Question

I’m having toubles with converting triple HEX color codes in an RGB color code.

What I’ve got so far for HEX to RGB is:

if(strlen($hex) == 3) {
        $color['r'] = hexdec(substr($hex, 0, 1) . $r);
        $color['g'] = hexdec(substr($hex, 1, 1) . $g);
        $color['b'] = hexdec(substr($hex, 2, 1) . $b);
    }

When I convert the RGB code back to HEX it’s a different one.

E.g.: #FFF becomes 15, 15, 15 but 15, 15, 15 is #0F0F0F

I’m also not sure about converting RGB back to triple HEX code. My code for RGB to HEX looks like this:

$hex = str_pad(dechex($r), 2, "0", STR_PAD_LEFT);
$hex.= str_pad(dechex($g), 2, "0", STR_PAD_LEFT);
$hex.= str_pad(dechex($b), 2, "0", STR_PAD_LEFT);

Any help is greatly appreciated! Thanks in advance!

Answer 1

It looks like you need to handle triplets in a different way: #XYZ = #XXYYZZ. #FFF should be, for example, the same as #FFFFFF, or well, (255, 255, 255), instead of (15, 15, 15).

So, a way to do this is with the following code:

if(strlen($hex) == 3) {
    $color['r'] = hexdec(substr($hex, 0, 1) . substr($hex, 0, 1));
    $color['g'] = hexdec(substr($hex, 1, 1) . substr($hex, 1, 1));
    $color['b'] = hexdec(substr($hex, 2, 1) . substr($hex, 2, 1));
}

Note I’m not including $r, $g and $b, as I don’t know why are you using them.