ash/wm/video_detector.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 ASH_WM_VIDEO_DETECTOR_H_
   6 #define ASH_WM_VIDEO_DETECTOR_H_
   7
   8 #include <map>
   9
  10 #include "ash/ash_export.h"
  11 #include "ash/shell_observer.h"
  12 #include "base/basictypes.h"
  13 #include "base/compiler_specific.h"
  14 #include "base/memory/linked_ptr.h"
  15 #include "base/observer_list.h"
  16 #include "base/scoped_observer.h"
  17 #include "base/time/time.h"
  18 #include "ui/aura/env_observer.h"
  19 #include "ui/aura/window_observer.h"
  20
  21 namespace aura {
  22 class Window;
  23 }
  24
  25 namespace gfx {
  26 class Rect;
  27 }
  28
  29 namespace ash {
  30
  31 class ASH_EXPORT VideoDetectorObserver {
  32  public:
  33   // Invoked periodically while a video is being played onscreen.
  34   virtual void OnVideoDetected(bool is_fullscreen) = 0;
  35
  36  protected:
  37   virtual ~VideoDetectorObserver() {}
  38 };
  39
  40 // Watches for updates to windows and tries to detect when a video is playing.
  41 // We err on the side of false positives and can be fooled by things like
  42 // continuous scrolling of a page.
  43 class ASH_EXPORT VideoDetector : public aura::EnvObserver,
  44                                  public aura::WindowObserver,
  45                                  public ShellObserver  {
  46  public:
  47   // Minimum dimensions in pixels that a window update must have to be
  48   // considered a potential video frame.
  49   static const int kMinUpdateWidth;
  50   static const int kMinUpdateHeight;
  51
  52   // Number of video-sized updates that we must see within a second in a window
  53   // before we assume that a video is playing.
  54   static const int kMinFramesPerSecond;
  55
  56   // Minimum amount of time between notifications to observers that a video is
  57   // playing.
  58   static const double kNotifyIntervalSec;
  59
  60   VideoDetector();
  61   virtual ~VideoDetector();
  62
  63   void set_now_for_test(base::TimeTicks now) { now_for_test_ = now; }
  64
  65   void AddObserver(VideoDetectorObserver* observer);
  66   void RemoveObserver(VideoDetectorObserver* observer);
  67
  68   // EnvObserver overrides.
  69   virtual void OnWindowInitialized(aura::Window* window) OVERRIDE;
  70
  71   // WindowObserver overrides.
  72   virtual void OnWindowPaintScheduled(aura::Window* window,
  73                                       const gfx::Rect& region) OVERRIDE;
  74   virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
  75
  76   // ShellObserver overrides.
  77   virtual void OnAppTerminating() OVERRIDE;
  78
  79  private:
  80   class WindowInfo;
  81   typedef std::map<aura::Window*, linked_ptr<WindowInfo> > WindowInfoMap;
  82
  83   // Possibly notifies observers in response to detection of a video in
  84   // |window|.  Notifications are rate-limited and don't get sent if the window
  85   // is invisible or offscreen.
  86   void MaybeNotifyObservers(aura::Window* window, base::TimeTicks now);
  87
  88   // Maps from a window that we're tracking to information about it.
  89   WindowInfoMap window_infos_;
  90
  91   ObserverList<VideoDetectorObserver> observers_;
  92
  93   // Last time at which we notified observers that a video was playing.
  94   base::TimeTicks last_observer_notification_time_;
  95
  96   // If set, used when the current time is needed.  This can be set by tests to
  97   // simulate the passage of time.
  98   base::TimeTicks now_for_test_;
  99
 100   ScopedObserver<aura::Window, aura::WindowObserver> observer_manager_;
 101
 102   bool is_shutting_down_;
 103
 104   DISALLOW_COPY_AND_ASSIGN(VideoDetector);
 105 };
 106
 107 }  // namespace ash
 108
 109 #endif  // ASH_WM_VIDEO_DETECTOR_H_