16進制的顏色值通常表示為#FFFFFF，當前也有縮減為#FFF，前提是兩位兩位必需相同，例如#FEFEFE這種，就不能進行縮減。而RGB的顏色格式是由3組0~255的數字構成，分別代表紅（Red）、綠（Green）、藍（Blue）的色值。
/**
* 將16進制顏色轉換為RGB
* author www.jb51.net
*/
function hex2rgb($hexColor){
$color=str_replace('#','',$hexColor);
if (strlen($color)> 3){
$rgb=array(
'r'=>hexdec(substr($color,0,2)),
'g'=>hexdec(substr($color,2,2)),
'b'=>hexdec(substr($color,4,2))
);
}else{
$r=substr($color,0,1). substr($color,0,1);
$g=substr($color,1,1). substr($color,1,1);
$b=substr($color,2,1). substr($color,2,1);
$rgb=array(
'r'=>hexdec($r),
'g'=>hexdec($g),
'b'=>hexdec($b)
);
}
return $rgb;
}
/**
* 十六進制轉RGB
* @param string $color 16進制顏色值
* @return array
*/
public static function hex2rgb($color) {
$hexColor = str_replace('#', '', $color);
$lens = strlen($hexColor);
if ($lens != 3 $lens != 6) {
return false;
}
$newcolor = '';
if ($lens == 3) {
for ($i = 0; $i $lens; $i++) {
$newcolor .= $hexColor[$i] . $hexColor[$i];
}
} else {
$newcolor = $hexColor;
}
$hex = str_split($newcolor, 2);
$rgb = [];
foreach ($hex as $key => $vls) {
$rgb[] = hexdec($vls);
}
return $rgb;
}
/**
* RGB轉 十六進制
* @param $rgb RGB顏色的字符串 如：rgb(255,255,255);
* @return string 十六進制顏色值 如：#FFFFFF
*/
function RGBToHex($rgb){
$regexp = "/^rgb\(([0-9]{0,3})\,\s*([0-9]{0,3})\,\s*([0-9]{0,3})\)/";
$re = preg_match($regexp, $rgb, $match);
$re = array_shift($match);
$hexColor = "#";
$hex = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F');
for ($i = 0; $i 3; $i++) {
$r = null;
$c = $match[$i];
$hexAr = array();
while ($c > 16) {
$r = $c % 16;
$c = ($c / 16) >> 0;
array_push($hexAr, $hex[$r]);
}
array_push($hexAr, $hex[$c]);
$ret = array_reverse($hexAr);
$item = implode('', $ret);
$item = str_pad($item, 2, '0', STR_PAD_LEFT);
$hexColor .= $item;
}
return $hexColor;
}
/**
* 十六進制 轉 RGB
*/
function hex2rgb($hexColor) {
$color = str_replace('#', '', $hexColor);
if (strlen($color) > 3) {
$rgb = array(
'r' => hexdec(substr($color, 0, 2)),
'g' => hexdec(substr($color, 2, 2)),
'b' => hexdec(substr($color, 4, 2))
);
} else {
$color = $hexColor;
$r = substr($color, 0, 1) . substr($color, 0, 1);
$g = substr($color, 1, 1) . substr($color, 1, 1);
$b = substr($color, 2, 1) . substr($color, 2, 1);
$rgb = array(
'r' => hexdec($r),
'g' => hexdec($g),
'b' => hexdec($b)
);
}
return $rgb;
}
