down static method
decrease system volume by step, step must be in range 0.0, 1.0
.
return the system volume value after decrease.
the return volume value may be not equals to the current volume - step.
Implementation
static Future<double> down({double step = _defaultStep}) async {
if (step < 0.0 || step > 1.0) {
return Future.error(ArgumentError.value(
step, "step must be not null and in range [0.0, 1.0]"));
} else {
var vol = await FijkPlugin._channel
.invokeMethod("volumeDown", <String, dynamic>{'step': step});
if (vol != null) return Future.value(vol);
return Future.value(0);
}
}