Store glyph bounds in WordMeasurement to avoid slow path width calc

Source/platform/fonts/Font.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  *
  * 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
@@ skipping 43 matching lines @@
 class FloatRect;
 class FontData;
 class FontMetrics;
 class FontSelector;
 class GlyphBuffer;
 class TextRun;
 struct TextRunPaintInfo;
 
 struct GlyphData;
 
-struct GlyphOverflow {
-    GlyphOverflow()
-        : left(0)
-        , right(0)
-        , top(0)
-        , bottom(0)
-        , computeBounds(false)
-    {
-    }
-
-    bool isZero() const
-    {
-        return !left && !right && !top && !bottom;
-    }
-
-    // If computeBounds, top and bottom are the maximum heights of the glyphs above and below the baseline, respectively.
-    // Otherwise they are the amounts of glyph overflows exceeding the font metrics' ascent and descent, respectively.
-    // Left and right are the amounts of glyph overflows exceeding the left and right edge of normal layout boundary, respectively.
-    // All fields are in absolute number of pixels rounded up to the nearest integer.
-    int left;
-    int right;
-    int top;
-    int bottom;
-    bool computeBounds;
-};
-
 class PLATFORM_EXPORT Font {
 public:
     Font();
     Font(const FontDescription&);
     ~Font();
 
     Font(const Font&);
     Font& operator=(const Font&);
 
     bool operator==(const Font& other) const;
     bool operator!=(const Font& other) const { return !(*this == other); }
 
     const FontDescription& fontDescription() const { return m_fontDescription; }
 
     void update(PassRefPtrWillBeRawPtr<FontSelector>) const;
 
     enum CustomFontNotReadyAction { DoNotPaintIfFontNotReady, UseFallbackIfFontNotReady };
     void drawText(SkCanvas*, const TextRunPaintInfo&, const FloatPoint&, float deviceScaleFactor, const SkPaint&) const;
     void drawBidiText(SkCanvas*, const TextRunPaintInfo&, const FloatPoint&, CustomFontNotReadyAction, float deviceScaleFactor, const SkPaint&) const;
     void drawEmphasisMarks(SkCanvas*, const TextRunPaintInfo&, const AtomicString& mark, const FloatPoint&, float deviceScaleFactor, const SkPaint&) const;
 
-    float width(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
+    // Glyph bounds will be the minimum rect containing all glyph strokes, in coordinates using
+    // (<text run x position>, <baseline position>) as the origin.
+    float width(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = nullptr, FloatRect* glyphBounds = nullptr) const;
 
     int offsetForPosition(const TextRun&, float position, bool includePartialGlyphs) const;
     FloatRect selectionRectForText(const TextRun&, const FloatPoint&, int h, int from = 0, int to = -1, bool accountForGlyphBounds = false) const;
 
     // Metrics that we query the FontFallbackList for.
     const FontMetrics& fontMetrics() const { return primaryFont()->fontMetrics(); }
     float spaceWidth() const { return primaryFont()->spaceWidth() + fontDescription().letterSpacing(); }
     float tabWidth(const SimpleFontData&, const TabSize&, float position) const;
     float tabWidth(const TabSize& tabSize, float position) const { return tabWidth(*primaryFont(), tabSize, position); }
 
@@ skipping 14 matching lines @@
     float buildGlyphBuffer(const TextRunPaintInfo&, GlyphBuffer&, const GlyphData* emphasisData = nullptr) const;
     PassTextBlobPtr buildTextBlob(const GlyphBuffer&) const;
     void paintGlyphs(SkCanvas*, const SkPaint&, const SimpleFontData*, const Glyph glyphs[], unsigned numGlyphs,
         const SkPoint pos[], const FloatRect& textRect, float deviceScaleFactor) const;
     void paintGlyphsHorizontal(SkCanvas*, const SkPaint&, const SimpleFontData*, const Glyph glyphs[], unsigned numGlyphs,
         const SkScalar xpos[], SkScalar constY, const FloatRect& textRect, float deviceScaleFactor) const;
     void drawGlyphs(SkCanvas*, const SkPaint&, const SimpleFontData*, const GlyphBuffer&, unsigned from, unsigned numGlyphs,
         const FloatPoint&, const FloatRect& textRect, float deviceScaleFactor) const;
     void drawTextBlob(SkCanvas*, const SkPaint&, const SkTextBlob*, const SkPoint& origin) const;
     void drawGlyphBuffer(SkCanvas*, const SkPaint&, const TextRunPaintInfo&, const GlyphBuffer&, const FloatPoint&, float deviceScaleFactor) const;
-    float floatWidthForSimpleText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, FloatRectOutsets* glyphBounds = 0) const;
+    float floatWidthForSimpleText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, FloatRect* glyphBounds = 0) const;
     int offsetForPositionForSimpleText(const TextRun&, float position, bool includePartialGlyphs) const;
     FloatRect selectionRectForSimpleText(const TextRun&, const FloatPoint&, int h, int from, int to, bool accountForGlyphBounds) const;
 
     bool getEmphasisMarkGlyphData(const AtomicString&, GlyphData&) const;
 
-    float floatWidthForComplexText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts, FloatRectOutsets* glyphBounds) const;
+    float floatWidthForComplexText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts, FloatRect* glyphBounds) const;
     int offsetForPositionForComplexText(const TextRun&, float position, bool includePartialGlyphs) const;
     FloatRect selectionRectForComplexText(const TextRun&, const FloatPoint&, int h, int from, int to) const;
 
     friend struct SimpleShaper;
 
 public:
     FontSelector* fontSelector() const;
 
     void willUseFontData(UChar32) const;
 
@@ skipping 42 matching lines @@
     // to the next tab stop is less than that, advance an additional tab stop.
     if (distanceToTabStop < fontDescription().letterSpacing())
         distanceToTabStop += baseTabWidth;
 
     return distanceToTabStop;
 }
 
 } // namespace blink
 
 #endif