/**
 *  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;
}