JS褪色技术实现

网上翻到一个控件产生褪色效果的示例代码，应该比较实用，记录下来
褪色技术英文全称The Fade Anything Technique，常用简称FAT

JS库原始地址 http://notes.ozmonet.com/Fade_Anything_Technique

// @name      The Fade Anything Technique
// @namespace http://www.axentric.com/aside/fat/
// @version   1.0-RC1
// @author    Adam Michela

var Fat = {
	make_hex : function (r,g,b) 
	{
		r = r.toString(16); if (r.length == 1) r = '0' + r;
		g = g.toString(16); if (g.length == 1) g = '0' + g;
		b = b.toString(16); if (b.length == 1) b = '0' + b;
		return "#" + r + g + b;
	},
	fade_all : function (dur)
	{
		var a = document.getElementsByTagName("*");
		for (var i = 0; i < a.length; i++) 
		{
			var o = a[i];
			var r = /fade-?(\w{3,6})?/.exec(o.className);
			if (r)
			{
				if (!r[1]) r[1] = "";
				if (o.id) Fat.fade_element(o.id,null,dur,"#"+r[1]);
			}
		}
	},
	fade_element : function (id, fps, duration, from, to) 
	{
		if (!fps) fps = 100;                            // How quickly to move to next color.
		if (!duration) duration = 2000;                 // Time from start to finish.
		if (!from || from=="#") from = "#FFFF33";       // Start from Bright Yellow.
		if (!to) to = this.get_bgcolor(id);

		var frames = Math.round(fps * (duration / 1000));
		var interval = duration / frames;
		var delay = interval;
		var frame = 0;

		if (from.length < 7) from += from.substr(1,3);
		if (to.length < 7) to += to.substr(1,3);

		var rf = parseInt(from.substr(1,2),16);
		var gf = parseInt(from.substr(3,2),16);
		var bf = parseInt(from.substr(5,2),16);
		var rt = parseInt(to.substr(1,2),16);
		var gt = parseInt(to.substr(3,2),16);
		var bt = parseInt(to.substr(5,2),16);

		var r,g,b,h;
		while (frame < frames)
		{
			r = Math.floor(rf * ((frames-frame)/frames) + rt * (frame/frames));
			g = Math.floor(gf * ((frames-frame)/frames) + gt * (frame/frames));
			b = Math.floor(bf * ((frames-frame)/frames) + bt * (frame/frames));
			h = this.make_hex(r,g,b);

			setTimeout("Fat.set_bgcolor('"+id+"','"+h+"')", delay);

			frame++;
			delay = interval * frame; 
		}
		setTimeout("Fat.set_bgcolor('"+id+"','"+to+"')", delay);
	},
	set_bgcolor : function (id, c)
	{
		var o = document.getElementById(id);
		o.style.backgroundColor = c;
	},
	get_bgcolor : function (id)
	{
		var o = document.getElementById(id);
		while(o)
		{
			var c;
			if (window.getComputedStyle) c = window.getComputedStyle(o,null).getPropertyValue("background-color");
			if (o.currentStyle) c = o.currentStyle.backgroundColor;
			if ((c != "" && c != "transparent") || o.tagName == "BODY") { break; }
 			o = o.parentNode;
		}
		if (c == undefined || c == "" || c == "transparent") c = "#FFFFFF";
		var rgb = c.match(/rgb\s*\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})\s*\)/);
		if (rgb) c = this.make_hex(parseInt(rgb[1]),parseInt(rgb[2]),parseInt(rgb[3]));
		return c;
	}
}

addLoadEvent(function ()  {
	Fat.fade_all();
});

// Safe OnLoad Function for Multiple Events
// http://simonwillison.net/2004/May/26/addLoadEvent/
function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			if (oldonload) {
				oldonload();
			}
			func();
		}
	}
}

调用示例代码

<!-- 将被执行褪色的图层 -->
<div id="message1">Options saved</div>
<script>
function blah()
{
	Fat.fade_element("message1", 100, 1000, "#FFFF33", "#FFFFFF");
}
// 页面加载后1秒执行褪色效果
setTimeout('blah()', 1000);
</script>