MediaStreamDispatcher

content/renderer/media/media_stream_dispatcher.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.
+
+#ifndef CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
+#define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_
+
+#include <list>
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/message_loop.h"
+#include "content/common/media/media_stream_options.h"
+#include "content/renderer/media/media_stream_dispatcher_eventhandler.h"
+#include "content/renderer/render_view_observer.h"
+
+// MediaStreamDispatcher is a delegate for the Media Stream API messages.
+// MediaStreams are used by WebKit to open media devices such as Video Capture
+// and Audio input devices.
+// It's the complement of MediaStreamDispatcherHost (owned by
+// BrowserRenderProcessHost).
+class MediaStreamDispatcher : public RenderViewObserver {
+ public:
+  explicit MediaStreamDispatcher(RenderView* render_view);
+  virtual ~MediaStreamDispatcher();
+
+  // Request a new media stream to be created.
+  // This can be used either of WebKit or a plugin.
+  // Note: The event_handler must be valid for as long as the stream exists.
+  void GenerateStream(int request_id,
+                      MediaStreamDispatcherEventHandler* event_handler,
+                      media_stream::GenerateStreamOptions components,
+                      const std::string& security_origin);
+
+  // Stop a started stream. Label is the label provided in OnStreamGenerated.
+  void StopStream(const std::string& label);
+
+  // Returns a StreamDeviceInfoArray given a label. This can be used for
+  // verifying if a label is an opened media stream.
+  const media_stream::StreamDeviceInfoArray& audio_device_array(

[scherkus (not reviewing), 2011/06/17 17:42:13]

this isn't any better since it's too easy to have the original array go out of
scope and Bad Things Happen.

once again would having a method like IsAudioDeviceOpen(...) suit your purposes?

if you absolutely have to have a copy of the array then pass in a
StreamDeviceInfoArray* as an out-param

[Per K, 2011/06/18 19:53:59]

The purpose of these two methods are for the media filter later to be able to
get the session_id that identifies an opened device so it can start/stop the
device and set resolution etc.. For video this id is used in
VideoCaptureImplManager::AddDevice - (VideoCaptureSesionId). 

At the moment it is only the session_id I know is needed so therefore I only
keep getter methods for getting that. Also - the stream API states that there
can be multiple devices in each list but only one selected video device. the
index is therefor the index in this video_device_array.  

+      const std::string& label);
+  const media_stream::StreamDeviceInfoArray& video_device_array(
+      const std::string& label);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, Basic);
+  FRIEND_TEST_ALL_PREFIXES(MediaStreamDispatcherTest, TestFailure);
+
+  typedef int IpcRequestId;
+  struct Request {
+    Request(MediaStreamDispatcherEventHandler* handler,
+            int request_id,
+            IpcRequestId ipc_request)
+        : handler(handler),
+          request_id(request_id),
+          ipc_request(ipc_request) {
+    }
+    MediaStreamDispatcherEventHandler* handler;
+    int request_id;
+    int ipc_request;
+  };
+
+  // Private class for keeping track of opened devices and who have
+  // opened it.
+  struct Stream {
+    MediaStreamDispatcherEventHandler* handler;
+    media_stream::StreamDeviceInfoArray audio_array;
+    media_stream::StreamDeviceInfoArray video_array;
+  };
+
+  // Messages from the browser.
+  virtual bool OnMessageReceived(const IPC::Message& message);
+  void OnStreamGenerated(
+      int request_id,
+      const std::string& label,
+      const media_stream::StreamDeviceInfoArray& audio_array,
+      const media_stream::StreamDeviceInfoArray& video_array);
+  void OnStreamGenerationFailed(int requestId);

[scherkus (not reviewing), 2011/06/17 17:42:13]

requestId -> request_id

[Per K, 2011/06/18 19:53:59]

Hard do change an old habit... Done.

+  void OnVideoDeviceFailed(const std::string& label, int index);
+  void OnAudioDeviceFailed(const std::string& label, int index);
+
+  IpcRequestId next_ipc_id_;
+  typedef std::map<std::string, Stream> LabelStreamMap;
+  LabelStreamMap label_stream_map_;
+
+  // List of calls made to GenerateStream that has not yet completed.
+  typedef std::list<Request> RequestList;
+  RequestList requests_;
+  MessageLoop* message_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaStreamDispatcher);
+};
+
+#endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_DISPATCHER_H_