ZK image validation

asked 2011-04-11 11:58:50 +0800

angelous
9 ● 1

Hi.

I'm devoloping a zk application with a form having an upload button. When clicked, it opens a browser window with a default "save as" dialog and upon confirmation it show an image preview. I'm trying to constraint the uploaded files to accept only images. This is easy to accomplish when the validation is only according with the file extension using an if clause like this:

if(media instanceof org.zkoss.image.Image){
//do something
}else{
Messagebox.show("Not an image: "+media, "Error", Messagebox.OK, Messagebox.ERROR);
}

So far so good, but here's my problem: If an invalid image is provided, this validation doesn't work. For instance a corrupted image (lenght zero) or renamed file: "qwerty.exe" to "querty.jpg". I've noticed that a warning is thrown, but i can't catch it with a try catch block.

Apr 11, 2011 5:40:50 PM org.zkoss.image.AImage init:126
WARNING: Unsupported image format: jpg; its width and height are assumed to zero

Is there any way to perform this validation? I'm using ZK 5.0.6.

Thanks in advance.