TextBlob: Start caching a text blob per InlineTextBox.

Source/core/rendering/InlineTextBox.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 45 matching lines @@
 #include "wtf/text/CString.h"
 #include "wtf/text/StringBuilder.h"
 
 #include <algorithm>
 
 namespace blink {
 
 struct SameSizeAsInlineTextBox : public InlineBox {
     unsigned variables[1];
     unsigned short variables2[2];
-    void* pointers[2];
+    void* pointers[3];
 };
 
 COMPILE_ASSERT(sizeof(InlineTextBox) == sizeof(SameSizeAsInlineTextBox), InlineTextBox_should_stay_small);
 
 typedef WTF::HashMap<const InlineTextBox*, LayoutRect> InlineTextBoxOverflowMap;
 static InlineTextBoxOverflowMap* gTextBoxesWithOverflow;
 
 static const int misspellingLineThickness = 3;
 
 void InlineTextBox::destroy()
 {
     AbstractInlineTextBox::willDestroy(this);
 
     if (!knownToHaveNoOverflow() && gTextBoxesWithOverflow)
         gTextBoxesWithOverflow->remove(this);
     InlineBox::destroy();
 }
 
 void InlineTextBox::markDirty()

[f(malita), 2014/09/16 00:18:29]

Do we need to invalidate the cache on markDirty()?

[jbroman, 2014/09/17 22:25:37]

I don't believe that we can actually paint a dirty InlineTextBox, but I'm not
certain. I'll invalidate to be safe, and leave a FIXME.

[leviw_travelin_and_unemployed, 2014/09/19 00:26:14]

Just to be clear: we should *never* paint a dirty InlineTextBox.

 {
     m_len = 0;
     m_start = 0;
     InlineBox::markDirty();
 }
 
 LayoutRect InlineTextBox::logicalOverflowRect() const
 {
     if (knownToHaveNoOverflow() || !gTextBoxesWithOverflow)
         return enclosingIntRect(logicalFrameRect());
@@ skipping 485 matching lines @@
         textPainter.setCombinedText(combinedText);
 
     if (!paintSelectedTextOnly) {
         // FIXME: Truncate right-to-left text correctly.
         int startOffset = 0;
         int endOffset = length;
         if (paintSelectedTextSeparately && selectionStart < selectionEnd) {
             startOffset = selectionEnd;
             endOffset = selectionStart;
         }
-        textPainter.paint(startOffset, endOffset, length, textStyle);
+        bool textBlobIsCacheable = RuntimeEnabledFeatures::textBlobEnabled() && startOffset == 0 && endOffset == length;
+        textPainter.paint(startOffset, endOffset, length, textStyle, textBlobIsCacheable ? &m_textBlobCache : 0);
     }
 
     if ((paintSelectedTextOnly || paintSelectedTextSeparately) && selectionStart < selectionEnd) {
         // paint only the text that is selected
         textPainter.paint(selectionStart, selectionEnd, length, selectionStyle);
     }
 
     // Paint decorations
     TextDecoration textDecorations = styleToUse->textDecorationsInEffect();
     if (textDecorations != TextDecorationNone && !paintSelectedTextOnly) {
@@ skipping 767 matching lines @@
     printedCharacters = fprintf(stderr, "\t%s %p", obj.renderName(), &obj);
     const int rendererCharacterOffset = 24;
     for (; printedCharacters < rendererCharacterOffset; printedCharacters++)
         fputc(' ', stderr);
     fprintf(stderr, "(%d,%d) \"%s\"\n", start(), start() + len(), value.utf8().data());
 }
 
 #endif
 
 } // namespace blink