/**
  * Get the kerning groups associated to a character
  * @param mixed $ch the character
  * @returns mixed the group
  */
 public function getKerningGroup($ch)
 {
     if ($this->direction != -1) {
         return $this->font_metrics[$this->direction]->getKerningGroup($ch);
     } else {
         return parent::getKerningGroup($ch);
     }
 }