Java image create square avatar without crop and maintain proportion

I have a system using jsf and prime faces and there is a upload image function and I need to generate thumbnails for this image, I found many ways on internet but none meet my requirements.

Actually I would like something like facebook avatar where we can resize and move the picture to fit into a blank square.

Requirements: Can be on image upload page using query, prime faces, etc... Can be on java side after image upload Can not crop image Must keep ratio Can add white, or transparent (better) area around the image if it is not square to make it square

I found some css or php examples but not for JAVA.

Thanks