SSVLSystemAlertVolume.c


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#include "SSVLSystemAlertVolume.h"

const AudioServicesPropertyID SSVLAudioServicesPropertySystemAlertVolume = 'ssvl';

OSStatus SSVLGetSystemVolume(Float32 *volume) {
	UInt32 volume_size = sizeof(*volume);

	OSStatus result = AudioServicesGetProperty(
		kAudioServicesPropertySystemAlertVolume,
		0,
		NULL,
		&volume_size,
		volume
	);

	// TODO: Sound PrefPane: If result != noErr, return 0.5?

	if (*volume != 0) {
		*volume = log(*volume) + 1.0;
	}
	else {
		*volume = 0;
	}

	return result;
}

OSStatus SSVLSetSystemVolume(Float32 volume) {
	volume = exp(volume - 1.0);

	return AudioServicesSetProperty(
		kAudioServicesPropertySystemAlertVolume,
		0,
		NULL,
		sizeof(volume),
		&volume
	);
}