//Copyright Locapoint.com & Naoki Ueda
// this class has a array of div names as parameter
// These divs will be switched like tab, with cross-fade effect. 
// Divs don't have to be in a sma position.
// 
// on call of this.ontab(n) will appear div(n) on top (with specified zindex)
// other divs will disappear and these zindex will be zero (behind)
//
//Usage
//
//	var xft;  //Global variable. Cross-Fade Tab switch.
//	//initialise:
	//Tabs does not have to be tab. 
//	xft = new xfadetabs(new Array("layer1", "layer2", "layer3"),3,200,"xft");


//	xft.ontab(1);


//Constructor
function xfadetabs(divarrays, zindex, millisec, thisobjname)
{
	//Members
	this.divs = divarrays;
	this.zindex = zindex;
	this.millisec = millisec;
	this.thisobjname = thisobjname;
	if(divarrays!=null){
		this.length = divarrays.length;
	}
	this.currentTop = 0;

	//Methods
	this.ontab;
//	this.hidexftabs();
//	this.showxftabs();


	//change the opacity for different browsers
	this.changeOpac = function(opacity, id) {
		var divobject = document.getElementById(id);
		if (divobject ==null){
			return;
		}
		var object=divobject.style; 
		object.opacity = (opacity / 100);
		object.MozOpacity = (opacity / 100);
		object.KhtmlOpacity = (opacity / 100);
		object.filter = "alpha(opacity=" + opacity + ")";
	}

	var n;
	for(n=0;n<this.length;n++){
		this.changeOpac(0,this.divs[n]);
	}

}
//Methods
new xfadetabs(null, 0,1000,"xft");	//Dummy Object
xfadetabs.prototype.ontab = function(tabnum){
	if(this.currentTop==tabnum){
		return;
	}

	var speed = Math.round(this.millisec / 100);
	var timer = 0;

	if(tabnum==0){
		src_divid.style.zIndex = 0;
		for(i = 0; i <= 100; i++){
			dec_i = 100 - i;
			setTimeout(thisobjname + ".changeOpac(" + dec_i + ",'" + src_divid + "')",(timer * speed));
			timer++;
		}		
		return;
	}

	var src_divid = this.divs[this.currentTop-1];
	var dest_divid = this.divs[tabnum-1];
	this.currentTop=tabnum;
	//set Opacity=0 for new Div
	this.changeOpac(0, dest_divid);

	//exchange Z-index between Divs (plane new one in front)
	var srcdivobj = document.getElementById(src_divid);
	if(srcdivobj!=null){
		srcdivobj.style.zIndex = 0;
	}
	var destdivobj = document.getElementById(dest_divid);
	if(destdivobj!=null){
		destdivobj.style.zIndex = this.zindex;
	}

	var destdivobj = document.getElementById(dest_divid);
	if(destdivobj!=null){
		destdivobj.style.visibility = "visible";
	}
	//fade exchange them
	//determine the direction for the blending, if start and end are the same nothing happens
	for(i = 0; i <= 100; i++){
		dec_i = 100 - i;
		setTimeout(this.thisobjname + ".changeOpac(" + dec_i + ",'" + src_divid + "')",(timer * speed));
		setTimeout(this.thisobjname + ".changeOpac(" + i + ",'" + dest_divid + "')",(timer * speed));
		timer++;
	}
	var srcdivobj = document.getElementById(src_divid);
	if(srcdivobj!=null){
		srcdivobj.style.visibility = "hidden";
	}

	return;
}
xfadetabs.prototype.hidexftabs = function(){
	this.ontab(0);
	return;
}
xfadetabs.prototype.showxftabs = function(){
	this.ontab(this.currentTop-1);
	return;
}