Convert RGBA into HEXADECIMAL or HEXADECIMAL into RGBA with transparency support.

hex2rgba-rgba2hex.php

<?php

function hex2rgba($hex) {
	$hex = str_replace("#", "", $hex);
	
	switch (strlen($hex)) {
		case 3 : 
			$r = hexdec(substr($hex, 0, 1).substr($hex, 0, 1));
			$g = hexdec(substr($hex, 1, 1).substr($hex, 1, 1));
			$b = hexdec(substr($hex, 2, 1).substr($hex, 2, 1));
			$a = 1;
			break;
		case 6 :
			$r = hexdec(substr($hex, 0, 2));
			$g = hexdec(substr($hex, 2, 2));
			$b = hexdec(substr($hex, 4, 2));
			$a = 1;
			break;
		case 8 :
			$a = hexdec(substr($hex, 0, 2)) / 255;
			$r = hexdec(substr($hex, 2, 2));
			$g = hexdec(substr($hex, 4, 2));
			$b = hexdec(substr($hex, 6, 2));
			break;
	}
	$rgba = array($r, $g, $b, $a);

   	return 'rgba('.implode(', ', $rgba).')';
}

function rgba2hex($string) {
	$rgba  = array();
	$hex   = '';
	$regex = '#\((([^()]+|(?R))*)\)#';
	if (preg_match_all($regex, $string ,$matches)) {
    	$rgba = explode(',', implode(' ', $matches[1]));
	} else {
		$rgba = explode(',', $string);
	}
	
	$rr = dechex($rgba['0']);
	$gg = dechex($rgba['1']);
	$bb = dechex($rgba['2']);
	$aa = '';
	
	if (array_key_exists('3', $rgba)) {
		$aa = dechex($rgba['3'] * 255);
	}
	
	return strtoupper("#$aa$rr$gg$bb");
}

echo 'rgba(175, 175, 175) --> ' . rgba2hex('rgba(175, 175, 175)') . '<br />';
echo 'rgba(175, 175, 175, 0.80) --> ' . rgba2hex('rgba(175, 175, 175, 0.80)') . '<br />';
echo '#CCAFAFAF --> ' . hex2rgba('#CCAFAFAF').'<br />';
echo '#AFAFAF --> ' . hex2rgba('#AFAFAF');

?>