可预览缩略图（实时预览）的上传图片界面

<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>= 120/80){
if(image.width>120){
ImgD.width=120;
ImgD.height=(image.height*120)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>80){
ImgD.height=80;
ImgD.width=(image.width*80)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
}
/*else{
ImgD.src="";
ImgD.alt=""
}*/
}

function FileChange(Value){
flag=false;
document.all.uploadimage.width=10;
document.all.uploadimage.height=10;
document.all.uploadimage.alt="";
document.all.uploadimage.src=Value;
}

function BeforeUpLoad(){
if(flag) alert("OK");else alert("FAIL");
}
</script>
<INPUT style="WIDTH: 143px; HEIGHT: 18px" type=file size=8 name=pic onchange="javascript:FileChange(this.value);">
<IMG id=uploadimage height=10 width=10 src="" onload="javascript:DrawImage(this);" ><BR>
<Button onclick="javascript:BeforeUpLoad();">提交</Button>