JS鼠标控制图片的缩放

<SCRIPT language=JavaScript type=text/JavaScript>
var isdrag=false;
function img_zoom(e, o) //图片鼠标滚轮缩放

{
var zoom = parseInt(o.style.zoom, 10) || 100;
zoom += event.wheelDelta / 12;
if (zoom > 0) o.style.zoom = zoom + '%';
return false;
}
function mouseover(){
div1.border="1";
div1.style.cursor="nw-resize";
}
function mouseout(){
div1.border="0";
}
function mousemove(){
if(isdrag){
div1.style.width=event.clientX;
//div1.style.height=event.clientY;
}
}
function mousedown(){
div1.setCapture();
isdrag = true;
div1.οnmοusemοve=mousemove;
}
function mouseup(){
div1.releaseCapture();
isdrag = false;
//event.returnValue=false;
}

</SCRIPT>
<IMG οnmοuseοver="mouseover()" οnmοuseοut="mouseout()" οnmοuseup="mouseup()" οnmοusedοwn="mousedown()" id="div1" onmousewheel="return img_zoom(event,this)"
alt="鼠标的滚轮控制图片自动缩放" src="http://www.google.com/intl/zh-CN_ALL/images/logo.gif"
οnlοad="javascript:if(this.width>screen.width-500)this.width=screen.width-500">