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      1 // Copyright 2013 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 MEDIA_BASE_USER_INPUT_MONITOR_H_
      6 #define MEDIA_BASE_USER_INPUT_MONITOR_H_
      7 
      8 #include "base/memory/ref_counted.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/observer_list_threadsafe.h"
     11 #include "base/synchronization/lock.h"
     12 #include "media/base/media_export.h"
     13 
     14 struct SkIPoint;
     15 
     16 namespace base {
     17 class SingleThreadTaskRunner;
     18 }  // namespace base
     19 
     20 namespace media {
     21 
     22 // Monitors and notifies about mouse movements and keyboard events.
     23 // Thread safe. The listeners are called on the thread where the listeners are
     24 // added.
     25 class MEDIA_EXPORT UserInputMonitor {
     26  public:
     27   // The interface to receive mouse movement events.
     28   class MEDIA_EXPORT MouseEventListener {
     29    public:
     30     // |position| is the new mouse position.
     31     virtual void OnMouseMoved(const SkIPoint& position) = 0;
     32 
     33    protected:
     34     virtual ~MouseEventListener() {}
     35   };
     36   typedef ObserverListThreadSafe<UserInputMonitor::MouseEventListener>
     37       MouseListenerList;
     38 
     39   UserInputMonitor();
     40   virtual ~UserInputMonitor();
     41 
     42   // Creates a platform-specific instance of UserInputMonitor.
     43   // |io_task_runner| is the task runner for an IO thread.
     44   // |ui_task_runner| is the task runner for a UI thread.
     45   static scoped_ptr<UserInputMonitor> Create(
     46       const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     47       const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner);
     48 
     49   // The same |listener| should only be added once.
     50   // The clients should make sure to call Remove*Listener before |listener| is
     51   // destroyed.
     52   void AddMouseListener(MouseEventListener* listener);
     53   void RemoveMouseListener(MouseEventListener* listener);
     54 
     55   // A caller must call EnableKeyPressMonitoring and
     56   // DisableKeyPressMonitoring in pair.
     57   void EnableKeyPressMonitoring();
     58   void DisableKeyPressMonitoring();
     59 
     60   // Returns the number of keypresses. The starting point from when it is
     61   // counted is not guaranteed, but consistent within the pair of calls of
     62   // EnableKeyPressMonitoring and DisableKeyPressMonitoring. So a caller can
     63   // use the difference between the values returned at two times to get the
     64   // number of keypresses happened within that time period, but should not make
     65   // any assumption on the initial value.
     66   virtual size_t GetKeyPressCount() const = 0;
     67 
     68  protected:
     69   scoped_refptr<MouseListenerList> mouse_listeners() {
     70     return mouse_listeners_;
     71   }
     72 
     73  private:
     74   virtual void StartKeyboardMonitoring() = 0;
     75   virtual void StopKeyboardMonitoring() = 0;
     76   virtual void StartMouseMonitoring() = 0;
     77   virtual void StopMouseMonitoring() = 0;
     78 
     79   base::Lock lock_;
     80   size_t key_press_counter_references_;
     81   size_t mouse_listeners_count_;
     82   scoped_refptr<MouseListenerList> mouse_listeners_;
     83 
     84   DISALLOW_COPY_AND_ASSIGN(UserInputMonitor);
     85 };
     86 
     87 }  // namespace media
     88 
     89 #endif  // MEDIA_BASE_USER_INPUT_MONITOR_H_
     90