app/active_window_watcher_x.h

   1 // Copyright (c) 2009 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 #ifndef APP_ACTIVE_WINDOW_WATCHER_X_H_
   6 #define APP_ACTIVE_WINDOW_WATCHER_X_H_
   7
   8 #include <gdk/gdk.h>
   9
  10 #include "base/basictypes.h"
  11 #include "base/observer_list.h"
  12 #include "base/singleton.h"
  13
  14 // This is a helper class that is used to keep track of which window the X
  15 // window manager thinks is active. Add an Observer to listener for changes to
  16 // the active window.
  17 class ActiveWindowWatcherX {
  18  public:
  19   class Observer {
  20    public:
  21     // |active_window| will be NULL if the active window isn't one of Chrome's.
  22     virtual void ActiveWindowChanged(GdkWindow* active_window) = 0;
  23   };
  24
  25   static void AddObserver(Observer* observer);
  26   static void RemoveObserver(Observer* observer);
  27
  28  private:
  29   friend struct DefaultSingletonTraits<ActiveWindowWatcherX>;
  30
  31   ActiveWindowWatcherX();
  32
  33   void Init();
  34
  35   // Sends a notification out through the NotificationService that the active
  36   // window has changed.
  37   void NotifyActiveWindowChanged();
  38
  39   // Callback for PropertyChange XEvents.
  40   static GdkFilterReturn OnWindowXEvent(GdkXEvent* xevent,
  41                                         GdkEvent* event,
  42                                         gpointer window_watcher);
  43
  44   ObserverList<Observer> observers_;
  45
  46   DISALLOW_COPY_AND_ASSIGN(ActiveWindowWatcherX);
  47 };
  48
  49 #endif  // APP_ACTIVE_WINDOW_WATCHER_X_H_