显示大图

<td align="center" bgcolor="#FFFFFF">
	<a href="/gb/prodshow.asp?id=846">
	<img src="http://www.baidu.com/img/baidu_sylogo1.gif" width="136" height="132" border=0 
	onMouseOver="showImage(this,'http://www.baidu.com/img/baidu_sylogo1.gif','3')"></a>
</td>
<script>
 if (document.all["_showImage"] == null) 
 document.write(' <img id = _showImage style = "z-index: 999;display: none;position: absolute;border: 1 solid black" onmouseout = "style.display = \'none\'">');
 
 /** * 显示弹出图片。 
  * @param tag 目标元素。弹出的框将显示在其旁边
  * @param url 需要弹出的图片的URL
  * @param pos 弹出位置。0=右，1=上，2=左，3=下，缺省为自动选择最佳方位。
  */
 function showImage(tag, url, pos)
 {
 	tag.attachEvent("onmouseout", mouseout);
 	var helper = document.all["_showImage"];
 	helper.removeAttribute("src");
 	helper.removeAttribute("width");
 	helper.removeAttribute("height");
 	helper.onload = showImage_show;
 	helper.src = url;

 	function mouseout()
 	{ 
		//if(event.toElement != helper) 
 		//注释本行将使鼠标移出原图时弹出图立即关闭 
 		helper.onmouseout();
 		helper.onload = null;
 		helper.removeAttribute("src");
 		tag.detachEvent("onmouoseout", arguments.callee);
 	}
 	function showImage_show()
 	{
 		var rc = tag.getBoundingClientRect();
 		helper.style.display = ""; 
		var rc2 = helper.getBoundingClientRect(); 
		helper.alt = (rc2.right-rc2.left)+"x"+(rc2.bottom-rc2.top); 
		var body = document.body; 
		var l = rc.left; 
		var t = rc.top; 
		var r = body.clientWidth-rc.right; 
		var b = body.clientHeight-rc.bottom; 
		var ratio = (rc2.bottom-rc2.top) / (rc2.right-rc2.left); 
		var pos = typeof(pos)!='undefined'?pos:-1; 
		if(pos >= 0) { 
			//指定了显示方位 
			var w = pos==1||pos==3?body.clientWidth : pos==0?r:l; 
			var h = pos==0||pos==2?body.clientHeight : pos==1?t:b; 
			if(h < w*ratio) w = h/ratio; 
			else if(w < h/ratio) h = w*ratio; } 
			else { 
			//未指定显示方位，自动选择 
			var pos0_2 = l < r ? 0 : 2; 
			var pos1_3 = t < b ? 3 : 1; 
			var w = l < r ? r : l; 
			var h = t < b ? b : t; 
			var h1 = w*ratio; 
			if(h1 > body.clientHeight) 
			h1 = body.clientHeight; 
			var h2 = body.clientWidth*ratio; 
			if(h2 > h) h2 = h; 
			if(h1 > h2) { 
				var pos = pos0_2; h = h1; w = h1 / ratio; } 
			else { 
			var pos = pos1_3; h = h2; w = h2 / ratio; } 
			} 
			if(rc2.bottom-rc2.top > h || rc2.right-rc2.left > w) { 
			helper.width = w; helper.height = h; 
			} 
			var rc2 = helper.getBoundingClientRect(); 
			l = (pos==1||pos==3?rc.left:pos==0?rc.right:rc.left-(rc2.right-rc2.left))+150; 
			t = (pos==0||pos==2?rc.top:pos==3?rc.bottom:rc.top-(rc2.bottom-rc2.top)); 
			var k = body.clientWidth-(l+rc2.right-rc2.left); 
			if(k < 0) l += k; 
			var k = body.clientHeight-(t+rc2.bottom-rc2.top); 
			if(k < 0) t += k; helper.style.left = -2+body.scrollLeft+l; 
			helper.style.top = -2+body.scrollTop+t; 
			} 
}
</script>