I’ll just leave this here. It’s an old piece of code I used for a theme, where users selected a colour and then set a custom transparency value.
<?php
/**
* Convert a Hexadecimal colour code to RGBA
*
* Converts a Hexadecimal colour code to RGB and returns an RGBA value.
*
* @param string $color Colour string
* @param string $opacity Colour opacity
* @return string
*/
function supernova_hex2rgb($color, $opacity) {
$color = trim($color, '#');
$hex = hexdec($color);
$r = hexdec(substr($color, 0, 2));
$g = hexdec(substr($color, 2, 2));
$b = hexdec(substr($color, 4, 2));
return $r . ', ' . $g . ', ' . $b . ', ' . $opacity;
}
?><style scope="inline">
selector {
background-color: rgba(<?php echo supernova_hex2rgb(get_option('header_background_colour'), '0.85'); ?>);
}
</style>I have moved to CSS variable since then, but it’s still useful.
