js 加载时自动调整图片大小

//  方法：setselectreadonly  用于设定极select控件readonly,
//        这个一个模拟只读不是真的只读
//        使用了onbeforeactivate,onfocus,onmouseover,onmouseout事件
//    示例：< img src='img.jpg' onload='imgautosize(imgd,fitwidth,fitheight)' > ;
//  create by sl 
// ---------------------------------------------------
function imgautosize(imgd,fitwidth,fitheight) 
{
var image1=new image(); 
image1.onload = function ()
{
    if(this.width>0 && this.height>0) 
    { 
        if(this.width/this.height>= fitwidth/fitheight) 
        { 
            if(this.width>fitwidth) 
            { 
                imgd.width=fitwidth; 
                imgd.height=(this.height*fitwidth)/this.width; 
            } 
            else 
            { 
                imgd.width=this.width; 
                imgd.height=this.height; 
            } 
        } 
        else 
        { 
            if(this.height>fitheight) 
            { 
                imgd.height=fitheight; 
                imgd.width=(this.width*fitheight)/this.height; 
            } 
            else 
            { 
                imgd.width=this.width; 
                imgd.height=this.height; 
            } 
        } 
    }
    image1 = null;
}

image1.src=imgd.src; 
imgd.style.cursor = 'hand';
imgd.onclick= function(){openwin(this.src,'imgphoto',600,400)};
imgd.title = "点击在新窗口中查看原图";
}