<html><body>
<script type="text/javascript">
var width = 640; var height = 400;
var c = document.createElement("canvas");
c.setAttribute('id',    'myCanvas'); 
c.setAttribute('style', 'border:1px solid black;'); 
c.setAttribute('width',  width);
c.setAttribute('height', height); 
document.body.appendChild(c);
var ctx = document.getElementById('myCanvas').getContext("2d");

var columnCount = 8;