1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128

#![allow(dead_code)]

//!
//! Data structures that handles advancing music time within a time signature.
//!

use super::{music_time::MusicTime, time_signature::TimeSignature};
use std::time::Duration;

#[derive(Debug)]
/// Data structure that handles advancing music time within a time signature.
pub struct MusicTimeCounter {
    current_time: MusicTime,
    time_signature: TimeSignature,
}

impl MusicTimeCounter {
    /// Create a new `MusicTimeCounter` with a `TimeSignature`.
    /// # Arguments
    ///
    /// * `time_signature` - The `TimeSignature` the `MusicTimeCounter` is constrained by.
    ///
    /// # Example
    /// ```
    /// use music_timer::{time_signature::TimeSignature, music_time_counter::MusicTimeCounter};
    /// let timer = MusicTimeCounter::new(TimeSignature::new(3, 4));
    /// ```
    pub fn new(time_signature: TimeSignature) -> Self {
        MusicTimeCounter {
            current_time: MusicTime::new(1, 1, 1),
            time_signature,
        }
    }

    /// Gets the current time of the counter.
    pub fn current_time(&self) -> &MusicTime {
        &self.current_time
    }

    /// Advance this counter by 1 beat.
    pub fn advance_beat(&mut self) {
        self.current_time.advance_beat(&self.time_signature);
    }

    /// Advance this counter by 1 beat interval.
    pub fn advance_beat_interval(&mut self) {
        self.current_time
            .advance_beat_interval(&self.time_signature);
    }

    /// Gets the time duration between beats.
    /// # Arguments
    ///
    /// * `bpm` - Beats per minute
    pub fn beat_target_frames(&self, bpm: f32) -> Duration {
        let seconds_per_beat = 60.0 / bpm;
        let beat_pulse_speed = seconds_per_beat * 1000000000.0;
        Duration::from_nanos(beat_pulse_speed as u64)
    }

    /// Gets the time duration between beat intervals.
    /// # Arguments
    ///
    /// * `bpm` - Beats per minute.
    pub fn beat_interval_target_frames(&self, bpm: f32) -> Duration {
        const INTERVAL_RESOLUTION: f32 = 16.0 / 2.0;
        let seconds_per_beat_interval = (60.0 / bpm) / INTERVAL_RESOLUTION;
        let beat_interval_pulse_speed = seconds_per_beat_interval * 1000000000.0;
        Duration::from_nanos(beat_interval_pulse_speed as u64)
    }

    /// Set the current music time of the counter.
    ///
    /// # Arguments
    /// * `current_time` - The new current time to set counter to.
    pub fn set_current_time(&mut self, current_time: MusicTime) -> &mut Self {
        self.current_time = current_time;
        self
    }
}

impl Default for MusicTimeCounter {
    /// Default `MusicTimeCounter` is created with a default `TimeSignature`.
    fn default() -> Self {
        MusicTimeCounter::new(TimeSignature::default())
    }
}

mod tests {
    #[test]
    fn test_beat_target_frames() {
        use crate::{music_time_counter::MusicTimeCounter, time_signature::TimeSignature};
        use std::time::Duration;

        let timer = MusicTimeCounter::new(TimeSignature::new(4, 4));
        let duration = timer.beat_target_frames(80.0);
        let expected = Duration::from_millis(750);
        assert_eq!(duration, expected);

        let timer = MusicTimeCounter::new(TimeSignature::new(4, 4));
        let duration = timer.beat_target_frames(60.0);
        let expected = Duration::from_secs(1);
        assert_eq!(duration, expected);
    }

    #[test]
    fn test_beat_interval_target_frames() {
        use crate::{music_time_counter::MusicTimeCounter, time_signature::TimeSignature};
        use std::time::Duration;

        let timer = MusicTimeCounter::new(TimeSignature::new(4, 4));
        let duration = timer.beat_interval_target_frames(60.0);
        let expected = Duration::from_millis(125);
        assert_eq!(duration, expected);
    }

    #[test]
    fn test_set_current_time() {
        use crate::{music_time::MusicTime, music_time_counter::MusicTimeCounter};

        let mut timer = MusicTimeCounter::default();
        assert_eq!(timer.current_time(), &MusicTime::new(1, 1, 1));
        timer.advance_beat();
        assert_eq!(timer.current_time(), &MusicTime::new(1, 2, 1));
        timer.set_current_time(MusicTime::new(3, 2, 1));
        assert_eq!(timer.current_time(), &MusicTime::new(3, 2, 1));
    }
}