How can I obtain a reference to the native window of the camera application in Android?

Question

I need a reference to a ANativeWindow structure to be fed to a image processing library based on OpenGL. I don't want to make a native activity or an additional application.
I also want to know if I can use, and how to obtain from native code, the window specific to the camera application, mentioning that I don't want the display to change during processing or the processing of the OpenGL based library to interfere with the camera application.

Answer 1

How can I obtain a reference to the native window of the camera application in Android?

You don't. That window is in another process, not yours.

I also want to know if I can use, and how to obtain from native code, the window specific to the camera application

This is not possible. Again, that window is in another process, not yours.