var intTimeStep=20;
var isIe=(window.ActiveXObject)?true:false;
var intAlphaStep=(isIe)?5:0.05;
var curSObj=null;
var curOpacity=null;
var interval = 3000;
var timer;
var nextWorktimer;
var wholetimer;

function startObjVisible(objId)
{
	curSObj=document.getElementById(objId);
	setObjState();
}
function setObjState(evTarget)
{
	if (curSObj.style.display==""){
		if (isIe)
			curSObj.style.cssText='Z-INDEX: 1; FILTER: alpha(opacity=100); POSITION: absolute;';
		curOpacity=1;
		setObjClose();
	}
	else{
		if(isIe)
		{
			curSObj.style.cssText='DISPLAY: none;Z-INDEX: 1; FILTER: alpha(opacity=0); POSITION: absolute;';
			curSObj.filters.alpha.opacity=0;
		}
		else {
			curSObj.style.opacity=0
		}
		curSObj.style.display='';
		curOpacity=0;
		setObjOpen();
	}
}
function setObjOpen()
{
	if(isIe)
	{
		curSObj.filters.alpha.opacity+=intAlphaStep;
		if (curSObj.filters.alpha.opacity<100) 
			timer = setTimeout('setObjOpen()',intTimeStep);
		else
			wholetimer = setTimeout("autoChange()", interval);
	}else{
		curOpacity+=intAlphaStep;
		curSObj.style.opacity =curOpacity;
		if (curOpacity<1) 
			timer = setTimeout('setObjOpen()',intTimeStep);
		else
			wholetimer = setTimeout("autoChange()", interval);
	}
}

function setObjClose()
{
	if(isIe)
	{
		curSObj.filters.alpha.opacity-=intAlphaStep;
		if (curSObj.filters.alpha.opacity>0) {
			timer = setTimeout('setObjClose()',intTimeStep);
		}
		else {
			curSObj.style.display="none";
		}
	}else{
		curOpacity-=intAlphaStep;
		if (curOpacity>0) 
		{
			curSObj.style.opacity =curOpacity;
			timer = setTimeout('setObjClose()',intTimeStep);
		}
		else {
			curSObj.style.display='none';
		}
	}
}



// 图片定义
var pictures =Array();
// 链接定义
var hrefs = Array();

var select = 0;

function clearAll()
{
	for(var i=0;i<4;i++)
	{
		clear(i);
	}
}
function clear(id) {
	pic = document.getElementById("pic_" + select);
	href = document.getElementById("href_" + select);
	pic.style.borderColor = "#000";
	href.className = "linkf";
}
function changePic(id) {
	
	clearAll();
	clearTimeout(wholetimer);
	clearTimeout(timer);
	
	if (id != select) {
		select = id;
		startObjVisible('imgDiv');
		
		//var pre_pic = document.getElementById("pic_" + select);
		// var pre_href = document.getElementById("href_" + select);

		var pic = document.getElementById("pic_" + id);
		var href = document.getElementById("href_" + id);
		
		
		// pre_pic.style.borderColor = "#000";
		pic.style.borderColor = "#a12137";
		
		// pre_href.className = "linkf";
		href.className = "linkg";
		
		
		if(nextWorktimer) clearTimeout(nextWorktimer);
		nextWorktimer = setTimeout("nextWork(" + id + ")", 100);
	
	}
}

function nextWork(id) {
	var el = document.getElementById('imgDiv');
	if (el.style.display == 'none')
	{
		//select = id;
		var mainPic = document.getElementById("main_pic");
		mainPic.src = pictures[select];
		
		var mainHref = document.getElementById("main_href");
		
		mainHref.href=hrefs[select];
		startObjVisible('imgDiv');
	}
	else 
	{
		if(nextWorktimer) clearTimeout(nextWorktimer);
		nextWorktimer = setTimeout("nextWork(" + id + ")", 100);
	}
}


function autoChange() {
	var id = (select + 1)%4;
	changePic(id);
}

window.onload=function() {
	var windowWidth = document.documentElement.clientWidth || document.body.clientWidth;
	var windowHeight = document.documentElement.clientHeight || document.body.clientHeight;
	
	//标准下，opera的窗口的可是高度为document.body.clientWidth
	if (window.opera)
	{
		windowWidth = document.body.clientWidth;
		windowHeight = document.body.clientHeight;
	}
	
	wholetimer = setTimeout("autoChange()", interval);
}