media/base/user_input_monitor.h

   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_