// 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,name)
{
	var test_page = document.getElementById('test_page').value;
	var test_name = document.getElementById('test_name').value;
	var test_title = document.getElementById('test_title').value;
	var pageTracker = _gat._getTracker("UA-4782081-5");
	pageTracker._setDomainName("tuniu.com");
	pageTracker._initData();
	var content = "/ABTest/"+test_title+"/"+test_name+"/"+test_page+"/"+name;
	pageTracker._trackPageview(content);
    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);
}