text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
  #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
  
  #include <string>
  
  #include "base/memory/scoped_ptr.h"
  #include "content/common/content_export.h"
  #include "media/video/capture/video_capture_device.h"
  
  namespace content {
  
  class RenderWidgetHost;
  
  // A virtualized VideoCaptureDevice that mirrors the displayed contents of a
  // tab (accessed via its associated WebContents instance), producing a stream of
  // video frames.
  //
  // An instance is created by providing a device_id.  The device_id contains the
  // routing ID for a RenderViewHost, and from the RenderViewHost instance, a
  // reference to its associated WebContents instance is acquired.  From then on,
  // WebContentsVideoCaptureDevice will capture from whatever render view is
  // currently associated with that WebContents instance.  This allows the
  // underlying render view to be swapped out (e.g., due to navigation or
  // crashes/reloads), without any interruption in capturing.
  class CONTENT_EXPORT WebContentsVideoCaptureDevice
      : public media::VideoCaptureDevice {
   public:
    // Construct from a |device_id| string of the form:
    //   "virtual-media-stream://render_process_id:render_view_id", where
    // |render_process_id| and |render_view_id| are decimal integers.
    // |destroy_cb| is invoked on an outside thread once all outstanding objects
    // are completely destroyed -- this will be some time after the
    // WebContentsVideoCaptureDevice is itself deleted.
    // TODO(miu): Passing a destroy callback suggests needing to revisit the
    // design philosophy of an asynchronous DeAllocate().  http://crbug.com/158641
    static media::VideoCaptureDevice* Create(const std::string& device_id);
  
    virtual ~WebContentsVideoCaptureDevice();
  
    // VideoCaptureDevice implementation.
    virtual void Allocate(int width,
                          int height,
                          int frame_rate,
                          VideoCaptureDevice::EventHandler* consumer) OVERRIDE;
    virtual void Start() OVERRIDE;
    virtual void Stop() OVERRIDE;
    virtual void DeAllocate() OVERRIDE;
  
    // Note: The following is just a pass-through of the device_id provided to the
    // constructor.  It does not change when the content of the page changes
    // (e.g., due to navigation), or when the underlying RenderView is
    // swapped-out.
    virtual const Name& device_name() OVERRIDE;
  
   private:
    class Impl;
  
    WebContentsVideoCaptureDevice(const Name& name,
                                  int render_process_id,
                                  int render_view_id);
  
    Name device_name_;
    const scoped_ptr<Impl> impl_;
  
    DISALLOW_COPY_AND_ASSIGN(WebContentsVideoCaptureDevice);
  };
  
  
  }  // namespace content
  
  #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
  