src/ui/gfx/sys_color_change_listener.cc

   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/sys_color_change_listener.h"
   6
   7 #if defined(OS_WIN)
   8 #include <windows.h>
   9 #endif
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/singleton.h"
  13 #include "base/observer_list.h"
  14 #include "ui/gfx/color_utils.h"
  15
  16 #if defined(OS_WIN)
  17 #include "ui/gfx/win/singleton_hwnd.h"
  18 #endif
  19
  20 namespace gfx {
  21
  22 namespace {
  23
  24 bool g_is_inverted_color_scheme = false;
  25 bool g_is_inverted_color_scheme_initialized = false;
  26
  27 void UpdateInvertedColorScheme() {
  28 #if defined(OS_WIN)
  29   int foreground_luminance = color_utils::GetLuminanceForColor(
  30       color_utils::GetSysSkColor(COLOR_WINDOWTEXT));
  31   int background_luminance = color_utils::GetLuminanceForColor(
  32       color_utils::GetSysSkColor(COLOR_WINDOW));
  33   HIGHCONTRAST high_contrast = {0};
  34   high_contrast.cbSize = sizeof(HIGHCONTRAST);
  35   g_is_inverted_color_scheme =
  36       SystemParametersInfo(SPI_GETHIGHCONTRAST, 0, &high_contrast, 0) &&
  37       ((high_contrast.dwFlags & HCF_HIGHCONTRASTON) != 0) &&
  38       foreground_luminance > background_luminance;
  39   g_is_inverted_color_scheme_initialized = true;
  40 #endif
  41 }
  42
  43 }  // namespace
  44
  45 bool IsInvertedColorScheme() {
  46   if (!g_is_inverted_color_scheme_initialized)
  47     UpdateInvertedColorScheme();
  48   return g_is_inverted_color_scheme;
  49 }
  50
  51 #if defined(OS_WIN)
  52 class SysColorChangeObserver : public gfx::SingletonHwnd::Observer {
  53  public:
  54   static SysColorChangeObserver* GetInstance();
  55
  56   void AddListener(SysColorChangeListener* listener);
  57   void RemoveListener(SysColorChangeListener* listener);
  58
  59  private:
  60   friend struct DefaultSingletonTraits<SysColorChangeObserver>;
  61
  62   SysColorChangeObserver();
  63   virtual ~SysColorChangeObserver();
  64
  65   virtual void OnWndProc(HWND hwnd,
  66                          UINT message,
  67                          WPARAM wparam,
  68                          LPARAM lparam) override;
  69
  70   ObserverList<SysColorChangeListener> listeners_;
  71 };
  72
  73 // static
  74 SysColorChangeObserver* SysColorChangeObserver::GetInstance() {
  75   return Singleton<SysColorChangeObserver>::get();
  76 }
  77
  78 SysColorChangeObserver::SysColorChangeObserver() {
  79   gfx::SingletonHwnd::GetInstance()->AddObserver(this);
  80 }
  81
  82 SysColorChangeObserver::~SysColorChangeObserver() {
  83   gfx::SingletonHwnd::GetInstance()->RemoveObserver(this);
  84 }
  85
  86 void SysColorChangeObserver::AddListener(SysColorChangeListener* listener) {
  87   listeners_.AddObserver(listener);
  88 }
  89
  90 void SysColorChangeObserver::RemoveListener(SysColorChangeListener* listener) {
  91   listeners_.RemoveObserver(listener);
  92 }
  93
  94 void SysColorChangeObserver::OnWndProc(HWND hwnd,
  95                                        UINT message,
  96                                        WPARAM wparam,
  97                                        LPARAM lparam) {
  98   if (message == WM_SYSCOLORCHANGE ||
  99       (message == WM_SETTINGCHANGE && wparam == SPI_SETHIGHCONTRAST)) {
 100     UpdateInvertedColorScheme();
 101     FOR_EACH_OBSERVER(SysColorChangeListener, listeners_, OnSysColorChange());
 102   }
 103 }
 104 #endif
 105
 106 ScopedSysColorChangeListener::ScopedSysColorChangeListener(
 107     SysColorChangeListener* listener)
 108     : listener_(listener) {
 109 #if defined(OS_WIN)
 110   SysColorChangeObserver::GetInstance()->AddListener(listener_);
 111 #endif
 112 }
 113
 114 ScopedSysColorChangeListener::~ScopedSysColorChangeListener() {
 115 #if defined(OS_WIN)
 116   SysColorChangeObserver::GetInstance()->RemoveListener(listener_);
 117 #endif
 118 }
 119
 120 }  // namespace gfx