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 type of mouse event.
  33   enum MouseEventType {
  34     MOUSE_MOVE,
  35     MOUSE_EXIT,
  36     MOUSE_PRESS
  37   };
  38
  39   virtual ~MouseWatcherHost();
  40
  41   // Return false when the mouse has moved outside the monitored region.
  42   virtual bool Contains(const gfx::Point& screen_point,
  43                         MouseEventType type) = 0;
  44 };
  45
  46 // MouseWatcher is used to watch mouse movement and notify its listener when the
  47 // mouse moves outside the bounds of a MouseWatcherHost.
  48 class VIEWS_EXPORT MouseWatcher {
  49  public:
  50   // Creates a new MouseWatcher. The |listener| will be notified when the |host|
  51   // determines that the mouse has moved outside its monitored region.
  52   // |host| will be owned by the watcher and deleted upon completion.
  53   MouseWatcher(MouseWatcherHost* host, MouseWatcherListener* listener);
  54   ~MouseWatcher();
  55
  56   // Sets the amount to delay before notifying the listener when the mouse exits
  57   // the host by way of going to another window.
  58   void set_notify_on_exit_time(base::TimeDelta time) {
  59     notify_on_exit_time_ = time;
  60   }
  61
  62   // Starts watching mouse movements. When the mouse moves outside the bounds of
  63   // the host the listener is notified. |Start| may be invoked any number of
  64   // times. If the mouse moves outside the bounds of the host the listener is
  65   // notified and watcher stops watching events.
  66   void Start();
  67
  68   // Stops watching mouse events.
  69   void Stop();
  70
  71  private:
  72   class Observer;
  73
  74   // Are we currently observing events?
  75   bool is_observing() const { return observer_.get() != NULL; }
  76
  77   // Notifies the listener and stops watching events.
  78   void NotifyListener();
  79
  80   // Host we're listening for events over.
  81   scoped_ptr<MouseWatcherHost> host_;
  82
  83   // Our listener.
  84   MouseWatcherListener* listener_;
  85
  86   // Does the actual work of listening for mouse events.
  87   scoped_ptr<Observer> observer_;
  88
  89   // See description above setter.
  90   base::TimeDelta notify_on_exit_time_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(MouseWatcher);
  93 };
  94
  95 }  // namespace views
  96
  97 #endif  // UI_VIEWS_MOUSE_WATCHER_H_