<!--
// 说明 ：用 Javascript 实现锚点(Anchor)间平滑跳转 
// 来源 ：ThickBox 2.1 
// 整理 ：Yanfu Xie [xieyanfu@yahoo.com.cn] 
// 网址 ：http://www.codebit.cn 
// 日期 ：07.01.17 

// 转换为数字
function intval(v)
{
	v = parseInt(v);
	return isNaN(v) ? 0 : v;
}

// 获取元素信息
function getPos(e)
{
	var l = 0;
	var t  = 0;
	var w = intval(e.style.width);
	var h = intval(e.style.height);
	var wb = e.offsetWidth;
	var hb = e.offsetHeight;
	while (e.offsetParent)
	{
		l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);
		t += e.offsetTop  + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);
		e = e.offsetParent;
	}
	l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);
	t  += e.offsetTop  + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);
	return {x: l, y: t, w: w, h: h, wb: wb, hb: hb};
}

// 获取滚动条信息
function getScroll()
{
	var t, l, w, h;

	if (document.documentElement && document.documentElement.scrollTop)
	{
		t = document.documentElement.scrollTop;
		l = document.documentElement.scrollLeft;
		w = document.documentElement.scrollWidth;
		h = document.documentElement.scrollHeight;
	}
	else if (document.body)
	{
		t = document.body.scrollTop;
		l = document.body.scrollLeft;
		w = document.body.scrollWidth;
		h = document.body.scrollHeight;
	}
	return {t: t, l: l, w: w, h: h};
}

// 锚点(Anchor)间平滑跳转
function Scroller(el, duration)
{
	if (typeof el != 'object')
	{
		el = document.getElementById(el);
	}

	if (!el)
		return;

	var z = this;
	z.el = el;
	z.p = getPos(el);
	z.s = getScroll();
	z.clear = function(){window.clearInterval(z.timer); z.timer = null};
	z.t=(new Date).getTime();

	z.step = function()
	{
		var t = (new Date).getTime();
		var p = (t - z.t) / duration;
		if (t >= duration + z.t)
		{
			z.clear();
			window.setTimeout(function(){z.scroll(z.p.y, z.p.x)}, 13);
		}
		else
		{
			st = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.y-z.s.t) + z.s.t;
			sl = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.x-z.s.l) + z.s.l;
			z.scroll(st, sl);
		}
};
z.scroll = function(t, l){window.scrollTo(l, t)};
z.timer = window.setInterval(function(){z.step();}, 13);
}
//-->