var menuimg=new Array(5);
var buffer=new Image();

var xhr;
var xhrtarget;
var xhrcount;
var xhrcomplete;

function preLoadImages() {
	for (i=0;i<4;i++) {
		menuimg[i]=new Image();
		menuimg[i].src="images/menu"+(i+2)+"s.png";
	}
	menuimg[4]=new Image();
	menuimg[4].src="images/menu7s.png";
}

function chImage(img1,img2) {
	buffer.src=document.getElementById(img1).src;
	document.getElementById(img1).src=img2.src;
}

function backImage(img) {
	document.getElementById(img).src=buffer.src;
}

function newHTTPRequest()
{
	if (window.XMLHttpRequest) return new XMLHttpRequest();
	else if (window.ActiveXObject) return new ActiveXObject("Microsoft.XMLHTTP");
	else return null;
}

function getRequest(url,target)
{
	if (target==null) target="docblock";
	xhrtarget=document.getElementById(target);
	if (!xhrtarget) {alert("Target not exsits!");return true;}

	document.getElementById("loadbox").style.display="inline-block";

	xhr=newHTTPRequest();
	if (!xhr) return true;

	xhr.open("GET",url,true);
	xhr.onreadystatechange=xhrStateChange;
	xhr.send(null);

	return false;
}

function xhrStateChange()
{
	if (xhr.readyState!=4) return;

	xhrtarget.innerHTML=xhr.responseText;
	xhrOnLoad(xhrtarget);
}

function xhrOnLoad(em)
{
	var imgs=em.getElementsByTagName("IMG");

	xhrcomplete=0;
	xhrcount=imgs.length;
	if (xhrcount==0) {
		document.getElementById("loadbox").style.display="none";
		return;
	}

	for (var i=0;i<xhrcount;i++) {
		imgs[i].onload=imgOnLoad;
	}
}

function imgOnLoad()
{
	lb=document.getElementById("loadbar");

	xhrcomplete++;

	lb.style.width=Math.round(xhrcomplete/xhrcount*100).toString()+"px";

	if (xhrcomplete==xhrcount) setTimeout("document.getElementById('loadbar').style.width='0px';document.getElementById('loadbox').style.display='none'",1500);
}