cc/layers/video_frame_provider.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 CC_LAYERS_VIDEO_FRAME_PROVIDER_H_
   6 #define CC_LAYERS_VIDEO_FRAME_PROVIDER_H_
   7
   8 #include "base/memory/ref_counted.h"
   9
  10 namespace media {
  11 class VideoFrame;
  12 }
  13
  14 namespace cc {
  15
  16 // Threading notes: This class may be used in a multi threaded manner.
  17 // Specifically, the implementation may call GetCurrentFrame() or
  18 // PutCurrentFrame() from the compositor thread. If so, the caller is
  19 // responsible for making sure Client::DidReceiveFrame() and
  20 // Client::DidUpdateMatrix() are only called from this same thread.
  21 class VideoFrameProvider {
  22  public:
  23   virtual ~VideoFrameProvider() {}
  24
  25   class Client {
  26    public:
  27     // Provider will call this method to tell the client to stop using it.
  28     // StopUsingProvider() may be called from any thread. The client should
  29     // block until it has PutCurrentFrame() any outstanding frames.
  30     virtual void StopUsingProvider() = 0;
  31
  32     // Notifies the provider's client that a call to GetCurrentFrame() will
  33     // return new data.
  34     virtual void DidReceiveFrame() = 0;
  35
  36     // Notifies the provider's client of a new UV transform matrix to be used.
  37     virtual void DidUpdateMatrix(const float* matrix) = 0;
  38
  39    protected:
  40     virtual ~Client() {}
  41   };
  42
  43   // May be called from any thread, but there must be some external guarantee
  44   // that the provider is not destroyed before this call returns.
  45   virtual void SetVideoFrameProviderClient(Client* client) = 0;
  46
  47   // This function places a lock on the current frame and returns a pointer to
  48   // it. Calls to this method should always be followed with a call to
  49   // PutCurrentFrame().
  50   // Only the current provider client should call this function.
  51   virtual scoped_refptr<media::VideoFrame> GetCurrentFrame() = 0;
  52
  53   // This function releases the lock on the video frame. It should always be
  54   // called after GetCurrentFrame(). Frames passed into this method
  55   // should no longer be referenced after the call is made. Only the current
  56   // provider client should call this function.
  57   virtual void PutCurrentFrame(
  58       const scoped_refptr<media::VideoFrame>& frame) = 0;
  59 };
  60
  61 }  // namespace cc
  62
  63 #endif  // CC_LAYERS_VIDEO_FRAME_PROVIDER_H_