public function crop($x, $y, $width, $height)
{
$this->preModify();
$this->resource->cropImage($width, $height, $x, $y);
$this->resource->setImagePage($width, $height, 0, 0);
$this->setWidth($width);
$this->setHeight($height);
$this->postModify();
return $this;
}