source: Dev/branches/rest-dojo-ui/client/dojox/timing/Streamer.js @ 256

define(["./_base"], function(){
        dojo.experimental("dojox.timing.Streamer");
        dojox.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 dojox.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(/* dojox.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;
                        }
                        throw new Error("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);
                }
        };
        return dojox.timing.Streamer;
});