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