Update SVG text layout to use shaped glyph data & go fast (O(n^2)->O(n))

third_party/WebKit/Source/platform/fonts/Font.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (c) 2007, 2008, 2010 Google 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
@@ skipping 734 matching lines @@
 
 // Return the rectangle for selecting the given range of code-points in the TextRun.
 FloatRect Font::selectionRectForComplexText(const TextRun& run,
     const FloatPoint& point, int height, int from, int to) const
 {
     CachingWordShaper shaper(m_fontFallbackList->shapeCache(m_fontDescription));
     CharacterRange range = shaper.getCharacterRange(this, run, from, to);
     return FloatRect(point.x() + range.start, point.y(), range.width(), height);
 }
 
+Vector<CharacterRange> Font::individualCharacterRanges(const TextRun& run,
+    int from, int to) const
+{
+    // TODO(pdr): Android is temporarily (crbug.com/577306) using the old simple
+    // shaper and using the complex shaper here can show differences between
+    // the two shapers. This function is currently only called through SVG
+    // which now exclusively uses the complex shaper, so the primary difference
+    // will be improved shaping in SVG when compared to HTML.
+    FontCachePurgePreventer purgePreventer;
+    CachingWordShaper shaper(m_fontFallbackList->shapeCache(m_fontDescription));
+    return shaper.individualCharacterRanges(this, run, from, to);
+}
+
 float Font::floatWidthForSimpleText(const TextRun& run, HashSet<const SimpleFontData*>* fallbackFonts, FloatRect* glyphBounds) const
 {
     SimpleShaper shaper(this, run, nullptr, fallbackFonts, glyphBounds);
     shaper.advance(run.length());
     return shaper.runWidthSoFar();
 }
 
 FloatRect Font::selectionRectForSimpleText(const TextRun& run, const FloatPoint& point, int h, int from, int to, bool accountForGlyphBounds) const
 {
     FloatRect bounds;
@@ skipping 64 matching lines @@
 {
     return m_fontFallbackList && m_fontFallbackList->loadingCustomFonts();
 }
 
 bool Font::isFallbackValid() const
 {
     return !m_fontFallbackList || m_fontFallbackList->isValid();
 }
 
 } // namespace blink