aiexperiments-ai-duet/static/app/keyboard/Midi.js
2016-11-11 13:52:19 -05:00

59 lines
1.5 KiB
JavaScript

/**
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import events from 'events'
import WebMidi from 'webmidi'
class Midi extends events.EventEmitter{
constructor(){
super()
this._isEnabled = false
WebMidi.enable((err) => {
if (!err){
this._isEnabled = true
if (WebMidi.inputs){
WebMidi.inputs.forEach((input) => this._bindInput(input))
}
WebMidi.addListener('connected', (device) => {
if (device.input){
this._bindInput(device.input)
}
})
}
})
}
_bindInput(inputDevice){
if (this._isEnabled){
WebMidi.addListener('disconnected', (device) => {
if (device.input){
device.input.removeListener('noteOn')
device.input.removeListener('noteOff')
}
})
inputDevice.addListener('noteon', 'all', (event) => {
this.emit('keyDown', event.note.number)
})
inputDevice.addListener('noteoff', 'all', (event) => {
this.emit('keyUp', event.note.number)
})
}
}
}
export {Midi}