public function calculateWidth($text, $size = self::TEXT_SIZE)
    {
        $size = $this->convertToPt($size);
        $box  = imagettfbbox($size, 0, $this->fontPath, $text);

        return round(abs($box[2] - $box[0]) + self::SHIELD_PADDING_EXTERNAL + self::SHIELD_PADDING_INTERNAL, 1);
    }