ManuelBieh.de – Web Development & Consulting

<?php
/**
 * Erzeugt einen linearen Farbverlauf von einer Farbe zu einer anderen Farbe
 *
 * @author    Manuel Bieh
 * @param     string      Hex-Wert als Ausgangsfarbe
 * @param     string      Hex-Wert als Zielfarbe
 * @param     integer     Anzahl der Zwischenschritte
 * @return    array
 */
function gradient($start, $end, $steps=16) {
 
	if( (strlen($start) != 6) || (strlen($end) != 6) ) {
		return false;
	}
 
	$s[0] = hexdec(substr($start, 0, 2));
	$s[1] = hexdec(substr($start, 2, 2));
	$s[2] = hexdec(substr($start, 4, 2));
 
	$e[0] = hexdec(substr($end, 0, 2));
	$e[1] = hexdec(substr($end, 2, 2));
	$e[2] = hexdec(substr($end, 4, 2));
 
	$diff[0] = $s[0] &gt; $e[0] ? ($s[0]-$e[0])/($steps-1) : ($e[0]-$s[0])/($steps-1);
	$diff[1] = $s[1] &gt; $e[1] ? ($s[1]-$e[1])/($steps-1) : ($e[1]-$s[1])/($steps-1);
	$diff[2] = $s[2] &gt; $e[2] ? ($s[2]-$e[2])/($steps-1) : ($e[2]-$s[2])/($steps-1);
 
	$r[0] = $s[0];
	$g[0] = $s[1];
	$b[0] = $s[2];
 
	for($i=1; $i&lt;=$steps-1; $i++) {
 
		$r[$i] = $s[0] &gt; $e[0] ? $s[0] -= $diff[0] : $s[0] += $diff[0];
		$r[$i] = round($r[$i]);
 
		$g[$i] = $s[1] &gt; $e[1] ? $s[1] -= $diff[1] : $s[1] += $diff[1];
		$g[$i] = round($g[$i]);
 
		$b[$i] = $s[2] &gt; $e[2] ? $s[2] -= $diff[2] : $s[2] += $diff[2];
		$b[$i] = round($b[$i]);
 
	}
 
	$r[$steps] = $e[0];
	$g[$steps] = $e[1];
	$b[$steps] = $e[2];
 
	$count = count($r);
 
	for($i=0; $i&lt;$count; $i++) {
		$color[$i] = str_pad(dechex($r[$i]), 2, '0', STR_PAD_LEFT) . 
str_pad(dechex($g[$i]), 2, '0', STR_PAD_LEFT) . 
str_pad(dechex($b[$i]), 2, '0', STR_PAD_LEFT);
	}
 
	return $color;
 
}
?>