/**
* Resize an image to fill a frame
*
* @since 1.0
* @access public
* @param int The target width.
* @param int The target height.
* @return SocialImage Returns itself for chaining.
*/
public function fill($width = null, $height = null)
{
$this->adapter->fill($this->image, $width, $height);
return $this;
}