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