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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef MOZILLA_AUDIONOTIFICATIONRECEIVER_H_
#define MOZILLA_AUDIONOTIFICATIONRECEIVER_H_
// clang-format off
/*
* Architecture to send/receive default device-changed notification:
*
* Chrome Process ContentProcess 1
* ------------------ ------------------
*
* AudioNotification DeviceChangeListener 1 DeviceChangeListener N
* | ^ | ^ ^
* (4)| |(2) |(3) |(8) .
* v | v | v
* AudioNotificationSender AudioNotificationReceiver
* ^ | ^ ^
* . (5)| |(1) |(7)
* . v | |
* . (P)ContentParent 1 (P)ContentChild 1
* . | ^
* . (6)| |
* . | |
* . | |
* . +------------------------------------+
* . PContent IPC
* .
* . Content Process M
* . ------------------
* . .
* v .
* (P)ContentParent M < . . . . . . . . . > (P)ContentChild M
* PContent IPC
*
* Steps
* --------
* 1) Initailize the AudioNotificationSender when ContentParent is created.
* 2) Create an AudioNotification to get the device-changed signal
* from the system.
* 3) Register the DeviceChangeListener to AudioNotificationReceiver when it's
* created. 4) When the default device is changed, AudioNotification get the
* signal and 5) Pass this message by AudioNotificationSender. 6) The
* AudioNotificationSender sends the device-changed notification via the
* PContent. 7) The ContentChild will call AudioNotificationReceiver to 8)
* Notify all the registered audio streams to reconfigure the output devices.
*
* Notes
* --------
* a) There is only one AudioNotificationSender and AudioNotification
* in a chrome process.
* b) There is only one AudioNotificationReceiver and might be many
* DeviceChangeListeners in a content process.
* c) There might be many ContentParent in a chrome process.
* d) There is only one ContentChild in a content process.
* e) All the DeviceChangeListeners are registered in the
* AudioNotificationReceiver. f) All the ContentParents are registered in the
* AudioNotificationSender.
*/
// clang-format on
namespace mozilla {
namespace audio {
// The base class that provides a ResetDefaultDevice interface that
// will be called in AudioNotificationReceiver::NotifyDefaultDeviceChanged
// when it receives device-changed notification from the chrome process.
class DeviceChangeListener {
protected:
virtual ~DeviceChangeListener(){};
public:
// The subclass shoule provide its own implementation switching the
// audio stream to the new default output device.
virtual void ResetDefaultDevice() = 0;
};
class AudioNotificationReceiver final {
public:
// Add the DeviceChangeListener into the subscribers list.
static void Register(DeviceChangeListener* aDeviceChangeListener);
// Remove the DeviceChangeListener from the subscribers list.
static void Unregister(DeviceChangeListener* aDeviceChangeListener);
// Notify all the streams that the default device has been changed.
static void NotifyDefaultDeviceChanged();
}; // AudioNotificationReceiver
} // namespace audio
} // namespace mozilla
#endif // MOZILLA_AUDIONOTIFICATIONRECEIVER_H_
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