calculateFontSpace = function calculateFontSpace(text, formObject, fontSize) {
  var font = formObject.scope.internal.getFont(formObject.fontName, formObject.fontStyle);
  var width = formObject.scope.getStringUnitWidth(text, {
    font: font,
    fontSize: parseFloat(fontSize),
    charSpace: 0
  }) * parseFloat(fontSize);
  var height = formObject.scope.getStringUnitWidth("3", {
    font: font,
    fontSize: parseFloat(fontSize),
    charSpace: 0
  }) * parseFloat(fontSize) * 1.5;
  return {
    height: height,
    width: width
  };
}
Small workaround for calculating the TextMetric approximately.

@param text
@param fontsize
@returns {TextMetrics} (Has Height and Width)