颜色明暗度调整

lighten-darken-color.js

var LightenDarkenColor = function(col, amt) {
	
	var usePound = false;
	if (col[0] == "#") {
		col = col.slice(1);
		usePound = true;
	}

	var num = parseInt(col,16);

	var r = (num >> 16) + amt;

	if ( r > 255 ) r = 255;
	else if  (r < 0) r = 0;

	var b = ((num >> 8) & 0x00FF) + amt;

	if ( b > 255 ) b = 255;
	else if  (b < 0) b = 0;

	var g = (num & 0x0000FF) + amt;

	if ( g > 255 ) g = 255;
	else if  ( g < 0 ) g = 0;

	return (usePound?"#":"") + (g | (b << 8) | (r << 16)).toString(16);
}