[Fuchsia] Avoid redundant IPC in PlatformFallbackFontForCharacter()

Previously PlatformFallbackFontForCharacter() was sending 2 font
provider requests and didn't guarantee that the returned font actually
contain requested character. Rewrote it to fix both issues.

Also added FontCache::GetBcp47LocaleForRequest() and updated all
matchFamilyStyleCharacter() callers to use it.

Bug: 957256
Change-Id: I989c1e0b8fdc46a81d4d58d63ae3f3d02133f357
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1586476Reviewed-by: Dominik Röttsches <drott@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Auto-Submit: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657319}

third_party/blink/renderer/platform/fonts/font_cache.cc

@@ -65,6 +65,11 @@
 
 namespace blink {
 
+// Special locale for retrieving the color emoji font based on the proposed
+// changes in UTR #51 for introducing an Emoji script code:
+// https://unicode.org/reports/tr51/#Emoji_Script
+static const char kColorEmojiLocale[] = "und-Zsye";
+
 SkFontMgr* FontCache::static_font_manager_ = nullptr;
 
 #if defined(OS_LINUX) || defined(OS_CHROMEOS)
@@ -461,4 +466,26 @@ sk_sp<SkTypeface> FontCache::CreateTypefaceFromUniqueName(
   return nullptr;
 }
 
+// static
+FontCache::Bcp47Vector FontCache::GetBcp47LocaleForRequest(
+    const FontDescription& font_description,
+    FontFallbackPriority fallback_priority) {
+  Bcp47Vector result;
+
+  // Fill in the list of locales in the reverse priority order.
+  // Skia expects the highest array index to be the first priority.
+  const LayoutLocale* content_locale = font_description.Locale();
+  if (const LayoutLocale* han_locale =
+          LayoutLocale::LocaleForHan(content_locale)) {
+    result.push_back(han_locale->LocaleForHanForSkFontMgr());
+  }
+  result.push_back(LayoutLocale::GetDefault().LocaleForSkFontMgr());
+  if (content_locale)
+    result.push_back(content_locale->LocaleForSkFontMgr());
+
+  if (fallback_priority == FontFallbackPriority::kEmojiEmoji)
+    result.push_back(kColorEmojiLocale);
+  return result;
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/fonts/font_cache.h

@@ -246,6 +246,11 @@ class PLATFORM_EXPORT FontCache {
   ~FontCache() = default;
 
  private:
+  // BCP47 list used when requesting fallback font for a character.
+  // inlineCapacity is set to 4: the array vector not need to hold more than 4
+  // elements.
+  using Bcp47Vector = WTF::Vector<const char*, 4>;
+
   scoped_refptr<SimpleFontData> PlatformFallbackFontForCharacter(
       const FontDescription&,
       UChar32,
@@ -255,6 +260,10 @@ class PLATFORM_EXPORT FontCache {
       const FontFaceCreationParams& creation_params,
       CString& name);
 
+  static Bcp47Vector GetBcp47LocaleForRequest(
+      const FontDescription& font_description,
+      FontFallbackPriority fallback_priority);
+
   friend class FontGlobalContext;
   FontCache();
 
@@ -292,14 +301,15 @@ class PLATFORM_EXPORT FontCache {
                                    const FontFaceCreationParams&,
                                    CString& name);
 
-#if defined(OS_ANDROID) || defined(OS_LINUX) || defined(OS_FUCHSIA)
+#if defined(OS_ANDROID) || defined(OS_LINUX)
   static AtomicString GetFamilyNameForCharacter(SkFontMgr*,
                                                 UChar32,
                                                 const FontDescription&,
                                                 FontFallbackPriority);
-#endif  // defined(OS_ANDROID) || defined(OS_LINUX) || defined(OS_FUCHSIA)
+#endif  // defined(OS_ANDROID) || defined(OS_LINUX)
 
-  scoped_refptr<SimpleFontData> FallbackOnStandardFontStyle(const FontDescription&,
+  scoped_refptr<SimpleFontData> FallbackOnStandardFontStyle(
+      const FontDescription&,
       UChar32);
 
   // Don't purge if this count is > 0;

third_party/blink/renderer/platform/fonts/fuchsia/font_cache_fuchsia.cc

@@ -46,18 +46,29 @@ void FontCache::SetSystemFontFamily(const AtomicString& family_name) {
 
 scoped_refptr<SimpleFontData> FontCache::PlatformFallbackFontForCharacter(
     const FontDescription& font_description,
-    UChar32 c,
+    UChar32 character,
     const SimpleFontData* font_data_to_substitute,
     FontFallbackPriority fallback_priority) {
   sk_sp<SkFontMgr> font_mgr(SkFontMgr::RefDefault());
-  AtomicString family_name = GetFamilyNameForCharacter(
-      font_mgr.get(), c, font_description, fallback_priority);
-  if (family_name.IsEmpty())
-    return GetLastResortFallbackFont(font_description, kDoNotRetain);
-  return FontDataFromFontPlatformData(
-      GetFontPlatformData(font_description,
-                          FontFaceCreationParams(family_name)),
-      kDoNotRetain);
+  CString family_name = font_description.Family().Family().Utf8();
+  Bcp47Vector locales =
+      GetBcp47LocaleForRequest(font_description, fallback_priority);
+  sk_sp<SkTypeface> typeface(font_mgr->matchFamilyStyleCharacter(
+      family_name.data(), font_description.SkiaFontStyle(), locales.data(),
+      locales.size(), character));
+  if (!typeface)
+    return nullptr;
+
+  bool synthetic_bold =
+      font_description.IsSyntheticBold() && !typeface->isBold();
+  bool synthetic_italic =
+      font_description.IsSyntheticItalic() && !typeface->isItalic();
+
+  auto font_data = std::make_unique<FontPlatformData>(
+      std::move(typeface), CString(), font_description.EffectiveFontSize(),
+      synthetic_bold, synthetic_italic, font_description.Orientation());
+
+  return FontDataFromFontPlatformData(font_data.get(), kDoNotRetain);
 }
 
 }  // namespace blink

third_party/blink/renderer/platform/fonts/skia/font_cache_skia.cc

@@ -60,13 +60,7 @@ AtomicString ToAtomicString(const SkString& str) {
   return AtomicString::FromUTF8(str.c_str(), str.size());
 }
 
-#if defined(OS_ANDROID) || defined(OS_LINUX) || defined(OS_FUCHSIA)
-// 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";
-
+#if defined(OS_ANDROID) || defined(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.
@@ -78,25 +72,10 @@ AtomicString FontCache::GetFamilyNameForCharacter(
     FontFallbackPriority fallback_priority) {
   DCHECK(fm);
 
-  const int kMaxLocales = 4;
-  const char* bcp47_locales[kMaxLocales];
-  int locale_count = 0;
-
-  // Fill in the list of locales in the reverse priority order.
-  // Skia expects the highest array index to be the first priority.
-  const LayoutLocale* content_locale = font_description.Locale();
-  if (const LayoutLocale* han_locale =
-          LayoutLocale::LocaleForHan(content_locale))
-    bcp47_locales[locale_count++] = han_locale->LocaleForHanForSkFontMgr();
-  bcp47_locales[locale_count++] =
-      LayoutLocale::GetDefault().LocaleForSkFontMgr();
-  if (content_locale)
-    bcp47_locales[locale_count++] = content_locale->LocaleForSkFontMgr();
-  if (fallback_priority == FontFallbackPriority::kEmojiEmoji)
-    bcp47_locales[locale_count++] = kAndroidColorEmojiLocale;
-  SECURITY_DCHECK(locale_count <= kMaxLocales);
+  Bcp47Vector locales =
+      GetBcp47LocaleForRequest(font_description, fallback_priority);
   sk_sp<SkTypeface> typeface(fm->matchFamilyStyleCharacter(
-      nullptr, SkFontStyle(), bcp47_locales, locale_count, c));
+      nullptr, SkFontStyle(), locales.data(), locales.size(), c));
   if (!typeface)
     return g_empty_atom;
 
@@ -104,7 +83,7 @@ AtomicString FontCache::GetFamilyNameForCharacter(
   typeface->getFamilyName(&skia_family_name);
   return ToAtomicString(skia_family_name);
 }
-#endif  // defined(OS_ANDROID) || defined(OS_LINUX) || defined(OS_FUCHSIA)
+#endif  // defined(OS_ANDROID) || defined(OS_LINUX)
 
 void FontCache::PlatformInit() {}
 

third_party/blink/renderer/platform/fonts/win/font_cache_skia_win.cc

@@ -197,22 +197,12 @@ scoped_refptr<SimpleFontData> FontCache::PlatformFallbackFontForCharacter(
   }
 
   if (use_skia_font_fallback_) {
-    const char* bcp47_locale = nullptr;
-    int locale_count = 0;
-    // If the font description has a locale, use that. Otherwise, Skia will
-    // fall back on the user's default locale.
-    // TODO(kulshin): extract locale fallback logic from
-    //   FontCacheAndroid.cpp and share that code
-    if (font_description.Locale()) {
-      bcp47_locale = font_description.Locale()->LocaleForSkFontMgr();
-      locale_count = 1;
-    }
-
     CString family_name = font_description.Family().Family().Utf8();
-
+    Bcp47Vector locales =
+        GetBcp47LocaleForRequest(font_description, fallback_priority);
     SkTypeface* typeface = font_manager_->matchFamilyStyleCharacter(
-        family_name.data(), font_description.SkiaFontStyle(), &bcp47_locale,
-        locale_count, character);
+        family_name.data(), font_description.SkiaFontStyle(), locales.data(),
+        locales.size(), character);
     if (typeface) {
       SkString skia_family;
       typeface->getFamilyName(&skia_family);