Some part of my code that I use:
There are basically two functions, one that uses an array of colors and divides them equally over 100% and another that does the actual fading between 2 colors.
The functions:
function getColor($start, $end, $percent) {
$sr=hexdec(substr($start, 0, 2));
$sg=hexdec(substr($start, 2, 2));
$sb=hexdec(substr($start, 4, 2));
$er=hexdec(substr($end, 0, 2));
$eg=hexdec(substr($end, 2, 2));
$eb=hexdec(substr($end, 4, 2));
$pc = $percent/100;
$r = floor($sr+($pc*($er-$sr)) + .5);
$g = floor($sg+($pc*($eg-$sg)) + .5);
$b = floor($sb+($pc*($eb-$sb)) + .5);
return(sprintf('%02X%02X%02X', $r, $g, $b));
}
function getGradient($colors, $percent) {
$div = count($colors) - 1;
$pct = (($percent * $div * 100) % 10000) / 100; //Partial percentage, still quite precise.
$cur = floor($percent / 100 * $div); //Current start color.
if ($percentage < 100 && $percent > 0) {
$color = getColor($colors[$cur], $colors[$cur + 1], $pct);
} elseif ($percent >= 100) {
$color = $colors[$div];
} else {
$color = $colors[0];
}
return $color;
}
Usage is actually very easy, just make an array of HEX colors (in strings)
$colors = array(’FF0000’,’FF9900’,’FFFF00’);
And call it with the percentage you want (can be ’precise’)
$current = getGradient($colors, 25);
In this example, the returned color will be between FF0000(red) and FF9900(orange) (so around FF4500)
