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      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_
    101