var wnd_bg;
var wnd_pg;
var wnd_pg_fill;

function body_onload()
{
	// initialize window variables
	wnd_bg = document.getElementById("bg");
	wnd_pg = document.getElementById("pg_top");
	wnd_pg_fill = document.getElementById("pg_fill");

	// set correct window size
	window_onresize();

	// initialize handlers
	window.onresize = window_onresize;
	
	// call 'derived' function
	if (typeof(body_onload_der) != "undefined")
		body_onload_der();
}

function window_onresize()
{
	var iCorrection = window.innerHeight;
	if (iCorrection == undefined) iCorrection = document.documentElement.clientHeight;

	iCorrection -= wnd_bg.offsetHeight - wnd_pg_fill.offsetHeight;

	if (672 > (wnd_pg.offsetHeight - wnd_pg_fill.offsetHeight + iCorrection))
		iCorrection = 672 - (wnd_pg.offsetHeight - wnd_pg_fill.offsetHeight);

	if (iCorrection > 0)
		wnd_pg_fill.style.height = iCorrection + "px";
	else
		wnd_pg_fill.style.height = "0px";
		
	// call 'derived' function
	if (typeof(window_onresize_der) != "undefined")
		window_onresize_der();
}

function findOffset(wnd)
{
	var res = [0, 0];
	while(wnd != null)
	{
		res[0] += wnd.offsetLeft;
		res[1] += wnd.offsetTop;
		wnd = wnd.offsetParent;
	}

	return res;
}

function moveBanner()
{
	var wnd_banner = document.getElementById("banner");
	var wnd_bannerblend = document.getElementById("bannerblend");

	var pos = findOffset(wnd_banner);
	wnd_bannerblend.style.left = pos[0] + "px";
	wnd_bannerblend.style.top = pos[1] + "px";
}

var wnd_bannerblend;
var changeBannerInterval;
var changeBannerStep;
var changeBannerStepSize;

function changeBannerBegin(imgSrc, StepSize, StepTime)
{
	clearInterval(changeBannerInterval);

	changeBannerStep = 0;
	changeBannerStepSize = StepSize;

	wnd_bannerblend = document.getElementById("bannerblend");
	wnd_bannerblend.style.filter = "Alpha(opacity=" + changeBannerStep + ")";
	wnd_bannerblend.style.opacity = changeBannerStep / 100;

	wnd_bannerblend.src = imgSrc;
	wnd_bannerblend.style.display = "inline";

	changeBannerInterval = setInterval(changeBannerNextStep, StepTime);
}

function changeBannerNextStep()
{
	changeBannerStep += changeBannerStepSize;

	if (changeBannerStep > 100)
		changeBannerStep = 100;
	
	wnd_bannerblend.style.filter = "Alpha(opacity=" + changeBannerStep + ")";
	wnd_bannerblend.style.opacity = changeBannerStep / 100;

	if (changeBannerStep == 100)
		changeBannerEnd();
}

function changeBannerEnd()
{
	clearInterval(changeBannerInterval);

	document.getElementById("banner").src = wnd_bannerblend.src;
	wnd_bannerblend.style.display = "none";
}