namespace mozilla;
  21 using namespace mozilla::layout;
  22
  23 NS_DECLARE_FRAME_PROPERTY_DELETABLE(FontInflationDataProperty,
  24                                     nsFontInflationData)
  25
  26 /* static */ nsFontInflationData* nsFontInflationData::FindFontInflationDataFor(
  27     const nsIFrame* aFrame) {
  28   // We have one set of font inflation data per block formatting context.
  29   const nsIFrame* bfc = FlowRootFor(aFrame);
  30   NS_ASSERTION(bfc->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT),
  31                "should have found a flow root");
  32   MOZ_ASSERT(aFrame->GetWritingMode().IsVertical() ==
  33                  bfc->GetWritingMode().IsVertical(),
  34              "current writing mode should match that of our flow root");
  35
  36   return bfc->GetProperty(FontInflationDataProperty());
  37 }
  38
  39 /* static */
  40 bool nsFontInflationData::UpdateFontInflationDataISizeFor(
  41     const ReflowInput& aReflowInput) {
  42   nsIFrame* bfc = aReflowInput.mFrame;
  43   NS_ASSERTION(bfc->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT),
  44                "should have been given a flow root");
  45   nsFontInflationData* data = bfc->GetProperty(FontInflationDataProperty());
  46   bool oldInflationEnabled;
  47   nscoord oldUsableISize;
  48   if (data) {
  49     oldUsableISize = data->mUsableISize;
  50     oldInflationEnabled = data->mInflationEnabled;
  51   } else {
  52     data = new nsFontInflationData(bfc);
  53     bfc->SetProperty(FontInflationDataProperty(), data);
  54     oldUsableISize = -1;
  55     oldInflationEnabled = true; /* not relevant */
  56   }
  57
  58   data->UpdateISize(aReflowInput);
  59
  60   if (oldInflationEnabled != data->mInflationEnabled) return true;
  61
  62   return oldInflationEnabled && oldUsableISize != data->mUsableISize;
  63 }
  64
  65 /* static */
  66 void nsFontInflationData::MarkFontInflationDataTextDirty(nsIFrame* aBFCFrame) {
  67   NS_ASSERTION(aBFCFrame->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT),
  68                "should have been given a flow root");
  69
  70   nsFontInflationData* data =
  71       aBFCFrame->GetProperty(FontInflationDataProperty());
  72   if (data) {
  73     data->MarkTextDirty();
  74   }
  75 }
  76
  77 nsFontInflationData::nsFontInflationData(nsIFrame* aBFCFrame)
  78     : mBFCFrame(aBFCFrame),
  79       mUsableISize(0),
  80       mTextAmount(0),
  81       mTextThreshold(0),
  82       mInflationEnabled(false),
  83       mTextDirty(true) {}
  84
  85 /**
  86  * Find the closest common ancestor between aFrame1 and aFrame2, except
  87  * treating the parent of a frame as the first-in-flow of its parent (so
  88  * the result doesn't change when breaking changes).
  89  *
  90  * aKnownCommonAncestor is a known common ancestor of both.
  91  */
  92 static nsIFrame* NearestCommonAncestorFirstInFlow(
  93     nsIFrame* aFrame1, nsIFrame* aFrame2, nsIFrame* aKnownCommonAncestor) {
  94   aFrame1 = aFrame1->FirstInFlow();
  95   aFrame2 = aFrame2->FirstInFlow();
  96   aKnownCommonAncestor = aKnownCommonAncestor->FirstInFlow();
  97
  98   AutoTArray<nsIFrame*, 32> ancestors1, ancestors2;
  99   for (nsIFrame* f = aFrame1; f != aKnownCommonAncestor;
 100        (f = f->GetParent()) && (f = f->FirstInFlow())) {
 101     ancestors1.AppendElement(f);
 102   }
 103   for (nsIFrame* f = aFrame2; f != aKnownCommonAncestor;
 104        (f = f->GetParent()) && (f = f->FirstInFlow())) {
 105     ancestors2.AppendElement(f);
 106   }
 107
 108   nsIFrame* result = aKnownCommonAncestor;
 109   uint32_t i1 = ancestors1.Length(), i2 = ancestors2.Length();
 110   while (i1-- != 0 && i2-- != 0) {
 111     if (ancestors1[i1] != ancestors2[i2]) {
 112       break;
 113     }
 114     result = ancestors1[i1];
 115   }
 116
 117   return result;
 118 }
 119
 120 static nscoord ComputeDescendantISize(const ReflowInput& aAncestorReflowInput,
 121                                       nsIFrame* aDescendantFrame) {
 122   nsIFrame* ancestorFrame = aAncestorReflowInput.mFrame->FirstInFlow();
 123   if (aDescendantFrame == ancestorFrame) {
 124     return aAncestorReflowInput.ComputedISize();
 125   }
 126
 127   AutoTArray<nsIFrame*, 16> frames;
 128   for (nsIFrame* f = aDescendantFrame; f != ancestorFrame;
 129        f = f->GetParent()->FirstInFlow()) {
 130     frames.AppendElement(f);
 131   }
 132
 133   // This ignores the inline-size contributions made by scrollbars, though in
 134   // reality we don't have any scrollbars on the sorts of devices on
 135   // which we use font inflation, so it's not a problem.  But it may
 136   // occasionally cause problems when writing tests on desktop.
 137
 138   uint32_t len = frames.Length();
 139   ReflowInput* reflowInputs =
 140       static_cast<ReflowInput*>(moz_xmalloc(sizeof(ReflowInput) * len));
 141   nsPresContext* presContext = aDescendantFrame->PresContext();
 142   for (uint32_t i = 0; i < len; ++i) {
 143     const ReflowInput& parentReflowInput =
 144         (i == 0) ? aAncestorReflowInput : reflowInputs[i - 1];
 145     nsIFrame* frame = frames[len - i - 1];
 146     WritingMode wm = frame->GetWritingMode();
 147     LogicalSize availSize = parentReflowInput.ComputedSize(wm);
 148     availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
 149     MOZ_ASSERT(frame->GetParent()->FirstInFlow() ==
 150                    parentReflowInput.mFrame->FirstInFlow(),
 151                "bad logic in this function");
 152     new (reflowInputs + i)
 153         ReflowInput(presContext, parentReflowInput, frame, availSize);
 154   }
 155
 156   MOZ_ASSERT(reflowInputs[len - 1].mFrame == aDescendantFrame,
 157              "bad logic in this function");
 158   nscoord result = reflowInputs[len - 1].ComputedISize();
 159
 160   for (uint32_t i = len; i-- != 0;) {
 161     reflowInputs[i].~ReflowInput();
 162   }
 163   free(reflowInputs);
 164
 165   return result;
 166 }
 167
 168 void nsFontInflationData::UpdateISize(const ReflowInput& aReflowInput) {
 169   nsIFrame* bfc = aReflowInput.mFrame;
 170   NS_ASSERTION(bfc->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT),
 171                "must be block formatting context");
 172
 173   nsIFrame* firstInflatableDescendant =
 174       FindEdgeInflatableFrameIn(bfc, eFromStart);
 175   if (!firstInflatableDescendant) {
 176     mTextAmount = 0;
 177     mTextThreshold = 0;  // doesn't matter
 178     mTextDirty = false;
 179     mInflationEnabled = false;
 180     return;
 181   }
 182   nsIFrame* lastInflatableDescendant = FindEdgeInflatableFrameIn(bfc, eFromEnd);
 183   MOZ_ASSERT(!firstInflatableDescendant == !lastInflatableDescendant,
 184              "null-ness should match; NearestCommonAncestorFirstInFlow"
 185              " will crash when passed null");
 186
 187   // Particularly when we're computing for the root BFC, the inline-size of
 188   // nca might differ significantly for the inline-size of bfc.
 189   nsIFrame* nca = NearestCommonAncestorFirstInFlow(
 190       firstInflatableDescendant, lastInflatableDescendant, bfc);
 191   while (!nca->IsContainerForFontSizeInflation()) {
 192     nca = nca->GetParent()->FirstInFlow();
 193   }
 194
 195   nscoord newNCAISize = ComputeDescendantISize(aReflowInput, nca);
 196
 197   // See comment above "font.size.inflation.lineThreshold" in
 198   // modules/libpref/src/init/StaticPrefList.yaml .
 199   PresShell* presShell = bfc->PresShell();
 200   uint32_t lineThreshold = presShell->FontSizeInflationLineThreshold();
 201   nscoord newTextThreshold = (newNCAISize * lineThreshold) / 100;
 202
 203   if (mTextThreshold <= mTextAmount && mTextAmount < newTextThreshold) {
 204     // Because we truncate our scan when we hit sufficient text, we now
 205     // need to rescan.
 206     mTextDirty = true;
 207   }
 208
 209   // Font inflation increases the font size for a given flow root so that the
 210   // text is legible when we've zoomed such that the respective nearest common
 211   // ancestor's (NCA) full inline-size (ISize) fills the screen. We assume how-
 212   // ever that we don't want to zoom out further than the root iframe's ISize
 213   // (i.e. the viewport for a top-level document, or the containing iframe
 214   // otherwise), since in some cases zooming out further might not even be
 215   // possible or make sense.
 216   // Hence the ISize assumed to be usable for displaying text is limited to the
 217   // visible area.
 218   nsPresContext* presContext = bfc->PresContext();
 219   MOZ_ASSERT(
 220       bfc->GetWritingMode().IsVertical() == nca->GetWritingMode().IsVertical(),
 221       "writing mode of NCA should match that of its flow root");
 222   nscoord iFrameISize = bfc->GetWritingMode().IsVertical()
 223                             ? presContext->GetVisibleArea().height
 224                             : presContext->GetVisibleArea().width;
 225   mUsableISize = std::min(iFrameISize, newNCAISize);
 226   mTextThreshold = newTextThreshold;
 227   mInflationEnabled = mTextAmount >= mTextThreshold;
 228 }
 229
 230 /* static */ nsIFrame* nsFontInflationData::FindEdgeInflatableFrameIn(
 231     nsIFrame* aFrame, SearchDirection aDirection) {
 232   // NOTE: This function has a similar structure to ScanTextIn!
 233
 234   // FIXME: Should probably only scan the text that's actually going to
 235   // be inflated!
 236
 237   nsIFormControlFrame* fcf = do_QueryFrame(aFrame);
 238   if (fcf) {
 239     return aFrame;
 240   }
 241
 242   // FIXME: aDirection!
 243   AutoTArray<FrameChildList, 4> lists;
 244   aFrame->GetChildLists(&lists);
 245   for (uint32_t i = 0, len = lists.Length(); i < len; ++i) {
 246     const nsFrameList& list =
 247         lists[(aDirection == eFromStart) ? i : len - i - 1].mList;
 248     for (nsIFrame* kid = (aDirection == eFromStart) ? list.FirstChild()
 249                                                     : list.LastChild();
 250          kid; kid = (aDirection == eFromStart) ? kid->GetNextSibling()
 251                                                : kid->GetPrevSibling()) {
 252       if (kid->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT)) {
 253         // Goes in a different set of inflation data.
 254         continue;
 255       }
 256
 257       if (kid->IsTextFrame()) {
 258         nsIContent* content = kid->GetContent();
 259         if (content && kid == content->GetPrimaryFrame()) {
 260           uint32_t len = nsTextFrameUtils::
 261               ComputeApproximateLengthWithWhitespaceCompression(
 262                   content->AsText(), kid->StyleText());
 263           if (len != 0) {
 264             return kid;
 265           }
 266         }
 267       } else {
 268         nsIFrame* kidResult = FindEdgeInflatableFrameIn(kid, aDirection);
 269         if (kidResult) {
 270           return kidResult;
 271         }
 272       }
 273     }
 274   }
 275
 276   return nullptr;
 277 }
 278
 279 void nsFontInflationData::ScanText() {
 280   mTextDirty = false;
 281   mTextAmount = 0;
 282   ScanTextIn(mBFCFrame);
 283   mInflationEnabled = mTextAmount >= mTextThreshold;
 284 }
 285
 286 static uint32_t DoCharCountOfLargestOption(nsIFrame* aContainer) {
 287   uint32_t result = 0;
 288   for (nsIFrame* option : aContainer->PrincipalChildList()) {
 289     uint32_t optionResult;
 290     if (option->GetContent()->IsHTMLElement(nsGkAtoms::optgroup)) {
 291       optionResult = DoCharCountOfLargestOption(option);
 292     } else {
 293       // REVIEW: Check the frame structure for this!
 294       optionResult = 0;
 295       for (nsIFrame* optionChild : option->PrincipalChildList()) {
 296         if (optionChild->IsTextFrame()) {
 297           optionResult += nsTextFrameUtils::
 298               ComputeApproximateLengthWithWhitespaceCompression(
 299                   optionChild->GetContent()->AsText(),
 300                   optionChild->StyleText());
 301         }
 302       }
 303     }
 304     if (optionResult > result) {
 305       result = optionResult;
 306     }
 307   }
 308   return result;
 309 }
 310
 311 static uint32_t CharCountOfLargestOption(nsIFrame* aListControlFrame) {
 312   return DoCharCountOfLargestOption(
 313       static_cast<nsListControlFrame*>(aListControlFrame)
 314           ->GetOptionsContainer());
 315 }
 316
 317 void nsFontInflationData::ScanTextIn(nsIFrame* aFrame) {
 318   // NOTE: This function has a similar structure to FindEdgeInflatableFrameIn!
 319
 320   // FIXME: Should probably only scan the text that's actually going to
 321   // be inflated!
 322
 323   for (const auto& childList : aFrame->ChildLists()) {
 324     for (nsIFrame* kid : childList.mList) {
 325       if (kid->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT)) {
 326         // Goes in a different set of inflation data.
 327         continue;
 328       }
 329
 330       LayoutFrameType fType = kid->Type();
 331       if (fType == LayoutFrameType::Text) {
 332         nsIContent* content = kid->GetContent();
 333         if (content && kid == content->GetPrimaryFrame()) {
 334           uint32_t len = nsTextFrameUtils::
 335               ComputeApproximateLengthWithWhitespaceCompression(
 336                   content->AsText(), kid->StyleText());
 337           if (len != 0) {
 338             nscoord fontSize = kid->StyleFont()->mFont.size.ToAppUnits();
 339             if (fontSize > 0) {
 340               mTextAmount += fontSize * len;
 341             }
 342           }
 343         }
 344       } else if (fType == LayoutFrameType::TextInput) {
 345         // We don't want changes to the amount of text in a text input
 346         // to change what we count towards inflation.
 347         nscoord fontSize = kid->StyleFont()->mFont.size.ToAppUnits();
 348         int32_t charCount =
 349             static_cast<nsTextControlFrame*>(kid)->GetColsOrDefault();
 350         mTextAmount += charCount * fontSize;
 351       } else if (fType == LayoutFrameType::ComboboxControl) {
 352         // See textInputFrame above (with s/amount of text/selected option/).
 353         // Don't just recurse down to the list control inside, since we
 354         // need to exclude the display frame.
 355         nscoord fontSize = kid->StyleFont()->mFont.size.ToAppUnits();
 356         int32_t charCount = static_cast<nsComboboxControlFrame*>(kid)
 357                                 ->CharCountOfLargestOptionForInflation();
 358         mTextAmount += charCount * fontSize;
 359       } else if (fType == LayoutFrameType::ListControl) {
 360         // See textInputFrame above (with s/amount of text/selected option/).
 361         nscoord fontSize = kid->StyleFont()->mFont.size.ToAppUnits();
 362         int32_t charCount = CharCountOfLargestOption(kid);
 363         mTextAmount += charCount * fontSize;
 364       } else {
 365         // recursive step
 366         ScanTextIn(kid);
 367       }
 368
 369       if (mTextAmount >= mTextThreshold) {
 370         return;
 371       }
 372     }
 373   }
 374 }