content/browser/renderer_host/media/web_contents_video_capture_device.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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "content/common/content_export.h"
  12 #include "media/video/capture/video_capture_device.h"
  13
  14 namespace content {
  15
  16 class RenderWidgetHost;
  17
  18 // A virtualized VideoCaptureDevice that mirrors the displayed contents of a
  19 // tab (accessed via its associated WebContents instance), producing a stream of
  20 // video frames.
  21 //
  22 // An instance is created by providing a device_id.  The device_id contains the
  23 // routing ID for a RenderViewHost, and from the RenderViewHost instance, a
  24 // reference to its associated WebContents instance is acquired.  From then on,
  25 // WebContentsVideoCaptureDevice will capture from whatever render view is
  26 // currently associated with that WebContents instance.  This allows the
  27 // underlying render view to be swapped out (e.g., due to navigation or
  28 // crashes/reloads), without any interruption in capturing.
  29 class CONTENT_EXPORT WebContentsVideoCaptureDevice
  30     : public media::VideoCaptureDevice {
  31  public:
  32   // Construct from a |device_id| string of the form:
  33   //   "virtual-media-stream://render_process_id:render_view_id", where
  34   // |render_process_id| and |render_view_id| are decimal integers.
  35   // |destroy_cb| is invoked on an outside thread once all outstanding objects
  36   // are completely destroyed -- this will be some time after the
  37   // WebContentsVideoCaptureDevice is itself deleted.
  38   // TODO(miu): Passing a destroy callback suggests needing to revisit the
  39   // design philosophy of an asynchronous DeAllocate().  http://crbug.com/158641
  40   static media::VideoCaptureDevice* Create(const std::string& device_id);
  41
  42   virtual ~WebContentsVideoCaptureDevice();
  43
  44   // VideoCaptureDevice implementation.
  45   virtual void Allocate(int width,
  46                         int height,
  47                         int frame_rate,
  48                         VideoCaptureDevice::EventHandler* consumer) OVERRIDE;
  49   virtual void Start() OVERRIDE;
  50   virtual void Stop() OVERRIDE;
  51   virtual void DeAllocate() OVERRIDE;
  52
  53   // Note: The following is just a pass-through of the device_id provided to the
  54   // constructor.  It does not change when the content of the page changes
  55   // (e.g., due to navigation), or when the underlying RenderView is
  56   // swapped-out.
  57   virtual const Name& device_name() OVERRIDE;
  58
  59  private:
  60   class Impl;
  61
  62   WebContentsVideoCaptureDevice(const Name& name,
  63                                 int render_process_id,
  64                                 int render_view_id);
  65
  66   Name device_name_;
  67   const scoped_ptr<Impl> impl_;
  68
  69   DISALLOW_COPY_AND_ASSIGN(WebContentsVideoCaptureDevice);
  70 };
  71
  72
  73 }  // namespace content
  74
  75 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_VIDEO_CAPTURE_DEVICE_H_