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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 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_
    110