var Fadomatic=Class.create({
  // Инициализация конструктора
	initialize : function (element, rate, initialOpacity, minOpacity, maxOpacity){
  		this.INTERVAL_MILLIS = 50;
  		this._element = element;
  		this._intervalId = null;
  		this._rate = rate;
  		this._isFadeOut = true;
        // Set initial opacity and bounds
  		// NB use 99 instead of 100 to avoid flicker at start of fade
  		this._minOpacity = 0;
  		this._maxOpacity = 99;
  		this._opacity = 99;

  		if (typeof minOpacity != 'undefined') {
    		if (minOpacity < 0) {
      			this._minOpacity = 0;
    		} else if (minOpacity > 99) {
      			this._minOpacity = 99;
    		} else {
      			this._minOpacity = minOpacity;
    		}
  		}

        if (typeof maxOpacity != 'undefined') {
    		if (maxOpacity < 0) {
      			this._maxOpacity = 0;
    		} else if (maxOpacity > 99) {
      			this._maxOpacity = 99;
    		} else {
      			this._maxOpacity = maxOpacity;
    		}

    		if (this._maxOpacity < this._minOpacity) {
      			this._maxOpacity = this._minOpacity;
    		}
  		}

        if (typeof initialOpacity != 'undefined') {
    		if (initialOpacity > this._maxOpacity) {
      			this._opacity = this._maxOpacity;
    		} else if (initialOpacity < this._minOpacity) {
      			this._opacity = this._minOpacity;
    		} else {
      			this._opacity = initialOpacity;
    		}
  		}

        // Выбор функции в зависимости от браузера

  		if(typeof element.style.opacity != 'undefined') {

    		this._updateOpacity = this._updateOpacityW3c;

  		}else if(typeof element.style.filter != 'undefined') {

    		// Если на объект еще не установлен альфа фильтр, то устанавливаем
    		if (element.style.filter.indexOf("alpha") == -1) {

      			// На случай если уже есть другие фильтры дописываем строку с альфа фильтром
      			var existingFilters="";
      			if (element.style.filter) {
        			existingFilters = element.style.filter+" ";
      			}
      			element.style.filter = existingFilters+"alpha(opacity="+this._opacity+")";
    		}

    		this._updateOpacity = this._updateOpacityMSIE;

  		}else {

    		this._updateOpacity = this._updateVisibility;
  		}

  		this._updateOpacity();
	},

	// Initiates a fade out
	fadeOut : function () {
  		this._isFadeOut = true;
  		this._beginFade();
	},

    // Initiates a fade in
	fadeIn : function () {
  		this._isFadeOut = false;
  		this._beginFade();
	},

    // Makes the element completely opaque, stops any fade in progress
	show : function () {
  		this.haltFade();
  		this._opacity = this._maxOpacity;
  		this._updateOpacity();
	},

    // Makes the element completely transparent, stops any fade in progress
	hide : function () {
  		this.haltFade();
  		this._opacity = 0;
  		this._updateOpacity();
	},

    // Halts any fade in progress
	haltFade : function () {

  		clearInterval(this._intervalId);
	},

    // Resumes a fade where it was halted
	resumeFade : function () {

  		this._beginFade();
	},

    // Pseudo-private members
	_beginFade : function () {

  		this.haltFade();
 		var objref = this;
  		this._intervalId = setInterval(function() { objref._tickFade(); },this.INTERVAL_MILLIS);
	},

    //------------------------
    _tickFade : function () {

  		if (this._isFadeOut) {
    		this._opacity -= this._rate;
    		if (this._opacity < this._minOpacity) {
      			this._opacity = this._minOpacity;
      			this.haltFade();
    		}
  		} else {
    		this._opacity += this._rate;
    		if (this._opacity > this._maxOpacity ) {
      			this._opacity = this._maxOpacity;
     	 		this.haltFade();
    		}
  		}

  		this._updateOpacity();
	},

    _updateVisibility : function () {

  		if (this._opacity > 0) {
    		this._element.style.visibility = 'visible';
  		} else {
    		this._element.style.visibility = 'hidden';
  		}
	},

	_updateOpacityW3c : function () {

  		this._element.style.opacity = this._opacity/100;
  		this._updateVisibility();
	},

	_updateOpacityMSIE : function () {

  		this._element.filters.alpha.opacity = this._opacity;
  		this._updateVisibility();
	}
});