###### (This is the legacy documentation for stable SDL2, the current stable version; [SDL3](https://wiki.libsdl.org/SDL3/) is the current development version.)
# SDL_EventFilter

A function pointer used for callbacks that watch the event queue.

## Header File

Defined in [SDL_events.h](https://github.com/libsdl-org/SDL/blob/SDL2/include/SDL_events.h)

## Syntax

```c
typedef int (SDLCALL * SDL_EventFilter) (void *userdata, SDL_Event * event);
```

## Function Parameters

|                  |                                                                                                                            |
| ---------------- | -------------------------------------------------------------------------------------------------------------------------- |
| **userdata**     | what was passed as `userdata` to [SDL_SetEventFilter](SDL_SetEventFilter)() or [SDL_AddEventWatch](SDL_AddEventWatch), etc |
| **event**        | the event that triggered the callback                                                                                      |

## Return Value

Returns 1 to permit event to be added to the queue, and 0 to disallow it.
When used with [SDL_AddEventWatch](SDL_AddEventWatch), the return value is
ignored.

## Code Examples

```c
int MyEventFunction(void *userdata, SDL_Event *event) {
    // Do things with userdata and event

    return 0; // Value will be ignored
}

// ...
SDL_AddEventWatch(MyEventFunction, NULL);
```

## See Also

* [SDL_SetEventFilter](SDL_SetEventFilter)
* [SDL_AddEventWatch](SDL_AddEventWatch)

----
[CategoryAPI](CategoryAPI), [CategoryAPIDatatype](CategoryAPIDatatype), [CategoryEvents](CategoryEvents)