Mojo Video Capture service in media/capture

media/capture/service/video_capture_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_VIDEO_CAPTURE_STREAM_IMPL_H_
+#define MEDIA_CAPTURE_SERVICE_VIDEO_CAPTURE_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 MojoSharedBufferVideoFrame;
+
+// This class bridges a VideoCaptureDeviceClientImpl with the mojo pipe where we
+// push captured VideoFrames.
+class VideoCaptureStreamImpl : public mojom::VideoCaptureStream,
+                               public VideoCaptureDeviceClientImpl::Delegate {
+ public:
+  // |stop_callback| is called when this object is stopped by its client.
+  // |error_callback| is called upon internal error or NotifyError().
+  VideoCaptureStreamImpl(
+      mojo::InterfaceRequest<mojom::VideoCaptureStream> request,
+      const base::Closure& stop_callback,
+      const base::Closure& error_callback);
+
+  ~VideoCaptureStreamImpl() override;
+
+  // mojom::VideoCaptureStream
+  void Start(mojom::VideoCaptureStreamClientPtr client) override;
+  void Stop() override;
+
+  // VideoCaptureDeviceClientImpl::Delegate
+  void OnFrame(const scoped_refptr<MojoSharedBufferVideoFrame>& frame,
+               const base::TimeTicks& timestamp) override;
+  void OnError(const std::string& reason) override;
+
+ private:
+  friend class VideoCaptureStreamImplTest;
+
+  // The following Notify* methods mimic those in VideoCaptureStreamClient 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 NotifyOnFrameAvailable(
+      const scoped_refptr<MojoSharedBufferVideoFrame>& frame,
+      const base::TimeTicks& timestamp);
+  void NotifyError(const mojo::String& error);
+
+  // Bound to the client's OnFrameAvailable message to let it notify us that
+  // it's finished with the VideoFrame identified by |buffer_id|.
+  void OnFrameConsumed(int32_t buffer_id);
+
+  mojo::Binding<mojom::VideoCaptureStream> binding_;
+  const base::Closure stop_callback_;
+  const base::Closure error_callback_;
+
+  mojom::VideoCaptureStreamClientPtr client_;
+
+  // 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, scoped_refptr<MojoSharedBufferVideoFrame>>
+      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<VideoCaptureStreamImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureStreamImpl);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CAPTURE_SERVICE_VIDEO_CAPTURE_STREAM_IMPL_H_