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// Copyright 2015 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 MEDIA_BASE_VIDEO_RENDERER_SINK_H_
#define MEDIA_BASE_VIDEO_RENDERER_SINK_H_
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/video_frame.h"
namespace media {
// VideoRendererSink is an interface representing the end-point for rendered
// video frames. An implementation is expected to periodically call Render() on
// a callback object.
class MEDIA_EXPORT VideoRendererSink {
public:
class RenderCallback {
public:
// Returns a VideoFrame for rendering which should be displayed within the
// presentation interval [|deadline_min|, |deadline_max|]. Returns NULL if
// no frame or no new frame (since the last Render() call) is available for
// rendering within the requested interval. Intervals are expected to be
// regular, contiguous, and monotonically increasing. Irregular intervals
// may affect the rendering decisions made by the underlying callback.
//
// If |background_rendering| is true, the VideoRenderSink is pumping
// callbacks at a lower frequency than normal and the results of the
// Render() call may not be used.
virtual scoped_refptr<VideoFrame> Render(base::TimeTicks deadline_min,
base::TimeTicks deadline_max,
bool background_rendering) = 0;
// Called by the sink when a VideoFrame previously returned via Render() was
// not actually rendered. Must be called before the next Render() call.
virtual void OnFrameDropped() = 0;
virtual ~RenderCallback() {}
};
// Starts video rendering. See RenderCallback for more details. Must be
// called to receive Render() callbacks. Callbacks may start immediately, so
// |callback| must be ready to receive callbacks before calling Start().
virtual void Start(RenderCallback* callback) = 0;
// Stops video rendering, waits for any outstanding calls to the |callback|
// given to Start() to complete before returning. No new calls to |callback|
// will be issued after this method returns. May be used as a means of power
// conservation by the sink implementation, so clients should call this
// liberally if no new frames are expected.
virtual void Stop() = 0;
// Instead of using a callback driven rendering path, allow clients to paint a
// single frame as they see fit without regard for the compositor; this is
// useful for painting poster images or hole frames without having to issue a
// Start() -> Render() -> Stop(). Clients are free to mix usage of Render()
// based painting and PaintSingleFrame().
virtual void PaintSingleFrame(const scoped_refptr<VideoFrame>& frame,
bool repaint_duplicate_frame = false) = 0;
virtual ~VideoRendererSink() {}
};
} // namespace media
#endif // MEDIA_BASE_VIDEO_RENDERER_SINK_H_
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