content/port/browser/render_widget_host_view_frame_subscriber.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_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_
   6 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/time/time.h"
  10
  11 namespace gfx {
  12 class Rect;
  13 class Size;
  14 }  // namespace gfx
  15
  16 namespace media {
  17 class VideoFrame;
  18 }  // namespace media
  19
  20 namespace content {
  21
  22 // Defines an interface for listening to events of frame presentation and to
  23 // instruct the platform layer (i.e. RenderWidgetHostViewPort) to copy a frame.
  24 //
  25 // Further processing is possible (e.g. scale and color space conversion)
  26 // through this interface. See ShouldCaptureFrame() for details.
  27 //
  28 // It is platform dependent which thread this object lives on, but it is
  29 // guaranteed to be used on a single thread.
  30 class RenderWidgetHostViewFrameSubscriber {
  31  public:
  32   virtual ~RenderWidgetHostViewFrameSubscriber() {}
  33
  34   // Called when a captured frame is available or the frame is no longer
  35   // needed by the platform layer.
  36   //
  37   // If |frame_captured| is true then frame provided contains valid content and
  38   // |timestamp| is the time when the frame was painted.
  39   //
  40   // If |frame_captured| is false then the content in frame provided is
  41   // invalid. There was an error during the process of frame capture or the
  42   // platform layer is shutting down. |timestamp| is also invalid in this case.
  43   typedef base::Callback<void(base::TimeTicks /* timestamp */,
  44                               bool /* frame_captured */)> DeliverFrameCallback;
  45
  46   // Called when a new frame is going to be presented at time
  47   // |present_time|. Implementation can decide whether the current frame should
  48   // be captured or not.
  49   //
  50   // Return true if the current frame should be captured. If so, |storage|
  51   // should will be set to hold an appropriately sized and allocated buffer
  52   // into which to copy the frame. The platform presenter will perform scaling
  53   // and color space conversion to fit into the output frame.
  54   //
  55   // Destination format is determined by |storage|, currently only
  56   // media::VideoFrame::YV12 is supported. Platform layer will perform color
  57   // space conversion if needed.
  58   //
  59   // When the frame is available |callback| will be called. It is up to the
  60   // platform layer to decide when to deliver a captured frame.
  61   //
  62   // Return false if the current frame should not be captured.
  63   virtual bool ShouldCaptureFrame(base::TimeTicks present_time,
  64                                   scoped_refptr<media::VideoFrame>* storage,
  65                                   DeliverFrameCallback* callback) = 0;
  66 };
  67
  68 }  // namespace content
  69
  70 #endif  // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_