Exportar Google Chart a Imagen PNG / Export Google Chart to Image PNG

helper_googlechart_to_png.js

/**
 * Requested
 * <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>
 * /


/**
 * Convert object to a canvas object
 */
function getImgCanvas(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);
  return canvas;
}

/**
 * Download Image
 */
function downloadImg(canvas, filename) {
  // create an "off-screen" anchor tag
  var lnk = document.createElement('a'),e;
  /// the key here is to set the download attribute of the a tag
  lnk.download = filename;
  /// convert canvas content to data-uri for link. When download
  /// attribute is set the content pointed to by link will be
  /// pushed as "download" in HTML5 capable browsers
  lnk.href = canvas.toDataURL("image/png;base64");
  /// create a "fake" click-event to trigger the download
  if (document.createEvent) {
      e = document.createEvent("MouseEvents");
      e.initMouseEvent("click", true, true, window,
              0, 0, 0, 0, 0, false, false, false,
              false, 0, null);

      lnk.dispatchEvent(e);
  } else if (lnk.fireEvent) {
      lnk.fireEvent("onclick");
  }
}

/**
 * Save Image
 */ 
function saveToImg(container_id, filename) {
  var canvas = getImgCanvas(document.getElementById(container_id));
  downloadImg(canvas, filename);
}



/**
 * USE
 * $("#btn_download").click(function() {
 *  saveToImg("content_id", "image.png");
 * });
 */