(function($){
 $.fn.lastScrollY= 0;
 $.fn.higo_plugins_ad = function(options){
         $(this).addClass("higo_plugins_ad");
         var settings = $.extend({
              src:null,                    
              closeSrc:null,               
              href:"#",
              autoHide:true,               
              hideSecond:10,               
              top:20,                      
              layout:"left",               
              width:100,                   
             height:100,                  
             opacity:0.5,
              setPosition:function(left, top){
                  return;
             }
         },options || {});
         
        if(settings.src && settings.closeSrc){        
             var imgEl = "<a href='" + settings.href + "' target='_blank'><img border=0 width='" + settings.width + "px' height='" + settings.height + "px' src='" + settings.src + "'/> <br></a>";
             var closeImgEl = "<a href=\"#\"; onclick=\"this.parentElement.style.visibility='hidden'\"><img border=0 src='" + settings.closeSrc +"'/></a>";
             
             $(this).append(imgEl + closeImgEl);
              
             $(this).css("position","absolute");
              $(this).css("top",settings.top + "px");
             $(this).css("opacity",settings.opacity);
             $(this).css("filter","alpha(opacity=" + parseInt(settings.opacity * 100)  + ")");
              
             switch(settings.layout) {
                case "left":
                      $(this).css("left","22px");
                      break;
                case "right":
                      $(this).css("right","22px");
                      break;
                 case "center":
                     var left = (parseInt(window.screen.availWidth) - parseInt(settings.width))/2 + "px";
                      $(this).css("left",left);
                      break;
                  default:
                      $(this).css("left","22px");
                     break;
             }
         } else {
             return;
        }
         
         if(settings.autoHide) {
            setTimeout("(function(){$('" + $(this).selector +  "').hide();})();",parseInt(settings.hideSecond) * 1000);
         }
         
         window.onscroll = function(){
              var diffY;
            if (document.documentElement && document.documentElement.scrollTop)
                  diffY = document.documentElement.scrollTop;
             else if (document.body)
                  diffY = document.body.scrollTop
             else {
                  /*Netscape stuff*/
             }
             
              percent= 1 * (diffY - $.fn.lastScrollY);
              if(percent>0)
                 percent=Math.ceil(percent);
             else 
                percent=Math.floor(percent);
             
             var top = $('.higo_plugins_ad').css("top");
            
             $('.higo_plugins_ad').css("top", parseInt(top) + percent + "px");
             $.fn.lastScrollY += percent;
         }
     }
 })(jQuery);