Overlay image (like snapchat) help

Hi,

I hope everyone is well.

I've searched the forum for how to overlay a graphic while using the camera (like snapchat)

I'd like to be able to put a still png image (with alpha background) over the camera picture, so when a user takes a photo the image looks (i hope) like it's there when the photo was taken.

Any ideas? can this be done?

Thanks

Mark