/**
  * Gets the character height of a character
  * @param mixed $ch a character
  * @param bool use_font_size default false -- 
  * @returns float the width
  */
 public function getCharacterHeight($ch, $use_font_size = false)
 {
     if ($this->direction != -1) {
         return $this->font_metrics[$this->direction]->getCharacterHeight($ch, $use_font_size);
     } else {
         return parent::getCharacterHeight($ch, $use_font_size);
     }
 }