Track the region where text is painted.

Source/core/platform/graphics/FontFastPath.cpp

 /**
  * Copyright (C) 2003, 2006, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  * Copyright (C) 2009 Torch Mobile, Inc.
  *
  * 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 425 matching lines @@
         initialAdvance = finalRoundingWidth + it.m_runWidthSoFar - afterWidth;
     } else
         initialAdvance = beforeWidth;
 
     if (run.rtl())
         glyphBuffer.reverse(0, glyphBuffer.size());
 
     return initialAdvance;
 }
 
-void Font::drawSimpleText(GraphicsContext* context, const TextRun& run, const FloatPoint& point, int from, int to) const
+void Font::drawSimpleText(GraphicsContext* context, const TextRun& run, const FloatPoint& point, const FloatRect& textRect, int from, int to) const
 {
     // This glyph buffer holds our glyphs+advances+font data for each glyph.
     GlyphBuffer glyphBuffer;
 
     float startX = point.x() + getGlyphsAndAdvancesForSimpleText(run, from, to, glyphBuffer);
 
     if (glyphBuffer.isEmpty())
         return;
 
     FloatPoint startPoint(startX, point.y());
-    drawGlyphBuffer(context, run, glyphBuffer, startPoint);
+    drawGlyphBuffer(context, run, glyphBuffer, startPoint, textRect);
 }
 
-void Font::drawEmphasisMarksForSimpleText(GraphicsContext* context, const TextRun& run, const AtomicString& mark, const FloatPoint& point, int from, int to) const
+void Font::drawEmphasisMarksForSimpleText(GraphicsContext* context, const TextRun& run, const AtomicString& mark, const FloatPoint& point, const FloatRect& textRect, int from, int to) const
 {
     GlyphBuffer glyphBuffer;
     float initialAdvance = getGlyphsAndAdvancesForSimpleText(run, from, to, glyphBuffer, ForTextEmphasis);
 
     if (glyphBuffer.isEmpty())
         return;
 
-    drawEmphasisMarks(context, run, glyphBuffer, mark, FloatPoint(point.x() + initialAdvance, point.y()));
+    drawEmphasisMarks(context, run, glyphBuffer, mark, FloatPoint(point.x() + initialAdvance, point.y()), textRect);
 }
 
-void Font::drawGlyphBuffer(GraphicsContext* context, const TextRun& run, const GlyphBuffer& glyphBuffer, const FloatPoint& point) const
+void Font::drawGlyphBuffer(GraphicsContext* context, const TextRun& run, const GlyphBuffer& glyphBuffer, const FloatPoint& point, const FloatRect& textRect) const
 {   
 #if !ENABLE(SVG_FONTS)
     UNUSED_PARAM(run);
 #endif
 
     // Draw each contiguous run of glyphs that use the same font data.
     const SimpleFontData* fontData = glyphBuffer.fontDataAt(0);
     FloatSize offset = glyphBuffer.offsetAt(0);
     FloatPoint startPoint(point);
     float nextX = startPoint.x() + glyphBuffer.advanceAt(0);
     int lastFrom = 0;
     int nextGlyph = 1;
 #if ENABLE(SVG_FONTS)
     TextRun::RenderingContext* renderingContext = run.renderingContext();
 #endif
     while (nextGlyph < glyphBuffer.size()) {
         const SimpleFontData* nextFontData = glyphBuffer.fontDataAt(nextGlyph);
         FloatSize nextOffset = glyphBuffer.offsetAt(nextGlyph);
 
         if (nextFontData != fontData || nextOffset != offset) {
 #if ENABLE(SVG_FONTS)
             if (renderingContext && fontData->isSVGFont())
                 renderingContext->drawSVGGlyphs(context, run, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint);
             else
 #endif
-                drawGlyphs(context, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint);
+                drawGlyphs(context, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint, textRect);
 
             lastFrom = nextGlyph;
             fontData = nextFontData;
             offset = nextOffset;
             startPoint.setX(nextX);
         }
         nextX += glyphBuffer.advanceAt(nextGlyph);
         nextGlyph++;
     }
 
 #if ENABLE(SVG_FONTS)
     if (renderingContext && fontData->isSVGFont())
         renderingContext->drawSVGGlyphs(context, run, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint);
     else
 #endif
-        drawGlyphs(context, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint);
+        drawGlyphs(context, fontData, glyphBuffer, lastFrom, nextGlyph - lastFrom, startPoint, textRect);
 }
 
 inline static float offsetToMiddleOfGlyph(const SimpleFontData* fontData, Glyph glyph)
 {
     if (fontData->platformData().orientation() == Horizontal) {
         FloatRect bounds = fontData->boundsForGlyph(glyph);
         return bounds.x() + bounds.width() / 2;
     }
     // FIXME: Use glyph bounds once they make sense for vertical fonts.
     return fontData->widthForGlyph(glyph) / 2;
 }
 
 inline static float offsetToMiddleOfGlyphAtIndex(const GlyphBuffer& glyphBuffer, size_t i)
 {
     return offsetToMiddleOfGlyph(glyphBuffer.fontDataAt(i), glyphBuffer.glyphAt(i));
 }
 
-void Font::drawEmphasisMarks(GraphicsContext* context, const TextRun& run, const GlyphBuffer& glyphBuffer, const AtomicString& mark, const FloatPoint& point) const
+void Font::drawEmphasisMarks(GraphicsContext* context, const TextRun& run, const GlyphBuffer& glyphBuffer, const AtomicString& mark, const FloatPoint& point, const FloatRect& textRect) const
 {
     FontCachePurgePreventer purgePreventer;
     
     GlyphData markGlyphData;
     if (!getEmphasisMarkGlyphData(mark, markGlyphData))
         return;
 
     const SimpleFontData* markFontData = markGlyphData.fontData;
     ASSERT(markFontData);
     if (!markFontData)
         return;
 
     Glyph markGlyph = markGlyphData.glyph;
     Glyph spaceGlyph = markFontData->spaceGlyph();
 
     float middleOfLastGlyph = offsetToMiddleOfGlyphAtIndex(glyphBuffer, 0);
     FloatPoint startPoint(point.x() + middleOfLastGlyph - offsetToMiddleOfGlyph(markFontData, markGlyph), point.y());
 
     GlyphBuffer markBuffer;
     for (int i = 0; i + 1 < glyphBuffer.size(); ++i) {
         float middleOfNextGlyph = offsetToMiddleOfGlyphAtIndex(glyphBuffer, i + 1);
         float advance = glyphBuffer.advanceAt(i) - middleOfLastGlyph + middleOfNextGlyph;
         markBuffer.add(glyphBuffer.glyphAt(i) ? markGlyph : spaceGlyph, markFontData, advance);
         middleOfLastGlyph = middleOfNextGlyph;
     }
     markBuffer.add(glyphBuffer.glyphAt(glyphBuffer.size() - 1) ? markGlyph : spaceGlyph, markFontData, 0);
 
-    drawGlyphBuffer(context, run, markBuffer, startPoint);
+    drawGlyphBuffer(context, run, markBuffer, startPoint, textRect);
 }
 
 float Font::floatWidthForSimpleText(const TextRun& run, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
 {
     WidthIterator it(this, run, fallbackFonts, glyphOverflow);
     GlyphBuffer glyphBuffer;
     it.advance(run.length(), (typesettingFeatures() & (Kerning | Ligatures)) ? &glyphBuffer : 0);
 
     if (glyphOverflow) {
         glyphOverflow->top = max<int>(glyphOverflow->top, ceilf(-it.minGlyphBoundingBoxY()) - (glyphOverflow->computeBounds ? 0 : fontMetrics().ascent()));
@@ skipping 61 matching lines @@
                 if (delta <= 0)
                     break;
             }
         }
     }
 
     return offset;
 }
 
 }