/**
 * @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
 *  	$('#marquee').marquee(options);
 * @options
 *		isEqual:true,//所有滚动的元素长宽是否相等,true,false
 *  	loop: 0,//循环滚动次数，0时无限
 *		direction: 'left',//滚动方向，'left','right','up','down'
 *		scrollAmount:1,//步长
 *		scrollDelay:20//时长
 */
(function($){

	$.fn.marquee = function(options){
		$.fn.marquee.setOpts(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 = $element.children();//滚动子元素
			var scrollSize=0;//滚动元素尺寸
			var _type = ($.fn.marquee.opts.direction == 'left' || $.fn.marquee.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
			$element.css(_type?'width':'height',10000);
			//获取滚动元素的尺寸
			if ($.fn.marquee.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;
			$.fn.marquee.scrollFunc = function(){
				var _dir = ($.fn.marquee.opts.direction == 'left' || $.fn.marquee.opts.direction == 'right') ? 'scrollLeft':'scrollTop';
				if ($.fn.marquee.opts.loop > 0) {
					numMoved+=$.fn.marquee.opts.scrollAmount;
					if(numMoved>scrollSize*$.fn.marquee.opts.loop){
						_scrollObj[_dir] = 0;
						return clearInterval(moveId);
					} 
				}

				if($.fn.marquee.opts.direction == 'left' || $.fn.marquee.opts.direction == 'up'){
					var newPos = _scrollObj[_dir] + $.fn.marquee.opts.scrollAmount;
					if(newPos>=scrollSize){
						newPos -= scrollSize;
					}
					_scrollObj[_dir] = newPos;
				}else{
					var newPos = _scrollObj[_dir] - $.fn.marquee.opts.scrollAmount;
					if(newPos<=0){
						newPos += scrollSize;
					}
					_scrollObj[_dir] = newPos;
				}
			}
			//滚动开始
			$.fn.marquee.moveId = setInterval($.fn.marquee.scrollFunc, $.fn.marquee.opts.scrollDelay);
			//鼠标划过停止滚动
			$marquee.hover(
				function(){
					clearInterval($.fn.marquee.moveId);
				},
				function(){
					clearInterval($.fn.marquee.moveId);
					$.fn.marquee.moveId = setInterval($.fn.marquee.scrollFunc, $.fn.marquee.opts.scrollDelay);
				}
			);
			
		});
	};
	$.fn.marquee.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:5//时长

	};
	$.fn.marquee.setDefaults = function(settings) {
		$.extend( $.fn.marquee.defaults, settings );
	};
	$.fn.marquee.setOpts = function(options){
		$.fn.marquee.opts = $.extend({},$.fn.marquee.defaults, options);
	};
})(jQuery);