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Fallback font match caching to fix emoji lag. #7208

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merged 4 commits into from
Dec 13, 2018
Merged

Fallback font match caching to fix emoji lag. #7208

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77d6e03
Cache MatchFallbackFont results per character to fix emoji lag
GaryQian Dec 13, 2018
4dabde5
Comments and cleanup
GaryQian Dec 13, 2018
4b5b161
Break out into helper function to isolate caching
GaryQian Dec 13, 2018
2dcd65f
Use auto for iterator
GaryQian Dec 13, 2018
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17 changes: 16 additions & 1 deletion third_party/txt/src/txt/font_collection.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -202,6 +202,22 @@ std::shared_ptr<minikin::FontFamily> FontCollection::CreateMinikinFontFamily(
const std::shared_ptr<minikin::FontFamily>& FontCollection::MatchFallbackFont(
uint32_t ch,
std::string locale) {
// Check if the ch's matched font has been cached. We cache the results of
// this method as repeated matchFamilyStyleCharacter calls can become
// extremely laggy when typing a large number of complex emojis.
auto lookup = fallback_match_cache_.find(ch);
if (lookup != fallback_match_cache_.end()) {
return *lookup->second;
}
const std::shared_ptr<minikin::FontFamily>* match =
&DoMatchFallbackFont(ch, locale);
fallback_match_cache_.insert(std::make_pair(ch, match));
return *match;
}

const std::shared_ptr<minikin::FontFamily>& FontCollection::DoMatchFallbackFont(
uint32_t ch,
std::string locale) {
for (const sk_sp<SkFontMgr>& manager : GetFontManagerOrder()) {
std::vector<const char*> bcp47;
if (!locale.empty())
Expand All @@ -219,7 +235,6 @@ const std::shared_ptr<minikin::FontFamily>& FontCollection::MatchFallbackFont(

return GetFallbackFontFamily(manager, family_name);
}

return g_null_family;
}

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12 changes: 12 additions & 0 deletions third_party/txt/src/txt/font_collection.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,8 @@ class FontCollection : public std::enable_shared_from_this<FontCollection> {
const std::string& family,
const std::string& locale);

// Provides a FontFamily that contains glyphs for ch. This caches previously
// matched fonts. Also see FontCollection::DoMatchFallbackFont.
const std::shared_ptr<minikin::FontFamily>& MatchFallbackFont(
uint32_t ch,
std::string locale);
Expand Down Expand Up @@ -80,12 +82,22 @@ class FontCollection : public std::enable_shared_from_this<FontCollection> {
std::shared_ptr<minikin::FontCollection>,
FamilyKey::Hasher>
font_collections_cache_;
// Cache that stores the results of MatchFallbackFont to ensure lag-free emoji
// font fallback matching.
std::unordered_map<uint32_t, const std::shared_ptr<minikin::FontFamily>*>
fallback_match_cache_;
std::unordered_map<std::string, std::shared_ptr<minikin::FontFamily>>
fallback_fonts_;
std::unordered_map<std::string, std::set<std::string>>
fallback_fonts_for_locale_;
bool enable_font_fallback_;

// Performs the actual work of MatchFallbackFont. The result is cached in
// fallback_match_cache_.
const std::shared_ptr<minikin::FontFamily>& DoMatchFallbackFont(
uint32_t ch,
std::string locale);

std::vector<sk_sp<SkFontMgr>> GetFontManagerOrder() const;

std::shared_ptr<minikin::FontFamily> CreateMinikinFontFamily(
Expand Down