/* 
 * jquery fixed plugins 1.5.1
 * author:
 * url:
 * data
 *
 *  update log:
 * 
 *  status       date            name      version           bug-description
 *  ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 *  created      2012-08-15    	 ru	       1.0               none
 
 *  modified     2012-09-02      ru        1.4.1             修复了webkit内核浏览器右边浮动有一定距离的bug(负外边距),增加了悬浮靠边的定位、是否显示关闭按钮、是否垂直居中定位
 
 *  modified     2013-01-02    	 ru	       1.5.1             增加了垂直方向的位置;把核心函数(关闭、展开、定位、最小化)重构,修复了webkit内核浏览器右边浮动最小化时没有显示出来
 *  ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------*/

;(function($){
    $.fn.fixed = function(options){
        var defaults = {
			top    			: null,
			halftop     	: false,
			durationtime 	: 500
        }
        var options = $.extend(defaults, options);		

        this.each(function(){			
           
			var thisbox = $(this),
				contentheight = thisbox.height(),
				boxtop = null,
				defaulttop = thisbox.offset().top,
				halftop = ($(window).height() - contentheight)/2
				;
				
			if(options.top == null){
				boxtop = defaulttop;
			}else {
				boxtop = options.top;
			}
			if( options.halftop ) {	boxtop = halftop; }
						
			thisbox.css("top", boxtop);
						
						
			//核心scroll事件			
			$(window).bind("scroll",function(){
				var offsettop = boxtop + $(window).scrolltop() + "px";
	            thisbox.animate({
					top: offsettop
	            },{
	            	duration: options.durationtime,	
	                queue: false
	            });
			});
			
				
        });	//end this.each

    };
})(jquery);