media/blink/video_frame_compositor.h

   1 // Copyright 2014 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 MEDIA_BLINK_VIDEO_FRAME_COMPOSITOR_H_
   6 #define MEDIA_BLINK_VIDEO_FRAME_COMPOSITOR_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "cc/layers/video_frame_provider.h"
  11 #include "media/base/media_export.h"
  12 #include "ui/gfx/geometry/size.h"
  13
  14 namespace media {
  15 class VideoFrame;
  16
  17 // VideoFrameCompositor handles incoming frames by notifying the compositor and
  18 // dispatching callbacks when detecting changes in video frames.
  19 //
  20 // Typical usage is to deliver ready-to-be-displayed video frames to
  21 // UpdateCurrentFrame() so that VideoFrameCompositor can take care of tracking
  22 // changes in video frames and firing callbacks as needed.
  23 //
  24 // VideoFrameCompositor must live on the same thread as the compositor.
  25 class MEDIA_EXPORT VideoFrameCompositor
  26     : NON_EXPORTED_BASE(public cc::VideoFrameProvider) {
  27  public:
  28   // |natural_size_changed_cb| is run with the new natural size of the video
  29   // frame whenever a change in natural size is detected. It is not called the
  30   // first time UpdateCurrentFrame() is called. Run on the same thread as the
  31   // caller of UpdateCurrentFrame().
  32   //
  33   // |opacity_changed_cb| is run when a change in opacity is detected. It *is*
  34   // called the first time UpdateCurrentFrame() is called. Run on the same
  35   // thread as the caller of UpdateCurrentFrame().
  36   //
  37   // TODO(scherkus): Investigate the inconsistency between the callbacks with
  38   // respect to why we don't call |natural_size_changed_cb| on the first frame.
  39   // I suspect it was for historical reasons that no longer make sense.
  40   VideoFrameCompositor(
  41       const base::Callback<void(gfx::Size)>& natural_size_changed_cb,
  42       const base::Callback<void(bool)>& opacity_changed_cb);
  43   ~VideoFrameCompositor() override;
  44
  45   // cc::VideoFrameProvider implementation.
  46   void SetVideoFrameProviderClient(
  47       cc::VideoFrameProvider::Client* client) override;
  48   scoped_refptr<VideoFrame> GetCurrentFrame() override;
  49   void PutCurrentFrame(const scoped_refptr<VideoFrame>& frame) override;
  50
  51   // Updates the current frame and notifies the compositor.
  52   void UpdateCurrentFrame(const scoped_refptr<VideoFrame>& frame);
  53
  54  private:
  55   base::Callback<void(gfx::Size)> natural_size_changed_cb_;
  56   base::Callback<void(bool)> opacity_changed_cb_;
  57
  58   cc::VideoFrameProvider::Client* client_;
  59
  60   scoped_refptr<VideoFrame> current_frame_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(VideoFrameCompositor);
  63 };
  64
  65 }  // namespace media
  66
  67 #endif  // MEDIA_BLINK_VIDEO_FRAME_COMPOSITOR_H_