60 lines
1.4 KiB
C++
60 lines
1.4 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#pragma once
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#include "time/PeriodClock.hxx"
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class MultipleOutputs;
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class BufferedOutputStream;
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/**
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* Cache for hardware/software volume levels.
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*/
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class MixerMemento {
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unsigned volume_software_set = 100;
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/** the cached hardware mixer value; invalid if negative */
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int last_hardware_volume = -1;
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/** the age of #last_hardware_volume */
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PeriodClock hardware_volume_clock;
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public:
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/**
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* Flush the hardware volume cache.
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*/
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void InvalidateHardwareVolume() noexcept {
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last_hardware_volume = -1;
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}
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[[gnu::pure]]
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int GetVolume(const MultipleOutputs &outputs) noexcept;
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/**
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* Throws on error.
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*
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* Note: the caller is responsible for emitting #IDLE_MIXER.
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*/
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void SetVolume(MultipleOutputs &outputs, unsigned volume);
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bool LoadSoftwareVolumeState(const char *line, MultipleOutputs &outputs);
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void SaveSoftwareVolumeState(BufferedOutputStream &os) const;
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/**
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* Generates a hash number for the current state of the software
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* volume control. This is used by timer_save_state_file() to
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* determine whether the state has changed and the state file should
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* be saved.
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*/
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[[gnu::pure]]
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unsigned GetSoftwareVolumeStateHash() const noexcept {
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return volume_software_set;
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}
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private:
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bool SetSoftwareVolume(MultipleOutputs &outputs, unsigned volume);
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void SetHardwareVolume(MultipleOutputs &outputs, unsigned volume);
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};
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