Overlay API


i’m absolutely new here and I hope you can help me.
First of all I hope this is the correct thread for my problem.

I’m working on an overlay plugin using Qt. That works fine for All Desktop applications but not for fullscreen games. So I found out that I need a graphic hook to display something over the game.

The NVFBC – FRAMEBUFFER CAPTURE sounds like it can do what I’m looking for, but before I run around and waste my time I though why don’t ask the experts.

Question: How can I display images/text on the screen, even over Fullscreen games (directX and openGL)?

So an documentation with an example (maybe hello world that’s displayed always on the screen would be awesome). Maybe the Nvidia share overlay is opensource?? Since I need to interact with my overlay the NVidia share is exactly what I need.

I’m working with Qt so far and in best case someone else already wrote an interface to display Qt Widgets as overlay.

best regards