Pass DOM locale to Skia in FontCache::getFontDataForCharacter

Source/core/platform/graphics/FontCache.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 47 matching lines @@
 FontCache::FontCache()
     : m_purgePreventCount(0)
 {
 }
 #endif // !OS(WIN) || ENABLE(GDI_FONTS_ON_WINDOWS)
 
 struct FontPlatformDataCacheKey {
     WTF_MAKE_FAST_ALLOCATED;
 public:
     FontPlatformDataCacheKey(const AtomicString& family = AtomicString(), float size = 0, unsigned weight = 0, bool italic = false,
-        bool isPrinterFont = false, FontOrientation orientation = Horizontal, FontWidthVariant widthVariant = RegularWidth)
+        bool isPrinterFont = false, FontOrientation orientation = Horizontal, FontWidthVariant widthVariant = RegularWidth,
+        const AtomicString& locale = AtomicString())
         : m_size(size * s_fontSizePrecisionMultiplier)
         , m_weight(weight)
         , m_family(family)
         , m_italic(italic)
         , m_printerFont(isPrinterFont)
         , m_orientation(orientation)
         , m_widthVariant(widthVariant)
+        , m_locale(locale)
     {
     }
 
     FontPlatformDataCacheKey(HashTableDeletedValueType) : m_size(hashTableDeletedSize()) { }
     bool isHashTableDeletedValue() const { return m_size == hashTableDeletedSize(); }
 
     bool operator==(const FontPlatformDataCacheKey& other) const
     {
         return equalIgnoringCase(m_family, other.m_family) && m_size == other.m_size
             && m_weight == other.m_weight && m_italic == other.m_italic && m_printerFont == other.m_printerFont
-            && m_orientation == other.m_orientation && m_widthVariant == other.m_widthVariant;
+            && m_orientation == other.m_orientation && m_widthVariant == other.m_widthVariant
+            && m_locale == other.m_locale;
     }
 
     unsigned m_size;
     unsigned m_weight;
     AtomicString m_family;
     bool m_italic;
     bool m_printerFont;
     FontOrientation m_orientation;
     FontWidthVariant m_widthVariant;
+    // Only set for platforms (e.g. Android) that FontCache::getFontDataForCharacter() may return different FontData
+    // for different locales of FontDescriptions.

[falken, 2013/09/25 08:11:51]

So eventually all platforms will want this? It seems we should do DOM-level
language based font fallback everywhere.

+    AtomicString m_locale;

[eseidel, 2013/09/25 15:51:13]

So WebKit doesn't seem to key based on locale.  I'm curious how they handle
these fonts correctly?  Do they?

 
 private:
     // Multiplying the floating point size by 100 gives two decimal
     // point precision which should be sufficient.
     static const unsigned s_fontSizePrecisionMultiplier = 100;
 
     static unsigned hashTableDeletedSize() { return 0xFFFFFFFFU; }
 };
 
 inline unsigned computeHash(const FontPlatformDataCacheKey& fontKey)

[eseidel, 2013/09/25 15:49:52]

This is webkit's impl:
http://trac.webkit.org/browser/trunk/Source/WebCore/platform/graphics/FontCac...

It appears we've inlined the description bits:
http://trac.webkit.org/browser/trunk/Source/WebCore/platform/graphics/FontCac...

 {
-    unsigned hashCodes[5] = {
-        CaseFoldingHash::hash(fontKey.m_family),
+    unsigned hashCodes[6] = {
+        fontKey.m_family.isNull() ? 0 : CaseFoldingHash::hash(fontKey.m_family),
         fontKey.m_size,
         fontKey.m_weight,
         fontKey.m_widthVariant,
-        static_cast<unsigned>(fontKey.m_orientation) << 2 | static_cast<unsigned>(fontKey.m_italic) << 1 | static_cast<unsigned>(fontKey.m_printerFont)
+        static_cast<unsigned>(fontKey.m_orientation) << 2 | static_cast<unsigned>(fontKey.m_italic) << 1 | static_cast<unsigned>(fontKey.m_printerFont),
+        fontKey.m_locale.isNull() ? 0 : CaseFoldingHash::hash(fontKey.m_locale)
     };
     return StringHasher::hashMemory<sizeof(hashCodes)>(hashCodes);
 }
 
 struct FontPlatformDataCacheKeyHash {
     static unsigned hash(const FontPlatformDataCacheKey& font)
     {
         return computeHash(font);
     }
 
@@ skipping 77 matching lines @@
     if (!gFontPlatformDataCache) {
         gFontPlatformDataCache = new FontPlatformDataCache;
         platformInit();
     }
 
     float fontSize;
     if (RuntimeEnabledFeatures::subpixelFontScalingEnabled())
         fontSize = fontDescription.computedSize();
     else
         fontSize = fontDescription.computedPixelSize();
+
     FontPlatformDataCacheKey key(familyName, fontSize, fontDescription.weight(), fontDescription.italic(),
-
-        fontDescription.usePrinterFont(), fontDescription.orientation(), fontDescription.widthVariant());
+        fontDescription.usePrinterFont(), fontDescription.orientation(), fontDescription.widthVariant(),
+#if OS(ANDROID)
+        // On Android FontPlatformData from different locales need to be distinguished
+        // to avoid conflict of glyphs from different locale-perferred fallback fonts.

[falken, 2013/09/25 08:11:51]

s/perferred/preferred

I think comment can use elaboration. Why is it an issue on Android and not other
platforms? Is it just a bug that we don't handle other platforms yet?

+        fontDescription.locale());
+#else
+        AtomicString());
+#endif
     FontPlatformData* result = 0;
     bool foundResult;
     FontPlatformDataCache::iterator it = gFontPlatformDataCache->find(key);
     if (it == gFontPlatformDataCache->end()) {
         result = createFontPlatformData(fontDescription, familyName);
         gFontPlatformDataCache->set(key, result);
         foundResult = result;
     } else {
         result = it->value;
         foundResult = true;
@@ skipping 367 matching lines @@
     case FontDescription::SansSerifFamily:
     default:
         fontPlatformData = getFontResourcePlatformData(description, sansStr);
         break;
     }
 
     return fontPlatformData;
 }
 
 } // namespace WebCore