NAME

       al_init_user_event_source - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro.h>

              void al_init_user_event_source(ALLEGRO_EVENT_SOURCE *src)

DESCRIPTION

       Initialise  an  event  source for emitting user events.  The space for the event source must already have
       been allocated.

       One possible way of creating custom event sources is to derive other structures with ALLEGRO_EVENT_SOURCE
       at the head, e.g.

              typedef struct THING THING;

              struct THING {
                  ALLEGRO_EVENT_SOURCE event_source;
                  int field1;
                  int field2;
                  /* etc. */
              };

              THING *create_thing(void)
              {
                  THING *thing = malloc(sizeof(THING));

                  if (thing) {
                      al_init_user_event_source(&thing->event_source);
                      thing->field1 = 0;
                      thing->field2 = 0;
                  }

                  return thing;
              }

       The  advantage  here  is  that  the  THING  pointer will be the same as the ALLEGRO_EVENT_SOURCE pointer.
       Events emitted by the event source will have the event source pointer as the source field, from which you
       can get a pointer to a THING by a simple cast (after ensuring checking the event is of the correct type).

       However, it is only one technique and you are not obliged to use it.

       The  user  event  source  will  never  be  destroyed  automatically.   You  must destroy it manually with
       al_destroy_user_event_source(3alleg5).

SEE ALSO

       ALLEGRO_EVENT_SOURCE(3alleg5),    al_destroy_user_event_source(3alleg5),     al_emit_user_event(3alleg5),
       ALLEGRO_USER_EVENT(3alleg5)