git.pond.sub.org Git - eow/blob - static/dojo-release-1.1.1/dojox/timing/Streamer.js

   1 if(!dojo._hasResource["dojox.timing.Streamer"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
   2 dojo._hasResource["dojox.timing.Streamer"] = true;
   3 dojo.provide("dojox.timing.Streamer");
   4
   5 dojo.require("dojox.timing._base");
   6
   7 dojox.timing.Streamer = function(
   8         /* function */input,
   9         /* function */output,
  10         /* int */interval,
  11         /* int */minimum,
  12         /* array */initialData
  13 ){
  14         //      summary
  15         //      Streamer will take an input function that pushes N datapoints into a
  16         //              queue, and will pass the next point in that queue out to an
  17         //              output function at the passed interval; this way you can emulate
  18         //              a constant buffered stream of data.
  19         //      input: the function executed when the internal queue reaches minimumSize
  20         //      output: the function executed on internal tick
  21         //      interval: the interval in ms at which the output function is fired.
  22         //      minimum: the minimum number of elements in the internal queue.
  23
  24         var self = this;
  25         var queue = [];
  26
  27         //      public properties
  28         this.interval = interval || 1000;
  29         this.minimumSize = minimum || 10;       //      latency usually == interval * minimumSize
  30         this.inputFunction = input || function(q){ };
  31         this.outputFunction = output || function(point){ };
  32
  33         //      more setup
  34         var timer = new dojox.timing.Timer(this.interval);
  35         var tick = function(){
  36                 self.onTick(self);
  37
  38                 if(queue.length < self.minimumSize){
  39                         self.inputFunction(queue);
  40                 }
  41
  42                 var obj = queue.shift();
  43                 while(typeof(obj) == "undefined" && queue.length > 0){
  44                         obj = queue.shift();
  45                 }
  46
  47                 //      check to see if the input function needs to be fired
  48                 //      stop before firing the output function
  49                 //      TODO: relegate this to the output function?
  50                 if(typeof(obj) == "undefined"){
  51                         self.stop();
  52                         return;
  53                 }
  54
  55                 //      call the output function.
  56                 self.outputFunction(obj);
  57         };
  58
  59         this.setInterval = function(/* int */ms){
  60                 //      summary
  61                 //      sets the interval in milliseconds of the internal timer
  62                 this.interval = ms;
  63                 timer.setInterval(ms);
  64         };
  65
  66         this.onTick = function(/* dojox.timing.Streamer */obj){ };
  67         // wrap the timer functions so that we can connect to them if needed.
  68         this.start = function(){
  69                 //      summary
  70                 //      starts the Streamer
  71                 if(typeof(this.inputFunction) == "function" && typeof(this.outputFunction) == "function"){
  72                         timer.start();
  73                         return;
  74                 }
  75                 throw new Error("You cannot start a Streamer without an input and an output function.");
  76         };
  77         this.onStart = function(){ };
  78         this.stop = function(){
  79                 //      summary
  80                 //      stops the Streamer
  81                 timer.stop();
  82         };
  83         this.onStop = function(){ };
  84
  85         //      finish initialization
  86         timer.onTick = this.tick;
  87         timer.onStart = this.onStart;
  88         timer.onStop = this.onStop;
  89         if(initialData){
  90                 queue.concat(initialData);
  91         }
  92 };
  93
  94 }