SDL_TimerCallback(3type)

💖 SDL_TimerCallback(3type) 💖

okay bestie, we're in the SDL3 DATATYPES section of the SDL3 manual and today's main character is SDL_TimerCallback — the function prototype for the millisecond timer callback function. yes. THE callback. the one that keeps your little alarm clock going round and round. 🎀

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✨ NAME ✨

SDL_TimerCallback — function prototype for the millisecond timer callback function. that's it, that's the whole name section, she's concise and she's iconic. 💅

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✨ SYNOPSIS ✨

first you gotta invite her in:

#include <SDL3/SDL_timer.h>

and here's the signature, copy it exactly bestie, no typos, she's sensitive:

typedef Uint32 (SDLCALL *SDL_TimerCallback)(void *userdata, SDL_TimerID timerID, Uint32 interval);

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✨ DESCRIPTION ✨

so here's the vibe 🌈: the callback function gets handed the current timer interval and it returns the next timer interval, both in milliseconds.

now the part you actually need to internalize, no cap:

• if the value it returns is the same as the one that was passed in, the periodic alarm just keeps going. same energy, no drama. 💫
• if it's anything else, a new alarm gets scheduled. glow up, new schedule.
• and if the callback returns 0, the periodic alarm is canceled and will be removed. she's gone. bye bestie. 💀

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✨ FUNCTION PARAMETERS ✨

• userdata — an arbitrary pointer that the app handed over through SDL_AddTimer, all for its own personal use. it's your little backpack of stuff, SDL doesn't peek inside. 🎒
• timerID — the current timer being processed. which one of your alarms is ringing rn, basically. ⏰
• interval — the current callback time interval. the now-interval. the one that's happening as we speak. ⌛

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✨ RETURN VALUE ✨

you return the new callback time interval, or 0 to disable further runs of the callback. that's the whole deal. 0 is the off switch, literally. 🔌

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✨ THREAD SAFETY ✨

okay this one matters, pay attention, fr fr 🫶

SDL may call this callback at any time from a background thread. any time. unhinged behavior, but it's legal. so the application is responsible for locking resources the callback touches that need to be protected. that's on you, not on SDL. lock your stuff. 🔒✨

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✨ AVAILABILITY ✨

this datatype is available since SDL 3.2.0. so if you're on something older, no she's not there yet, sorry bestie. 🦋

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✨ SEE ALSO ✨

• SDL_AddTimer(3) — the one who invites the callback to the party in the first place 💌

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and that's the whole page, you ate it, periodt 👑

signing off with love from the Simple Directmedia Layer girlies, SDL 3.4.18, dated right there with SDL_TimerCallback(3type) — mwah, go schedule something cute 💖🎀🦋