public function radius($int_rx, $int_ry = 0)
    {
        if (!is_integer($int_rx) || !is_integer($int_ry)) {
            throw new \InvalidArgumentException('Radius must be integer value!');
        }

        if ($int_ry == 0) {
            $this->radius->r = $int_rx;
            $this->radius->w = 2 * $int_rx;
            $this->radius->h = 2 * $int_rx;
            $this->radius->is_circle = true;
        } else {
            $this->radius->rx = $int_rx;
            $this->radius->ry = $int_ry;
            $this->radius->w = 2 * $int_rx;
            $this->radius->h = 2 * $int_ry;
            $this->radius->is_circle = false;
        }

        return $this;
    }