settings/audio/
utils.rs

1// Copyright 2021 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5/// Rounds the given volume level to the nearest 1%. Input should be a float between 0.0 and 1.0 and
6/// the result will also be clamped to this range.
7///
8/// Rounding should be applied to audio levels handled by settings service that come from external
9/// sources.
10pub(crate) fn round_volume_level(volume: f32) -> f32 {
11    #[allow(clippy::manual_clamp)]
12    ((volume * 100.0).round() / 100.0).max(0.0).min(1.0)
13}
14
15#[cfg(test)]
16mod tests {
17    use super::round_volume_level;
18
19    // Various tests to verify rounding works as expected.
20    #[fuchsia::test]
21    // We're testing rounding so we want explicit float comparisons.
22    #[allow(clippy::float_cmp)]
23    fn test_round_volume() {
24        assert_eq!(round_volume_level(1.0), 1.0);
25        assert_eq!(round_volume_level(0.0), 0.0);
26        assert_eq!(round_volume_level(0.222222), 0.22);
27        assert_eq!(round_volume_level(0.349), 0.35);
28        assert_eq!(round_volume_level(0.995), 1.0);
29        assert_eq!(round_volume_level(0.994), 0.99);
30    }
31
32    // Verifies that values below 0.0 round to 0.0.
33    #[fuchsia::test]
34    // We're testing rounding so we want explicit float comparisons.
35    #[allow(clippy::float_cmp)]
36    fn test_round_volume_below_range() {
37        assert_eq!(round_volume_level(-1.0), 0.0);
38        assert_eq!(round_volume_level(-0.1), 0.0);
39        assert_eq!(round_volume_level(-0.0), 0.0);
40        assert_eq!(round_volume_level(std::f32::MIN), 0.0);
41    }
42
43    // Verifies that values above 1.0 round to 1.0.
44    #[fuchsia::test]
45    // We're testing rounding so we want explicit float comparisons.
46    #[allow(clippy::float_cmp)]
47    fn test_round_volume_above_range() {
48        assert_eq!(round_volume_level(2.0), 1.0);
49        assert_eq!(round_volume_level(1.1), 1.0);
50        assert_eq!(round_volume_level(std::f32::MAX), 1.0);
51    }
52}