/*网站背景设置
 *使用方法: window.onload = bar('on'); //开 window.onload = bar('off'); //关
*/
function bar(onOff)
{
	var ObjectBody = document.documentElement;
	onOff == 'on' ? ObjectBody.style.backgroundImage = 'url(images/backgroundLayout.gif)' :  ObjectBody.style.backgroundImage = '';
}

/*菜单显示隐藏
 *使用方法: <strong onclick="nav('obj1')">点我</strong><div id="obj1">内容</div>
*/
nav = function(obj)
{
	document.getElementById(obj).style.display == '' ? document.getElementById(obj).style.display = 'none' : document.getElementById(obj).style.display = '';
}

/*
 * @Date: 11:33 2009-04-22 星期三
 * @Author: 李求是
 * @Note: 相册(不包含缩略图). 大图id = 'bigPhoto'. 小图列表id = 'photoList'
 * @Example: 
 *		<div>
 *			<span onclick="preNexPhoto('p')">pre</span>
 *			<span onclick="preNexPhoto('n')">next</span>
 *		</div>
 *		<div>
 *			<img width="434" height="200" id="bigPhoto" src="" />
 *		</div>
 *		<div>
 *			<div id="photoList">
 *				<p><img id="photo1" onclick="document.getElementById('bigPhoto').src = this.src;flag = 1" src="images/1.jpg" /></p>
 *				<p><img id="photo2" onclick="document.getElementById('bigPhoto').src = this.src;flag = 2" src="images/2.gif" /></p>
 *				<p><img id="photo3" onclick="document.getElementById('bigPhoto').src = this.src;flag = 3" src="images/3.jpg" /></p>
 *				<p><img id="photo4" onclick="document.getElementById('bigPhoto').src = this.src;flag = 4" src="images/4.jpg" /></p>
 *			</div>
 *		</div>
 */
var flag = 1;
preNexPhoto = function(pn)		//'p'是上一张;'n'是下一张
{
	var photoLen = document.getElementById('photoList').getElementsByTagName('img').length;	//取得共有几张小图
	var msg1 = '上面没有了';
	var msg2 = '下面没有了';
	
	//上一张
	prePhoto = function()
	{
		if(flag == 1)
		{
			alert(msg1);
			return false;
		}
		else if(flag == 0)
		{
			alert(msg1);
			return false;
		}
		else
		{
			flag--;		//自减
			var preImg = document.getElementById('photo' + flag).src;	//上一张图片地址
			document.getElementById('bigPhoto').src = preImg;	//更改大图地址
		}
	}
	
	//下一张
	nexPhoto = function()
	{
		if(flag == photoLen)
		{
			alert(msg2);
			return false;
		}
		else
		{
			flag++;		//自增
			var nexImg = document.getElementById('photo' + flag).src;	//下一张图片地址
			document.getElementById('bigPhoto').src = nexImg;	//更改大图地址
		}
	}
	
	//若pn为"p"则执行"上一张",反之则执行"下一张"
	pn == 'p' ? prePhoto() : nexPhoto();
}