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/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include "system/PeriodClock.hxx"
class MultipleOutputs;
class BufferedOutputStream;
/**
* Cache for hardware/software volume levels.
*/
class MixerMemento {
unsigned volume_software_set = 100;
/** the cached hardware mixer value; invalid if negative */
int last_hardware_volume = -1;
/** the age of #last_hardware_volume */
PeriodClock hardware_volume_clock;
public:
/**
* Flush the hardware volume cache.
*/
void InvalidateHardwareVolume() noexcept {
last_hardware_volume = -1;
}
[[gnu::pure]]
int GetVolume(const MultipleOutputs &outputs) noexcept;
/**
* Throws on error.
*
* Note: the caller is responsible for emitting #IDLE_MIXER.
*/
void SetVolume(MultipleOutputs &outputs, unsigned volume);
bool LoadSoftwareVolumeState(const char *line, MultipleOutputs &outputs);
void SaveSoftwareVolumeState(BufferedOutputStream &os) const;
/**
* Generates a hash number for the current state of the software
* volume control. This is used by timer_save_state_file() to
* determine whether the state has changed and the state file should
* be saved.
*/
[[gnu::pure]]
unsigned GetSoftwareVolumeStateHash() const noexcept {
return volume_software_set;
}
private:
bool SetSoftwareVolume(MultipleOutputs &outputs, unsigned volume);
void SetHardwareVolume(MultipleOutputs &outputs, unsigned volume);
};