/**
 *  author:		Timothy Groves - http://www.brandspankingnew.net
 *	version:		1.3 - 2006-11-02
 *					1.2 - 2006-11-01
 *					1.1 - 2006-09-29
 *					1.0 - 2006-09-25
 *
 *	requires:	nothing
 *
 */

/**
 * altered by W. P. 'Mac' McMeans [PhotoGangNews.com] on 27 NOV 2006
 *
 * 1) added cycles parm, to specify max iterations
 *
 */



var useBSNns;

if (useBSNns)
{
	if (typeof(bsn) == "undefined")
		bsn = {}
	var _bsn = bsn;
}
else
{
	var _bsn = this;
}





_bsn.Crossfader = function (divs, fadetime, delay, cycles )
{	
	this.nAct = -1;
	this.aDivs = divs;
	
	for (var i=0;i<divs.length;i++)
	{
		document.getElementById(divs[i]).style.opacity = 0;
		document.getElementById(divs[i]).style.position = "absolute";
		document.getElementById(divs[i]).style.filter = "alpha(opacity=0)";
		document.getElementById(divs[i]).style.visibility = "hidden";
	}
	
	this.nDur = fadetime;
	this.nDelay = delay;
	this.nMaxCycle = cycles;
	
	// by Mac
	this.nCurrentCycle = 0;
	//////////////////////////////

	this._newfade();
}


_bsn.Crossfader.prototype._newfade = function() {
	if (this.nID1) { clearInterval(this.nID1); }
	
	this.nOldAct = this.nAct;
	this.nAct++;
	if (!this.aDivs[this.nAct])	{
		this.nAct = 0;
		
		// by Mac
		this.nCurrentCycle++;
		if( this.nCurrentCycle == this.nMaxCycle ) { this.nOldAct = 0; }
		/////////////////////////////////////////////////////
	}
	
	if (this.nAct == this.nOldAct) { return false; }
	
	document.getElementById( this.aDivs[this.nAct] ).style.visibility = "visible";
		
	this.nInt = 50;
	this.nTime = 0;
	
	var p=this;
	this.nID2 = setInterval(function() { p._fade() }, this.nInt);
}


_bsn.Crossfader.prototype._fade = function() {
	this.nTime += this.nInt;  
	
	var ieop = Math.round( this._easeInOut(this.nTime, 0, 1, this.nDur) * 100 );
	var op = ieop / 100;
	document.getElementById( this.aDivs[this.nAct] ).style.opacity = op;
	document.getElementById( this.aDivs[this.nAct] ).style.filter = "alpha(opacity="+ieop+")";
	
	if (this.nOldAct > -1) 	{
		document.getElementById( this.aDivs[this.nOldAct] ).style.opacity = 1 - op;
		document.getElementById( this.aDivs[this.nOldAct] ).style.filter = "alpha(opacity="+(100 - ieop)+")";
	}
	
	if (this.nTime == this.nDur) 	{
		clearInterval( this.nID2 );
		
		if (this.nOldAct > -1) {
			document.getElementById( this.aDivs[this.nOldAct] ).style.visibility = "hidden";	
		}

		var p=this;
		this.nID1 = setInterval(function() { p._newfade() }, this.nDelay);
	}
}



_bsn.Crossfader.prototype._easeInOut = function(t,b,c,d) {
	return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}