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(This is the documentation for SDL3, which is under heavy development and the API is changing! SDL2 is the current stable version!)


Call a callback function at a future time.

Header File

Defined in <SDL3/SDL_timer.h>


SDL_TimerID SDL_AddTimerNS(Uint64 interval, SDL_NSTimerCallback callback, void *userdata);

Function Parameters

Uint64 interval the timer delay, in nanoseconds, passed to callback.
SDL_NSTimerCallback callback the SDL_TimerCallback function to call when the specified interval elapses.
void * userdata a pointer that is passed to callback.

Return Value

(SDL_TimerID) Returns a timer ID or 0 on failure; call SDL_GetError() for more information.


If you use this function, you must pass SDL_INIT_TIMER to SDL_Init().

The callback function is passed the current timer interval and the user supplied parameter from the SDL_AddTimerNS() call and should return the next timer interval. If the value returned from the callback is 0, the timer is canceled.

The callback is run on a separate thread, and for short timeouts can potentially be called before this function returns.

Timers take into account the amount of time it took to execute the callback. For example, if the callback took 250 ns to execute and returned 1000 (ns), the timer would only wait another 750 ns before its next iteration.

Timing may be inexact due to OS scheduling. Be sure to note the current time with SDL_GetTicksNS() or SDL_GetPerformanceCounter() in case your callback needs to adjust for variances.

Thread Safety

It is safe to call this function from any thread.


This function is available since SDL 3.0.0.

See Also

CategoryAPI, CategoryAPIFunction, CategoryTimer

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