Device-Lock Mode (no root):
Locks the device when it is covered.
Blackscreen Mode (root):
Starts/Kills an app with a black background when the device is covered/uncovered.
(This will need an extra app! More informations at runtime.)
Superuser: Kill Blackscreen-App, Install Blackscreen-App
Device-Admin: Lock the device
Accessibility Service: Checking Foreground App (Used to check if the Blackscreen-App is running)