/**
  *  Get the width of a character in a fixed width font (for the current direction)
  *  @returns number Returns null if called when the current font is not fixed width
  */
 public function getFixedWidth()
 {
     if ($this->direction != -1) {
         return $this->font_metrics[$this->direction]->getFixedWidth();
     } else {
         parent::getFixedWidth();
     }
 }