SDL_VideoDriverName (3) - Linux Manuals
SDL_VideoDriverName: Obtain the name of the video driver
NAMESDL_VideoDriverName - Obtain the name of the video driver
The buffer pointed to by namebuf is filled up to a maximum of maxlen characters (include the NULL terminator) with the name of the initialised video driver. The driver name is a simple one word identifier like "x11" or "windib".