[Javascript][jQuery]模拟Marquee无缝滚动

/**
* @classDescription 模拟Marquee，无间断滚动内容
* @author Aken Li(www.kxbd.com)
* @DOM
*      <div id="marquee">
*          <ul>
*               <li></li>
*               <li></li>
*          </ul>
*      </div>
* @CSS
*      #marquee {width:200px;height:50px;overflow:hidden;}
* @Usage
*      $('#marquee').kxbdMarquee(options);
* @options
*    isEqual:true,//所有滚动的元素长宽是否相等,true,false
*      loop: 0,//循环滚动次数，0时无限
*    direction: 'left',//滚动方向，'left','right','up','down'
*    scrollAmount:1,//步长
*    scrollDelay:20//时长
*/
(function($){

    $.fn.kxbdMarquee = function(options){
        var opts = $.extend({},$.fn.kxbdMarquee.defaults, options);
        
        return this.each(function(){
            var $marquee = $(this);//滚动元素容器
            var _scrollObj = $marquee.get(0);//滚动元素容器DOM
            var scrollW = $marquee.width();//滚动元素容器的宽度
            var scrollH = $marquee.height();//滚动元素容器的高度
            var $element = $marquee.children(); //滚动元素
            var $kids = $element.children();//滚动子元素
            var scrollSize=0;//滚动元素尺寸
            var _type = (opts.direction == 'left' || opts.direction == 'right') ? 1:0;//滚动类型，1左右，0上下
            
            //防止滚动子元素比滚动元素宽而取不到实际滚动子元素宽度
            $element.css(_type?'width':'height',10000);
            //获取滚动元素的尺寸
            if (opts.isEqual) {
                scrollSize = $kids[_type?'outerWidth':'outerHeight']() * $kids.length;
            }else{
                $kids.each(function(){
                    scrollSize += $(this)[_type?'outerWidth':'outerHeight']();
                });
            }
            //滚动元素总尺寸小于容器尺寸，不滚动
            if (scrollSize<(_type?scrollW:scrollH)) return;
            //克隆滚动子元素将其插入到滚动元素后，并设定滚动元素宽度
            $element.append($kids.clone()).css(_type?'width':'height',scrollSize*2);
            
            var numMoved = 0;
            function scrollFunc(){
                var _dir = (opts.direction == 'left' || opts.direction == 'right') ? 'scrollLeft':'scrollTop';
                if (opts.loop > 0) {
                    numMoved+=opts.scrollAmount;
                    if(numMoved>scrollSize*opts.loop){
                        _scrollObj[_dir] = 0;
                        return clearInterval(moveId);
                    }
                }
                if(opts.direction == 'left' || opts.direction == 'up'){
                    _scrollObj[_dir] +=opts.scrollAmount;
                    if(_scrollObj[_dir]>=scrollSize){
                        _scrollObj[_dir] = 0;
                    }
                }else{
                    _scrollObj[_dir] -=opts.scrollAmount;
                    if(_scrollObj[_dir]<=0){
                        _scrollObj[_dir] = scrollSize;
                    }
                }
            }
            //滚动开始
            var moveId = setInterval(scrollFunc, opts.scrollDelay);
            //鼠标划过停止滚动
            $marquee.hover(
                function(){
                    clearInterval(moveId);
                },
                function(){
                    clearInterval(moveId);
                    moveId = setInterval(scrollFunc, opts.scrollDelay);
                }
            );
            
        });
    };
    $.fn.kxbdMarquee.defaults = {
        isEqual:true,//所有滚动的元素长宽是否相等,true,false
        loop: 0,//循环滚动次数，0时无限
        direction: 'left',//滚动方向，'left','right','up','down'
        scrollAmount:1,//步长
        scrollDelay:20//时长

    };
    $.fn.kxbdMarquee.setDefaults = function(settings) {
        $.extend( $.fn.kxbdMarquee.defaults, settings );
    };
})(jQuery);