js等比例縮放圖片

    <script language=javascript>
    <!--
    var flag=false;
    function drawimage(imgd){
    var image=new image();
    image.src=imgd.src;
    if(image.width>0 && image.height>0){
    flag=true;
    if(image.width/image.height>= 164/112){
    if(image.width>164){
    imgd.width=164;
    imgd.height=(image.height*164)/image.width;
    }else{
    imgd.width=image.width;
    imgd.height=image.height;
    } //forasp
    imgd.alt=image.width+x+image.height;
    }
    else{
    if(image.height>112){
    imgd.height=112;
    imgd.width=(image.width*112)/image.height;
    }else{
    imgd.width=image.width;
    imgd.height=image.height;
    }
    imgd.alt=image.width+x+image.height;
    }
    }
    } //-->
    </script>
    <a href=./img.jpg target=_blank><img src=5_1.jpg border=0 width=164 height=112 onload=javascript:drawimage(this);></a>