piano/js/components/Key/Board.js

/*jshint browser:true */
/*globals React, App */

(function () {
    'use strict';

    /**
     * Display keyboard
     */
    App.components.create('Key', {
        displayName: 'Board',
        mixins: [React.addons.PureRenderMixin],
        clicked: false,
        
        statics: {
            offset: 27 + App.MIDI.keyOffset,
            keysToNotes: [
                65, 50, 90, 51, 69, 82, 53, 84, 54, 89, 55, 85, 73,
                57, 79, 48, 80, 87, 83, 88, 68, 67, 70, 86, 66, 72,
                78, 74, 188, 190, 76, 191, 77, 223, 192, 16
            ]
        },
        
        /**
         * Set given note on given channel
         *
         * @param {note: number}        Note number
         * @param {channel: number}     Channel ID
         * @param {velocity: number}    Note velocity
         */
        on: function (note, channel, velocity) {
            var key = this.refs['key-' + note];
            
            if (key) {
                key.on(channel, velocity);
            }
        },
        
        /**
         * Check whether given note plays on given channel
         *
         * @param {note: number}    Note number
         * @param {channel: number} Channel ID
         */
        isOn: function (note, channel) {
            var key = this.refs['key-' + note];
            return (key.state.channels.indexOf(channel) > -1);
        },
        
        /**
         * Set given note off given channel
         *
         * @param {note: number}    Note number
         * @param {channel: number} Channel ID
         */
        off: function (note, channel) {
            var key = this.refs['key-' + note];
            
            if (key) {
                key.off(channel);
            }
        },
        
        /**
         * Set all notes off
         */
        allOff: function () {
            var i, keys = this.refs;
            
            for (i in keys) {
                if (keys.hasOwnProperty(i) && i.substr(0, 4) === 'key-') {
                    keys[i].off();
                }
            }
        },
        
        /**
         * Events
         */
        componentDidMount: function () {
            window.addEventListener('keydown', this.keyDown);
            window.addEventListener('keyup', this.keyUp);
            window.addEventListener('mouseup', this.release);
        },
        
        componentWillUnmount: function () {
            window.removeEventListener('keydown', this.keyDown);
            window.removeEventListener('keyup', this.keyUp);
            window.removeEventListener('mouseup', this.release);
        },
        
        /* mouse click */
        click: function (e) {
            if (e.button !== 0) {
                return;
            }
            
            this.clicked = true;
        },
        
        /* mouse release */
        release: function () {
            this.clicked = false;
        },
        
        /* play keys with keyboard (the real one) */
        keyDown: function (e) {
            var code = e.keyCode, index,
                Keyboard = App.components.Key.Board;
            
            // play note
            if ((index = Keyboard.keysToNotes.indexOf(code)) > -1) {
                index += Keyboard.offset;
                
                if (!this.isOn(index, -1)) {
                    this.on(index, -1, 127);
                }
                
                e.preventDefault();
            }
        },
        
        /* release keys */
        keyUp: function (e) {
            var index, Keyboard = App.components.Key.Board;
            
            if ((index = Keyboard.keysToNotes.indexOf(e.keyCode)) > -1) {
                this.off(index + Keyboard.offset, -1);
                
                e.preventDefault();
            }
        },
        
        /**
         * Whether keys should be played on mouse over
         */
        canPlay: function () {
            return this.clicked;
        },
        
        /** 
         * Render keyboard
         */
        render: function () {
            var i, offset = App.MIDI.keyOffset,
                length = 88 + offset, keys = [];
            
            for (i = offset; i < length; i += 1) {
                keys.push(App.components.Key.Key({
                    key: i,
                    ref: 'key-' + i,
                    
                    note: i,
                    canPlay: this.canPlay
                }));
            }
            
            return React.DOM.p({
                className: 'keyboard',
                onMouseDown: this.click
            }, keys);
        }
    });
}());