Store glyph bounds in WordMeasurement to avoid slow path width calc

Source/core/layout/LayoutText.h

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004-2009, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 68 matching lines @@
     bool is8Bit() const { return m_text.is8Bit(); }
     const LChar* characters8() const { return m_text.impl()->characters8(); }
     const UChar* characters16() const { return m_text.impl()->characters16(); }
     bool hasEmptyText() const { return m_text.isEmpty(); }
     UChar characterAt(unsigned) const;
     UChar uncheckedCharacterAt(unsigned) const;
     UChar operator[](unsigned i) const { return uncheckedCharacterAt(i); }
     unsigned textLength() const { return m_text.length(); } // non virtual implementation of length()
     void positionLineBox(InlineBox*);
 
-    virtual float width(unsigned from, unsigned len, const Font&, LayoutUnit xPos, TextDirection, HashSet<const SimpleFontData*>* fallbackFonts = nullptr, GlyphOverflow* = nullptr) const;
-    virtual float width(unsigned from, unsigned len, LayoutUnit xPos, TextDirection, bool firstLine = false, HashSet<const SimpleFontData*>* fallbackFonts = nullptr, GlyphOverflow* = nullptr) const;
+    virtual float width(unsigned from, unsigned len, const Font&, LayoutUnit xPos, TextDirection, HashSet<const SimpleFontData*>* fallbackFonts = nullptr, FloatRect* glyphBounds = nullptr) const;
+    virtual float width(unsigned from, unsigned len, LayoutUnit xPos, TextDirection, bool firstLine = false, HashSet<const SimpleFontData*>* fallbackFonts = nullptr, FloatRect* glyphBounds = nullptr) const;
 
     float minLogicalWidth() const;
     float maxLogicalWidth() const;
 
     void trimmedPrefWidths(LayoutUnit leadWidth,
         LayoutUnit& firstLineMinWidth, bool& hasBreakableStart,
         LayoutUnit& lastLineMinWidth, bool& hasBreakableEnd,
         bool& hasBreakableChar, bool& hasBreak,
         LayoutUnit& firstLineMaxWidth, LayoutUnit& lastLineMaxWidth,
         LayoutUnit& minWidth, LayoutUnit& maxWidth, bool& stripFrontSpaces,
@@ skipping 50 matching lines @@
     virtual UChar previousCharacter() const;
 
     virtual void addLayerHitTestRects(LayerHitTestRects&, const DeprecatedPaintLayer* currentLayer, const LayoutPoint& layerOffset, const LayoutRect& containerRect) const override;
 
     virtual InlineTextBox* createTextBox(int start, unsigned short length); // Subclassed by SVG.
 
     virtual void invalidateDisplayItemClients(const LayoutBoxModelObject& paintInvalidationContainer) const override;
 
 private:
     void computePreferredLogicalWidths(float leadWidth);
-    void computePreferredLogicalWidths(float leadWidth, HashSet<const SimpleFontData*>& fallbackFonts, GlyphOverflow&);
+    void computePreferredLogicalWidths(float leadWidth, HashSet<const SimpleFontData*>& fallbackFonts, FloatRect& glyphBounds);
 
     bool computeCanUseSimpleFontCodePath() const;
 
     // Make length() private so that callers that have a LayoutText*
     // will use the more efficient textLength() instead, while
     // callers with a LayoutObject* can continue to use length().
     virtual unsigned length() const override final { return textLength(); }
 
     virtual void paint(const PaintInfo&, const LayoutPoint&) override final { ASSERT_NOT_REACHED(); }
     virtual void layout() override final { ASSERT_NOT_REACHED(); }
     virtual bool nodeAtPoint(HitTestResult&, const HitTestLocation&, const LayoutPoint&, HitTestAction) override final { ASSERT_NOT_REACHED(); return false; }
 
     void deleteTextBoxes();
     bool containsOnlyWhitespace(unsigned from, unsigned len) const;
-    float widthFromCache(const Font&, int start, int len, float xPos, TextDirection, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow*) const;
+    float widthFromFont(const Font&, int start, int len, float leadWidth, float textWidthSoFar, TextDirection, HashSet<const SimpleFontData*>* fallbackFonts, FloatRect* glyphBoundsAccumulation) const;
 
     void secureText(UChar mask);
 
     bool isText() const = delete; // This will catch anyone doing an unnecessary check.
 
     virtual LayoutRect clippedOverflowRectForPaintInvalidation(const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState* = nullptr) const override;
 
     void checkConsistency() const;
 
     // We put the bitfield first to minimize padding on 64-bit.
@@ skipping 48 matching lines @@
 inline LayoutText* Text::layoutObject() const
 {
     return toLayoutText(CharacterData::layoutObject());
 }
 
 void applyTextTransform(const ComputedStyle*, String&, UChar);
 
 } // namespace blink
 
 #endif // LayoutText_h