Track the region where text is painted.

Source/core/platform/graphics/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 79 matching lines @@
     bool operator!=(const Font& other) const { return !(*this == other); }
 
     const FontDescription& fontDescription() const { return m_fontDescription; }
 
     int pixelSize() const { return fontDescription().computedPixelSize(); }
     float size() const { return fontDescription().computedSize(); }
 
     void update(PassRefPtr<FontSelector>) const;
 
     enum CustomFontNotReadyAction { DoNotPaintIfFontNotReady, UseFallbackIfFontNotReady };
-    void drawText(GraphicsContext*, const TextRun&, const FloatPoint&, int from = 0, int to = -1, CustomFontNotReadyAction = DoNotPaintIfFontNotReady) const;
-    void drawEmphasisMarks(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, int from = 0, int to = -1) const;
+    void drawText(GraphicsContext*, const TextRun&, const FloatPoint&, const FloatRect& textRect, int from = 0, int to = -1, CustomFontNotReadyAction = DoNotPaintIfFontNotReady) const;
+    void drawEmphasisMarks(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, const FloatRect& textRect, int from = 0, int to = -1) const;
 
     float width(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
     float width(const TextRun&, int& charsConsumed, String& glyphName) const;
 
     PassOwnPtr<TextLayout> createLayout(RenderText*, float xPos, bool collapseWhiteSpace) const;
     static void deleteLayout(TextLayout*);
     static float width(TextLayout&, unsigned from, unsigned len, HashSet<const SimpleFontData*>* fallbackFonts = 0);
 
     int offsetForPosition(const TextRun&, float position, bool includePartialGlyphs) const;
     FloatRect selectionRectForText(const TextRun&, const FloatPoint&, int h, int from = 0, int to = -1) const;
@@ skipping 54 matching lines @@
     enum CodePath { Auto, Simple, Complex, SimpleWithGlyphOverflow };
     CodePath codePath(const TextRun&) const;
     static CodePath characterRangeCodePath(const LChar*, unsigned) { return Simple; }
     static CodePath characterRangeCodePath(const UChar*, unsigned len);
     
 private:
     enum ForTextEmphasisOrNot { NotForTextEmphasis, ForTextEmphasis };
 
     // Returns the initial in-stream advance.
     float getGlyphsAndAdvancesForSimpleText(const TextRun&, int from, int to, GlyphBuffer&, ForTextEmphasisOrNot = NotForTextEmphasis) const;
-    void drawSimpleText(GraphicsContext*, const TextRun&, const FloatPoint&, int from, int to) const;
-    void drawEmphasisMarksForSimpleText(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, int from, int to) const;
-    void drawGlyphs(GraphicsContext*, const SimpleFontData*, const GlyphBuffer&, int from, int to, const FloatPoint&) const;
-    void drawGlyphBuffer(GraphicsContext*, const TextRun&, const GlyphBuffer&, const FloatPoint&) const;
-    void drawEmphasisMarks(GraphicsContext*, const TextRun&, const GlyphBuffer&, const AtomicString&, const FloatPoint&) const;
+    void drawSimpleText(GraphicsContext*, const TextRun&, const FloatPoint&, const FloatRect& textRect, int from, int to) const;
+    void drawEmphasisMarksForSimpleText(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, const FloatRect& textRect, int from, int to) const;
+    void drawGlyphs(GraphicsContext*, const SimpleFontData*, const GlyphBuffer&, int from, int to, const FloatPoint&, const FloatRect& textRect) const;
+    void drawGlyphBuffer(GraphicsContext*, const TextRun&, const GlyphBuffer&, const FloatPoint&, const FloatRect& textRect) const;
+    void drawEmphasisMarks(GraphicsContext*, const TextRun&, const GlyphBuffer&, const AtomicString&, const FloatPoint&, const FloatRect& textRect) const;

[eseidel, 2013/04/18 21:04:38]

The rest of these arguments would benifit from clearer names.  Not that you need
to do that in this patch, just noting.

[alokp, 2013/04/18 22:22:37]

Will do in a separate patch.

     float floatWidthForSimpleText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
     int offsetForPositionForSimpleText(const TextRun&, float position, bool includePartialGlyphs) const;
     FloatRect selectionRectForSimpleText(const TextRun&, const FloatPoint&, int h, int from, int to) const;
 
     bool getEmphasisMarkGlyphData(const AtomicString&, GlyphData&) const;
 
     static bool canReturnFallbackFontsForComplexText();
     static bool canExpandAroundIdeographsInComplexText();
 
     // Returns the initial in-stream advance.
     float getGlyphsAndAdvancesForComplexText(const TextRun&, int from, int to, GlyphBuffer&, ForTextEmphasisOrNot = NotForTextEmphasis) const;
-    void drawComplexText(GraphicsContext*, const TextRun&, const FloatPoint&, int from, int to) const;
-    void drawEmphasisMarksForComplexText(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, int from, int to) const;
+    void drawComplexText(GraphicsContext*, const TextRun&, const FloatPoint&, const FloatRect& textRect, int from, int to) const;
+    void drawEmphasisMarksForComplexText(GraphicsContext*, const TextRun&, const AtomicString& mark, const FloatPoint&, const FloatRect& textRect, int from, int to) const;
     float floatWidthForComplexText(const TextRun&, HashSet<const SimpleFontData*>* fallbackFonts = 0, GlyphOverflow* = 0) 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 WidthIterator;
     friend class SVGTextRunRenderingContext;
 
 public:
     // Useful for debugging the different font rendering code paths.
     static void setCodePath(CodePath);
@@ skipping 128 matching lines @@
 
 }
 
 namespace WTF {
 
 template <> void deleteOwnedPtr<WebCore::TextLayout>(WebCore::TextLayout*);
 
 }
 
 #endif