Use unicode-range to prevent unnecessary @font-face donwnloads

Source/core/platform/graphics/SimpleFontData.h

 /*
  * This file is part of the internal font implementation.
  *
  * Copyright (C) 2006, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007-2008 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 29 matching lines @@
 #include "wtf/PassOwnPtr.h"
 #include "wtf/text/StringHash.h"
 #include "wtf/UnusedParam.h"
 
 #if OS(DARWIN)
 #include "wtf/RetainPtr.h"
 #endif
 
 namespace WebCore {
 
+class CSSFontFaceSource;
 class FontDescription;
 class SharedBuffer;
 struct WidthIterator;
 
 enum FontDataVariant { AutoVariant, NormalVariant, SmallCapsVariant, EmphasisMarkVariant, BrokenIdeographVariant };
 enum Pitch { UnknownPitch, FixedPitch, VariablePitch };
 
 class SimpleFontData : public FontData {
 public:
     class AdditionalFontData {
         WTF_MAKE_FAST_ALLOCATED;
     public:
         virtual ~AdditionalFontData() { }
 
         virtual void initializeFontData(SimpleFontData*, float fontSize) = 0;
         virtual float widthForSVGGlyph(Glyph, float fontSize) const = 0;
         virtual bool fillSVGGlyphPage(GlyphPage*, unsigned offset, unsigned length, UChar* buffer, unsigned bufferLength, const SimpleFontData*) const = 0;
         virtual bool applySVGGlyphSelection(WidthIterator&, GlyphData&, bool mirror, int currentCharacter, unsigned& advanceLength) const = 0;
     };
 
     // Used to create platform fonts.
-    static PassRefPtr<SimpleFontData> create(const FontPlatformData& platformData, bool isCustomFont = false, bool isLoading = false, bool isTextOrientationFallback = false)
+    static PassRefPtr<SimpleFontData> create(const FontPlatformData& platformData, bool isCustomFont = false, bool isLoadingFallback = false, bool isTextOrientationFallback = false)
     {
-        return adoptRef(new SimpleFontData(platformData, isCustomFont, isLoading, isTextOrientationFallback));
+        return adoptRef(new SimpleFontData(platformData, isCustomFont, isLoadingFallback, isTextOrientationFallback));
     }
 
     // Used to create SVG Fonts.
     static PassRefPtr<SimpleFontData> create(PassOwnPtr<AdditionalFontData> fontData, float fontSize, bool syntheticBold, bool syntheticItalic)
     {
         return adoptRef(new SimpleFontData(fontData, fontSize, syntheticBold, syntheticItalic));
     }
 
     virtual ~SimpleFontData();
 
@@ skipping 65 matching lines @@
     virtual const SimpleFontData* fontDataForCharacter(UChar32) const;
     virtual bool containsCharacters(const UChar*, int length) const;
 
     Glyph glyphForCharacter(UChar32) const;
 
     void determinePitch();
     Pitch pitch() const { return m_treatAsFixedPitch ? FixedPitch : VariablePitch; }
 
     AdditionalFontData* fontData() const { return m_fontData.get(); }
     bool isSVGFont() const { return m_fontData; }
+    bool isLoadingFallback() const { return m_isLoadingFallback; }
 
     virtual bool isCustomFont() const { return m_isCustomFont; }
-    virtual bool isLoading() const { return m_isLoading; }
+    virtual bool isLoading() const { return m_isLoadingFallback && m_isUsed; }
     virtual bool isSegmented() const;
 
     const GlyphData& missingGlyphData() const { return m_missingGlyphData; }
     void setMissingGlyphData(const GlyphData& glyphData) { m_missingGlyphData = glyphData; }
 
+    void beginLoadIfNeeded() const;
+
 #ifndef NDEBUG
     virtual String description() const;
 #endif
 
 #if OS(DARWIN)
     const SimpleFontData* getCompositeFontReferenceFontData(NSFont *key) const;
     NSFont* getNSFont() const { return m_platformData.font(); }
 #endif
 
 #if OS(DARWIN)
     CFDictionaryRef getCFStringAttributes(TypesettingFeatures, FontOrientation) const;
 #endif
 
 #if OS(DARWIN) || USE(HARFBUZZ)
     bool canRenderCombiningCharacterSequence(const UChar*, size_t) const;
 #endif
 
     bool applyTransforms(GlyphBufferGlyph* glyphs, GlyphBufferAdvance* advances, size_t glyphCount, TypesettingFeatures typesettingFeatures) const
     {
         UNUSED_PARAM(glyphs);
         UNUSED_PARAM(advances);
         UNUSED_PARAM(glyphCount);
         UNUSED_PARAM(typesettingFeatures);
         return false;
     }
 
+    void setCSSFontFaceSource(CSSFontFaceSource* source) { m_fontFaceSource = source; }
+    void clearCSSFontFaceSource() { m_fontFaceSource = 0; }
+
 private:
-    SimpleFontData(const FontPlatformData&, bool isCustomFont = false, bool isLoading = false, bool isTextOrientationFallback = false);
+    SimpleFontData(const FontPlatformData&, bool isCustomFont = false, bool isLoadingFallback = false, bool isTextOrientationFallback = false);
 
     SimpleFontData(PassOwnPtr<AdditionalFontData> , float fontSize, bool syntheticBold, bool syntheticItalic);
 
     void platformInit();
     void platformGlyphInit();
     void platformCharWidthInit();
     void platformDestroy();
 
     void initCharWidths();
 
     PassRefPtr<SimpleFontData> createScaledFontData(const FontDescription&, float scaleFactor) const;
     PassRefPtr<SimpleFontData> platformCreateScaledFontData(const FontDescription&, float scaleFactor) const;
 
     FontMetrics m_fontMetrics;
     float m_maxCharWidth;
     float m_avgCharWidth;
 
     FontPlatformData m_platformData;
     OwnPtr<AdditionalFontData> m_fontData;
 
     mutable OwnPtr<GlyphMetricsMap<FloatRect> > m_glyphToBoundsMap;
     mutable GlyphMetricsMap<float> m_glyphToWidthMap;
 
     bool m_treatAsFixedPitch;
     bool m_isCustomFont;  // Whether or not we are custom font loaded via @font-face
-    bool m_isLoading; // Whether or not this custom font is still in the act of loading.
+    bool m_isLoadingFallback; // Whether or not this is a temporary font data for a custom font which is not yet loaded.
 
     bool m_isTextOrientationFallback;
     bool m_isBrokenIdeographFallback;
 #if ENABLE(OPENTYPE_VERTICAL)
     RefPtr<OpenTypeVerticalData> m_verticalData;
 #endif
     bool m_hasVerticalGlyphs;
 
     Glyph m_spaceGlyph;
     float m_spaceWidth;
@@ skipping 20 matching lines @@
 
     private:
         DerivedFontData(bool custom)
             : forCustomFont(custom)
         {
         }
     };
 
     mutable OwnPtr<DerivedFontData> m_derivedFontData;
 
+    mutable bool m_isUsed;

[eseidel, 2013/09/10 15:07:26]

I see.  Normally we don't have non-used SimpleFontDatas, but I guess we can for
custom fonts?  I wonder if we should have some sort of subclass of
SimpleFontData in that case.

Alternatively we shoudl consider moving all of the custom-font related memebers
into a helper object which is held by SimpleFontData.  Then it would be clear
that they're ignored by non-custom fonts.

m_customFontData.isUsed
m_customFontData.fontFaceSource
m_customFontData.isLoadingFallback

etc.

We could possibly even make this an OwnPtr to reduce the size of SimpleFontData.
 I think we only have a few hundred SimpleFontData objects per renderer, so I
doubt it matters too much.

[Kunihiko Sakamoto, 2013/09/11 13:28:09]

Thanks for the suggestion. Moved these fields to a helper object.

+    CSSFontFaceSource* m_fontFaceSource;
+
 #if OS(DARWIN)
     float m_syntheticBoldOffset;
 
     mutable HashMap<unsigned, RetainPtr<CFDictionaryRef> > m_CFStringAttributes;
 #endif
 
 #if OS(DARWIN) || USE(HARFBUZZ)
     mutable OwnPtr<HashMap<String, bool> > m_combiningCharacterSequenceSupport;
 #endif
 };
@@ skipping 38 matching lines @@
 #endif
     else
         width = platformWidthForGlyph(glyph);
 
     m_glyphToWidthMap.setMetricsForGlyph(glyph, width);
     return width;
 }
 
 } // namespace WebCore
 #endif // SimpleFontData_h