1al_init_user_event_source(3)                      al_init_user_event_source(3)
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NAME

6       al_init_user_event_source - Allegro 5 API
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SYNOPSIS

9              #include <allegro5/allegro.h>
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11              void al_init_user_event_source(ALLEGRO_EVENT_SOURCE *src)
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DESCRIPTION

14       Initialise an event source for emitting user events.  The space for the
15       event source must already have been allocated.
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17       One possible way of creating custom event sources is  to  derive  other
18       structures with ALLEGRO_EVENT_SOURCE at the head, e.g.
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20              typedef struct THING THING;
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22              struct THING {
23                  ALLEGRO_EVENT_SOURCE event_source;
24                  int field1;
25                  int field2;
26                  /* etc. */
27              };
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29              THING *create_thing(void)
30              {
31                  THING *thing = malloc(sizeof(THING));
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33                  if (thing) {
34                      al_init_user_event_source(&thing->event_source);
35                      thing->field1 = 0;
36                      thing->field2 = 0;
37                  }
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39                  return thing;
40              }
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42       The  advantage  here  is that the THING pointer will be the same as the
43       ALLEGRO_EVENT_SOURCE pointer.  Events emitted by the event source  will
44       have  the  event source pointer as the source field, from which you can
45       get a pointer to a THING by a simple cast (after ensuring checking  the
46       event is of the correct type).
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48       However, it is only one technique and you are not obliged to use it.
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50       The  user event source will never be destroyed automatically.  You must
51       destroy it manually with al_destroy_user_event_source(3).
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SEE ALSO

54       ALLEGRO_EVENT_SOURCE(3),               al_destroy_user_event_source(3),
55       al_emit_user_event(3), ALLEGRO_USER_EVENT(3)
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59Allegro reference manual                          al_init_user_event_source(3)
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