Tone.js/Tone/source/Source.js

import Tone from "../core/Tone";
import "../core/Transport";
import "../component/Volume";
import "../core/Master";
import "../type/Type";
import "../core/TimelineState";
import "../signal/Signal";
import "../core/AudioNode";

/**
 *  @class  Base class for sources. Sources have start/stop methods
 *          and the ability to be synced to the
 *          start/stop of Tone.Transport.
 *
 *  @constructor
 *  @extends {Tone.AudioNode}
 *  @example
 * //Multiple state change events can be chained together,
 * //but must be set in the correct order and with ascending times
 *
 * // OK
 * state.start().stop("+0.2");
 * // AND
 * state.start().stop("+0.2").start("+0.4").stop("+0.7")
 *
 * // BAD
 * state.stop("+0.2").start();
 * // OR
 * state.start("+0.3").stop("+0.2");
 *
 */
Tone.Source = function(options){

	options = Tone.defaultArg(options, Tone.Source.defaults);
	Tone.AudioNode.call(this);

	/**
	 *  The output volume node
	 *  @type  {Tone.Volume}
	 *  @private
	 */
	this._volume = this.output = new Tone.Volume(options.volume);

	/**
	 * The volume of the output in decibels.
	 * @type {Decibels}
	 * @signal
	 * @example
	 * source.volume.value = -6;
	 */
	this.volume = this._volume.volume;
	this._readOnly("volume");

	/**
	 * 	Keep track of the scheduled state.
	 *  @type {Tone.TimelineState}
	 *  @private
	 */
	this._state = new Tone.TimelineState(Tone.State.Stopped);
	this._state.memory = 100;

	/**
	 *  The synced `start` callback function from the transport
	 *  @type {Function}
	 *  @private
	 */
	this._synced = false;

	/**
	 *  Keep track of all of the scheduled event ids
	 *  @type  {Array}
	 *  @private
	 */
	this._scheduled = [];

	//make the output explicitly stereo
	this._volume.output.output.channelCount = 2;
	this._volume.output.output.channelCountMode = "explicit";
	//mute initially
	this.mute = options.mute;
};

Tone.extend(Tone.Source, Tone.AudioNode);

/**
 *  The default parameters
 *  @static
 *  @const
 *  @type {Object}
 */
Tone.Source.defaults = {
	"volume" : 0,
	"mute" : false
};

/**
 *  Returns the playback state of the source, either "started" or "stopped".
 *  @type {Tone.State}
 *  @readOnly
 *  @memberOf Tone.Source#
 *  @name state
 */
Object.defineProperty(Tone.Source.prototype, "state", {
	get : function(){
		if (this._synced){
			if (Tone.Transport.state === Tone.State.Started){
				return this._state.getValueAtTime(Tone.Transport.seconds);
			} else {
				return Tone.State.Stopped;
			}
		} else {
			return this._state.getValueAtTime(this.now());
		}
	}
});

/**
 * Mute the output.
 * @memberOf Tone.Source#
 * @type {boolean}
 * @name mute
 * @example
 * //mute the output
 * source.mute = true;
 */
Object.defineProperty(Tone.Source.prototype, "mute", {
	get : function(){
		return this._volume.mute;
	},
	set : function(mute){
		this._volume.mute = mute;
	}
});

//overwrite these functions
Tone.Source.prototype._start = Tone.noOp;
Tone.Source.prototype.restart = Tone.noOp;
Tone.Source.prototype._stop = Tone.noOp;

/**
 *  Start the source at the specified time. If no time is given,
 *  start the source now.
 *  @param  {Time} [time=now] When the source should be started.
 *  @returns {Tone.Source} this
 *  @example
 * source.start("+0.5"); //starts the source 0.5 seconds from now
 */
Tone.Source.prototype.start = function(time, offset, duration){
	if (Tone.isUndef(time) && this._synced){
		time = Tone.Transport.seconds;
	} else {
		time = this.toSeconds(time);
		time = Math.max(time, this.context.currentTime);
	}
	//if it's started, stop it and restart it
	if (this._state.getValueAtTime(time) === Tone.State.Started){
		this._state.cancel(time);
		this._state.setStateAtTime(Tone.State.Started, time);
		this.restart(time, offset, duration);
	} else {
		this._state.setStateAtTime(Tone.State.Started, time);
		if (this._synced){
			// add the offset time to the event
			var event = this._state.get(time);
			event.offset = Tone.defaultArg(offset, 0);
			event.duration = duration;
			var sched = Tone.Transport.schedule(function(t){
				this._start(t, offset, duration);
			}.bind(this), time);
			this._scheduled.push(sched);

			//if it's already started
			if (Tone.Transport.state === Tone.State.Started){
				this._syncedStart(this.now(), Tone.Transport.seconds);
			}
		} else {
			this._start.apply(this, arguments);
		}
	}
	return this;
};

/**
 *  Stop the source at the specified time. If no time is given,
 *  stop the source now.
 *  @param  {Time} [time=now] When the source should be stopped.
 *  @returns {Tone.Source} this
 *  @example
 * source.stop(); // stops the source immediately
 */
Tone.Source.prototype.stop = function(time){
	if (Tone.isUndef(time) && this._synced){
		time = Tone.Transport.seconds;
	} else {
		time = this.toSeconds(time);
		time = Math.max(time, this.context.currentTime);
	}
	if (!this._synced){
		this._stop.apply(this, arguments);
	} else {
		var sched = Tone.Transport.schedule(this._stop.bind(this), time);
		this._scheduled.push(sched);
	}
	this._state.cancel(time);
	this._state.setStateAtTime(Tone.State.Stopped, time);
	return this;
};

/**
 *  Sync the source to the Transport so that all subsequent
 *  calls to `start` and `stop` are synced to the TransportTime
 *  instead of the AudioContext time.
 *
 *  @returns {Tone.Source} this
 *  @example
 * //sync the source so that it plays between 0 and 0.3 on the Transport's timeline
 * source.sync().start(0).stop(0.3);
 * //start the transport.
 * Tone.Transport.start();
 *
 *  @example
 * //start the transport with an offset and the sync'ed sources
 * //will start in the correct position
 * source.sync().start(0.1);
 * //the source will be invoked with an offset of 0.4
 * Tone.Transport.start("+0.5", 0.5);
 */
Tone.Source.prototype.sync = function(){
	this._synced = true;
	this._syncedStart = function(time, offset){
		if (offset > 0){
			// get the playback state at that time
			var stateEvent = this._state.get(offset);
			// listen for start events which may occur in the middle of the sync'ed time
			if (stateEvent && stateEvent.state === Tone.State.Started && stateEvent.time !== offset){
				// get the offset
				var startOffset = offset - this.toSeconds(stateEvent.time);
				var duration;
				if (stateEvent.duration){
					duration = this.toSeconds(stateEvent.duration) - startOffset;
				}
				this._start(time, this.toSeconds(stateEvent.offset) + startOffset, duration);
			}
		}
	}.bind(this);
	this._syncedStop = function(time){
		var seconds = Tone.Transport.getSecondsAtTime(Math.max(time - this.sampleTime, 0));
		if (this._state.getValueAtTime(seconds) === Tone.State.Started){
			this._stop(time);
		}
	}.bind(this);
	Tone.Transport.on("start loopStart", this._syncedStart);
	Tone.Transport.on("stop pause loopEnd", this._syncedStop);
	return this;
};

/**
 *  Unsync the source to the Transport. See Tone.Source.sync
 *  @returns {Tone.Source} this
 */
Tone.Source.prototype.unsync = function(){
	if (this._synced){
		Tone.Transport.off("stop pause loopEnd", this._syncedStop);
		Tone.Transport.off("start loopStart", this._syncedStart);
	}
	this._synced = false;
	// clear all of the scheduled ids
	for (var i = 0; i < this._scheduled.length; i++){
		var id = this._scheduled[i];
		Tone.Transport.clear(id);
	}
	this._scheduled = [];
	this._state.cancel(0);
	return this;
};

/**
 *	Clean up.
 *  @return {Tone.Source} this
 */
Tone.Source.prototype.dispose = function(){
	Tone.AudioNode.prototype.dispose.call(this);
	this.unsync();
	this._scheduled = null;
	this._writable("volume");
	this._volume.dispose();
	this._volume = null;
	this.volume = null;
	this._state.dispose();
	this._state = null;
};

export default Tone.Source;