test_play.rs - mozsearch

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extern crate midir;

use std::thread::sleep;

use std::time::Duration;

use std::io::{stdin, stdout, Write};

use std::error::Error;

use midir::{MidiOutput, MidiOutputPort};

fn main() {

    match run() {

        Ok(_) => (),

        Err(err) => println!("Error: {}", err)

fn run() -> Result<(), Box<dyn Error>> {

    let midi_out = MidiOutput::new("My Test Output")?;

    // Get an output port (read from console if multiple are available)

    let out_ports = midi_out.ports();

    let out_port: &MidiOutputPort = match out_ports.len() {

        0 => return Err("no output port found".into()),

        1 => {

            println!("Choosing the only available output port: {}", midi_out.port_name(&out_ports[0]).unwrap());

            &out_ports[0]

},

        _ => {

            println!("\nAvailable output ports:");

            for (i, p) in out_ports.iter().enumerate() {

                println!("{}: {}", i, midi_out.port_name(p).unwrap());

            print!("Please select output port: ");

            stdout().flush()?;

            let mut input = String::new();

            stdin().read_line(&mut input)?;

            out_ports.get(input.trim().parse::<usize>()?)

                     .ok_or("invalid output port selected")?

};

    println!("\nOpening connection");

    let mut conn_out = midi_out.connect(out_port, "midir-test")?;

    println!("Connection open. Listen!");

        // Define a new scope in which the closure `play_note` borrows conn_out, so it can be called easily

        let mut play_note = |note: u8, duration: u64| {

            const NOTE_ON_MSG: u8 = 0x90;

            const NOTE_OFF_MSG: u8 = 0x80;

            const VELOCITY: u8 = 0x64;

            // We're ignoring errors in here

            let _ = conn_out.send(&[NOTE_ON_MSG, note, VELOCITY]);

            sleep(Duration::from_millis(duration * 150));

            let _ = conn_out.send(&[NOTE_OFF_MSG, note, VELOCITY]);

};

        sleep(Duration::from_millis(4 * 150));

        play_note(66, 4);

        play_note(65, 3);

        play_note(63, 1);

        play_note(61, 6);

        play_note(59, 2);

        play_note(58, 4);

        play_note(56, 4);

        play_note(54, 4);

    sleep(Duration::from_millis(150));

    println!("\nClosing connection");

    // This is optional, the connection would automatically be closed as soon as it goes out of scope

    conn_out.close();

    println!("Connection closed");

    Ok(())