/**
 * Create opacity object
 */
OpacityObject = Class.create();

OpacityObject.prototype = {
  /**
   * Constructor
   * @param string sElementClass
   * @param string sNormalImage
   * @param string sHoverImage
   */
  initialize: function(sElementClass, sNormalImage, sHoverImage) {
    this.sElementClass = sElementClass;
    this.sNormalImage = sNormalImage;
    this.sHoverImage = sHoverImage;
    this.aLayerObject = [];

    /**
     * Check IE < 7 ver.
     */
    Prototype.Browser.Version = (navigator.userAgent.toLowerCase().match( /.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/ ) || [])[1];
    if (Prototype.Browser.IE && Prototype.Browser.Version < 7) {
      this.bPngAlpha = true;
    }
  },

  /**
   * Changes image opacity on window load
   */
  vOnLoadOpacity: function() {
    this.aLayerObject = $$(this.sElementClass);

    if (this.bPngAlpha) {
      var sImg = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + this.sNormalImage + "', sizingMethod='scale')";
      var sHover = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + this.sHoverImage + "', sizingMethod='scale')";
      //progid:DXImageTransform.Microsoft.AlphaImageLoader
      this.aLayerObject.each(function(oElm) {
        $(oElm).setStyle({
            backgroundImage: 'none',
            filter: sImg
        });
        /**
         * Add hover effect for IE < 7
         * @param {Object} event
         */
        $(oElm).observe('mouseover', function(event) {
          $(oElm).setStyle({
            backgroundImage: 'none',
            filter: sHover
          });
        });

        $(oElm).observe('mouseout', function(event) {
          $(oElm).setStyle({
            backgroundImage: 'none',
            filter: sImg
          });
        });

      });
    } //if (this.bPngAlpha)
  },

  vActivateOnLoad: function() {
    Event.observe(window, "load", this.vOnLoadOpacity.bind(this));
  }
}

/**
 * Inicialization
 */
var oOpacityObject = new OpacityObject('.tooltipImg',
  '/typo3conf/ext/21torr_hotspot_visual/tmpl/img/btn1.png',
  '/typo3conf/ext/21torr_hotspot_visual/tmpl/img/btn2.png'
);

oOpacityObject.vActivateOnLoad();