How to convert Html to Image using Java

Hi All,
I need to convert a GWT(Google web toolkit) UI to the image file.
Can anyone give me a suggestions to proceed?

I have googled and I found most of the thing with respect to ActiveX
controls. I am not supposed to use ActiveX.

I have looked some AWT / swing coding to convert the html page to image but i am not able to get the full website or when i try some site to convert as a image then it not rendered fully.

Thanks