Method play_tone

sdl/src/host.rs:364–405

Reproduces `tone` using SDL's audio queue.

(&mut self, tone: Tone)

    /// Reproduces `tone` using SDL's audio queue.
    fn play_tone(&mut self, tone: Tone) -> io::Result<()> {
        if tone.frequency_hz == 0 {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "Tone frequency must be positive",
            ));
        }

        let sample_count = (tone.duration.as_secs_f64() * f64::from(AUDIO_SAMPLE_RATE))
            .round()
            .clamp(0.0, usize::MAX as f64) as usize;
        if sample_count == 0 {
            return Ok(());
        }

        let samples = match tone.waveform {
            Waveform::Square => {
                let half_period = f64::from(AUDIO_SAMPLE_RATE) / f64::from(tone.frequency_hz) / 2.0;
                let amplitude = i16::MAX / 4;
                let mut samples = Vec::with_capacity(sample_count);
                for i in 0..sample_count {
                    let sample = if (((i as f64) / half_period).floor() as u64).is_multiple_of(2) {
                        amplitude
                    } else {
                        -amplitude
                    };
                    samples.push(sample);
                }
                samples
            }
        };

        let audio_device = self.get_audio_device()?;
        audio_device.clear();
        audio_device.queue_audio(&samples).map_err(string_error_to_io_error)?;
        audio_device.resume();
        while audio_device.size() > 0 {
            thread::sleep(Duration::from_millis(1));
        }
        audio_device.pause();
        Ok(())
    }
}

impl RasterOps for Context {