mirror of
https://github.com/Tonejs/Tone.js
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104 lines
No EOL
2.7 KiB
JavaScript
104 lines
No EOL
2.7 KiB
JavaScript
define(["Tone/core/Tone", "Tone/core/Timeline"], function (Tone) {
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"use strict";
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/**
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* @class Tone.Draw is useful for synchronizing visuals and audio events.
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* Callbacks from Tone.Transport or any of the Tone.Event classes
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* always happen _before_ the scheduled time and are not synchronized
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* to the animation frame so they are not good for triggering tightly
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* synchronized visuals and sound. Tone.Draw makes it easy to schedule
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* callbacks using the AudioContext time and uses requestAnimationFrame.
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*
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* @singleton
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* @extends {Tone}
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* @example
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* Tone.Transport.schedule(function(time){
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* //use the time argument to schedule a callback with Tone.Draw
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* Tone.Draw.schedule(function(){
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* //do drawing or DOM manipulation here
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* }, time)
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* }, "+0.5")
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*/
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Tone.Draw = function(){
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/**
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* All of the events.
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* @type {Tone.Timeline}
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* @private
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*/
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this._events = new Tone.Timeline();
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/**
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* The time after which events are not invoked.
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* @type {Number}
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*/
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this.expiration = 0.25;
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/**
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* The amount of time before the scheduled time
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* that the callback can be invoked. Default is
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* half the time of an animation frame (0.008 seconds).
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* @type {Number}
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*/
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this.anticipation = 0.008;
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/**
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* The draw loop
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* @type {Function}
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* @private
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*/
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this._boundDrawLoop = this._drawLoop.bind(this);
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//start the loop
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this._drawLoop();
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};
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Tone.extend(Tone.Draw);
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/**
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* Schedule a function at the given time to be invoked
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* on the nearest animation frame.
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* @param {Function} callback Callback is invoked at the given time.
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* @param {Time} time The time relative to the AudioContext time
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* to invoke the callback.
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* @return {Tone.Draw} this
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*/
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Tone.Draw.prototype.schedule = function(callback, time){
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this._events.addEvent({
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callback : callback,
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time : this.toSeconds(time)
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});
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return this;
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};
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/**
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* Cancel events scheduled after the given time
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* @param {Time=} after Time after which scheduled events will
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* be removed from the scheduling timeline.
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* @return {Tone.Draw} this
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*/
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Tone.Draw.prototype.cancel = function(after){
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this._events.cancel(this.toSeconds(after));
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return this;
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};
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/**
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* The draw loop
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* @private
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*/
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Tone.Draw.prototype._drawLoop = function(){
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requestAnimationFrame(this._boundDrawLoop);
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var now = Tone.now();
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while(this._events.length && this._events.peek().time - this.anticipation <= now){
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var event = this._events.shift();
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if (now - event.time <= this.expiration){
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event.callback();
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}
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}
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};
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//make a singleton
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Tone.Draw = new Tone.Draw();
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return Tone.Draw;
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}); |