/**
 *  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;
}