SDL Wiki
(This is the legacy documentation for stable SDL2, the current stable version; SDL3 is the current development version.)

SDL_AddTimer

Call a callback function at a future time.

Syntax

SDL_TimerID SDL_AddTimer(Uint32 interval,
                         SDL_TimerCallback callback,
                         void *param);

Function Parameters

interval the timer delay, in milliseconds, passed to callback
callback the SDL_TimerCallback function to call when the specified interval elapses
param a pointer that is passed to callback

Return Value

Returns a timer ID or 0 if an error occurs; call SDL_GetError() for more information.

Remarks

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_AddTimer() 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.

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

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

Version

This function is available since SDL 2.0.0.

Example

// Function to be called after a certain time

Uint32 callback(Uint32 interval, void* name) {

    printf("Hello %s!\n", static_cast<char*>(name));
       
    return 0;
}

...

// Initialize timer

if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) < 0)

...

// Set timer to 1 second

SDL_TimerID timerID = SDL_AddTimer(1000, callback, const_cast<char*>("SDL"));

// Main loop

while(!quit) {
    ...
}

// Remove timer after main loop

SDL_RemoveTimer(timerID);

CategoryAPI


[ edit | delete | history | feedback | raw ]

[ front page | index | search | recent changes | git repo | offline html ]

All wiki content is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0).
Wiki powered by ghwikipp.