visual-cortex-capture 0.1.0

Screen-capture abstraction for visual-cortex: frames, regions, rates, the FrameSource trait, and the macOS ScreenCaptureKit backend.
Documentation 
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use std::time::Duration;

/// How often a watcher evaluates, or a source captures. Stored as a period.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Rate {
    period: Duration,
}

impl Rate {
    /// A rate of `hz` evaluations per second. Panics if `hz` is not positive and finite.
    pub fn hz(hz: f64) -> Self {
        assert!(
            hz.is_finite() && hz > 0.0,
            "Rate::hz requires a positive, finite value"
        );
        Self {
            period: Duration::from_secs_f64(1.0 / hz),
        }
    }

    /// One evaluation every `period`.
    pub fn every(period: Duration) -> Self {
        assert!(!period.is_zero(), "Rate::every requires a non-zero period");
        Self { period }
    }

    pub fn period(&self) -> Duration {
        self.period
    }

    pub fn is_faster_than(&self, other: &Rate) -> bool {
        self.period < other.period
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn hz_converts_to_period() {
        assert_eq!(Rate::hz(2.0).period(), Duration::from_millis(500));
        assert_eq!(Rate::hz(10.0).period(), Duration::from_millis(100));
    }

    #[test]
    fn every_wraps_a_duration() {
        assert_eq!(
            Rate::every(Duration::from_secs(3)).period(),
            Duration::from_secs(3)
        );
    }

    #[test]
    fn faster_means_smaller_period() {
        assert!(Rate::hz(10.0).is_faster_than(&Rate::hz(2.0)));
        assert!(!Rate::hz(1.0).is_faster_than(&Rate::hz(1.0)));
    }

    #[test]
    #[should_panic]
    fn zero_hz_panics() {
        let _ = Rate::hz(0.0);
    }
}