var bannerImgDelay = 5500;

var startBannerImgId = Math.floor(Math.random() * nbBannerImgs);
var currentBannerImg = startBannerImgId;

var ie = document.all;

var fadeInterval = null;
var fadeStartValue = 1;
var fadeStopValue = 0;
var fadeStepDelay = 30;
var fadeStep = 0.03;
var ieFadeCoef = 100;

function fadeStepFct(elementId, pFadeStep, pFadeInterval, callbackFct)
{
	opacity = getOpacity(elementId);
	if (isNaN(opacity))
		opacity = fadeStartValue;
	if (document.all)
		opacity += Math.floor(pFadeStep * ieFadeCoef);
	else
		opacity += pFadeStep;
	setOpacity(elementId, opacity);
	opacity = getOpacity(elementId);
	if ((pFadeStep < 0 && opacity <= fadeStopValue) ||
		(pFadeStep > 0 && opacity >= fadeStopValue) ||
		(pFadeStep == 0))
	{
		clearInterval(pFadeInterval);
		eval(callbackFct);
	}
}

function fade(elementId, pFadeStopValue, callbackFct)
{
	clearInterval(fadeInterval);
	fadeStopValue = pFadeStopValue;
	opacity = getOpacity(elementId);
	pFadeStep = Math.abs(fadeStep);
	if (opacity > fadeStopValue)
		pFadeStep = -pFadeStep;
	fadeInterval = setInterval('fadeStepFct("'+elementId+'", ' + pFadeStep + ', fadeInterval, "' + callbackFct + '")', fadeStepDelay)
}

function getOpacity(element)
{
	if (ie)
	{
		return parseFloat(document.getElementById(element).filters[0].opacity);
	}
	else
		return parseFloat(document.getElementById(element).style.opacity);
}
function setOpacity(element, opacity)
{
	if (ie)
	{
		document.getElementById(element).filters[0].opacity = opacity * ieFadeCoef;
	}
	else
		document.getElementById(element).style.opacity = opacity;
}

function randBannerImgs(path)
{
	var bannerImgId;
	do
	{
		var ok = true;
		bannerImgId = Math.floor(Math.random() * nbBannerImgs);
		if (currentBannerImg == bannerImgId && ok)
			ok = false;
	} while (!ok);
	switchBannerImg(path, bannerImgId);
}
function getNextBannerImg(path)
{
	var bannerImgId = (currentBannerImg + 1) % nbBannerImgs;
	switchBannerImg(path, bannerImgId);
}
function switchBannerImgEnd(path, bannerImgId)
{
	document.getElementById("banner_img").style.backgroundImage = document.getElementById("banner_img_bg").style.backgroundImage;
	setOpacity("banner_img", 1);
	setTimeout('document.getElementById("banner_img_bg").style.backgroundImage = "url(\'' + path + bannerImgFiles[bannerImgId] + '\')"', 1000);
}
function switchBannerImg(path, bannerImgId)
{
	currentBannerImg = bannerImgId;
	fade("banner_img", 0, "switchBannerImgEnd('" + path + "', '" + bannerImgId + "')");
}