VideoCaptureHost

content/browser/renderer_host/video_capture_memory.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.
+
+// VideoCaptureMemory is the glue between VideoCaptureHost, VideoCaptureManager
+// and VideoCaptrurDevice.
+// It provides functions for VideoCaptureHost to start a VideoCaptureDevice and
+// is responsible for keeping track of TransportDIBs and filling them with I420
+// video frames for IPC communication between VideoCaptureHost and
+// VideoCaptureMessageFilter.
+// It implements media::VideoCaptureDevice::EventHandler to get video frames
+// from a VideoCaptureDevice object and do color conversion straight into the
+// TransportDIBs to avoid a memory copy.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_MEMORY_H_
+#define CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_MEMORY_H_
+
+#include <list>
+#include <map>
+
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "base/task.h"
+#include "media/video/capture/video_capture_device.h"
+#include "media/video/capture/video_capture_types.h"
+#include "ui/gfx/surface/transport_dib.h"
+
+class VideoCaptureMemory
+    : public base::RefCountedThreadSafe<VideoCaptureMemory>,
+      public media::VideoCaptureDevice::EventHandler {
+ public:
+  // Id used for identifying an object of VideoCaptureMemory
+  typedef std::pair<int32, int> VideoCaptureMemoryId;
+  class EventHandler {
+   public:
+    // An Error have occurred in the VideoCaptureDevice.
+    virtual void OnError(VideoCaptureMemoryId id) = 0;
+    // An TransportDIB have been filled with I420 video.
+    virtual void OnBufferReady(VideoCaptureMemoryId id,
+                               TransportDIB::Handle handle,
+                               base::Time timestamp) = 0;
+    // The frame resolution the VideoCaptureDevice capture video in.
+    virtual void OnFrameInfo(VideoCaptureMemoryId id,
+                             int width,
+                             int height,
+                             int frame_rate) = 0;
+    // Report that this object can be deleted.
+    virtual void OnReadyToDelete(VideoCaptureMemoryId id) = 0;
+
+   protected:
+    virtual ~EventHandler() {}
+  };
+
+  VideoCaptureMemory(VideoCaptureMemoryId id,
+                     VideoCaptureMemory::EventHandler* event_handler);
+  ~VideoCaptureMemory();
+
+  // Starts video capturing and tries to use the resolution specified in
+  // params.
+  // When capturing has started EventHandler::OnFrameInfo is called with
+  // resolution that best matches the requested that the video capture device
+  // support.
+  void StartCapture(const media::VideoCaptureParams& params);
+  // Stop video capture.
+  // When the capture is stopped and all TransportDIBS have been returned
+  // EventHandler::OnReadyToDelete will be called.
+  // stopped_task may be null but it can be used to get a notification when the
+  // device is stopped.
+  void StopCapture(Task* stopped_task);
+  // Return a DIB previously given in EventHandler::OnBufferReady.
+  void ReturnTransportDIB(TransportDIB::Handle handle);
+
+  // Implement media::VideoCaptureDevice::EventHandler
+  virtual void OnIncomingCapturedFrame(const uint8* data,
+                                       int length,
+                                       base::Time timestamp);
+  virtual void OnError();
+  virtual void OnFrameInfo(const media::VideoCaptureDevice::Capability& info);
+
+ private:
+  typedef std::list<TransportDIB::Handle> DIBHANDLEList;

[wjia(left Chromium), 2011/05/19 04:24:37]

typedef precedes where it's used. 

[Per K, 2011/05/19 08:55:31]

Done.

+  typedef std::map<TransportDIB::Handle, TransportDIB*> DIBMap;
+
+  // Called by VideoCaptureManager when a device have been stopped.
+  void OnDeviceStopped(Task* stopped_task);
+
+  // Lock to protect free_dibs_.
+  base::Lock lock_;
+  bool report_ready_to_delete_;
+  // Free DIBS that can be filled with video frames.
+  DIBHANDLEList free_dibs_;
+  // All DIBS created by this object.
+  DIBMap owned_dibs_;
+  EventHandler& event_handler_;
+  // The parameter that was requested when starting the capture device.
+  media::VideoCaptureParams params_;
+  // Id used for identifying this object.
+  VideoCaptureMemoryId id_;
+  media::VideoCaptureDevice::Capability frame_info_;
+};
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_MEMORY_H_