/**
 * @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
 *  	$('#marquee').kxbdMarquee(options);
 * @options
 *		delay:等待多久后滚动，单位秒
 *		isEqual:true,//所有滚动的元素长宽是否相等,true,false
 *  	loop: 0,//循环滚动次数，0时无限
 *		direction: 'left',//滚动方向，'left','right','up','down'
 *		scrollAmount:1,//步长
 *		scrollDelay:20//时长
 *		controlBtn:{left:'#goL',right:'#goR'},//控制加速滚动的按钮ID，有四个属性left,right,up,down分别对应四个方向
 *		newAmount:4,//加速滚动的步长
 *		eventA:'mouseenter',//鼠标事件，加速
 *		eventB:'mouseleave'//鼠标事件，原速
 */
(function($) {

    $.fn.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') {
                    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;
            if (opts.delay > 0) {
                setTimeout(function() {
                    moveId = setInterval(scrollFunc, opts.scrollDelay);
                }, opts.delay * 1000);
            } else {
                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.kxbdMarquee.defaults = {
        delay: 0,
        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: 30, //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.kxbdMarquee.setDefaults = function(settings) {
        $.extend($.fn.kxbdMarquee.defaults, settings);
    };

})(jQuery);