blink fonts: Load Android SkFontMgr on Linux.

third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp

Index: third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp b/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
index b0acb93ae827f9027dc7e10cd064062910bb43ba..ab4dd06b3666ebc22fc6a23ed1cd6d95b9423d1b 100644
--- a/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
+++ b/third_party/WebKit/Source/platform/fonts/skia/FontCacheSkia.cpp
@@ -31,6 +31,8 @@
 #include "SkFontMgr.h"
 #include "SkStream.h"
 #include "SkTypeface.h"
+#include "platform/Language.h"
+#include "platform/fonts/AcceptLanguagesResolver.h"
 #include "platform/fonts/AlternateFontFamily.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontDescription.h"
@@ -58,6 +60,64 @@ static PassRefPtr<SkTypeface> typefaceForFontconfigInterfaceIdAndTtcIndex(int fo
 
 namespace blink {
 
+// Android special locale for retrieving the color emoji font
+// based on the proposed changes in UTR #51 for introducing
+// an Emoji script code:
+// http://www.unicode.org/reports/tr51/proposed.html#Emoji_Script
+static const char* kAndroidColorEmojiLocale = "und-Zsye";
+
+// SkFontMgr requires script-based locale names, like "zh-Hant" and "zh-Hans",
+// instead of "zh-CN" and "zh-TW".
+static CString toSkFontMgrLocale(const String& locale)
+{
+    if (!locale.startsWith("zh", TextCaseInsensitive))
+        return locale.ascii();
+
+    switch (localeToScriptCodeForFontSelection(locale)) {
+    case USCRIPT_SIMPLIFIED_HAN:
+        return "zh-Hans";
+    case USCRIPT_TRADITIONAL_HAN:
+        return "zh-Hant";
+    default:
+        return locale.ascii();
+    }
+}
+
+#if OS(ANDROID) || OS(LINUX)
+// This function is called on android or when we are emulating android fonts on linux and the
+// embedder has overriden the default fontManager with WebFontRendering::setSkiaFontMgr.
+// static
+AtomicString FontCache::getFamilyNameForCharacter(SkFontMgr* fm, UChar32 c, const FontDescription& fontDescription, FontFallbackPriority fallbackPriority)
+{
+    ASSERT(fm);
+
+    const size_t kMaxLocales = 4;
+    const char* bcp47Locales[kMaxLocales];
+    size_t localeCount = 0;
+
+    if (fallbackPriority == FontFallbackPriority::EmojiEmoji) {
+        bcp47Locales[localeCount++] = kAndroidColorEmojiLocale;
+    }
+    if (const char* hanLocale = AcceptLanguagesResolver::preferredHanSkFontMgrLocale())
+        bcp47Locales[localeCount++] = hanLocale;
+    CString defaultLocale = toSkFontMgrLocale(defaultLanguage());
+    bcp47Locales[localeCount++] = defaultLocale.data();
+    CString fontLocale;
+    if (!fontDescription.locale().isEmpty()) {
+        fontLocale = toSkFontMgrLocale(fontDescription.locale());
+        bcp47Locales[localeCount++] = fontLocale.data();
+    }
+    ASSERT_WITH_SECURITY_IMPLICATION(localeCount < kMaxLocales);
+    RefPtr<SkTypeface> typeface = adoptRef(fm->matchFamilyStyleCharacter(0, SkFontStyle(), bcp47Locales, localeCount, c));
+    if (!typeface)
+        return emptyAtom;
+
+    SkString skiaFamilyName;
+    typeface->getFamilyName(&skiaFamilyName);
+    return skiaFamilyName.c_str();
+}
+#endif
+
 void FontCache::platformInit()
 {
 }
@@ -111,7 +171,7 @@ PassRefPtr<SimpleFontData> FontCache::getLastResortFallbackFont(const FontDescri
     return fontDataFromFontPlatformData(fontPlatformData, shouldRetain);
 }
 
-#if OS(WIN)
+#if OS(WIN) || OS(LINUX)
 static inline SkFontStyle fontStyle(const FontDescription& fontDescription)
 {
     int width = static_cast<int>(fontDescription.stretch());
@@ -172,6 +232,14 @@ PassRefPtr<SkTypeface> FontCache::createTypeface(const FontDescription& fontDesc
     }
 #endif
 
+#if OS(LINUX)
+    // On linux if the fontManager has been overridden then we should be calling the embedder
+    // provided font Manager rather than calling SkTypeface::CreateFromName which may redirect the
+    // call to the default font Manager.
+    if (m_fontManager)
+        return adoptRef(m_fontManager->matchFamilyStyle(name.data(), fontStyle(fontDescription)));
+#endif
+
     // FIXME: Use m_fontManager, SkFontStyle and matchFamilyStyle instead of
     // CreateFromName on all platforms.
     return adoptRef(SkTypeface::CreateFromName(name.data(), static_cast<SkTypeface::Style>(style)));