SDL_AddEventWatch

Use this function to add a callback to be triggered when an event is added to the event queue.

Syntax

void SDL_AddEventWatch(SDL_EventFilter filter,
                       void*           userdata)

Function Parameters

Code Examples

You can add your code example here

Remarks

int YourEventFilter(void*      userdata,
                    SDL_Event* event)

• where YourEventFilter is the name of your function and its parameters are:

  userdata	what was passed as userdata to SDL_AddEventWatch()
  event	the event that triggered the callback

• 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().

Related Functions

• SDL_DelEventWatch

• SDL_SetEventFilter

CategoryAPI, CategoryEvents