Didn't I read a feature request for something like this only a few days ago somewhere?
Nice reaction time, Good work!

Works pretty good already. Can't be used at the same time as camera app (expected behaviour), but does not break anything – after exiting Looking glass, the camera app resumed showing something. Didn't test while recording a video or such shenanigans.

The picture actually refocussed twice while testing but I've got no idea if I did it or how I did it. If possible, refocussing would be really everything I can think of to make this great. Perhaps on tap and/or every x seconds?

I also like the 'non gui'. The icon looks a bit jagged though. If you'd like, I'll draw a new one for you in all relevant resolutions… PM me if interested.

Edit:
I could not sleep so I drew something anyway and made a Pull request. Feel free to use or disregard