chrome/browser/font_family_cache.cc

   1 // Copyright 2014 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/font_family_cache.h"
   6
   7 #include <stddef.h>
   8
   9 #include <map>
  10
  11 #include "base/functional/bind.h"
  12 #include "base/memory/ptr_util.h"
  13 #include "base/strings/stringprintf.h"
  14 #include "base/strings/utf_string_conversions.h"
  15 #include "chrome/browser/font_pref_change_notifier_factory.h"
  16 #include "chrome/browser/profiles/profile.h"
  17 #include "chrome/common/pref_font_webkit_names.h"
  18 #include "chrome/common/pref_names.h"
  19 #include "components/prefs/pref_service.h"
  20
  21 // Identifies the user data on the profile.
  22 const char kFontFamilyCacheKey[] = "FontFamilyCacheKey";
  23
  24 FontFamilyCache::FontFamilyCache(Profile* profile)
  25     : prefs_(profile->GetPrefs()) {
  26   font_change_registrar_.Register(
  27       FontPrefChangeNotifierFactory::GetForProfile(profile),
  28       base::BindRepeating(&FontFamilyCache::OnPrefsChanged,
  29                           base::Unretained(this)));
  30 }
  31
  32 FontFamilyCache::~FontFamilyCache() = default;
  33
  34 void FontFamilyCache::FillFontFamilyMap(
  35     Profile* profile,
  36     const char* map_name,
  37     blink::web_pref::ScriptFontFamilyMap* map) {
  38   FontFamilyCache* cache =
  39       static_cast<FontFamilyCache*>(profile->GetUserData(&kFontFamilyCacheKey));
  40   if (!cache) {
  41     cache = new FontFamilyCache(profile);
  42     profile->SetUserData(&kFontFamilyCacheKey, base::WrapUnique(cache));
  43   }
  44
  45   cache->FillFontFamilyMap(map_name, map);
  46 }
  47
  48 void FontFamilyCache::FillFontFamilyMap(
  49     const char* map_name,
  50     blink::web_pref::ScriptFontFamilyMap* map) {
  51   // TODO(falken): Get rid of the brute-force scan over possible
  52   // (font family / script) combinations - see http://crbug.com/308095.
  53   for (size_t i = 0; i < prefs::kWebKitScriptsForFontFamilyMapsLength; ++i) {
  54     const char* script = prefs::kWebKitScriptsForFontFamilyMaps[i];
  55     std::u16string result = FetchAndCacheFont(script, map_name);
  56     if (!result.empty())
  57       (*map)[script] = result;
  58   }
  59 }
  60
  61 std::u16string FontFamilyCache::FetchFont(const char* script,
  62                                           const char* map_name) {
  63   std::string pref_name = base::StringPrintf("%s.%s", map_name, script);
  64   std::string font = prefs_->GetString(pref_name.c_str());
  65   std::u16string font16 = base::UTF8ToUTF16(font);
  66
  67   // Lazily constructs the map if it doesn't already exist.
  68   ScriptFontMap& map = font_family_map_[map_name];
  69   map[script] = font16;
  70   return font16;
  71 }
  72
  73 std::u16string FontFamilyCache::FetchAndCacheFont(const char* script,
  74                                                   const char* map_name) {
  75   FontFamilyMap::const_iterator it = font_family_map_.find(map_name);
  76   if (it != font_family_map_.end()) {
  77     auto it2 = it->second.find(script);
  78     if (it2 != it->second.end())
  79       return it2->second;
  80   }
  81
  82   return FetchFont(script, map_name);
  83 }
  84
  85 // There are ~1000 entries in the cache. Avoid unnecessary object construction,
  86 // including std::string.
  87 void FontFamilyCache::OnPrefsChanged(const std::string& pref_name) {
  88   const size_t delimiter_length = 1;
  89   const char delimiter = '.';
  90   for (auto& it : font_family_map_) {
  91     const char* map_name = it.first;
  92     size_t map_name_length = strlen(map_name);
  93
  94     // If the map name doesn't match, move on.
  95     if (pref_name.compare(0, map_name_length, map_name) != 0)
  96       continue;
  97
  98     ScriptFontMap& map = it.second;
  99     for (auto it2 = map.begin(); it2 != map.end(); ++it2) {
 100       const char* script = it2->first;
 101       size_t script_length = strlen(script);
 102
 103       // If the length doesn't match, move on.
 104       if (pref_name.size() !=
 105           map_name_length + script_length + delimiter_length)
 106         continue;
 107
 108       // If the script doesn't match, move on.
 109       if (pref_name.compare(
 110               map_name_length + delimiter_length, script_length, script) != 0)
 111         continue;
 112
 113       // If the delimiter doesn't match, move on.
 114       if (pref_name[map_name_length] != delimiter)
 115         continue;
 116
 117       // Clear the cache.
 118       map.erase(it2);
 119       break;
 120     }
 121   }
 122 }