blink fonts: Load Android SkFontMgr on Linux.

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

 /*
  * Copyright (c) 2006, 2007, 2008, 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "SkFontMgr.h"
 #include "SkStream.h"
 #include "SkTypeface.h"
+#include "platform/Language.h"
 #include "platform/fonts/AlternateFontFamily.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontDescription.h"
 #include "platform/fonts/FontFaceCreationParams.h"
 #include "platform/fonts/SimpleFontData.h"
 #include "public/platform/Platform.h"
 #include "public/platform/linux/WebSandboxSupport.h"
 #include "wtf/Assertions.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/CString.h"
@@ skipping 36 matching lines @@
     SkAutoTUnref<SkFontConfigInterface> fci(SkFontConfigInterface::RefGlobal());
     SkFontConfigInterface::FontIdentity fontIdentity;
     fontIdentity.fID = fontconfigInterfaceId;
     fontIdentity.fTTCIndex = ttcIndex;
     return adoptRef(fci->createTypeface(fontIdentity));
 }
 #endif
 
 namespace blink {
 
+// 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)
+{
+    ASSERT(fm);
+
+    const char* bcp47Locales[2];
+    int localeCount = 0;
+    CString defaultLocale = toSkFontMgrLocale(defaultLanguage());
+    bcp47Locales[localeCount++] = defaultLocale.data();
+    CString fontLocale;
+    if (!fontDescription.locale().isEmpty()) {
+        fontLocale = toSkFontMgrLocale(fontDescription.locale());
+        bcp47Locales[localeCount++] = fontLocale.data();
+    }
+    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()
 {
 }
 
 PassRefPtr<SimpleFontData> FontCache::fallbackOnStandardFontStyle(
     const FontDescription& fontDescription, UChar32 character)
 {
     FontDescription substituteDescription(fontDescription);
     substituteDescription.setStyle(FontStyleNormal);
     substituteDescription.setWeight(FontWeightNormal);
@@ skipping 120 matching lines @@
     }
 
     if (m_fontManager) {
         return adoptRef(useDirectWrite()
             ? m_fontManager->matchFamilyStyle(name.data(), fontStyle(fontDescription))
             : m_fontManager->legacyCreateTypeface(name.data(), style)
             );
     }
 #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->legacyCreateTypeface(name.data(), style));

[bungeman-chromium, 2016/02/29 22:48:50]

This is a little bit sneaky, but I think this should instead be

m_fontManager->matchFamilyStyle(name.data(), fontStyle(fontDescription))

It appears that legacyCreateTypeface was chosen here to mirror what
CreateFromName below would do. However, there is no real need to be limited that
way. By using matchFamilyStyle you should get better weight selection (and
probably better fallback).

The CreateFromName call below eventually should be a call to matchFamilyStyle on
the default font manager (and I think this is now possible, I'll have to see
what changes).

[Khushal, 2016/03/01 18:52:43]

You're right, I was trying to be consistent with the other uses of font manager
but I guess its not necessary. The legacyCreateTypeface for the
SkFontMgr_android currently routes the call to matchFamilyStyle itself so there
is no need to have this indirection. The SkFontHost_fontconfig implementation
though returns null for matchFamilyStyle and we have to use
legacyCreateTypeface.

+#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)));
 }
 
 #if !OS(WIN)
 PassOwnPtr<FontPlatformData> FontCache::createFontPlatformData(const FontDescription& fontDescription,
     const FontFaceCreationParams& creationParams, float fontSize)
 {
     CString name;
     RefPtr<SkTypeface> tf(createTypeface(fontDescription, creationParams, name));
     if (!tf)
         return nullptr;
 
     return adoptPtr(new FontPlatformData(tf,
         name.data(),
         fontSize,
         (fontDescription.weight() >= FontWeight600 && !tf->isBold()) || fontDescription.isSyntheticBold(),
         ((fontDescription.style() == FontStyleItalic || fontDescription.style() == FontStyleOblique) && !tf->isItalic()) || fontDescription.isSyntheticItalic(),
         fontDescription.orientation(),
         fontDescription.useSubpixelPositioning()));
 }
 #endif // !OS(WIN)
 
 } // namespace blink