Jquery 类网页微信二维码图块滚动效果具体实现

/*
 * 创建浮动图片广告（Generate a dock AD image）
 *
 * USAGE: 
 *  $(selector).higo_plugins_ad({
 *      src:null,                    // 广告图片路径
 *      closeSrc:null,               // 关闭图片路径
 *      href:"#",                    // 广告图片链接地址
 *      autoHide:true,               // 是否自动隐藏
 *      hideSecond:10,               // 延迟隐藏秒数
 *      top:20,                      // 距离顶部偏移高度
 *      layout:"left",               // 默认图片位置：left 居左 ,right 居右, center 居中, 
 *      width:100,                   // 宽度
 *      height:100,                  // 高度
 *      opacity:0.5              // 透明度opacity:0.5(firefox), filter:alpha(opacity=50)(IE)
 *      setPosition:function(left, top){ // 预留自定义显示位置的方法（尚未实现）
 *          return;
 *      }   
 *  })
 */

(function($){ 
    $.fn.ad = function(options){ 
        var lastScrollY= 0; 
        var czd = $(this); 
        var settings = $.extend({ 
            src:null,                     
            closeSrc:null,                
            href:"#", 
            autoHide:true,                
            hideSecond:10, 
            position: "top",              
            top:20,     
            bottom: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"); 
            if(settings.position=='top'){ 
                $(this).css("top",settings.top + "px"); 
            } else { 
                $(this).css("bottom",settings.bottom + "px"); 
            } 
            $(this).css("opacity",settings.opacity); 
            $(this).css("filter","alpha(opacity=" + parseInt(settings.opacity * 100)  + ")"); 

            switch(settings.layout) { 
                case "left": 
                    $(this).css("left","-100px"); 
                    break; 
                case "right": 
                    $(this).css("right","-100px"); 
                    break; 
                case "center": 
                    var left = (parseInt(window.screen.availWidth) - parseInt(settings.width))/2 + "px"; 
                    $(this).css("left",left); 
                    break; 
                default: 
                    $(this).css("left","-100px"); 
                    break; 
            } 
        } else { 
            return; 
        } 

        if(settings.autoHide) { 
            setTimeout("(function(){$('" + $(this).selector +  "').hide();})();",parseInt(settings.hideSecond) * 1000; 
        } 
        //别名不同导致事件驱动不一样：scroll与onscroll 
        $(window).bind("scroll", 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 - lastScrollY); 
            if(percent>0) 
                percent=Math.ceil(percent); 
            else  
                percent=Math.floor(percent); 

            if(settings.position=='top'){ 
                var top = czd.css("top"); 
                czd.css("top", parseInt(top) + percent + "px"); 
                lastScrollY += percent; 
            } else { 
                var top = czd.css("bottom"); 

                czd.css("bottom", parseInt(top) - percent + "px");lastScrollY += percent; 
            } 

        }); 
    } 
})(jQuery);

<decorator:head /> 
        <script type="text/javascript" src="<%=basePath%>js/jquery.czd_plugins_ad.js"></script> 
        <script language="javascript"> 
        $(document).ready(function(){ 
            $("#leftbelow").ad({ 
                src:"<%=basePath%>/images/qrcode.png",                   
                closeSrc:"<%=basePath%>/images/closeAd.gif",        
                autoHide:false,                
                hideSecond:5,                
                top:480,  
                layout:"left",                
                width:100,                    
                height:100,                  
                opacity:5 
                }); 

            $("#left").ad({ 
                src:"<%=basePath%>/images/longtentianxia20131010.jpg",                     
                closeSrc:"<%=basePath%>/images/closeAd.gif",                
                href:"......",                     
                autoHide:false,                
                hideSecond:5,                
                top:-70,                       
                layout:"left",                
                width:100,                    
                height:500 ,                
                opacity:5  
            }); 
            $("#right").ad({ 
                src:"<%=basePath%>/images/yingxiaodasai201203012.jpg",                   
                closeSrc:"<%=basePath%>/images/closeAd.gif",        
                href:"......",                     
                autoHide:false,                
                hideSecond:5,                
                top:-70,                       
                layout:"right",                
                width:100,                    
                height:500,                  
                opacity:5 
            }); 
        }); 
</script>

<body class="homeBackgroup"> 
          <div id="center"> </div> 

      <%@include file="/page/public/sideBar.jsp"%> 
      <div class="shadow"> 

        <div id="container"> 
            <div id="header"> 
                <%@include file="/page/public/top.jsp"%> 
            </div> 
            <div id="mainContent"> 

                        <div id="left"></div> 

                    <decorator:body /> 

                        <div id="right"></div> 
                        <div id="leftbelow"></div> 

            </div> 
            <div id="footer" > 
                <%@include file="/page/public/bottom.jsp"%> 
            </div> 
            <div id="back-top"> 
                <a href="#top"><span></span></a> 
            </div> 
        </div> 
      </div>   
</body>