| // 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. |
| |
| #ifndef CHROME_BROWSER_FONT_FAMILY_CACHE_H_ |
| #define CHROME_BROWSER_FONT_FAMILY_CACHE_H_ |
| |
| #include <string> |
| #include <unordered_map> |
| |
| #include "base/gtest_prod_util.h" |
| #include "base/macros.h" |
| #include "base/supports_user_data.h" |
| #include "chrome/browser/font_pref_change_notifier.h" |
| #include "third_party/blink/public/common/web_preferences/web_preferences.h" |
| |
| class PrefService; |
| class Profile; |
| |
| FORWARD_DECLARE_TEST(FontFamilyCacheTest, Caching); |
| |
| // Caches font family preferences associated with a PrefService. This class |
| // relies on the assumption that each concatenation of map_name + '.' + script |
| // is a unique string. It also relies on the assumption that the (const char*) |
| // keys used in both inner and outer maps are compile time constants. |
| // This class caches the strings necessary to update |
| // "blink::web_pref::ScriptFontFamilyMap". This is necessary since Chrome |
| // attempts to update blink::web_pref::ScriptFontFamilyMap 20000 times at |
| // startup. See https://crbug.com/308095. |
| class FontFamilyCache : public base::SupportsUserData::Data { |
| public: |
| explicit FontFamilyCache(Profile* profile); |
| ~FontFamilyCache() override; |
| |
| // Gets or creates the relevant FontFamilyCache, and then fills |map|. |
| static void FillFontFamilyMap(Profile* profile, |
| const char* map_name, |
| blink::web_pref::ScriptFontFamilyMap* map); |
| |
| // Fills |map| with font family preferences. |
| void FillFontFamilyMap(const char* map_name, |
| blink::web_pref::ScriptFontFamilyMap* map); |
| |
| protected: |
| // Exposed and virtual for testing. |
| // Fetches the font without checking the cache. |
| virtual std::u16string FetchFont(const char* script, const char* map_name); |
| |
| private: |
| FRIEND_TEST_ALL_PREFIXES(::FontFamilyCacheTest, Caching); |
| |
| // Map from script to font. |
| // Key comparison uses pointer equality. |
| using ScriptFontMap = std::unordered_map<const char*, std::u16string>; |
| |
| // Map from font family to ScriptFontMap. |
| // Key comparison uses pointer equality. |
| using FontFamilyMap = std::unordered_map<const char*, ScriptFontMap>; |
| |
| // Checks the cache for the font. If not present, fetches the font and stores |
| // the result in the cache. |
| // This method needs to be very fast, because it's called ~20,000 times on a |
| // fresh launch with an empty profile. It's important to avoid unnecessary |
| // object construction, hence the heavy use of const char* and the minimal use |
| // of std::string. |
| // |script| and |map_name| must be compile time constants. Two behaviors rely |
| // on this: key comparison uses pointer equality, and keys must outlive the |
| // maps. |
| std::u16string FetchAndCacheFont(const char* script, const char* map_name); |
| |
| // Called when font family preferences changed. |
| // Invalidates the cached entry, and removes the relevant observer. |
| // Note: It is safe to remove the observer from the pref change callback. |
| void OnPrefsChanged(const std::string& pref_name); |
| |
| // Cache of font family preferences. |
| FontFamilyMap font_family_map_; |
| |
| // Weak reference. |
| // Note: The lifetime of this object is tied to the lifetime of the |
| // PrefService, so there is no worry about an invalid pointer. |
| const PrefService* prefs_; |
| |
| // Reacts to profile font changes. |font_change_registrar_| will be |
| // automatically unregistered when the FontPrefChangeNotifier is destroyed as |
| // part of Profile destruction, thus ensuring safe unregistration even though |
| // |this| is destroyed after the Profile destructor completes as part of |
| // Profile's super class destructor ~base::SupportsUserData. |
| FontPrefChangeNotifier::Registrar font_change_registrar_; |
| |
| DISALLOW_COPY_AND_ASSIGN(FontFamilyCache); |
| }; |
| |
| #endif // CHROME_BROWSER_FONT_FAMILY_CACHE_H_ |