define(["Tone/core/Tone", "Tone/core/Context"], function (Tone) { /** * shim * @private */ if (!window.hasOwnProperty("OfflineAudioContext") && window.hasOwnProperty("webkitOfflineAudioContext")){ window.OfflineAudioContext = window.webkitOfflineAudioContext; } /** * @class Wrapper around the OfflineAudioContext * @extends {Tone.Context * @param {Number} channels The number of channels to render * @param {Number} duration The duration to render in samples * @param {Number} sampleRate the sample rate to render at */ Tone.OfflineContext = function(channels, duration, sampleRate){ /** * The offline context * @private * @type {OfflineAudioContext} */ var offlineContext = new OfflineAudioContext(channels, duration * sampleRate, sampleRate); //wrap the methods/members Tone.Context.call(this, { "context" : offlineContext, "clockSource" : "offline", "lookAhead" : 0, "updateInterval" : 128 / sampleRate }); /** * A private reference to the duration * @private * @type {Number} */ this._duration = duration; /** * An artificial clock source * @type {Number} * @private */ this._currentTime = 0; }; Tone.extend(Tone.OfflineContext, Tone.Context); /** * Override the now method to point to the internal clock time * @return {Number} */ Tone.OfflineContext.prototype.now = function(){ return this._currentTime; }; /** * Render the output of the OfflineContext * @return {Promise} */ Tone.OfflineContext.prototype.render = function(){ while(this._duration - this._currentTime >= 0){ //invoke all the callbacks on that time this.emit("tick"); //increment the clock this._currentTime += Tone.prototype.blockTime; } //promise returned is not yet implemented in all browsers return new Promise(function(done){ this._context.oncomplete = function(e){ done(e.renderedBuffer); }; this._context.startRendering(); }.bind(this)); }; /** * Close the context * @return {Number} */ Tone.OfflineContext.prototype.close = function(){ this._context = null; }; return Tone.OfflineContext; });