php - 十六进制代码亮度 PHP？

Question

我希望我网站上的用户能够选择十六进制颜色，我只想为深色显示白色文本，为浅色显示黑色文本。你能用十六进制代码(最好是 PHP)计算出亮度吗？

Answer 1

$hex = "78ff2f"; //Bg color in hex, without any prefixing #!

//break up the color in its RGB components
$r = hexdec(substr($hex,0,2));
$g = hexdec(substr($hex,2,2));
$b = hexdec(substr($hex,4,2));

//do simple weighted avarage
//
//(This might be overly simplistic as different colors are perceived
// differently. That is a green of 128 might be brighter than a red of 128.
// But as long as it's just about picking a white or black text color...)
if($r + $g + $b > 382){
    //bright color, use dark font
}else{
    //dark color, use bright font
}