mirror of
https://github.com/Tonejs/Tone.js
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303 lines
No EOL
8.2 KiB
JavaScript
303 lines
No EOL
8.2 KiB
JavaScript
define(["Tone/core/Tone", "Tone/signal/TimelineSignal", "Tone/core/TimelineState"], function (Tone) {
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"use strict";
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/**
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* @class A sample accurate clock which provides a callback at the given rate.
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* While the callback is not sample-accurate (it is still susceptible to
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* loose JS timing), the time passed in as the argument to the callback
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* is precise. For most applications, it is better to use Tone.Transport
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* instead of the Clock by itself since you can synchronize multiple callbacks.
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*
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* @constructor
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* @extends {Tone}
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* @param {function} callback The callback to be invoked with the time of the audio event
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* @param {Frequency} frequency The rate of the callback
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* @example
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* //the callback will be invoked approximately once a second
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* //and will print the time exactly once a second apart.
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* var clock = new Tone.Clock(function(time){
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* console.log(time);
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* }, 1);
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*/
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Tone.Clock = function(){
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var options = this.optionsObject(arguments, ["callback", "frequency"], Tone.Clock.defaults);
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/**
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* The callback function to invoke at the scheduled tick.
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* @type {Function}
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*/
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this.callback = options.callback;
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/**
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* The time which the clock will schedule events in advance
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* of the current time. Scheduling notes in advance improves
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* performance and decreases the chance for clicks caused
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* by scheduling events in the past. If set to "auto",
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* this value will be automatically computed based on the
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* rate of requestAnimationFrame (0.016 seconds). Larger values
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* will yeild better performance, but at the cost of latency.
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* Values less than 0.016 are not recommended.
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* @type {Number|String}
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*/
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this._lookAhead = "auto";
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/**
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* The lookahead value which was automatically
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* computed using a time-based averaging.
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* @type {Number}
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* @private
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*/
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this._computedLookAhead = 1/60;
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/**
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* The value afterwhich events are thrown out
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* @type {Number}
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* @private
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*/
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this._threshold = 0.5;
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/**
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* The next time the callback is scheduled.
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* @type {Number}
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* @private
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*/
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this._nextTick = -1;
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/**
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* The last time the callback was invoked
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* @type {Number}
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* @private
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*/
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this._lastUpdate = 0;
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/**
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* The id of the requestAnimationFrame
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* @type {Number}
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* @private
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*/
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this._loopID = -1;
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/**
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* The rate the callback function should be invoked.
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* @type {BPM}
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* @signal
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*/
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this.frequency = new Tone.TimelineSignal(options.frequency, Tone.Type.Frequency);
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/**
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* The number of times the callback was invoked. Starts counting at 0
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* and increments after the callback was invoked.
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* @type {Ticks}
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* @readOnly
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*/
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this.ticks = 0;
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/**
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* The state timeline
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* @type {Tone.TimelineState}
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* @private
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*/
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this._state = new Tone.TimelineState(Tone.State.Stopped);
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/**
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* A pre-binded loop function to save a tiny bit of overhead
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* of rebinding the function on every frame.
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* @type {Function}
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* @private
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*/
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this._boundLoop = this._loop.bind(this);
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this._readOnly("frequency");
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//start the loop
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this._loop();
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};
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Tone.extend(Tone.Clock);
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/**
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* The defaults
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* @const
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* @type {Object}
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*/
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Tone.Clock.defaults = {
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"callback" : Tone.noOp,
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"frequency" : 1,
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"lookAhead" : "auto",
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};
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/**
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* Returns the playback state of the source, either "started", "stopped" or "paused".
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* @type {Tone.State}
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* @readOnly
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* @memberOf Tone.Clock#
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* @name state
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*/
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Object.defineProperty(Tone.Clock.prototype, "state", {
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get : function(){
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return this._state.getStateAtTime(this.now());
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}
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});
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/**
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* The time which the clock will schedule events in advance
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* of the current time. Scheduling notes in advance improves
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* performance and decreases the chance for clicks caused
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* by scheduling events in the past. If set to "auto",
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* this value will be automatically computed based on the
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* rate of requestAnimationFrame (0.016 seconds). Larger values
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* will yeild better performance, but at the cost of latency.
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* Values less than 0.016 are not recommended.
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* @type {Number|String}
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* @memberOf Tone.Clock#
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* @name lookAhead
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*/
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Object.defineProperty(Tone.Clock.prototype, "lookAhead", {
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get : function(){
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return this._lookAhead;
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},
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set : function(val){
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if (val === "auto"){
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this._lookAhead = "auto";
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} else {
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this._lookAhead = this.toSeconds(val);
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}
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}
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});
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/**
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* Start the clock at the given time. Optionally pass in an offset
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* of where to start the tick counter from.
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* @param {Time} time The time the clock should start
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* @param {Ticks=} offset Where the tick counter starts counting from.
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* @return {Tone.Clock} this
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*/
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Tone.Clock.prototype.start = function(time, offset){
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time = this.toSeconds(time);
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if (this._state.getStateAtTime(time) !== Tone.State.Started){
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this._state.addEvent({
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"state" : Tone.State.Started,
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"time" : time,
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"offset" : offset
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});
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}
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return this;
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};
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/**
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* Stop the clock. Stopping the clock resets the tick counter to 0.
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* @param {Time} [time=now] The time when the clock should stop.
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* @returns {Tone.Clock} this
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* @example
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* clock.stop();
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*/
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Tone.Clock.prototype.stop = function(time){
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time = this.toSeconds(time);
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if (this._state.getStateAtTime(time) !== Tone.State.Stopped){
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this._state.setStateAtTime(Tone.State.Stopped, time);
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}
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return this;
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};
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/**
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* Pause the clock. Pausing does not reset the tick counter.
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* @param {Time} [time=now] The time when the clock should stop.
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* @returns {Tone.Clock} this
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*/
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Tone.Clock.prototype.pause = function(time){
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time = this.toSeconds(time);
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if (this._state.getStateAtTime(time) === Tone.State.Started){
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this._state.setStateAtTime(Tone.State.Paused, time);
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}
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return this;
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};
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/**
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* The scheduling loop.
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* @param {Number} time The current page time starting from 0
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* when the page was loaded.
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* @private
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*/
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Tone.Clock.prototype._loop = function(time){
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this._loopID = requestAnimationFrame(this._boundLoop);
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//compute the look ahead
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if (this._lookAhead === "auto"){
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if (!this.isUndef(time)){
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var diff = (time - this._lastUpdate) / 1000;
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this._lastUpdate = time;
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//throw away large differences
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if (diff < this._threshold){
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//averaging
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this._computedLookAhead = (9 * this._computedLookAhead + diff) / 10;
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}
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}
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} else {
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this._computedLookAhead = this._lookAhead;
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}
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//get the frequency value to compute the value of the next loop
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var now = this.now();
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//if it's started
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var lookAhead = this._computedLookAhead * 2;
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var event = this._state.getEvent(now + lookAhead);
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var state = Tone.State.Stopped;
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if (event){
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state = event.state;
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//if it was stopped and now started
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if (this._nextTick === -1 && state === Tone.State.Started){
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this._nextTick = event.time;
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if (!this.isUndef(event.offset)){
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this.ticks = event.offset;
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}
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}
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}
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if (state === Tone.State.Started){
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while (now + lookAhead > this._nextTick){
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//catch up
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if (now > this._nextTick + this._threshold){
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this._nextTick = now;
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}
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var tickTime = this._nextTick;
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this._nextTick += 1 / this.frequency.getValueAtTime(this._nextTick);
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this.callback(tickTime);
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this.ticks++;
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}
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} else if (state === Tone.State.Stopped){
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this._nextTick = -1;
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this.ticks = 0;
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}
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};
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/**
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* Returns the scheduled state at the given time.
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* @param {Time} time The time to query.
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* @return {String} The name of the state input in setStateAtTime.
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* @example
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* clock.start("+0.1");
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* clock.getStateAtTime("+0.1"); //returns "started"
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*/
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Tone.Clock.prototype.getStateAtTime = function(time){
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return this._state.getStateAtTime(time);
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};
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/**
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* Clean up
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* @returns {Tone.Clock} this
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*/
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Tone.Clock.prototype.dispose = function(){
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cancelAnimationFrame(this._loopID);
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Tone.TimelineState.prototype.dispose.call(this);
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this._writable("frequency");
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this.frequency.dispose();
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this.frequency = null;
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this._boundLoop = Tone.noOp;
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this._nextTick = Infinity;
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this.callback = null;
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this._state.dispose();
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this._state = null;
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};
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return Tone.Clock;
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}); |