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Clock.js
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Clock.js
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define(["Tone/core/Tone", "Tone/source/TickSource", "Tone/core/TimelineState",
"Tone/core/Emitter", "Tone/core/Context"], function(Tone){
"use strict";
/**
* @class A sample accurate clock which provides a callback at the given rate.
* While the callback is not sample-accurate (it is still susceptible to
* loose JS timing), the time passed in as the argument to the callback
* is precise. For most applications, it is better to use Tone.Transport
* instead of the Clock by itself since you can synchronize multiple callbacks.
*
* @constructor
* @extends {Tone.Emitter}
* @param {function} callback The callback to be invoked with the time of the audio event
* @param {Frequency} frequency The rate of the callback
* @example
* //the callback will be invoked approximately once a second
* //and will print the time exactly once a second apart.
* var clock = new Tone.Clock(function(time){
* console.log(time);
* }, 1);
*/
Tone.Clock = function(){
var options = Tone.defaults(arguments, ["callback", "frequency"], Tone.Clock);
Tone.Emitter.call(this);
/**
* The callback function to invoke at the scheduled tick.
* @type {Function}
*/
this.callback = options.callback;
/**
* The next time the callback is scheduled.
* @type {Number}
* @private
*/
this._nextTick = 0;
/**
* The tick counter
* @type {Tone.TickSource}
* @private
*/
this._tickSource = new Tone.TickSource(options.frequency);
/**
* The last time the loop callback was invoked
* @private
* @type {Number}
*/
this._lastUpdate = 0;
/**
* The rate the callback function should be invoked.
* @type {BPM}
* @signal
*/
this.frequency = this._tickSource.frequency;
this._readOnly("frequency");
/**
* The state timeline
* @type {Tone.TimelineState}
* @private
*/
this._state = new Tone.TimelineState(Tone.State.Stopped);
//add an initial state
this._state.setStateAtTime(Tone.State.Stopped, 0);
/**
* The loop function bound to its context.
* This is necessary to remove the event in the end.
* @type {Function}
* @private
*/
this._boundLoop = this._loop.bind(this);
//bind a callback to the worker thread
this.context.on("tick", this._boundLoop);
};
Tone.extend(Tone.Clock, Tone.Emitter);
/**
* The defaults
* @const
* @type {Object}
*/
Tone.Clock.defaults = {
"callback" : Tone.noOp,
"frequency" : 1,
};
/**
* Returns the playback state of the source, either "started", "stopped" or "paused".
* @type {Tone.State}
* @readOnly
* @memberOf Tone.Clock#
* @name state
*/
Object.defineProperty(Tone.Clock.prototype, "state", {
get : function(){
return this._state.getValueAtTime(this.now());
}
});
/**
* Start the clock at the given time. Optionally pass in an offset
* of where to start the tick counter from.
* @param {Time=} time The time the clock should start
* @param {Ticks=} offset Where the tick counter starts counting from.
* @return {Tone.Clock} this
*/
Tone.Clock.prototype.start = function(time, offset){
time = this.toSeconds(time);
if (this._state.getValueAtTime(time) !== Tone.State.Started){
this._state.setStateAtTime(Tone.State.Started, time);
this._tickSource.start(time, offset);
if (time < this._lastUpdate){
this.emit("start", time, offset);
}
}
return this;
};
/**
* Stop the clock. Stopping the clock resets the tick counter to 0.
* @param {Time} [time=now] The time when the clock should stop.
* @returns {Tone.Clock} this
* @example
* clock.stop();
*/
Tone.Clock.prototype.stop = function(time){
time = this.toSeconds(time);
this._state.cancel(time);
this._state.setStateAtTime(Tone.State.Stopped, time);
this._tickSource.stop(time);
if (time < this._lastUpdate){
this.emit("stop", time);
}
return this;
};
/**
* Pause the clock. Pausing does not reset the tick counter.
* @param {Time} [time=now] The time when the clock should stop.
* @returns {Tone.Clock} this
*/
Tone.Clock.prototype.pause = function(time){
time = this.toSeconds(time);
if (this._state.getValueAtTime(time) === Tone.State.Started){
this._state.setStateAtTime(Tone.State.Paused, time);
this._tickSource.pause(time);
if (time < this._lastUpdate){
this.emit("pause", time);
}
}
return this;
};
/**
* The number of times the callback was invoked. Starts counting at 0
* and increments after the callback was invoked.
* @type {Ticks}
*/
Object.defineProperty(Tone.Clock.prototype, "ticks", {
get : function(){
return Math.ceil(this.getTicksAtTime(this.now()));
},
set : function(t){
this._tickSource.ticks = t;
}
});
/**
* The time since ticks=0 that the Clock has been running. Accounts
* for tempo curves
* @type {Seconds}
*/
Object.defineProperty(Tone.Clock.prototype, "seconds", {
get : function(){
return this._tickSource.seconds;
},
set : function(s){
this._tickSource.seconds = s;
}
});
/**
* Return the elapsed seconds at the given time.
* @param {Time} time When to get the elapsed seconds
* @return {Seconds} The number of elapsed seconds
*/
Tone.Clock.prototype.getSecondsAtTime = function(time){
return this._tickSource.getSecondsAtTime(time);
};
/**
* Set the clock's ticks at the given time.
* @param {Ticks} ticks The tick value to set
* @param {Time} time When to set the tick value
* @return {Tone.Clock} this
*/
Tone.Clock.prototype.setTicksAtTime = function(ticks, time){
this._tickSource.setTicksAtTime(ticks, time);
return this;
};
/**
* Get the clock's ticks at the given time.
* @param {Time} time When to get the tick value
* @return {Ticks} The tick value at the given time.
*/
Tone.Clock.prototype.getTicksAtTime = function(time){
return this._tickSource.getTicksAtTime(time);
};
/**
* Get the time of the next tick
* @param {Ticks} ticks The tick number.
* @param {Time} before
* @return {Tone.Clock} this
*/
Tone.Clock.prototype.nextTickTime = function(offset, when){
when = this.toSeconds(when);
var currentTick = this.getTicksAtTime(when);
return this._tickSource.getTimeOfTick(currentTick+offset, when);
};
/**
* The scheduling loop.
* @private
*/
Tone.Clock.prototype._loop = function(){
var startTime = this._lastUpdate;
var endTime = this.now();
this._lastUpdate = endTime;
if (startTime !== endTime){
//the state change events
this._state.forEachBetween(startTime, endTime, function(e){
switch (e.state){
case Tone.State.Started :
var offset = this._tickSource.getTicksAtTime(e.time);
this.emit("start", e.time, offset);
break;
case Tone.State.Stopped :
if (e.time !== 0){
this.emit("stop", e.time);
}
break;
case Tone.State.Paused :
this.emit("pause", e.time);
break;
}
}.bind(this));
//the tick callbacks
this._tickSource.forEachTickBetween(startTime, endTime, function(time, ticks){
this.callback(time, ticks);
}.bind(this));
}
};
/**
* Returns the scheduled state at the given time.
* @param {Time} time The time to query.
* @return {String} The name of the state input in setStateAtTime.
* @example
* clock.start("+0.1");
* clock.getStateAtTime("+0.1"); //returns "started"
*/
Tone.Clock.prototype.getStateAtTime = function(time){
time = this.toSeconds(time);
return this._state.getValueAtTime(time);
};
/**
* Clean up
* @returns {Tone.Clock} this
*/
Tone.Clock.prototype.dispose = function(){
Tone.Emitter.prototype.dispose.call(this);
this.context.off("tick", this._boundLoop);
this._writable("frequency");
this._tickSource.dispose();
this._tickSource = null;
this.frequency = null;
this._boundLoop = null;
this._nextTick = Infinity;
this.callback = null;
this._state.dispose();
this._state = null;
};
return Tone.Clock;
});