//w是图片宽度,h是图片高度, w=0时按高度缩小, h=0时按宽度缩小
function drawpic(obj,w,h)
{
	if (w==0)
	{if (obj.clientHeight>h){obj.style.height=h+'px';}return true;}
	
	if (h==0)
	{if (obj.clientWidth>w){obj.style.width=w+'px';}return true;}
	
	if (obj.clientHeight/obj.clientWidth>(h/w))
	{obj.style.height=h+'px';}
	else
	{obj.style.width=w+'px';}
}

//更换验证码
function chgvcode()
{
	var obj=document.getElementById("verify");
	obj.src=obj.src+"?rnd=2";
	return false;
}