var BG_INDEX = 1;
var BG_MAX = 21;
var gBgImage = new Image();

function test() {
	alert("image download complete");
}

function changeBackground() {
	BG_INDEX = ((BG_INDEX + 1) % BG_MAX);
	if(BG_INDEX == 0) {
		BG_INDEX = 1;
	}
	
	var url;
	if(BG_INDEX < 10) {
		url = "image/bg/bg0" +  BG_INDEX + ".jpg";
	} else { 
		url = "image/bg/bg" + BG_INDEX + ".jpg";
	}
	
	gBgImage.src = url;
	
	return false;
}


function backgroundImageOnLoad() {
	var body = document.getElementById("background");
	var body2 = document.getElementById("background2");
	
	alert("background image on load");
	
	var url;
	if(BG_INDEX < 10) {
		url = "url(image/bg/bg0" +  BG_INDEX + ".jpg)";
	} else { 
		url = "url(image/bg/bg" + BG_INDEX + ".jpg)";
	}
	
	body2.style.backgroundImage = body.style.backgroundImage;
	body.style.backgroundImage = url;
}

function changeBackgroundDissolve() {
	
	BG_INDEX = ((BG_INDEX + 1) % BG_MAX);
	if(BG_INDEX == 0) {
		BG_INDEX = 1;
	}
	
	var url;
	if(BG_INDEX < 10) {
		url = "url(image/bg/bg0" +  BG_INDEX + ".jpg)";
	} else { 
		url = "url(image/bg/bg" + BG_INDEX + ".jpg)";
	}
	
	var bgImg = new Image();
	bgImg.onload = backgroundImageOnLoad;
	bgImg.src = url;
	
	return false;
}


function loadImageHandler() {
	var body = document.getElementById("body");
	body.style.backgroundImage = "url('" + gBgImage.src + "')";
	//resizeHandler();
}

function setImageHandler() {
	BG_INDEX = (Math.round(Math.random() * 100)) % BG_MAX;
	gBgImage.onload = loadImageHandler;
}


function setBackgroundImageHandler() {
	setImageHandler();
	
	var anchor = document.getElementById("logo");
	anchor.onclick = changeBackground;
	changeBackground();
	
}