What happens when the screen is locked?

I am working with camera API to develop android app. I am using flash in this application and I need it to be ON all the time. I was able to turn flash ON during startup and after calling onResume()

, but I can't figure out what to do after the screen is locked . When I lock my screen and then unlock it, the flash does not turn ON .

I need to understand how this can be done and enable flash after unlocking the screen if the application is running (not onPause()

).

Any advice or advice is appreciated! Thanks in advance!