# fps_meter.rs - source
Source of the Rust file `maplibre/src/util/fps_meter.rs`.

    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

    use std::time::Duration;

    use instant::Instant;

    /// Measures the frames per second.
    ///
    /// # Example
    /// ```
    /// use maplibre::util::FPSMeter;
    ///
    /// let mut meter = FPSMeter::new();
    ///
    /// // call the following the the render loop
    /// meter.update_and_print();
    /// ```
    pub struct FPSMeter {
        next_report: Instant,
        frame_count: u32,
    }

    impl FPSMeter {
        pub fn new() -> Self {
            let start = Instant::now();
            Self {
                next_report: start + Duration::from_secs(1),
                frame_count: 0,
            }
        }

        pub fn update_and_print(&mut self) {
            self.frame_count += 1;
            let now = Instant::now();
            if now >= self.next_report {
                log::info!("{} FPS", self.frame_count);
                self.frame_count = 0;
                self.next_report = now + Duration::from_secs(1);
            }
        }
    }

    impl Default for FPSMeter {
        fn default() -> Self {
            Self::new()
        }
    }