ui/views/mouse_watcher.h

   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 #ifndef UI_VIEWS_MOUSE_WATCHER_H_
   6 #define UI_VIEWS_MOUSE_WATCHER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/time/time.h"
  11 #include "ui/gfx/insets.h"
  12 #include "ui/views/views_export.h"
  13
  14 namespace gfx {
  15 class Point;
  16 }
  17
  18 namespace views {
  19
  20 // MouseWatcherListener is notified when the mouse moves outside the host.
  21 class VIEWS_EXPORT MouseWatcherListener {
  22  public:
  23   virtual void MouseMovedOutOfHost() = 0;
  24
  25  protected:
  26   virtual ~MouseWatcherListener();
  27 };
  28
  29 // The MouseWatcherHost determines what region is to be monitored.
  30 class VIEWS_EXPORT MouseWatcherHost {
  31  public:
  32   // The MouseEventType can be used as a hint.
  33   enum MouseEventType {
  34     // The mouse moved within the window which was current when the MouseWatcher
  35     // was created.
  36     MOUSE_MOVE,
  37     // The mouse moved exited the window which was current when the MouseWatcher
  38     // was created.
  39     MOUSE_EXIT
  40   };
  41
  42   virtual ~MouseWatcherHost();
  43
  44   // Return false when the mouse has moved outside the monitored region.
  45   virtual bool Contains(const gfx::Point& screen_point,
  46                         MouseEventType type) = 0;
  47 };
  48
  49 // MouseWatcher is used to watch mouse movement and notify its listener when the
  50 // mouse moves outside the bounds of a MouseWatcherHost.
  51 class VIEWS_EXPORT MouseWatcher {
  52  public:
  53   // Creates a new MouseWatcher. The |listener| will be notified when the |host|
  54   // determines that the mouse has moved outside its monitored region.
  55   // |host| will be owned by the watcher and deleted upon completion.
  56   MouseWatcher(MouseWatcherHost* host, MouseWatcherListener* listener);
  57   ~MouseWatcher();
  58
  59   // Sets the amount to delay before notifying the listener when the mouse exits
  60   // the host by way of going to another window.
  61   void set_notify_on_exit_time(base::TimeDelta time) {
  62     notify_on_exit_time_ = time;
  63   }
  64
  65   // Starts watching mouse movements. When the mouse moves outside the bounds of
  66   // the host the listener is notified. |Start| may be invoked any number of
  67   // times. If the mouse moves outside the bounds of the host the listener is
  68   // notified and watcher stops watching events.
  69   void Start();
  70
  71   // Stops watching mouse events.
  72   void Stop();
  73
  74  private:
  75   class Observer;
  76
  77   // Are we currently observing events?
  78   bool is_observing() const { return observer_.get() != NULL; }
  79
  80   // Notifies the listener and stops watching events.
  81   void NotifyListener();
  82
  83   // Host we're listening for events over.
  84   scoped_ptr<MouseWatcherHost> host_;
  85
  86   // Our listener.
  87   MouseWatcherListener* listener_;
  88
  89   // Does the actual work of listening for mouse events.
  90   scoped_ptr<Observer> observer_;
  91
  92   // See description above setter.
  93   base::TimeDelta notify_on_exit_time_;
  94
  95   DISALLOW_COPY_AND_ASSIGN(MouseWatcher);
  96 };
  97
  98 }  // namespace views
  99
 100 #endif  // UI_VIEWS_MOUSE_WATCHER_H_