(CANCELED) Improve performance of large option list with CJK text

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 221 matching lines @@
 
 float Font::width(const TextRun& run, HashSet<const SimpleFontData*>* fallbackFonts, FloatRect* glyphBounds) const
 {
     FontCachePurgePreventer purgePreventer;
 
     if (codePath(TextRunPaintInfo(run)) == ComplexPath)
         return floatWidthForComplexText(run, fallbackFonts, glyphBounds);
     return floatWidthForSimpleText(run, fallbackFonts, glyphBounds);
 }
 
+float Font::widthForUnbrokenRun(const TextRun& run) const
+{
+    if (run.length() <= 1 || run.is8Bit())
+        return width(run);
+
+    float totalWidth = 0;
+    const unsigned length = run.length();
+    for (unsigned startIndex = 0; startIndex < length; ) {
+        UChar32 ch;
+        unsigned endIndex = startIndex;
+        U16_NEXT(run.characters16(), endIndex, length, ch);
+        if (Character::isCJKIdeographOrSymbol(ch)) {
+            // For scripts that do not delimit words by spaces, split each
+            // character so that input text matches to what the line breaker
+            // requests. This improves the cache efficiency in
+            // CachingWordShaper.
+            for (unsigned i = endIndex; i < length; endIndex = i) {
+                U16_NEXT(run.characters16(), i, length, ch);
+                if (!(U_GET_GC_MASK(ch) & U_GC_M_MASK))
+                    break;
+            }
+        } else {
+            // For scripts that delimit words by spaces, let CachingWordShaper
+            // handle words.
+            for (unsigned i = endIndex; i < length; endIndex = i) {
+                U16_NEXT(run.characters16(), i, length, ch);
+                if (Character::isCJKIdeographOrSymbol(ch))
+                    break;
+            }
+        }
+        if (!startIndex && endIndex == length)
+            return width(run);
+        TextRun subRun = run.subRun(startIndex, endIndex - startIndex);
+        totalWidth += width(subRun);
+        startIndex = endIndex;
+    }
+    return totalWidth;
+}
+
 PassTextBlobPtr Font::buildTextBlob(const GlyphBuffer& glyphBuffer) const
 {
     SkTextBlobBuilder builder;
     bool hasVerticalOffsets = glyphBuffer.hasVerticalOffsets();
 
     unsigned i = 0;
     while (i < glyphBuffer.size()) {
         const SimpleFontData* fontData = glyphBuffer.fontDataAt(i);
 
         // FIXME: Handle vertical text.
@@ skipping 582 matching lines @@
 {
     return m_fontFallbackList && m_fontFallbackList->loadingCustomFonts();
 }
 
 bool Font::isFallbackValid() const
 {
     return !m_fontFallbackList || m_fontFallbackList->isValid();
 }
 
 } // namespace blink