Try last resort on no-match in platformFallbackForCharacter on Android

On Android, some locale-preferred fonts (e.g. DroidSansFallback.ttf for
Chinese locale) doesn't contain all characters that the default locale
system fonts contain.

For characters that is missing in the font, fallback to the default
locale system font, by calling getLastResortFallbackFont() in
FontCache::platformFallbackForCharacter().

Also modified getLastResortFallbackFont() to prefer Skia default font
instead of the hard-coded default font (sans) and to map also cursive
and fantasy generic families.

Combined similar code in FontCacheSkia.cpp.

BUG=347121
TEST=FontCacheAndroid.platformFallbackForCharacter (will be enabled in another CL)
R=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/185863007

git-svn-id: svn://svn.chromium.org/blink/trunk@168410 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/platform/fonts/AlternateFontFamily.h

@@ -106,18 +106,26 @@ inline const AtomicString& alternateFamilyName(const AtomicString& familyName)
 
 inline const AtomicString getFallbackFontFamily(const FontDescription& description)
 {
-    DEFINE_STATIC_LOCAL(const AtomicString, sansStr, ("Sans", AtomicString::ConstructFromLiteral));
-    DEFINE_STATIC_LOCAL(const AtomicString, serifStr, ("Serif", AtomicString::ConstructFromLiteral));
-    DEFINE_STATIC_LOCAL(const AtomicString, monospaceStr, ("Monospace", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, sansStr, ("sans-serif", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, serifStr, ("serif", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, monospaceStr, ("monospace", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, cursiveStr, ("cursive", AtomicString::ConstructFromLiteral));
+    DEFINE_STATIC_LOCAL(const AtomicString, fantasyStr, ("fantasy", AtomicString::ConstructFromLiteral));
 
     switch (description.genericFamily()) {
+    case FontDescription::SansSerifFamily:
+        return sansStr;
     case FontDescription::SerifFamily:
         return serifStr;
     case FontDescription::MonospaceFamily:
         return monospaceStr;
-    case FontDescription::SansSerifFamily:
+    case FontDescription::CursiveFamily:
+        return cursiveStr;
+    case FontDescription::FantasyFamily:
+        return fantasyStr;
     default:
-        return sansStr;
+        // Let the caller use the system default font.
+        return emptyAtom;
     }
 }
 

third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp

@@ -64,7 +64,8 @@ static AtomicString getFamilyNameForCharacter(UChar32 c, UScriptCode script)
 
     SkString skiaFamilyName;
     if (!SkGetFallbackFamilyNameForChar(c, locale, &skiaFamilyName) || skiaFamilyName.isEmpty())
-        return AtomicString();
+        return emptyAtom;
+
     return skiaFamilyName.c_str();
 }
 
@@ -72,7 +73,7 @@ PassRefPtr<SimpleFontData> FontCache::platformFallbackForCharacter(const FontDes
 {
     AtomicString familyName = getFamilyNameForCharacter(c, fontDescription.script());
     if (familyName.isEmpty())
-        return nullptr;
+        return getLastResortFallbackFont(fontDescription, DoNotRetain);
     return fontDataFromFontPlatformData(getFontPlatformData(fontDescription, familyName), DoNotRetain);
 }
 

third_party/WebKit/Source/platform/fonts/android/FontCacheAndroidTest.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "platform/fonts/FontCache.h"
+
+#include "platform/fonts/SimpleFontData.h"
+#include <gtest/gtest.h>
+
+namespace WebCore {
+
+TEST(FontCacheAndroid, platformFallbackForCharacter)
+{
+    // A Latin character in the common locale system font, but not in the
+    // Chinese locale-preferred font.
+    const UChar32 testChar = 228;
+
+    FontDescription fontDescription;
+    fontDescription.setScript(USCRIPT_SIMPLIFIED_HAN);
+    fontDescription.setGenericFamily(FontDescription::StandardFamily);
+
+    FontCache* fontCache = FontCache::fontCache();
+    ASSERT_TRUE(fontCache);
+    RefPtr<SimpleFontData> fontData = fontCache->platformFallbackForCharacter(fontDescription, testChar, 0);
+    EXPECT_TRUE(fontData);
+}
+
+} // namespace WebCore

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

@@ -86,7 +86,7 @@ PassRefPtr<SimpleFontData> FontCache::platformFallbackForCharacter(const FontDes
     return fontDataFromFontPlatformData(&platformData, DoNotRetain);
 }
 
-#endif // !OS(WINDOWNS) && !OS(ANDROID)
+#endif // !OS(WIN) && !OS(ANDROID)
 
 PassRefPtr<SimpleFontData> FontCache::getLastResortFallbackFont(const FontDescription& description, ShouldRetain shouldRetain)
 {
@@ -107,29 +107,10 @@ PassRefPtr<SimpleFontData> FontCache::getLastResortFallbackFont(const FontDescri
 
 PassRefPtr<SkTypeface> FontCache::createTypeface(const FontDescription& fontDescription, const AtomicString& family, CString& name)
 {
-    name = "";
-
     // If we're creating a fallback font (e.g. "-webkit-monospace"), convert the name into
     // the fallback name (like "monospace") that fontconfig understands.
     if (!family.length() || family.startsWith("-webkit-")) {
-        static const struct {
-            FontDescription::GenericFamilyType mType;
-            const char* mName;
-        } fontDescriptions[] = {
-            { FontDescription::SerifFamily, "serif" },
-            { FontDescription::SansSerifFamily, "sans-serif" },
-            { FontDescription::MonospaceFamily, "monospace" },
-            { FontDescription::CursiveFamily, "cursive" },
-            { FontDescription::FantasyFamily, "fantasy" }
-        };
-
-        FontDescription::GenericFamilyType type = fontDescription.genericFamily();
-        for (unsigned i = 0; i < SK_ARRAY_COUNT(fontDescriptions); i++) {
-            if (type == fontDescriptions[i].mType) {
-                name = fontDescriptions[i].mName;
-                break;
-            }
-        }
+        name = getFallbackFontFamily(fontDescription).string().utf8();
     } else {
         // convert the name to utf8
         name = family.utf8();
@@ -167,6 +148,6 @@ FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontD
         fontDescription.useSubpixelPositioning());
     return result;
 }
-#endif // !OS(WINDOWNS)
+#endif // !OS(WIN)
 
 } // namespace WebCore