/*
 *  Sequential Image Fader
 *  fader.js
 */
var _fade;

if (_fade) {
  if (typeof(ods) == "undefined")
    ods = {}
    var _ods = ods;
} else {
    var _ods = this;
}

function $() {
	var elements = new Array();
	for (var i = 0; i < arguments.length; i++) {
		var element = arguments[i];
		if (typeof element == 'string')
			element = document.getElementById(element);
		if (arguments.length == 1)
			return element;
		elements.push(element);
	}
	return elements;
}

_ods.Crossfader = function (divs, fadetime, delay) {	
  this.nAct = -1; this.aDivs = divs;
  for (var i=0;i<divs.length;i++) {
    $(divs[i]).style.opacity = 0;
    $(divs[i]).style.position = "absolute";
    $(divs[i]).style.filter = "alpha(opacity=0)";
    $(divs[i]).style.visibility = "hidden"
  }
  this.nDur = fadetime; this.nDelay = delay; this._newfade();
}

_ods.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; }
  $( this.aDivs[this.nAct] ).style.visibility = "visible";
  this.nInt = 50; this.nTime = 0; var p=this;
  this.nID2 = setInterval(function() { p._fade() }, this.nInt);
}

_ods.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;
  $( this.aDivs[this.nAct] ).style.opacity = op;
  $( this.aDivs[this.nAct] ).style.filter = "alpha(opacity="+ieop+")";
  if (this.nOldAct > -1) {
    $( this.aDivs[this.nOldAct] ).style.opacity = 1 - op;
    $( 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);
  }
}

_ods.Crossfader.prototype._easeInOut = function(t,b,c,d) {
  return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}