public static function getInstance($x, $y, $id, $width, $height, $style = null)
 {
     $rect = new SVGRect('<rect></rect>');
     $rect->setX($x);
     $rect->setY($y);
     $rect->setWidth($width);
     $rect->setHeight($height);
     $rect->setId($id);
     $rect->setStyle($style);
     return $rect;
 }