Difference between revisions of "Real-time graphing"

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Line 27: Line 27:
 
             if (200 == transport.status) {
 
             if (200 == transport.status) {
 
                 t = transport.responseText;
 
                 t = transport.responseText;
 +
                document.getElementById('debug').innerHTML = t;
 
                 a = parseFloat(t);
 
                 a = parseFloat(t);
 
                 if (x.length<30) {
 
                 if (x.length<30) {
Line 48: Line 49:
 
Start();
 
Start();
 
</jsxgraph>
 
</jsxgraph>
 +
<html><div id="debug"></div></html>
  
 
===The underlying JavaScript code===
 
===The underlying JavaScript code===
 +
<source lang="html4strict">
 +
  <script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/prototype.js"></script>
 +
  <style>
 +
    #jxgbox {
 +
      background-color:black;
 +
    }
 +
  </style>
 +
</source>
 +
 
<source lang="javascript">
 
<source lang="javascript">
 
var brd, g,  
 
var brd, g,  

Revision as of 10:33, 18 December 2009

The underlying JavaScript code

  <script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/prototype.js"></script>
  <style>
    #jxgbox {
       background-color:black;
    }
  </style>
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);
?>