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javascriptcanvaschartsundefined

canvg is undefined error

I am trying to use the code from Battlehorse to convert A Google Visualization chart to an image to save to a server. I was able to get this to work on localhost but when I attempt to use it on the Web Server I get the error "canvg is undefined". The Web Server is running IIS 7. I have searched quite a bit and have not been able to find any information regarding this error. Does anyone know what causes this error or how to resolve it?

http://www.battlehorse.net/page/topics/charts/save_google_charts_as_image.html

enter image description here

Code Sample:

<html>
<head>
<script type="text/javascript" src="http://canvg.googlecode.com/svn/trunk/rgbcolor.js"></script> 
<script type="text/javascript" src="http://canvg.googlecode.com/svn/trunk/canvg.js"></script>
<script type="text/javascript">
function getImgData(chartContainer) {
  var chartArea = chartContainer.getElementsByTagName('svg')[0].parentNode;
  var svg = chartArea.innerHTML;
  var doc = chartContainer.ownerDocument;
  var canvas = doc.createElement('canvas');
  canvas.setAttribute('width', chartArea.offsetWidth);
  canvas.setAttribute('height', chartArea.offsetHeight);

  canvas.setAttribute(
  'style',
  'position: absolute; ' +
  'top: ' + (-chartArea.offsetHeight * 2) + 'px;' +
  'left: ' + (-chartArea.offsetWidth * 2) + 'px;');
  doc.body.appendChild(canvas);
  canvg(canvas, svg);
  var imgData = canvas.toDataURL("image/png");
  canvas.parentNode.removeChild(canvas);
  return imgData;}           

function alert10() {
  try {
    var textbox1 = document.getElementById('textbox1');
    textbox1.value = getImgData(document.getElementById('chart1_div'));           
  }
  catch (err) {
    alert(err.message);
  }
}
</script>
</head>
Solution

  • I figured it out. The problem was that the site was running with SSL enabled and I was calling external script files by http protocols. I had to adjust the external script file references to either use https OR change them to relative like this:

    <script type="text/javascript" src="//canvg.googlecode.com/svn/trunk/rgbcolor.js"></script> 
<script type="text/javascript" src="//canvg.googlecode.com/svn/trunk/canvg.js"></script>

    Using the protocol relative path like "//..." makes sure it will work in both HTTP and HTTPS