Jquery 类网页微信二维码图块滚动效果具体实现_jquery

/*
 * 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 = "
"; 
            var closeImgEl = ""; 

            $(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);