public function getMetricsFromSvg($svg, &$output)
 {
     $output = $output;
     $svgXml = com_wiris_util_xml_WXmlUtils::parseXML($svg);
     $width = $svgXml->firstElement()->get("width");
     $height = $svgXml->firstElement()->get("height");
     $baseline = $svgXml->firstElement()->get("wrs:baseline");
     $r = null;
     if ($output !== null) {
         $output["width"] = "" . $width;
         $output["height"] = "" . $height;
         $output["baseline"] = "" . $baseline;
         $r = "";
     } else {
         $r = "&cw=" . $width . "&ch=" . $height . "&cb=" . $baseline;
     }
     return $r;
 }