media/capture/video/video_capture_device_factory.h

// Copyright 2014 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_VIDEO_VIDEO_CAPTURE_DEVICE_FACTORY_H_
#define MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_FACTORY_H_

#include "base/macros.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_checker.h"
#include "build/chromeos_buildflags.h"
#include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
#include "media/capture/video/video_capture_device.h"
#include "media/capture/video/video_capture_device_info.h"

namespace media {

// VideoCaptureDeviceFactory is the base class for creation of video capture
// devices in the different platforms. VCDFs are created by MediaStreamManager
// on UI thread and plugged into VideoCaptureManager, who owns and operates them
// in Device Thread (a.k.a. Audio Thread).
// Typical operation is to first call GetDevicesInfo() to obtain information
// about available devices. The obtained descriptors can then be used to either
// obtain the supported formats of a device using GetSupportedFormats(), or to
// create an instance of VideoCaptureDevice for the device using CreateDevice().
// TODO(chfremer): Add a layer on top of the platform-specific implementations
// that uses strings instead of descriptors as keys for accessing devices.
// crbug.com/665065
class CAPTURE_EXPORT VideoCaptureDeviceFactory {
 public:
  VideoCaptureDeviceFactory();

  VideoCaptureDeviceFactory(const VideoCaptureDeviceFactory&) = delete;
  VideoCaptureDeviceFactory& operator=(const VideoCaptureDeviceFactory&) =
      delete;

  virtual ~VideoCaptureDeviceFactory();

  // Creates a VideoCaptureDevice object. Returns NULL if something goes wrong.
  virtual std::unique_ptr<VideoCaptureDevice> CreateDevice(
      const VideoCaptureDeviceDescriptor& device_descriptor) = 0;

  // Enumerates video capture devices and passes the results to the supplied
  // |callback|. The callback is called synchronously or asynchronously on the
  // same thread. The callback is guaranteed not to be called after the factory
  // is destroyed.
  using GetDevicesInfoCallback = base::OnceCallback<void(
      std::vector<VideoCaptureDeviceInfo> devices_info)>;
  virtual void GetDevicesInfo(GetDevicesInfoCallback callback) = 0;

 protected:
  base::ThreadChecker thread_checker_;
};

}  // namespace media

#endif  // MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_FACTORY_H_