var BrowserDetect = {
	init: function () {
		this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
		this.version = this.searchVersion(navigator.userAgent)
			|| this.searchVersion(navigator.appVersion)
			|| "an unknown version";
		this.OS = this.searchString(this.dataOS) || "an unknown OS";
	},
	searchString: function (data) {
		for (var i=0;i<data.length;i++)	{
			var dataString = data[i].string;
			var dataProp = data[i].prop;
			this.versionSearchString = data[i].versionSearch || data[i].identity;
			if (dataString) {
				if (dataString.indexOf(data[i].subString) != -1)
					return data[i].identity;
			}
			else if (dataProp)
				return data[i].identity;
		}
	},
	searchVersion: function (dataString) {
		var index = dataString.indexOf(this.versionSearchString);
		if (index == -1) return;
		return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
	},
	dataBrowser: [
		{
			string: navigator.userAgent,
			subString: "Chrome",
			identity: "Chrome"
		},
		{ 	string: navigator.userAgent,
			subString: "OmniWeb",
			versionSearch: "OmniWeb/",
			identity: "OmniWeb"
		},
		{
			string: navigator.vendor,
			subString: "Apple",
			identity: "Safari",
			versionSearch: "Version"
		},
		{
			prop: window.opera,
			identity: "Opera"
		},
		{
			string: navigator.vendor,
			subString: "iCab",
			identity: "iCab"
		},
		{
			string: navigator.vendor,
			subString: "KDE",
			identity: "Konqueror"
		},
		{
			string: navigator.userAgent,
			subString: "Firefox",
			identity: "Firefox"
		},
		{
			string: navigator.vendor,
			subString: "Camino",
			identity: "Camino"
		},
		{		// for newer Netscapes (6+)
			string: navigator.userAgent,
			subString: "Netscape",
			identity: "Netscape"
		},
		{
			string: navigator.userAgent,
			subString: "MSIE",
			identity: "Explorer",
			versionSearch: "MSIE"
		},
		{
			string: navigator.userAgent,
			subString: "Gecko",
			identity: "Mozilla",
			versionSearch: "rv"
		},
		{ 		// for older Netscapes (4-)
			string: navigator.userAgent,
			subString: "Mozilla",
			identity: "Netscape",
			versionSearch: "Mozilla"
		}
	],
	dataOS : [
		{
			string: navigator.platform,
			subString: "Win",
			identity: "Windows"
		},
		{
			string: navigator.platform,
			subString: "Mac",
			identity: "Mac"
		},
		{
			   string: navigator.userAgent,
			   subString: "iPhone",
			   identity: "iPhone/iPod"
	    },
		{
			string: navigator.platform,
			subString: "Linux",
			identity: "Linux"
		}
	]

};
BrowserDetect.init();

// mettre un minimum de 4 images !!!
var coef = 0.05 ; // avancement de l'opacité
var temps = 50 ; // temps entre chaque changement d'opacité
var temps_pause = 2000 ; // temps d'attente entre 2 changements d'images
var nombre_image = 27 ; // nombre d'images a faire bouger
var prefix_image = '/images/logos/'; // chemin + prefix du nom des images
var suffix_image = '.png' ; // suffix + '.extension' du nom des images

// pas touche
var indice = 2; // les 2 premiere image sont deja charger dans le HTML, on commence a la 3eme

var userAgent = BrowserDetect.browser;
var userAgentVersion = BrowserDetect.version;

var webBrowser = 0;

var isIE = 1;
var isFF = 2;
var isFF35 = 3;

var img1 = null;
var img2 = null ;
var sens = 1;
var tabImg;  // tab contenant les images

function prechargerImg(){
  tabImg = new Array(nombre_image);
  for (var i=0; i <= nombre_image - 1; i++){
	tabImg[i]=new Image();
	tabImg[i].src = prefix_image+(i+1)+suffix_image;
  }
}

function checkUserAgent()
{
	if (userAgent == 'Explorer')
		webBrowser = isIE;
	else if (userAgent == 'Firefox')
		if (userAgentVersion == '3.5')
			webBrowser = isFF35;
	else
		webBrowser = isFF;
}

function init()
{
	img1 = document.getElementById("defilement1") ;
	img2 = document.getElementById("defilement2") ;

	checkUserAgent();
	prechargerImg();
	change_opacity();
}

function change_opacity()
{	
	var opacity1 = 0 ;
	var opacity2 = 0 ;
	if (webBrowser == isIE)
	{	opacity1 = parseFloat(img1.filters.alpha.opacity);
		opacity2 = parseFloat(img2.filters.alpha.opacity);
	}
	else if (webBrowser == isFF35)
	{	opacity1 = parseFloat(img1.style.opacity);
		opacity2 = parseFloat(img2.style.opacity);
	}
	else
	{	opacity1 = parseFloat(img1.style.MozOpacity);
		opacity2 = parseFloat(img2.style.MozOpacity);
	}

	if (sens)
	{	if (webBrowser == isIE)
		{	img1.filters.alpha.opacity = opacity1 + coef * 100;
			img2.filters.alpha.opacity = opacity2 - coef * 100;
		}
		else if (webBrowser == isFF35)
		{	img1.style.opacity = opacity1 + coef;
			img2.style.opacity = opacity2 - coef;
		}
		else
		{	img1.style.MozOpacity = opacity1 + coef;
			img2.style.MozOpacity = opacity2 - coef;
		}
	}
	else
	{
		if (webBrowser == isIE)
		{	img1.filters.alpha.opacity = opacity1 - coef * 100;
			img2.filters.alpha.opacity = opacity2 + coef * 100;
		}
		else if (webBrowser == isFF35)
		{	img1.style.opacity = opacity1 - coef;
			img2.style.opacity = opacity2 + coef;
		}
		else
		{	img1.style.MozOpacity = opacity1 - coef;
			img2.style.MozOpacity = opacity2 + coef;
		}
	}

	if (webBrowser == isIE)
	{	opacity1 = parseFloat(img1.filters.alpha.opacity);
		opacity2 = parseFloat(img2.filters.alpha.opacity);
	}
	else if (webBrowser == isFF35)
	{	opacity1 = parseFloat(img1.style.opacity);
		opacity2 = parseFloat(img2.style.opacity);
	}
	else
	{	opacity1 = parseFloat(img1.style.MozOpacity);
		opacity2 = parseFloat(img2.style.MozOpacity);
	}

	// on fait varié le sens d'opacité
	if (opacity2  <= 0)
	{	img2.src=tabImg[indice++].src;
		sens = 0;
		if (indice == (tabImg.length)) indice=0;
		window.setTimeout("change_opacity()",temps_pause) ;
		return 0;
	}
	else if (opacity1 <= 0)
	{	img1.src=tabImg[indice++].src;
		sens = 1;
		if (indice == (tabImg.length)) indice=0;
		window.setTimeout("change_opacity()",temps_pause) ;
		return 0;
	}
	window.setTimeout("change_opacity()",temps) ; // recursion toutes les 30 millisec
}