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;
}