SDL_AddEventWatch - Add a callback to be triggered when an event is added to the event queue.

       This function is available since SDL 3.2.0.

filter will be called when an event happens, and its return value is ignored.

       WARNING:  Be  very  careful  of  what  you  do in the event filter function, as it may run in a different
       thread!

       If the quit event is generated by a signal (e.g. SIGINT), it  will  bypass  the  internal  queue  and  be
       delivered to the watch callback immediately, and arrive at the next event poll.

       Note:  the callback is called for events posted by the user through SDL_PushEvent(), but not for disabled
       events, nor for events by a filter callback set with SDL_SetEventFilter(), nor for events posted  by  the
       user through SDL_PeepEvents().

filter an SDL_EventFilter function to call when an event happens.

       userdata
              a pointer that is passed to filter.

       SDL_AddEventWatch - Add a callback to be triggered when an event is added to the event queue.

       for more information.

SDL_RemoveEventWatch(3), SDL_SetEventFilter(3)

Simple Directmedia Layer                           SDL 3.2.20                               SDL_AddEventWatch(3)

#include<SDL3/SDL_events.h>boolSDL_AddEventWatch(SDL_EventFilterfilter,void*userdata);

       It is safe to call this function from any thread.