Allegro 5 api
#include <allegro5/allegro.h> bool al_get_monitor_info(int adapter, ALLEGRO_MONITOR_INFO *info)
Get information about a monitor\[aq]s position on the desktop. adapter is a number from 0 to al_get_num_video_adapters()-1.
Returns true on success, false on failure.
ALLEGRO_MONITOR_INFO(3alleg5), al_get_num_video_adapters(3alleg5)