private function convertColor($hex, $alpha = false)
    {
        $hex = str_replace('#', '', $hex);
        $length = strlen($hex);
        $rgb['0'] = hexdec($length == 6 ? substr($hex, 0, 2) : ($length == 3 ? str_repeat(substr($hex, 0, 1), 2) : 0));
        $rgb['1'] = hexdec($length == 6 ? substr($hex, 2, 2) : ($length == 3 ? str_repeat(substr($hex, 1, 1), 2) : 0));
        $rgb['2'] = hexdec($length == 6 ? substr($hex, 4, 2) : ($length == 3 ? str_repeat(substr($hex, 2, 1), 2) : 0));
        if ($alpha) {
            $rgb['2'] = $alpha;
        }

        return $rgb;
    }