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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QAUDIOSTATEMACHINE_P_H
#define QAUDIOSTATEMACHINE_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include "qaudiostatemachineutils_p.h"
#include <qpointer.h>
#include <atomic>
QT_BEGIN_NAMESPACE
class QAudioStateChangeNotifier;
/* QAudioStateMachine provides an opportunity to
* toggle QAudio::State with QAudio::Error in
* a thread-safe manner.
* The toggling functions return a notifier,
* which notifies about the change via
* QAudioStateChangeNotifier::stateChanged and errorChanged.
*
* The state machine is supposed to be used mostly in
* QAudioSink and QAudioSource implementations.
*/
class Q_MULTIMEDIA_EXPORT QAudioStateMachine
{
public:
using RawState = AudioStateMachineUtils::RawState;
class Notifier
{
public:
void reset()
{
if (auto stateMachine = std::exchange(m_stateMachine, nullptr))
stateMachine->reset(m_state, m_prevState);
}
~Notifier() { reset(); }
Notifier(const Notifier &) = delete;
Notifier(Notifier &&other) noexcept
: m_stateMachine(std::exchange(other.m_stateMachine, nullptr)),
m_state(other.m_state),
m_prevState(other.m_prevState)
{
}
operator bool() const { return m_stateMachine != nullptr; }
QAudio::State prevAudioState() const { return AudioStateMachineUtils::toAudioState(m_prevState); }
QAudio::State audioState() const { return AudioStateMachineUtils::toAudioState(m_state); }
bool isDraining() const { return AudioStateMachineUtils::isDrainingState(m_state); }
bool isStateChanged() const { return prevAudioState() != audioState(); }
private:
Notifier(QAudioStateMachine *stateMachine = nullptr, RawState state = QAudio::StoppedState,
RawState prevState = QAudio::StoppedState)
: m_stateMachine(stateMachine), m_state(state), m_prevState(prevState)
{
}
private:
QAudioStateMachine *m_stateMachine;
RawState m_state;
const RawState m_prevState;
friend class QAudioStateMachine;
};
QAudioStateMachine(QAudioStateChangeNotifier ¬ifier);
~QAudioStateMachine();
QAudio::State state() const;
QAudio::Error error() const;
bool isActiveOrIdle() const;
bool isDraining() const;
// atomicaly checks if the state is stopped and marked as drained
std::pair<bool, bool> getDrainedAndStopped() const;
// Stopped[draining] -> Stopped
bool onDrained();
// Active/Idle/Suspended -> Stopped
// or Active -> Stopped[draining] for shouldDrain = true
Notifier stop(QAudio::Error error = QAudio::NoError, bool shouldDrain = false,
bool forceUpdateError = false);
// Active/Idle/Suspended -> Stopped
Notifier stopOrUpdateError(QAudio::Error error = QAudio::NoError)
{
return stop(error, false, true);
}
// Stopped -> Active/Idle
Notifier start(bool isActive = true);
// Active/Idle -> Suspended + saves the exchanged state
Notifier suspend();
// Suspended -> saved state (Active/Idle)
Notifier resume();
// Idle -> Active
Notifier activateFromIdle();
// Active/Idle -> Active/Idle + updateError
Notifier updateActiveOrIdle(bool isActive, QAudio::Error error = QAudio::NoError);
// Any -> Any; better use more strict methods
Notifier forceSetState(QAudio::State state, QAudio::Error error = QAudio::NoError);
// force set the error
Notifier setError(QAudio::Error error);
private:
template <typename StatesChecker, typename NewState>
Notifier changeState(const StatesChecker &statesChecker, const NewState &newState);
void reset(RawState state, RawState prevState);
private:
QPointer<QAudioStateChangeNotifier> m_notifier;
std::atomic<RawState> m_state = QAudio::StoppedState;
QAudio::State m_suspendedInState = QAudio::SuspendedState;
};
QT_END_NAMESPACE
#endif // QAUDIOSTATEMACHINE_P_H
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