Mojo Video Capture service in media/capture

media/capture/service/stream_impl.h

+// Copyright 2016 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_CAPTURE_SERVICE_STREAM_IMPL_H_
+#define MEDIA_CAPTURE_SERVICE_STREAM_IMPL_H_
+
+#include <map>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "media/capture/interfaces/video_capture.mojom.h"
+#include "media/capture/service/video_capture_device_client_impl.h"
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+#include "mojo/public/cpp/system/buffer.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+class TimeTicks;
+}
+
+namespace media {
+class VideoFrame;
+}
+
+namespace media {
+
+class MojoVideoFrame;
+
+// This class bridges a VideoCaptureDeviceClientImpl with the mojo pipe where we
+// push captured VideoFrames.
+class StreamImpl : public mojom::Stream,
+                   public VideoCaptureDeviceClientImpl::Delegate {
+ public:
+  // |start_callback| is called when this object is started by its client.
+  // |close_callback| is called when this object is stopped by its client.
+  // |error_callback| is called upon internal error or NotifyError().
+  StreamImpl(mojo::InterfaceRequest<mojom::Stream> request,
+             const base::Closure& start_callback,
+             const base::Closure& close_callback,
+             const base::Closure& error_callback);
+
+  ~StreamImpl() override;
+
+  // mojom::Stream
+  void Start(mojom::StreamClientPtr client) override;
+  void Stop() override;
+
+  // VideoCaptureDeviceClientImpl::Delegate
+  void OnFrame(const scoped_refptr<MojoVideoFrame>& frame,
+               const base::TimeTicks& timestamp) override;
+  void OnError(const std::string& reason) override;
+
+ private:
+  friend class StreamImplTest;
+
+  // The following Notify* methods mimic those in StreamClient and act as a
+  // bridge to Mojo. They all must not be called until the stream has been
+  // Start()ed.
+
+  // Pushes a |frame| to the client.
+  void NotifyFrameAvailable(const scoped_refptr<MojoVideoFrame>& frame,
+                            const base::TimeTicks& timestamp);
+  void NotifyError(const mojo::String& error);
+
+  // Bound for the client to notify us that it's done with the VideoFrame

[perkj_chrome, 2016/03/03 13:12:41]

bound to what? Bound to the video frame destructor forwarded to the client ? 

[mcasas, 2016/03/03 18:41:15]

Explained.

+  // identified by |buffer_id|.
+  void OnFrameConsumed(int32_t buffer_id);
+
+  mojo::Binding<mojom::Stream> binding_;
+  const base::Closure start_callback_;
+  const base::Closure close_callback_;
+  const base::Closure error_callback_;
+
+  mojom::StreamClientPtr client_;
+
+  bool paused_ = false;
+
+  // Map of VideoFrames in use by a client. Each VF gets an id assigned by which
+  // the client knows it. The buffer ID is just a simple running counter.
+  int running_buffer_id_ = 0;
+  std::map<int32_t, const scoped_refptr<MojoVideoFrame>&> in_use_video_frames_;
+
+  // The TaskRunner where this class lives, needed for OnFrame() and OnError()
+  // to PostTask() to.
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  base::WeakPtrFactory<StreamImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(StreamImpl);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CAPTURE_SERVICE_STREAM_IMPL_H_