var flag=false;
function DrawImage(ImgD,iwidth,iheight){
//参数(图片,允许的宽度,允许的高度)
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>= iwidth/iheight){
if(image.width>iwidth){ 
ImgD.width=iwidth;
ImgD.height=(image.height*iwidth)/image.width;
}else{
ImgD.width=image.width; 
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>iheight){ 
ImgD.height=iheight;
ImgD.width=(image.width*iheight)/image.height; 
}else{
ImgD.width=image.width; 
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
}
}


(function() {
			var oImg = document.getElementById("preview");
			function getAbsPos(event) {
				if(event.pageX || event.pageY){ return { x: event.pageX, y: event.pageY };}
 				return { x: event.clientX + document.documentElement.scrollLeft, y: event.clientY + document.documentElement.scrollTop }
			}
			function showPreview(event, url) {
				event = event || window.event;
				var pos = getAbsPos(event);
				oImg.style.display = "block";
				oImg.style.left = pos.x + 10 + "px";
				oImg.style.top = pos.y - 10 + "px";
				var s = oImg.innerHTML;
				if(s.indexOf(url) == -1) {
					oImg.innerHTML = '<img onload="javascript:DrawImage(this,180,200)" src="' + url + '" style="position:absolute;display:block;left:0;bottom:0;background:#fff;border:1px #ccc solid;padding:1px;" />';
				}
			}
			function hidePreview() {
				oImg.style.display = "none";
			}
			if (!document.all) document.captureEvents(Event.MOUSEMOVE);
			document.onmousemove = function(event) {
				event = event || window.event;
				var node = event.target || event.srcElement;
				if(node.tagName && node.tagName.toUpperCase() == "A" && node.getAttribute("rel")) {
					var t =  node.getAttribute("rel");
					if(t && t.length) {
						showPreview(event, t);
						return;
					}
				}
				hidePreview();
			}
})();