VideoCaptureManager opens/closes, starts/stops and enumerates video capture devices. VideoCapture...

content/browser/media_stream/video_capture_manager.h

+// Copyright (c) 2011 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.
+
+// VideoCaptureManager is used to open/close, start/stop as well as enumerate
+// available video capture devices. All functions are expected to be called from
+// the Browser::IO thread. VideoCaptureManager will open OS dependent instances
+// of VideoCaptureDevice. A device can only be opened once.
+
+#ifndef CONTENT_BROWSER_MEDIA_STREAM_VIDEO_CAPTURE_MANAGER_H_
+#define CONTENT_BROWSER_MEDIA_STREAM_VIDEO_CAPTURE_MANAGER_H_
+#pragma once

[wjia(left Chromium), 2011/05/06 00:11:31]

pragma is not needed.

[mflodman1, 2011/05/06 11:52:38]

Done.

+
+// TODO(mflodman) Use device type instead of int!
+#include <map>
+
+#include "base/lazy_instance.h"
+#include "base/threading/thread.h"
+#include "content/browser/media_stream/media_stream_provider.h"
+#include "media/video/capture/video_capture_types.h"
+#include "media/video/capture/video_capture_device.h"

[mflodman1, 2011/05/05 11:11:22]

Will change include order or _types.h and device.h in next upload.

[mflodman1, 2011/05/06 11:52:38]

Done.

+
+namespace media_stream {
+
+class VideoCaptureManager
+    : public MediaStreamProvider {
+  public:
+  // Calling Start of this id will open the first device, even though open has
+  // not been called. Temporary(?) before MediaStreamManager is submitted.

[wjia(left Chromium), 2011/05/06 00:11:31]

Will this enum stay even after MediaStreamManager is added? If not, could you
add TODO here since it will be changed (removed?) after MediaStreamManager is
submitted?

[mflodman1, 2011/05/06 11:52:38]

Comment updated, removed last part.
I don't know. This will still be there if it is needed by some other team than
WebRtc that won't use MediaStreamManager, e.g. Pepper.

+  enum { kStartOpenSessionId = 0 };
+
+  // Called to get a pointer to the singleton
+  static VideoCaptureManager* Get();
+
+  // Implements MediaStreamProvider:
+  //    Register, Unregister, Open, Close, EnumerateDevices

[wjia(left Chromium), 2011/05/06 00:11:31]

no need to have comments for each function. These comments would be in base
class.

[mflodman1, 2011/05/06 11:52:38]

Done.

+  // Registers a listener to get results from Open, Close and EnumerateDevices.
+  virtual int Register(MediaStreamType service_type,

[wjia(left Chromium), 2011/05/06 00:11:31]

what's the meaning of returned value? If there are only 0 and non-zero, bool is
recommended.

[mflodman1, 2011/05/06 11:52:38]

Done.

+                       MediaStreamProviderListener* listener);
+  virtual void Unregister(MediaStreamType stream_type,
+                          MediaStreamProviderListener* listener);
+
+  // Enumerates existing video capture devices and calls the registered
+  // listener.
+  virtual void EnumerateDevices(MediaStreamType stream_type);
+
+  // Opens the specified device. The device is not started and it is still
+  // possible for other applications to open the device before the device is
+  // started.
+  virtual MediaCaptureSessionId Open(MediaStreamType stream_type,
+                                     const MediaCaptureDeviceInfo& device);
+  virtual void Close(MediaStreamType stream_type,
+                     MediaCaptureSessionId capture_session_id);

[wjia(left Chromium), 2011/05/06 00:11:31]

How many modules will call Open/Close? If there are multiple, is it needed to
have policy such as only whoever opens the device can close the device?

[mflodman1, 2011/05/06 11:52:38]

Only one module will call Open/Close, only one listener is allowed.

+
+  // Functions used to start and stop media flow.
+  // Start allocates the device and no other application can use the device
+  // before Stop is called.
+  void Start(const media::VideoCaptureParams& capture_params,
+             media::VideoCaptureDevice::EventHandler* video_capture_receiver);
+
+  // 'stopped_task' will be called when a device has been stopped and no more

[wjia(left Chromium), 2011/05/06 00:11:31]

would it good to rephrase this to:
Stop device capture referenced by |capture_session_id|. No more frames will be
delivered to the frame receiver, and |stopped_task| will be called.

[mflodman1, 2011/05/06 11:52:38]

Comment updated.

+  // frames will be delivered to the frame receiver.
+  void Stop(const media::VideoCaptureSessionId capture_session_id,
+            Task* stopped_task);
+
+  virtual ~VideoCaptureManager();
+
+  // Used for unit test to make sure a fake device is used instead of a real
+  // video capture device, due to time requirements.
+  static void CreateTestManager();
+  MessageLoop* GetMessageLoop();
+
+ protected:
+  // Used for testing to mock platform dependent device code.
+  void UseFakeDevice();
+  static bool use_fake_device_;
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<VideoCaptureManager>;
+
+  VideoCaptureManager();
+
+  // Called by the public functions, executed on vc_device_thread_.
+  void OnEnumerateDevices();
+  void OnOpen(MediaCaptureSessionId capture_session_id,
+              const MediaCaptureDeviceInfo device);
+  void OnClose(MediaCaptureSessionId capture_session_id);
+  void OnStart(const media::VideoCaptureParams capture_params,
+               media::VideoCaptureDevice::EventHandler* video_capture_receiver);
+  void OnStop(const media::VideoCaptureSessionId capture_session_id,
+              Task* stopped_task);
+
+
+  // Executed on Browser::IO thread to call Listener.
+  void OnOpened(MediaCaptureSessionId capture_session_id);
+  void OnClosed(MediaCaptureSessionId capture_session_id);
+  void OnDevicesEnumerated(const MediaCaptureDevices& devices);
+  void OnError(MediaCaptureSessionId capture_session_id,
+               MediaStreamProviderError error);
+
+  // Executed on vc_device_thread_ to make sure Listener is called from
+  // Browser::IO thread.
+  void PostOnOpened(MediaCaptureSessionId capture_session_id);
+  void PostOnClosed(MediaCaptureSessionId capture_session_id);
+  void PostOnDevicesEnumerated(
+      const MediaCaptureDevices& devices);
+  void PostOnError(MediaCaptureSessionId capture_session_id,
+                   MediaStreamProviderError error);
+
+  // Called on Browser::IO thread, forwarders to the singleton methods.
+  // Required to avoid the ownership of the manager object to be managed by both
+  // RefCountedThreadSafe and LazyInstance.
+  static void OnOpenedProxy(MediaCaptureSessionId capture_session_id);
+  static void OnClosedProxy(MediaCaptureSessionId capture_session_id);
+  static void OnDevicesEnumeratedProxy(const MediaCaptureDevices devices);
+  static void OnErrorProxy(MediaCaptureSessionId capture_session_id,
+                           MediaStreamProviderError error);
+
+  // Helpers
+  void GetAvailableDevices(media::VideoCaptureDevice::Names* device_names);
+  bool DeviceOpened(const media::VideoCaptureDevice::Name& device_name);
+  bool IsOnCaptureDeviceThread() const;
+
+  // Thread for all calls to VideoCaptureDevice
+  base::Thread vc_device_thread_;
+
+  // Only accessed on IO thread
+  MediaStreamProviderListener* listener_;
+  MediaCaptureSessionId new_capture_session_id_;
+
+  // Only accessed from vc_device_thread_
+  typedef std::map<int, media::VideoCaptureDevice*> VideoCaptureDevices;
+  VideoCaptureDevices devices_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureManager);
+};
+
+}  // namespace media_stream
+
+DISABLE_RUNNABLE_METHOD_REFCOUNT(media_stream::VideoCaptureManager);
+
+#endif  // CONTENT_BROWSER_MEDIA_STREAM_VIDEO_CAPTURE_MANAGER_H_

[mflodman1, 2011/05/05 11:11:22]

Will add newline in next upload.

[mflodman1, 2011/05/06 11:52:38]

Done.