Difference between revisions of "Real-time graphing"

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Line 3: Line 3:
 
   <style>
 
   <style>
 
     #jxgbox {
 
     #jxgbox {
       background-color:black;
+
       /*background-color:black;*/
 
     }
 
     }
 
   </style>
 
   </style>
Line 78: Line 78:
  
 
Start = function() {
 
Start = function() {
     periodical = setInterval(fetchData,500);  // Start the periodical update
+
     periodical = setInterval(fetchData,1000);  // Start the periodical update
 
};
 
};
  

Revision as of 10:23, 18 December 2009

The underlying JavaScript code

var brd, g, 
    x = [], y = [];

brd = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox:[0,20,30,-2]});

fetchData = function() {
    new Ajax.Request('/ajax/fakesensor.php', {
        onComplete: function(transport) {
            var t, a;
            if (200 == transport.status) {
                t = transport.responseText;
                a = parseFloat(t);
                if (x.length<30) {
                    x.push(x.length);
                } else {
                    y.splice(0,1);
                }
                y.push(a);
                if (!g) {                   // If the curve does not exist yet, create it.
                    g = brd.createElement('curve', [x,y],{strokeWidth:3, strokeColor:'green'}); 
                } 
                brd.update();
            };
    }});
};

Start = function() {
    periodical = setInterval(fetchData,1000);  // Start the periodical update
};

Start();

The PHP code of fakesensor.php

<?php
   echo mt_rand(0,20);
?>