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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 // TODO(hclam): This class should be renamed to VideoCaptureService.
      6 
      7 // This class provides access to a video capture device in the browser
      8 // process through IPC. The main function is to deliver video frames
      9 // to a client.
     10 //
     11 // THREADING
     12 //
     13 // VideoCaptureImplManager lives only on the render thread. All methods
     14 // must be called on this thread.
     15 //
     16 // VideoFrames are delivered on the IO thread. Callbacks provided by
     17 // a client are also called on the IO thread.
     18 
     19 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
     20 #define CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
     21 
     22 #include <map>
     23 
     24 #include "base/callback.h"
     25 #include "base/memory/linked_ptr.h"
     26 #include "base/memory/ref_counted.h"
     27 #include "base/memory/scoped_ptr.h"
     28 #include "base/memory/weak_ptr.h"
     29 #include "base/message_loop/message_loop_proxy.h"
     30 #include "base/synchronization/lock.h"
     31 #include "base/threading/thread_checker.h"
     32 #include "content/common/content_export.h"
     33 #include "content/common/media/video_capture.h"
     34 #include "content/public/renderer/media_stream_video_sink.h"
     35 #include "media/video/capture/video_capture_types.h"
     36 
     37 namespace content {
     38 
     39 class VideoCaptureImpl;
     40 class VideoCaptureMessageFilter;
     41 
     42 class CONTENT_EXPORT VideoCaptureImplManager {
     43  public:
     44   VideoCaptureImplManager();
     45   virtual ~VideoCaptureImplManager();
     46 
     47   // Open a device associated with the session ID.
     48   // This method must be called before any methods with the same ID
     49   // is used.
     50   // Returns a callback that should be used to release the acquired
     51   // resources.
     52   base::Closure UseDevice(media::VideoCaptureSessionId id);
     53 
     54   // Start receiving video frames for the given session ID.
     55   //
     56   // |state_update_cb| will be called on the IO thread when capturing
     57   // state changes.
     58   // States will be one of the following four:
     59   // * VIDEO_CAPTURE_STATE_STARTED
     60   // * VIDEO_CAPTURE_STATE_STOPPED
     61   // * VIDEO_CAPTURE_STATE_PAUSED
     62   // * VIDEO_CAPTURE_STATE_ERROR
     63   //
     64   // |deliver_frame_cb| will be called on the IO thread when a video
     65   // frame is ready.
     66   //
     67   // Returns a callback that is used to stop capturing. Note that stopping
     68   // video capture is not synchronous. Client should handle the case where
     69   // callbacks are called after capturing is instructed to stop, typically
     70   // by binding the passed callbacks on a WeakPtr.
     71   base::Closure StartCapture(
     72       media::VideoCaptureSessionId id,
     73       const media::VideoCaptureParams& params,
     74       const VideoCaptureStateUpdateCB& state_update_cb,
     75       const VideoCaptureDeliverFrameCB& deliver_frame_cb);
     76 
     77   // Get supported formats supported by the device for the given session
     78   // ID. |callback| will be called on the IO thread.
     79   void GetDeviceSupportedFormats(
     80       media::VideoCaptureSessionId id,
     81       const VideoCaptureDeviceFormatsCB& callback);
     82 
     83   // Get supported formats currently in use for the given session ID.
     84   // |callback| will be called on the IO thread.
     85   void GetDeviceFormatsInUse(
     86       media::VideoCaptureSessionId id,
     87       const VideoCaptureDeviceFormatsCB& callback);
     88 
     89   // Make all existing VideoCaptureImpl instances stop/resume delivering
     90   // video frames to their clients, depends on flag |suspend|.
     91   void SuspendDevices(bool suspend);
     92 
     93   VideoCaptureMessageFilter* video_capture_message_filter() const {
     94     return filter_.get();
     95   }
     96 
     97  protected:
     98   virtual VideoCaptureImpl* CreateVideoCaptureImplForTesting(
     99       media::VideoCaptureSessionId id,
    100       VideoCaptureMessageFilter* filter) const;
    101 
    102  private:
    103   void StopCapture(int client_id, media::VideoCaptureSessionId id);
    104   void UnrefDevice(media::VideoCaptureSessionId id);
    105 
    106   // The int is used to count clients of the corresponding VideoCaptureImpl.
    107   // VideoCaptureImpl objects are owned by this object. But they are
    108   // destroyed on the IO thread. These are raw pointers because we destroy
    109   // them manually.
    110   typedef std::map<media::VideoCaptureSessionId,
    111                    std::pair<int, VideoCaptureImpl*> >
    112       VideoCaptureDeviceMap;
    113   VideoCaptureDeviceMap devices_;
    114 
    115   // This is an internal ID for identifying clients of VideoCaptureImpl.
    116   // The ID is global for the render process.
    117   int next_client_id_;
    118 
    119   scoped_refptr<VideoCaptureMessageFilter> filter_;
    120 
    121   // Bound to the render thread.
    122   base::ThreadChecker thread_checker_;
    123 
    124   // Bound to the render thread.
    125   // NOTE: Weak pointers must be invalidated before all other member variables.
    126   base::WeakPtrFactory<VideoCaptureImplManager> weak_factory_;
    127 
    128   DISALLOW_COPY_AND_ASSIGN(VideoCaptureImplManager);
    129 };
    130 
    131 }  // namespace content
    132 
    133 #endif  // CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_MANAGER_H_
    134