mediocre-blog/assets/trading-in-the-rain/MIDI.js/js/midi/plugin.webmidi.js
2020-04-26 18:15:15 -06:00

93 lines
2.6 KiB
JavaScript

/*
----------------------------------------------------------------------
Web MIDI API - Native Soundbanks
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http://webaudio.github.io/web-midi-api/
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*/
(function(root) { 'use strict';
var plugin = null;
var output = null;
var channels = [];
var midi = root.WebMIDI = {api: 'webmidi'};
midi.send = function(data, delay) { // set channel volume
output.send(data, delay * 1000);
};
midi.setController = function(channel, type, value, delay) {
output.send([channel, type, value], delay * 1000);
};
midi.setVolume = function(channel, volume, delay) { // set channel volume
output.send([0xB0 + channel, 0x07, volume], delay * 1000);
};
midi.programChange = function(channel, program, delay) { // change patch (instrument)
output.send([0xC0 + channel, program], delay * 1000);
};
midi.pitchBend = function(channel, program, delay) { // pitch bend
output.send([0xE0 + channel, program], delay * 1000);
};
midi.noteOn = function(channel, note, velocity, delay) {
output.send([0x90 + channel, note, velocity], delay * 1000);
};
midi.noteOff = function(channel, note, delay) {
output.send([0x80 + channel, note, 0], delay * 1000);
};
midi.chordOn = function(channel, chord, velocity, delay) {
for (var n = 0; n < chord.length; n ++) {
var note = chord[n];
output.send([0x90 + channel, note, velocity], delay * 1000);
}
};
midi.chordOff = function(channel, chord, delay) {
for (var n = 0; n < chord.length; n ++) {
var note = chord[n];
output.send([0x80 + channel, note, 0], delay * 1000);
}
};
midi.stopAllNotes = function() {
output.cancel();
for (var channel = 0; channel < 16; channel ++) {
output.send([0xB0 + channel, 0x7B, 0]);
}
};
midi.connect = function(opts) {
root.setDefaultPlugin(midi);
var errFunction = function(err) { // well at least we tried!
if (window.AudioContext) { // Chrome
opts.api = 'webaudio';
} else if (window.Audio) { // Firefox
opts.api = 'audiotag';
} else { // no support
return;
}
root.loadPlugin(opts);
};
///
navigator.requestMIDIAccess().then(function(access) {
plugin = access;
var pluginOutputs = plugin.outputs;
if (typeof pluginOutputs == 'function') { // Chrome pre-43
output = pluginOutputs()[0];
} else { // Chrome post-43
output = pluginOutputs[0];
}
if (output === undefined) { // nothing there...
errFunction();
} else {
opts.onsuccess && opts.onsuccess();
}
}, errFunction);
};
})(MIDI);