title: Export Highcharts to jsPDF - canvg error
body: <p>I'm looking for a solution about highcharts export to PDF with jsPDF.
  I used this solution to export my graph as image to my pdf -> <a href="https://stackoverflow.com/questions/25630811/export-highcharts-to-pdf-using-javascript-and-local-server-no-internet-connec?answertab=active#tab-top">Export Highcharts to PDF (using javascript and local server - no internet connection)</a> </p>
  
  <p>It's working fine, but for some graph i could not generate the image because of this error :</p>
  
  <pre><code>Uncaught TypeError: undefined is not a function -- canvg.js:2000
  svg.Element.text.getAnchorDelta -- canvg.js:2010
  svg.Element.text.renderChild -- canvg.js:1989
  svg.Element.text.renderChildren -- canvg.js:679
  svg.Element.ElementBase.render -- canvg.js:698
  svg.Element.ElementBase.renderChildren -- canvg.js:679
  svg.Element.ElementBase.render -- canvg.js:698
  svg.Element.ElementBase.renderChildren -- canvg.js:679
  svg.Element.ElementBase.render -- canvg.js:2723
  svg.loadXmlDoc.draw -- canvg.js:2733
  svg.loadXmlDoc -- canvg.js:2646
  svg.loadXml -- canvg.js:62
  canvg -- indicateurs.js:3237
  $.bind.H.Chart.createCanvas -- indicateurs.js:3171
  (anonymous function) -- jquery-1.10.2.min.js:4
  x.extend.each -- indicateurs.js:3164
  _indicateurs.hightcharts.graph_to_pdf -- indicateurs.js:3262
  (anonymous function) -- jquery-1.10.2.min.js:5
  x.event.dispatch -- jquery-1.10.2.min.js:5
  x.event.add.v.handle
  </code></pre>
  
  <p>Following, the canvas method throwing the error (canvg.js) :</p>
  
  <pre><code>        this.getAnchorDelta = function (ctx, parent, startI) {
              var textAnchor = this.style('text-anchor').valueOrDefault('start');
              if (textAnchor != 'start') {
                  var width = 0;
                  for (var i=startI; i&lt;parent.children.length; i++) {
                      var child = parent.children[i];
                      if (i &gt; startI &amp;&amp; child.attribute('x').hasValue()) break; // new group
                      width += child.measureTextRecursive(ctx);       // ######## PROBLEM LOCATED ON THIS LINE
                  }
                  return -1 * (textAnchor == 'end' ? width : width / 2.0);
              }
              return 0;
          }
  </code></pre>
  
  <p>Any first ideas about what could be make this error ?</p>