var xmlHttp;
var cgid;
function mainajax(ac,changeid,para){
cgid=changeid;
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
  {
  alert ("您的浏览器不支持AJAX！");
  return;
  }
var url="/mainajax.php";
url=url+"?ac="+ac;
url=url+"&p="+para;
if(ac=='login'){
if(document.getElementById("usr").value=="")
	{
		alert("请输入用户名！");
		document.getElementById("usr").focus();
		return false;
	}
if(document.getElementById("pwd").value=="")
	{
		alert("请输入密码！");
		document.getElementById("pwd").focus();
		return false;
}
url=url+"&usr="+document.getElementById("usr").value;
url=url+"&pwd="+document.getElementById("pwd").value;
}
url=url+"&sid="+Math.random();
//alert(url);
xmlHttp.onreadystatechange=stateChanged;
xmlHttp.open("GET",url,true);
xmlHttp.send(null);
}

function stateChanged(){ 
 if (xmlHttp.readyState==4){
   document.getElementById(cgid).innerHTML=xmlHttp.responseText;
 }
}

function GetXmlHttpObject(){
var xmlHttp=null;
try
  {
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
return xmlHttp;
}

//end ajax

function delCookie(name){
 var exp = new Date();
 exp.setTime(exp.getTime() - 1);
 var cval=getCookie(name);
 if(cval!=null) document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}
function getCookie(name){//取cookies函数
 var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
 if(arr != null) return unescape(arr[2]); return null;
}
function setTab(name,cursel,n){
for(i=1;i<=n;i++){
var menu=document.getElementById(name+i);
var con=document.getElementById("con_"+name+"_"+i);
menu.className=i==cursel?"hover":"";
con.style.display=i==cursel?"block":"none";
}
}
function findPosX(obj) {
	var curleft = 0;
	if (obj.offsetParent) {
		while (obj.offsetParent) {
			curleft += obj.offsetLeft;
			obj = obj.offsetParent;
		}
	} else if (obj.x) curleft += obj.x;
	return curleft;
}
function findPosY(obj) {
	var curtop = 0;
	if (obj.offsetParent) {
		while (obj.offsetParent) {
			curtop += obj.offsetTop;
			obj = obj.offsetParent;
		}
	} else if (obj.y) curtop += obj.y;
	return curtop;
}
function DrawImage(ImgD,w,h){
var image=new Image();
var iwidth = w;
var iheight = h;
image.src=ImgD.src;
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>= iwidth/iheight){
if(image.width>iwidth){
ImgD.width=iwidth;
ImgD.height=(image.height*iwidth)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
//ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>iheight){
ImgD.height=iheight;
ImgD.width=(image.width*iheight)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
//ImgD.alt=image.width+"×"+image.height;
}
}
}
//调用方式<img src="<?=$rs1['pic'];?>" border="0" onload="javascript:DrawImage(this,500,375)">