/**
 *  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
 *
 */

var useBSNns;

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





_bsn.Crossfader = function (divs, fadetime, delay )
{    
    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._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;
    
    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;
}