VideoCaptureHost

content/browser/renderer_host/video_capture_host.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.
+//
+// VideoCaptureHost serves video capture related requests from VideCaptureImpl

[wjia(left Chromium), 2011/05/11 23:23:31]

The counterpart of VideoCaptureHost is VideoCaptureMessageFilter in renderer
process. VideoCaptureMessageFilter takes care of message routing and device_id,
while VideoCaptureImpl presents video capture device to its clients.
VideoCaptureImpl is the major horse to generate messages. The device_id is
created by VCMessageFilter and assigned to a VCImpl.

With this information, could you rephrase some comments (here and below) related
to modules in renderer process?

[Per K, 2011/05/16 11:49:39]

Done.

+// which lives inside the render process and provide access to video capture
+// hardware.
+//
+// This class is owned by BrowserRenderProcessHost, and instantiated on UI
+// thread, but all other operations and method calls happen on IO thread.
+//
+// Here's an example of a typical IPC dialog for video capture:
+//
+//   Renderer                          VideoCaptureHost
+//      |                                     |
+//      |  VideoCaptureHostMsg_Start >        |
+//      |  < VideoCaptureMsg_DeviceInfo       |
+//      |                                     |
+//      | < VideoCaptureMsg_StateChanged      |
+//      |        (kStarted)                   |
+//      | < VideoCaptureMsg_BufferReady       |
+//      |             ...                     |
+//      | < VideoCaptureMsg_BufferReady       |
+//      |             ...                     |
+//      | VideoCaptureHostMsg_BufferReady >   |
+//      | VideoCaptureHostMsg_BufferReady >   |
+//      |                                     |
+//      |             ...                     |
+//      |                                     |
+//      | < VideoCaptureMsg_BufferReady       |
+//      |  VideoCaptureHostMsg_Stop >         |
+//      | VideoCaptureHostMsg_BufferReady >   |
+//      | < VideoCaptureMsg_StateChanged      |
+//      |         (kStopped)                  |
+//      v                                     v
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_HOST_H_
+#define CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_HOST_H_
+
+#include <list>
+#include <map>
+
+#include "content/browser/browser_message_filter.h"
+#include "content/browser/renderer_host/video_capture_memory.h"
+#include "ipc/ipc_message.h"
+#include "media/video/capture/video_capture.h"
+
+class VideoCaptureHost : public BrowserMessageFilter,
+                         public VideoCaptureMemory::EventHandler {
+ public:
+  VideoCaptureHost();
+
+  // BrowserMessageFilter implementation.
+  virtual void OnChannelClosing();
+  virtual void OnDestruct() const;
+  virtual bool OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok);
+
+  // VideoCaptureMemory::EventHandler implementation.
+  virtual void OnError(VideoCaptureMemory::VCEntryId entry);
+  virtual void OnBufferReady(VideoCaptureMemory::VCEntryId entry,
+                             TransportDIB::Handle handle,
+                             base::Time timestamp);
+  virtual void OnFrameInfo(VideoCaptureMemory::VCEntryId entry,
+                           int width,
+                           int height,
+                           int frame_per_second);
+
+ private:
+  friend class BrowserThread;
+  friend class DeleteTask<VideoCaptureHost>;
+  friend class MockVideoCaptureHost;
+  friend class VideoCaptureHostTest;
+
+  typedef std::map<int, VideoCaptureMemory*> VCEntryMap;
+
+  virtual ~VideoCaptureHost();
+
+  // IPC message: Start capture on the VideoCaptureDevice referenced by
+  // VideoCaptureParams::session_id.
+  // device_id is an id created by VideoCaptureImpl to identify a session
+  // between a VideoCaptureImpl and a VideoCaptureHost.
+  void OnStartCapture(const IPC::Message& msg, int device_id,
+                      const media::VideoCaptureParams& params);
+
+  // IPC message: Stop capture on device referenced by device_id.
+  void OnStopCapture(const IPC::Message& msg, int device_id);
+
+  // IPC message: Pause capture on device referenced by device_id.
+  void OnPauseCapture(const IPC::Message& msg, int device_id);
+
+  // IPC message: Receive an empty buffer from renderer. Send it to device
+  // referenced by |device_id|.
+  void OnReceiveEmptyBuffer(const IPC::Message& msg,
+                            int device_id,
+                            TransportDIB::Handle handle);
+
+  // Called by VideoCaptureManager when a device have been stopped.
+  void OnDeviceStoped(int device_id);

[wjia(left Chromium), 2011/05/11 23:23:31]

OnDeviceStopped

[Per K, 2011/05/16 11:49:39]

Done.

+
+  // Removed the VideoCaptureMemory from the list of started devices.
+  // Called on the IO thread when OnDeviceStoped have been called
+  // by the VideoCaptureManager.
+  void DoDeviceStoped(int device_id);

[wjia(left Chromium), 2011/05/11 23:23:31]

ditto

[Per K, 2011/05/16 11:49:39]

Done.

+
+  // Send a filled buffer to the VideoCaptureMessageFilter.
+  void DoSendFilledBuffer(VideoCaptureMemory::VCEntryId entry,
+                          TransportDIB::Handle handle,
+                          base::Time timestamp);
+
+  // Send a information about frame resolution and frame rate
+  // to the VideoCaptureMessageFilter.
+  void DoSendFrameInfo(VideoCaptureMemory::VCEntryId entry,
+                       int width,
+                       int height,
+                       int frame_per_second);
+
+  // Handle error coming from VideoCaptureDevice.
+  void DoHandleError(VideoCaptureMemory::VCEntryId entry);
+
+  // Sends the new state to the VideoCaptureImpl.
+  void SendDeviceStopped(int32 render_view_id, int device_id);
+
+  // Send an error message to the renderer.
+  void SendErrorMessage(int32 render_view_id, int device_id);
+
+  // Stop the related VideCaptureDevice.
+  void StopVideoCapture(VideoCaptureMemory::VCEntryId entry);
+
+  // A helper method to look up a VideoCaptureMemory. Returns NULL if not found.
+  VideoCaptureMemory* LookupStartedDevicesById(int device_id);
+  VideoCaptureMemory* LookupStopedDevicesById(int device_id);

[wjia(left Chromium), 2011/05/11 23:23:31]

ditto

[Per K, 2011/05/16 11:49:39]

Done.

+
+  // A map of device_id to VideoCaptureMemory objects that is currently
+  // capturing.
+  VCEntryMap vc_entries_;
+  // A map of device_id to VideoCaptureMemory objects that have been stopped
+  // but not all transport dibs have been returned by VideoCaptureImpl.
+  VCEntryMap vc_stoped_entries_;

[wjia(left Chromium), 2011/05/11 23:23:31]

ditto

[Per K, 2011/05/16 11:49:39]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureHost);
+};
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_HOST_H_