Tone.js/Tone/core/Context.js

574 lines
14 KiB
JavaScript

define(["Tone/core/Tone", "Tone/core/Emitter", "Tone/core/Timeline", "Tone/shim/AudioContext"], function(Tone){
/**
* @class Wrapper around the native AudioContext.
* @extends {Tone.Emitter}
* @param {AudioContext=} context optionally pass in a context
*/
Tone.Context = function(){
Tone.Emitter.call(this);
var options = Tone.defaults(arguments, ["context"], Tone.Context);
if (!options.context){
options.context = new window.AudioContext();
if (!options.context){
throw new Error("could not create AudioContext. Possibly too many AudioContexts running already.");
}
}
this._context = options.context;
// extend all of the methods
for (var prop in this._context){
this._defineProperty(this._context, prop);
}
/**
* The default latency hint
* @type {String}
* @private
*/
this._latencyHint = options.latencyHint;
/**
* An object containing all of the constants AudioBufferSourceNodes
* @type {Object}
* @private
*/
this._constants = {};
///////////////////////////////////////////////////////////////////////
// WORKER
///////////////////////////////////////////////////////////////////////
/**
* The amount of time events are scheduled
* into the future
* @type {Number}
*/
this.lookAhead = options.lookAhead;
/**
* A reference to the actual computed update interval
* @type {Number}
* @private
*/
this._computedUpdateInterval = 0;
/**
* A reliable callback method
* @private
* @type {Ticker}
*/
this._ticker = new Ticker(this.emit.bind(this, "tick"), options.clockSource, options.updateInterval);
///////////////////////////////////////////////////////////////////////
// TIMEOUTS
///////////////////////////////////////////////////////////////////////
/**
* All of the setTimeout events.
* @type {Tone.Timeline}
* @private
*/
this._timeouts = new Tone.Timeline();
/**
* The timeout id counter
* @private
* @type {Number}
*/
this._timeoutIds = 0;
this.on("tick", this._timeoutLoop.bind(this));
};
Tone.extend(Tone.Context, Tone.Emitter);
Tone.Emitter.mixin(Tone.Context);
/**
* defaults
* @static
* @type {Object}
*/
Tone.Context.defaults = {
"clockSource" : "worker",
"latencyHint" : "interactive",
"lookAhead" : 0.1,
"updateInterval" : 0.03
};
/**
* Define a property on this Tone.Context.
* This is used to extend the native AudioContext
* @param {AudioContext} context
* @param {String} prop
* @private
*/
Tone.Context.prototype._defineProperty = function(context, prop){
if (Tone.isUndef(this[prop])){
Object.defineProperty(this, prop, {
get : function(){
if (typeof context[prop] === "function"){
return context[prop].bind(context);
} else {
return context[prop];
}
},
set : function(val){
context[prop] = val;
}
});
}
};
/**
* The current audio context time
* @return {Number}
*/
Tone.Context.prototype.now = function(){
return this._context.currentTime + this.lookAhead;
};
/**
* Promise which is invoked when the context is running.
* Tries to resume the context if it's not started.
* @return {Promise}
*/
Tone.Context.prototype.ready = function(){
return new Promise(function(done){
if (this._context.state === "running"){
done();
} else {
this._context.resume().then(function(){
done();
});
}
}.bind(this));
};
/**
* Promise which is invoked when the context is running.
* Tries to resume the context if it's not started.
* @return {Promise}
*/
Tone.Context.prototype.close = function(){
return this._context.close().then(function(){
Tone.Context.emit("close", this);
}.bind(this));
};
/**
* Generate a looped buffer at some constant value.
* @param {Number} val
* @return {BufferSourceNode}
*/
Tone.Context.prototype.getConstant = function(val){
if (this._constants[val]){
return this._constants[val];
} else {
var buffer = this._context.createBuffer(1, 128, this._context.sampleRate);
var arr = buffer.getChannelData(0);
for (var i = 0; i < arr.length; i++){
arr[i] = val;
}
var constant = this._context.createBufferSource();
constant.channelCount = 1;
constant.channelCountMode = "explicit";
constant.buffer = buffer;
constant.loop = true;
constant.start(0);
this._constants[val] = constant;
return constant;
}
};
/**
* The private loop which keeps track of the context scheduled timeouts
* Is invoked from the clock source
* @private
*/
Tone.Context.prototype._timeoutLoop = function(){
var now = this.now();
while (this._timeouts && this._timeouts.length && this._timeouts.peek().time <= now){
this._timeouts.shift().callback();
}
};
/**
* A setTimeout which is gaurenteed by the clock source.
* Also runs in the offline context.
* @param {Function} fn The callback to invoke
* @param {Seconds} timeout The timeout in seconds
* @returns {Number} ID to use when invoking Tone.Context.clearTimeout
*/
Tone.Context.prototype.setTimeout = function(fn, timeout){
this._timeoutIds++;
var now = this.now();
this._timeouts.add({
callback : fn,
time : now + timeout,
id : this._timeoutIds
});
return this._timeoutIds;
};
/**
* Clears a previously scheduled timeout with Tone.context.setTimeout
* @param {Number} id The ID returned from setTimeout
* @return {Tone.Context} this
*/
Tone.Context.prototype.clearTimeout = function(id){
this._timeouts.forEach(function(event){
if (event.id === id){
this.remove(event);
}
});
return this;
};
/**
* How often the Web Worker callback is invoked.
* This number corresponds to how responsive the scheduling
* can be. Context.updateInterval + Context.lookAhead gives you the
* total latency between scheduling an event and hearing it.
* @type {Number}
* @memberOf Tone.Context#
* @name updateInterval
*/
Object.defineProperty(Tone.Context.prototype, "updateInterval", {
get : function(){
return this._ticker.updateInterval;
},
set : function(interval){
this._ticker.updateInterval = interval;
}
});
/**
* What the source of the clock is, either "worker" (Web Worker [default]),
* "timeout" (setTimeout), or "offline" (none).
* @type {String}
* @memberOf Tone.Context#
* @name clockSource
*/
Object.defineProperty(Tone.Context.prototype, "clockSource", {
get : function(){
return this._ticker.type;
},
set : function(type){
this._ticker.type = type;
}
});
/**
* The type of playback, which affects tradeoffs between audio
* output latency and responsiveness.
*
* In addition to setting the value in seconds, the latencyHint also
* accepts the strings "interactive" (prioritizes low latency),
* "playback" (prioritizes sustained playback), "balanced" (balances
* latency and performance), and "fastest" (lowest latency, might glitch more often).
* @type {String|Seconds}
* @memberOf Tone.Context#
* @name latencyHint
* @example
* //set the lookAhead to 0.3 seconds
* Tone.context.latencyHint = 0.3;
*/
Object.defineProperty(Tone.Context.prototype, "latencyHint", {
get : function(){
return this._latencyHint;
},
set : function(hint){
var lookAhead = hint;
this._latencyHint = hint;
if (Tone.isString(hint)){
switch (hint){
case "interactive" :
lookAhead = 0.1;
this._context.latencyHint = hint;
break;
case "playback" :
lookAhead = 0.8;
this._context.latencyHint = hint;
break;
case "balanced" :
lookAhead = 0.25;
this._context.latencyHint = hint;
break;
case "fastest" :
this._context.latencyHint = "interactive";
lookAhead = 0.01;
break;
}
}
this.lookAhead = lookAhead;
this.updateInterval = lookAhead/3;
}
});
/**
* Unlike other dispose methods, this returns a Promise
* which executes when the context is closed and disposed
* @returns {Promise} this
*/
Tone.Context.prototype.dispose = function(){
return this.close().then(function(){
Tone.Emitter.prototype.dispose.call(this);
this._ticker.dispose();
this._ticker = null;
this._timeouts.dispose();
this._timeouts = null;
for (var con in this._constants){
this._constants[con].disconnect();
}
this._constants = null;
}.bind(this));
};
/**
* @class A class which provides a reliable callback using either
* a Web Worker, or if that isn't supported, falls back to setTimeout.
* @private
*/
var Ticker = function(callback, type, updateInterval){
/**
* Either "worker" or "timeout"
* @type {String}
* @private
*/
this._type = type;
/**
* The update interval of the worker
* @private
* @type {Number}
*/
this._updateInterval = updateInterval;
/**
* The callback to invoke at regular intervals
* @type {Function}
* @private
*/
this._callback = Tone.defaultArg(callback, Tone.noOp);
//create the clock source for the first time
this._createClock();
};
/**
* The possible ticker types
* @private
* @type {Object}
*/
Ticker.Type = {
Worker : "worker",
Timeout : "timeout",
Offline : "offline"
};
/**
* Generate a web worker
* @return {WebWorker}
* @private
*/
Ticker.prototype._createWorker = function(){
//URL Shim
window.URL = window.URL || window.webkitURL;
var blob = new Blob([
//the initial timeout time
"var timeoutTime = "+(this._updateInterval * 1000).toFixed(1)+";" +
//onmessage callback
"self.onmessage = function(msg){" +
" timeoutTime = parseInt(msg.data);" +
"};" +
//the tick function which posts a message
//and schedules a new tick
"function tick(){" +
" setTimeout(tick, timeoutTime);" +
" self.postMessage('tick');" +
"}" +
//call tick initially
"tick();"
]);
var blobUrl = URL.createObjectURL(blob);
var worker = new Worker(blobUrl);
worker.onmessage = this._callback.bind(this);
this._worker = worker;
};
/**
* Create a timeout loop
* @private
*/
Ticker.prototype._createTimeout = function(){
this._timeout = setTimeout(function(){
this._createTimeout();
this._callback();
}.bind(this), this._updateInterval * 1000);
};
/**
* Create the clock source.
* @private
*/
Ticker.prototype._createClock = function(){
if (this._type === Ticker.Type.Worker){
try {
this._createWorker();
} catch (e){
// workers not supported, fallback to timeout
this._type = Ticker.Type.Timeout;
this._createClock();
}
} else if (this._type === Ticker.Type.Timeout){
this._createTimeout();
}
};
/**
* @memberOf Ticker#
* @type {Number}
* @name updateInterval
* @private
*/
Object.defineProperty(Ticker.prototype, "updateInterval", {
get : function(){
return this._updateInterval;
},
set : function(interval){
this._updateInterval = Math.max(interval, 128/44100);
if (this._type === Ticker.Type.Worker){
this._worker.postMessage(Math.max(interval * 1000, 1));
}
}
});
/**
* The type of the ticker, either a worker or a timeout
* @memberOf Ticker#
* @type {Number}
* @name type
* @private
*/
Object.defineProperty(Ticker.prototype, "type", {
get : function(){
return this._type;
},
set : function(type){
this._disposeClock();
this._type = type;
this._createClock();
}
});
/**
* Clean up the current clock source
* @private
*/
Ticker.prototype._disposeClock = function(){
if (this._timeout){
clearTimeout(this._timeout);
this._timeout = null;
}
if (this._worker){
this._worker.terminate();
this._worker.onmessage = null;
this._worker = null;
}
};
/**
* Clean up
* @private
*/
Ticker.prototype.dispose = function(){
this._disposeClock();
this._callback = null;
};
/**
* Shim all connect/disconnect and some deprecated methods which are still in
* some older implementations.
* @private
*/
Tone.getContext(function(){
var nativeConnect = AudioNode.prototype.connect;
var nativeDisconnect = AudioNode.prototype.disconnect;
//replace the old connect method
function toneConnect(B, outNum, inNum){
if (B.input){
inNum = Tone.defaultArg(inNum, 0);
if (Tone.isArray(B.input)){
return this.connect(B.input[inNum]);
} else {
return this.connect(B.input, outNum, inNum);
}
} else {
try {
if (B instanceof AudioNode){
nativeConnect.call(this, B, outNum, inNum);
return B;
} else {
nativeConnect.call(this, B, outNum);
return B;
}
} catch (e){
throw new Error("error connecting to node: "+B+"\n"+e);
}
}
}
//replace the old disconnect method
function toneDisconnect(B, outNum, inNum){
if (B && B.input && Tone.isArray(B.input)){
inNum = Tone.defaultArg(inNum, 0);
this.disconnect(B.input[inNum], outNum, 0);
} else if (B && B.input){
this.disconnect(B.input, outNum, inNum);
} else {
try {
if (B instanceof AudioParam){
nativeDisconnect.call(this, B, outNum);
} else {
nativeDisconnect.apply(this, arguments);
}
} catch (e){
throw new Error("error disconnecting node: "+B+"\n"+e);
}
}
}
if (AudioNode.prototype.connect !== toneConnect){
AudioNode.prototype.connect = toneConnect;
AudioNode.prototype.disconnect = toneDisconnect;
}
});
// set the audio context initially, and if one is not already created
if (Tone.supported && !Tone.initialized){
Tone.context = new Tone.Context();
// log on first initialization
// allow optional silencing of this log
if (!window.TONE_SILENCE_VERSION_LOGGING){
// eslint-disable-next-line no-console
console.log("%c * Tone.js " + Tone.version + " * ", "background: #000; color: #fff");
}
} else if (!Tone.supported){
// eslint-disable-next-line no-console
console.warn("This browser does not support Tone.js");
}
return Tone.Context;
});