dojo.provide("dojo.lang.timing.Streamer");
dojo.require("dojo.lang.timing.Timer");
dojo.lang.timing.Streamer = function(
/* function */input,
/* function */output,
/* int */interval,
/* int */minimum,
/* array */initialData
){
// summary
// Streamer will take an input function that pushes N datapoints into a
// queue, and will pass the next point in that queue out to an
// output function at the passed interval; this way you can emulate
// a constant buffered stream of data.
// input: the function executed when the internal queue reaches minimumSize
// output: the function executed on internal tick
// interval: the interval in ms at which the output function is fired.
// minimum: the minimum number of elements in the internal queue.
var self = this;
var queue = [];
// public properties
this.interval = interval || 1000;
this.minimumSize = minimum || 10; // latency usually == interval * minimumSize
this.inputFunction = input || function(q){ };
this.outputFunction = output || function(point){ };
// more setup
var timer = new dojo.lang.timing.Timer(this.interval);
var tick = function(){
self.onTick(self);
if(queue.length < self.minimumSize){
self.inputFunction(queue);
}
var obj = queue.shift();
while(typeof(obj) == "undefined" && queue.length > 0){
obj = queue.shift();
}
// check to see if the input function needs to be fired
// stop before firing the output function
// TODO: relegate this to the output function?
if(typeof(obj) == "undefined"){
self.stop();
return;
}
// call the output function.
self.outputFunction(obj);
};
this.setInterval = function(/* int */ms){
// summary
// sets the interval in milliseconds of the internal timer
this.interval = ms;
timer.setInterval(ms);
};
this.onTick = function(/* dojo.lang.timing.Streamer */obj){ };
// wrap the timer functions so that we can connect to them if needed.
this.start = function(){
// summary
// starts the Streamer
if(typeof(this.inputFunction) == "function" && typeof(this.outputFunction) == "function"){
timer.start();
return;
}
dojo.raise("You cannot start a Streamer without an input and an output function.");
};
this.onStart = function(){ };
this.stop = function(){
// summary
// stops the Streamer
timer.stop();
};
this.onStop = function(){ };
// finish initialization
timer.onTick = this.tick;
timer.onStart = this.onStart;
timer.onStop = this.onStop;
if(initialData){
queue.concat(initialData);
}
};