Use this function to set up a filter to process all events before they change internal state and are posted to the internal event queue.
void SDL_SetEventFilter(SDL_EventFilter filter, void* userdata)
the function to call when an event happens; see Remarks for details
a pointer that is passed to filter
You can add your code example here
The function prototype for filter is:
int YourEventFilter(void* userdata, SDL_Event* event)
where YourEventFilter is the name of your function and its parameters are:
what was passed as userdata to SDL_SetEventFilter()
the event that triggered the callback
If filter returns 1, then the event will be added to the internal queue. If it returns 0, then the event will be dropped from the queue, but the internal state will still be updated. This allows selective filtering of dynamically arriving events.
WARNING: Be very careful of what you do in the event filter function, as it may run in a different thread!
There is one caveat when dealing with the SDL_QUIT event type. The event filter is only called when the window manager desires to close the application window. If the event filter returns 1, then the window will be closed, otherwise the window will remain open if possible.
If the quit event is generated by an interrupt signal, it will bypass the internal queue and be delivered to the application at the next event poll.
Note: Disabled events never make it to the event filter function; see SDL_EventState().
Note: If you just want to inspect events without filtering, you should use SDL_AddEventWatch() instead.