code: public function crop($width, $height, $offset_x = null, $offset_y = null)
      {
          switch ($offset_x) {
              case 'left':
                  $offset_x = 0;
                  break;
              case 'right':
                  $offset_x = (int)($this->getWidth() - $width);
                  break;
              case 'center':
                  $offset_x = (int)(($this->getWidth() - $width) / 2);
                  break;
          }
          switch ($offset_y) {
              case 'top':
                  $offset_y = 0;
                  break;
              case 'bottom':
                  $offset_y = (int)($this->getHeight() - $height);
                  break;
              case 'middle':
                  $offset_y = (int)(($this->getHeight() - $height) / 2);
                  break;
          }
          return parent::crop($width, $height, $offset_x, $offset_y);
      }
docs: {@inheritdoc}