/**
 * @classdescription 模拟marquee，无间断滚动内容
 * @author aken li(www.kxbd.com)
 * @date 2009-07-17
 * @dom
 *  	<div id="marquee">
 *  		<ul>
 *   			<li></li>
 *   			<li></li>
 *  		</ul>
 *  	</div>
 * @css
 *  	#marquee {width:200px;height:50px;overflow:hidden;}
 * @usage
 *  	$('#marquee').j$_mrq(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
 *		controlbtn:{left:'#gol',right:'#gor'},//控制加速滚动的按钮id，有四个属性left,right,up,down分别对应四个方向
 *		newamount:4,//加速滚动的步长
 *		eventa:'mouseenter',//鼠标事件，加速
 *		eventb:'mouseleave'//鼠标事件，原速
 */
(function($){

	$.fn.j$_mrq = function(options){
		var opts = $.extend({},$.fn.j$_mrq.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'){
					var newpos = _scrollobj[_dir] + opts.scrollamount;
					if(newpos>=scrollsize){
						newpos -= scrollsize;
					}
					_scrollobj[_dir] = newpos;
				}else{
					var newpos = _scrollobj[_dir] - opts.scrollamount;
					if(newpos<=0){
						newpos += scrollsize;
					}
					_scrollobj[_dir] = newpos;
				}
			};
			//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);
				}
			);
			
			//控制加速运动
			if(opts.controlbtn){
				$.each(opts.controlbtn, function(i,val){
					$(val).bind(opts.eventa,function(){
						opts.direction = i;
						opts.oldamount = opts.scrollamount;
						opts.scrollamount = opts.newamount;
					}).bind(opts.eventb,function(){
						opts.scrollamount = opts.oldamount;
					});
				});
			}
		});
	};
	$.fn.j$_mrq.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
		newamount:3,//加速滚动的步长
		eventa:'mousedown',//鼠标事件，加速
		eventb:'mouseup'//鼠标事件，原速
	};
	
	$.fn.j$_mrq.setdefaults = function(settings) {
		$.extend( $.fn.j$_mrq.defaults, settings );
	};
	
})(jquery);