(function($){

	$.fn.imagezoom = function(options){

		var settings = {
			xzoom: 310,
			yzoom: 310,
			offset: 10,
			position: "btr",
			preload: 1
		};

		if(options) {
			$.extend(settings, options);
		}

		var noalt = '';

		var self = this;

		$(this).bind("mouseenter", function(ev){

			var imageleft = $(this).offset().left;//元素左边距
			var imagetop = $(this).offset().top;//元素顶边距


			var imagewidth = $(this).get(0).offsetwidth;//图片宽度
			var imageheight = $(this).get(0).offsetheight;//图片高度

			var boxleft = $(this).parent().offset().left;//父框左边距
			var boxtop = $(this).parent().offset().top;//父框顶边距
			var boxwidth = $(this).parent().width();//父框宽度
			var boxheight = $(this).parent().height();//父框高度

			noalt= $(this).attr("alt");//图片标题
			var bigimage = $(this).attr("rel");//大图地址
			$(this).attr("alt",'');//清空图片alt


			if($("div.zoomdiv").get().length == 0){
				$(document.body).append("<div class='zoomdiv'><img class='bigimg' src='"+bigimage+"'/></div><div class='zoommask'>&nbsp;</div>");//放大镜框及遮罩
			}


			if(settings.position == "btr"){
				//如果超过了屏幕宽度 将放大镜放在右边
				if(boxleft + boxwidth + settings.offset + settings.xzoom > screen.width){
					leftpos = boxleft  - settings.offset - settings.xzoom;
				}else{
					leftpos = boxleft + boxwidth + settings.offset;
				}
			}else{
				leftpos = imageleft - settings.xzoom - settings.offset;
				if(leftpos < 0){
					leftpos = imageleft + imagewidth  + settings.offset;
				}
			}

			$("div.zoomdiv").css({ top: boxtop,left: leftpos });
			$("div.zoomdiv").width(settings.xzoom);
			$("div.zoomdiv").height(settings.yzoom);
			$("div.zoomdiv").show();

			$(this).css('cursor','crosshair');

			$(document.body).mousemove(function(e){

				mouse = new mouseevent(e);
				if(mouse.x<imageleft || mouse.x>imageleft+imagewidth || mouse.y<imagetop || mouse.y>imagetop+imageheight){
					mouseoutimage();
					return;
				}

				var bigwidth = $(".bigimg").get(0).offsetwidth;
				var bigheight = $(".bigimg").get(0).offsetheight;

				var scaley ='x';
				var scalex ='y';


				//设置遮罩层尺寸
				if(isnan(scalex)|isnan(scaley)){
					var scalex = (bigwidth/imagewidth);
					var scaley = (bigheight/imageheight);
					$("div.zoommask").width((settings.xzoom)/scalex );
					$("div.zoommask").height((settings.yzoom)/scaley);
					$("div.zoommask").css('visibility','visible');
				}



				xpos = mouse.x- $("div.zoommask").width()/2 ;
				ypos = mouse.y- $("div.zoommask").height()/2 ;
				
				xposs = mouse.x- $("div.zoommask").width()/2 - imageleft;
				yposs = mouse.y- $("div.zoommask").height()/2 - imagetop ;
				
				xpos = (mouse.x - $("div.zoommask").width()/2 < imageleft ) ? imageleft : (mouse.x + $("div.zoommask").width()/2 > imagewidth + imageleft ) ?  (imagewidth + imageleft -$("div.zoommask").width()): xpos;
				ypos = (mouse.y - $("div.zoommask").height()/2 < imagetop ) ? imagetop : (mouse.y + $("div.zoommask").height()/2  > imageheight + imagetop ) ?  (imageheight + imagetop - $("div.zoommask").height()) : ypos;


				$("div.zoommask").css({ top:ypos,left:xpos});
				$("div.zoomdiv").get(0).scrollleft = xposs * scalex;
				$("div.zoomdiv").get(0).scrolltop  = yposs * scaley;


			});

		});


		function mouseoutimage(){
			$(self).attr("alt",noalt);
			$(document.body).unbind("mousemove");
			$("div.zoommask").remove();
			$("div.zoomdiv").remove();
		}

		//预加载
		count = 0;
		if(settings.preload){
			$('body').append("<div style='display:none;' class='jqpreload"+count+"'></div>");

			$(this).each(function(){

				var imagetopreload= $(this).attr("rel");

				var content = jquery('div.jqpreload'+count+'').html();

				jquery('div.jqpreload'+count+'').html(content+'<img src=\"'+imagetopreload+'\">');

			});

		}

	}

})(jquery);


function mouseevent(e) {
	this.x = e.pagex;
	this.y = e.pagey;
}