media/base/output_device.h

   1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_BASE_OUTPUT_DEVICE_H_
   6 #define MEDIA_BASE_OUTPUT_DEVICE_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "media/audio/audio_parameters.h"
  12 #include "media/base/media_export.h"
  13 #include "url/origin.h"
  14
  15 namespace media {
  16
  17 // Result of an audio output device switch operation
  18 enum SwitchOutputDeviceResult {
  19   SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS = 0,
  20   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_FOUND,
  21   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_AUTHORIZED,
  22   SWITCH_OUTPUT_DEVICE_RESULT_ERROR_INTERNAL,
  23   SWITCH_OUTPUT_DEVICE_RESULT_LAST = SWITCH_OUTPUT_DEVICE_RESULT_ERROR_INTERNAL,
  24 };
  25
  26 typedef base::Callback<void(SwitchOutputDeviceResult)> SwitchOutputDeviceCB;
  27
  28 // OutputDevice is an interface that allows performing operations related
  29 // audio output devices.
  30
  31 class OutputDevice {
  32  public:
  33   // Attempts to switch the audio output device.
  34   // Once the attempt is finished, |callback| is invoked with the
  35   // result of the operation passed as a parameter. The result is a value from
  36   // the  media::SwitchOutputDeviceResult enum.
  37   // There is no guarantee about the thread where |callback| will
  38   // be invoked, so users are advised to use media::BindToCurrentLoop() to
  39   // ensure that |callback| runs on the correct thread.
  40   // Note also that copy constructors and destructors for arguments bound to
  41   // |callback| may run on arbitrary threads as |callback| is moved across
  42   // threads. It is advisable to bind arguments such that they are released by
  43   // |callback| when it runs in order to avoid surprises.
  44   virtual void SwitchOutputDevice(const std::string& device_id,
  45                                   const url::Origin& security_origin,
  46                                   const SwitchOutputDeviceCB& callback) = 0;
  47
  48   // Returns the device's audio output parameters.
  49   // If the parameters are not available, this method blocks until they
  50   // become available. Must never be called on the IO thread.
  51   virtual AudioParameters GetOutputParameters() = 0;
  52
  53  protected:
  54   virtual ~OutputDevice() {}
  55 };
  56
  57 }  // namespace media
  58
  59 #endif  // MEDIA_BASE_OUTPUT_DEVICE_H_