Tone.js/Tone/instrument/PolySynth.js

define(["Tone/core/Tone", "Tone/instrument/MonoSynth", "Tone/source/Source"], 
function(Tone){

	"use strict";

	/**
	 *  @class  Tone.PolySynth handles voice creation and allocation for any
	 *          instruments passed in as the second paramter. PolySynth is 
	 *          not a synthesizer by itself, it merely manages voices of 
	 *          one of the other types of synths, allowing any of the 
	 *          monophonic synthesizers to be polyphonic. 
	 *
	 *  @constructor
	 *  @extends {Tone.Instrument}
	 *  @param {number|Object} [polyphony=4] The number of voices to create
	 *  @param {function} [voice=Tone.MonoSynth] The constructor of the voices
	 *                                            uses Tone.MonoSynth by default. 
	 *  @example
	 * //a polysynth composed of 6 Voices of MonoSynth
	 * var synth = new Tone.PolySynth(6, Tone.MonoSynth).toMaster();
	 * //set the attributes using the set interface
	 * synth.set("detune", -1200);
	 * //play a chord
	 * synth.triggerAttackRelease(["C4", "E4", "A4"], "4n");
	 */
	Tone.PolySynth = function(){

		Tone.Instrument.call(this);

		var options = this.optionsObject(arguments, ["polyphony", "voice"], Tone.PolySynth.defaults);

		/**
		 *  the array of voices
		 *  @type {Array}
		 */
		this.voices = new Array(options.polyphony);

		/**
		 *  If there are no more voices available,
		 *  should an active voice be stolen to play the new note?
		 *  @type {Boolean}
		 */
		this.stealVoices = true;

		/**
		 *  the queue of free voices
		 *  @private
		 *  @type {Array}
		 */
		this._freeVoices = [];

		/**
		 *  keeps track of which notes are down
		 *  @private
		 *  @type {Object}
		 */
		this._activeVoices = {};

		//create the voices
		for (var i = 0; i < options.polyphony; i++){
			var v = new options.voice(arguments[2], arguments[3]);
			this.voices[i] = v;
			v.connect(this.output);
		}

		//make a copy of the voices
		this._freeVoices = this.voices.slice(0);
		//get the prototypes and properties
	};

	Tone.extend(Tone.PolySynth, Tone.Instrument);

	/**
	 *  the defaults
	 *  @const
	 *  @static
	 *  @type {Object}
	 */
	Tone.PolySynth.defaults = {
		"polyphony" : 4,
		"voice" : Tone.MonoSynth
	};

	/**
	 *  Trigger the attack portion of the note
	 *  @param  {Frequency|Array} notes The notes to play. Accepts a single
	 *                                  Frequency or an array of frequencies.
	 *  @param  {Time} [time=now]  The start time of the note.
	 *  @param {number} [velocity=1] The velocity of the note.
	 *  @returns {Tone.PolySynth} this
	 *  @example
	 * //trigger a chord immediately with a velocity of 0.2
	 * poly.triggerAttack(["Ab3", "C4", "F5"], undefined, 0.2);
	 */
	Tone.PolySynth.prototype.triggerAttack = function(notes, time, velocity){
		if (!Array.isArray(notes)){
			notes = [notes];
		}
		for (var i = 0; i < notes.length; i++){
			var val = notes[i];
			var stringified = JSON.stringify(val);
			//retrigger the same note if possible
			if (this._activeVoices.hasOwnProperty(stringified)){
				this._activeVoices[stringified].triggerAttack(val, time, velocity);
			} else if (this._freeVoices.length > 0){
				var voice = this._freeVoices.shift();
				voice.triggerAttack(val, time, velocity);
				this._activeVoices[stringified] = voice;
			} else if (this.stealVoices){ //steal a voice				
				//take the first voice
				for (var voiceName in this._activeVoices){
					this._activeVoices[voiceName].triggerAttack(val, time, velocity);
					break;
				}
			}
		}
		return this;
	};

	/**
	 *  Trigger the attack and release after the specified duration
	 *  
	 *  @param  {Frequency|Array} notes The notes to play. Accepts a single
	 *                                  Frequency or an array of frequencies.
	 *  @param  {Time} duration the duration of the note
	 *  @param  {Time} [time=now]     if no time is given, defaults to now
	 *  @param  {number} [velocity=1] the velocity of the attack (0-1)
	 *  @returns {Tone.PolySynth} this
	 *  @example
	 * //trigger a chord for a duration of a half note 
	 * poly.triggerAttackRelease(["Eb3", "G4", "C5"], "2n");
	 */
	Tone.PolySynth.prototype.triggerAttackRelease = function(notes, duration, time, velocity){
		time = this.toSeconds(time);
		this.triggerAttack(notes, time, velocity);
		this.triggerRelease(notes, time + this.toSeconds(duration));
		return this;
	};

	/**
	 *  Trigger the release of the note. Unlike monophonic instruments, 
	 *  a note (or array of notes) needs to be passed in as the first argument.
	 *  @param  {Frequency|Array} notes The notes to play. Accepts a single
	 *                                  Frequency or an array of frequencies.
	 *  @param  {Time} [time=now]  When the release will be triggered. 
	 *  @returns {Tone.PolySynth} this
	 *  @example
	 * poly.triggerRelease(["Ab3", "C4", "F5"], "+2n");
	 */
	Tone.PolySynth.prototype.triggerRelease = function(notes, time){
		if (!Array.isArray(notes)){
			notes = [notes];
		}
		for (var i = 0; i < notes.length; i++){
			//get the voice
			var stringified = JSON.stringify(notes[i]);
			var voice = this._activeVoices[stringified];
			if (voice){
				voice.triggerRelease(time);
				this._freeVoices.push(voice);
				delete this._activeVoices[stringified];
				voice = null;
			}
		}
		return this;
	};

	/**
	 *  Set a member/attribute of the voices. 
	 *  @param {Object|string} params
	 *  @param {number=} value
	 *  @param {Time=} rampTime
	 *  @returns {Tone.PolySynth} this
	 *  @example
	 * poly.set({
	 * 	"filter" : {
	 * 		"type" : "highpass"
	 * 	},
	 * 	"envelope" : {
	 * 		"attack" : 0.25
	 * 	}
	 * });
	 */
	Tone.PolySynth.prototype.set = function(params, value, rampTime){
		for (var i = 0; i < this.voices.length; i++){
			this.voices[i].set(params, value, rampTime);
		}
		return this;
	};

	/**
	 *  Get the synth's attributes. Given no arguments get
	 *  will return all available object properties and their corresponding
	 *  values. Pass in a single attribute to retrieve or an array
	 *  of attributes. The attribute strings can also include a "."
	 *  to access deeper properties.
	 *  @param {Array=} params the parameters to get, otherwise will return 
	 *  					   all available.
	 */
	Tone.PolySynth.prototype.get = function(params){
		return this.voices[0].get(params);
	};

	/**
	 *  Trigger the release portion of all the currently active voices.
	 *  @param {Time} [time=now] When the notes should be released.
	 *  @return {Tone.PolySynth} this
	 */
	Tone.PolySynth.prototype.releaseAll = function(time){
		for (var i = 0; i < this.voices.length; i++){
			this.voices[i].triggerRelease(time);
		}
		return this;
	};

	/**
	 *  Clean up.
	 *  @returns {Tone.PolySynth} this
	 */
	Tone.PolySynth.prototype.dispose = function(){
		Tone.Instrument.prototype.dispose.call(this);
		for (var i = 0; i < this.voices.length; i++){
			this.voices[i].dispose();
			this.voices[i] = null;
		}
		this.voices = null;
		this._activeVoices = null;
		this._freeVoices = null;
		return this;
	};

	return Tone.PolySynth;
});