(function($){
    $.fn.extend({
        jScroll:function(opt){
            //参数初始化
            if(!opt) var opt={};
            var _btnUp = $("#"+ opt.up);//Shawphy:向上按钮
            var _btnDown = $("#"+ opt.down);//Shawphy:向下按钮
            var timerID;
            var _this=this.eq(0).find("ul:first");

            var     lineH=_this.find("li:first").height(), //获取行高
                    line=opt.line?parseInt(opt.line,10):parseInt(this.height()/lineH,10), //每次滚动的行数，默认为一屏，即父容器高度
                    speed=opt.speed?parseInt(opt.speed,10):500; //卷动速度，数值越大，速度越慢（毫秒）
                    timer=opt.timer //?parseInt(opt.timer,10):3000; //滚动的时间间隔（毫秒）
            if(line==0) line=1;
            var upHeight=0-line*lineH;
            //滚动函数
            var scrollUp=function(){
                    _btnUp.unbind("click",scrollUp); //Shawphy:取消向上按钮的函数绑定
                    _this.animate({
                            marginTop:upHeight
                    },speed,function(){
                            for(i=1;i<=line;i++){
                                    _this.find("li:first").appendTo(_this);
                            }
                            _this.css({marginTop:0});
                            _btnUp.bind("click",scrollUp); //Shawphy:绑定向上按钮的点击事件
                    });

            }
            //Shawphy:向下翻页函数
            var scrollDown=function(){
                    _btnDown.unbind("click",scrollDown);
                    for(i=1;i<=line;i++){
                            _this.find("li:last").show().prependTo(_this);
                    }
                    _this.css({marginTop:upHeight});
                    _this.animate({
                            marginTop:0
                    },speed,function(){
                            _btnDown.bind("click",scrollDown);
                    });
            }
           //Shawphy:自动播放
            var autoPlay = function(){
                    if(timer)timerID = window.setInterval(scrollUp,timer);
            };
            var autoStop = function(){
                    if(timer)window.clearInterval(timerID);
            };
            
             //鼠标事件绑定
            _this.hover(autoStop,autoPlay).mouseout();
            _btnUp.css("cursor","pointer").click( scrollUp ).hover(autoStop,autoPlay);//Shawphy:向上向下鼠标事件绑定
            _btnDown.css("cursor","pointer").click( scrollDown ).hover(autoStop,autoPlay);
        }    
    })
})(jQuery);