/**
 *  
 *   version:   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;
   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 op = this._easeInOut(this.nTime, 0, 1, this.nDur);
   var ieop = op*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;
}