public function seekToOffsetInteger($offset)
    {
        $indexes = explode(self::XY_SEPARATOR, $offset);
        try {
            if (count($indexes)==2) {
                if ($indexes[0]=='') {
                    $this->seekY($indexes[1]);
                } else {
                    $this->seekXY($offset);
                }
            } else {
                $this->seekX($offset);
            }
        } catch (OutOfRangeException $e) {
            throw $e;
        }
        return $this;
    }