Avoid re-parsing of string in fillText and measureText in Canvas

Source/platform/fonts/WidthIterator.cpp

 /*
  * Copyright (C) 2003, 2006, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  * Copyright (C) 2014 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 51 matching lines @@
         if (isAfterExpansion && !m_run.allowsTrailingExpansion())
             expansionOpportunityCount--;
 
         if (!expansionOpportunityCount)
             m_expansionPerOpportunity = 0;
         else
             m_expansionPerOpportunity = m_expansion / expansionOpportunityCount;
     }
 }
 
-GlyphData WidthIterator::glyphDataForCharacter(CharacterData& charData)
+GlyphData WidthIterator::glyphDataForCharacter(CharacterData& charData, bool normalizeSpace)
 {
     ASSERT(m_font);
 
 #if ENABLE(SVG_FONTS)
     if (TextRun::RenderingContext* renderingContext = m_run.renderingContext()) {
         return renderingContext->glyphDataForCharacter(*m_font, m_run, *this, charData.character,
             m_run.rtl(), charData.characterOffset, charData.clusterLength);
     }
 #endif
 
-    return m_font->glyphDataForCharacter(charData.character, m_run.rtl());
+    return m_font->glyphDataForCharacter(charData.character, m_run.rtl(), normalizeSpace);
 }
 
 float WidthIterator::characterWidth(UChar32 character, const GlyphData& glyphData) const
 {
     const SimpleFontData* fontData = glyphData.fontData;
     ASSERT(fontData);
 
     if (UNLIKELY(character == '\t' && m_run.allowTabs()))
         return m_font->tabWidth(*fontData, m_run.tabSize(), m_run.xPos() + m_runWidthSoFar);
 
     float width = fontData->widthForGlyph(glyphData.glyph);
 
     // SVG uses horizontalGlyphStretch(), when textLength is used to stretch/squeeze text.
     if (UNLIKELY(m_run.horizontalGlyphStretch() != 1))
         width *= m_run.horizontalGlyphStretch();
 
     return width;
 }
 
-void WidthIterator::cacheFallbackFont(UChar32 character, const SimpleFontData* fontData,
+void WidthIterator::cacheFallbackFont(const SimpleFontData* fontData,
     const SimpleFontData* primaryFont)
 {
     if (fontData == primaryFont)
         return;
 
-    // FIXME: This does a little extra work that could be avoided if
-    // glyphDataForCharacter() returned whether it chose to use a small caps font.
-    if (m_font->fontDescription().variant() == FontVariantNormal || character == toUpper(character)) {
-        m_fallbackFonts->add(fontData);
-    } else {
-        ASSERT(m_font->fontDescription().variant() == FontVariantSmallCaps);
-        const GlyphData uppercaseGlyphData = m_font->glyphDataForCharacter(toUpper(character),
-            m_run.rtl());
-        if (uppercaseGlyphData.fontData != primaryFont)
-            m_fallbackFonts->add(uppercaseGlyphData.fontData);
-    }
+    m_fallbackFonts->add(fontData);
 }
 
 float WidthIterator::adjustSpacing(float width, const CharacterData& charData,
     const SimpleFontData& fontData, GlyphBuffer* glyphBuffer)
 {
     // Account for letter-spacing.
     if (width)
         width += m_font->fontDescription().letterSpacing();
 
     static bool expandAroundIdeographs = FontPlatformFeatures::canExpandAroundIdeographsInComplexText();
@@ skipping 55 matching lines @@
 }
 
 template <typename TextIterator>
 unsigned WidthIterator::advanceInternal(TextIterator& textIterator, GlyphBuffer* glyphBuffer)
 {
     bool hasExtraSpacing = (m_font->fontDescription().letterSpacing() || m_font->fontDescription().wordSpacing() || m_expansion)
         && !m_run.spacingDisabled();
 
     const SimpleFontData* primaryFont = m_font->primaryFont();
     const SimpleFontData* lastFontData = primaryFont;
+    bool normalizeSpace = m_run.normalizeSpace();
 
     CharacterData charData;
     while (textIterator.consume(charData.character, charData.clusterLength)) {
         charData.characterOffset = textIterator.currentCharacter();
 
-        const GlyphData glyphData = glyphDataForCharacter(charData);
+        const GlyphData glyphData = glyphDataForCharacter(charData, normalizeSpace);
         Glyph glyph = glyphData.glyph;
         const SimpleFontData* fontData = glyphData.fontData;
         ASSERT(fontData);
 
         // Now that we have a glyph and font data, get its width.
         float width = characterWidth(charData.character, glyphData);
 
         if (m_fallbackFonts && lastFontData != fontData && width) {
             lastFontData = fontData;
-            cacheFallbackFont(charData.character, fontData, primaryFont);
+            cacheFallbackFont(fontData, primaryFont);
         }
 
         if (hasExtraSpacing)
             width = adjustSpacing(width, charData, *fontData, glyphBuffer);
 
         if (m_accountForGlyphBounds)
             updateGlyphBounds(glyphData, width, !charData.characterOffset);
 
         if (m_forTextEmphasis && !Character::canReceiveTextEmphasis(charData.character))
             glyph = 0;
@@ skipping 36 matching lines @@
     float initialWidth = m_runWidthSoFar;
 
     if (!advance(m_currentCharacter + 1))
         return false;
 
     width = m_runWidthSoFar - initialWidth;
     return true;
 }
 
 } // namespace blink