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.
5 #ifndef CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_
6 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_
8 #include "base/callback.h"
9 #include "base/time/time.h"
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.
25 // Further processing is possible (e.g. scale and color space conversion)
26 // through this interface. See ShouldCaptureFrame() for details.
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 {
32 virtual ~RenderWidgetHostViewFrameSubscriber() {}
34 // Called when a captured frame is available or the frame is no longer
35 // needed by the platform layer.
37 // If |frame_captured| is true then frame provided contains valid content and
38 // |timestamp| is the time when the frame was painted.
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(
44 base::Time /* timestamp */,
45 bool /* frame_captured */)> DeliverFrameCallback;
47 // Called when a new frame is going to be presented at time
48 // |present_time|. Implementation can decide whether the current frame should
49 // be captured or not.
51 // Return true if the current frame should be captured. If so, |storage|
52 // should will be set to hold an appropriately sized and allocated buffer
53 // into which to copy the frame. The platform presenter will perform scaling
54 // and color space conversion to fit into the output frame.
56 // Destination format is determined by |storage|, currently only
57 // media::VideoFrame::YV12 is supported. Platform layer will perform color
58 // space conversion if needed.
60 // When the frame is available |callback| will be called. It is up to the
61 // platform layer to decide when to deliver a captured frame.
63 // Return false if the current frame should not be captured.
64 virtual bool ShouldCaptureFrame(
65 base::Time present_time,
66 scoped_refptr<media::VideoFrame>* storage,
67 DeliverFrameCallback* callback) = 0;
70 } // namespace content
72 #endif // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_