1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 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 "ui/gfx/font_smoothing_win.h" 6 7 #include "base/memory/singleton.h" 8 #include "ui/gfx/win/singleton_hwnd.h" 9 10 namespace { 11 12 // Helper class to cache font smoothing settings and listen for notifications 13 // to re-query them from the system. 14 class CachedFontSmoothingSettings : public gfx::SingletonHwnd::Observer { 15 public: 16 static CachedFontSmoothingSettings* GetInstance(); 17 18 // Returns the cached Windows font smoothing settings. Queries the settings 19 // via Windows APIs and begins listening for changes when called for the 20 // first time. 21 void GetFontSmoothingSettings(bool* smoothing_enabled, 22 bool* cleartype_enabled); 23 24 private: 25 friend struct DefaultSingletonTraits<CachedFontSmoothingSettings>; 26 27 CachedFontSmoothingSettings(); 28 virtual ~CachedFontSmoothingSettings(); 29 30 // Listener for WM_SETTINGCHANGE notifications. 31 virtual void OnWndProc(HWND hwnd, 32 UINT message, 33 WPARAM wparam, 34 LPARAM lparam) OVERRIDE; 35 36 // Queries the font settings from the system. 37 void QueryFontSettings(); 38 39 // Indicates whether the SingletonHwnd::Observer has been registered. 40 bool observer_added_; 41 42 // Indicates whether |smoothing_enabled_| and |cleartype_enabled_| are valid 43 // or need to be re-queried from the system. 44 bool need_to_query_settings_; 45 46 // Indicates that font smoothing is enabled. 47 bool smoothing_enabled_; 48 49 // Indicates that the ClearType font smoothing is enabled. 50 bool cleartype_enabled_; 51 52 DISALLOW_COPY_AND_ASSIGN(CachedFontSmoothingSettings); 53 }; 54 55 // static 56 CachedFontSmoothingSettings* CachedFontSmoothingSettings::GetInstance() { 57 return Singleton<CachedFontSmoothingSettings>::get(); 58 } 59 60 void CachedFontSmoothingSettings::GetFontSmoothingSettings( 61 bool* smoothing_enabled, 62 bool* cleartype_enabled) { 63 // If cached settings are stale, query them from the OS. 64 if (need_to_query_settings_) { 65 QueryFontSettings(); 66 need_to_query_settings_ = false; 67 } 68 if (!observer_added_) { 69 gfx::SingletonHwnd::GetInstance()->AddObserver(this); 70 observer_added_ = true; 71 } 72 *smoothing_enabled = smoothing_enabled_; 73 *cleartype_enabled = cleartype_enabled_; 74 } 75 76 CachedFontSmoothingSettings::CachedFontSmoothingSettings() 77 : observer_added_(false), 78 need_to_query_settings_(true), 79 smoothing_enabled_(false), 80 cleartype_enabled_(false) { 81 } 82 83 CachedFontSmoothingSettings::~CachedFontSmoothingSettings() { 84 // Can't remove the SingletonHwnd observer here since SingletonHwnd may have 85 // been destroyed already (both singletons). 86 } 87 88 void CachedFontSmoothingSettings::OnWndProc(HWND hwnd, 89 UINT message, 90 WPARAM wparam, 91 LPARAM lparam) { 92 if (message == WM_SETTINGCHANGE) 93 need_to_query_settings_ = true; 94 } 95 96 void CachedFontSmoothingSettings::QueryFontSettings() { 97 smoothing_enabled_ = false; 98 cleartype_enabled_ = false; 99 100 BOOL enabled = false; 101 if (SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &enabled, 0) && enabled) { 102 smoothing_enabled_ = true; 103 104 UINT smooth_type = 0; 105 if (SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &smooth_type, 0)) 106 cleartype_enabled_ = (smooth_type == FE_FONTSMOOTHINGCLEARTYPE); 107 } 108 } 109 110 } // namespace 111 112 namespace gfx { 113 114 void GetCachedFontSmoothingSettings(bool* smoothing_enabled, 115 bool* cleartype_enabled) { 116 CachedFontSmoothingSettings::GetInstance()->GetFontSmoothingSettings( 117 smoothing_enabled, 118 cleartype_enabled); 119 } 120 121 } // namespace gfx 122