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annotate docs/man3/SDL_AddTimer.3 @ 4159:a1b03ba2fcd0 SDL-1.2
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| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 08 Dec 2008 00:25:42 +0000 |
| parents | 4e3b250c950e |
| children | 1238da4a7112 |
| rev | line source |
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1 .TH "SDL_AddTimer" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
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3 SDL_AddTimer \- Add a timer which will call a callback after the specified number of milliseconds has elapsed\&. |
| 0 | 4 .SH "SYNOPSIS" |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBSDL_TimerID \fBSDL_AddTimer\fP\fR(\fBUint32 interval, SDL_NewTimerCallback callback, void *param\fR); | |
| 9 .SH "CALLBACK" | |
| 10 .PP | |
| 11 .nf | |
| 12 \f(CW/* type definition for the "new" timer callback function */ | |
| 13 typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);\fR | |
| 14 .fi | |
| 15 .PP | |
| 16 .SH "DESCRIPTION" | |
| 17 .PP | |
| 18 Adds a callback function to be run after the specified number of milliseconds has elapsed\&. The callback function is passed the current timer interval and the user supplied parameter from the \fBSDL_AddTimer\fP call and returns the next timer interval\&. If the returned value from the callback is the same as the one passed in, the periodic alarm continues, otherwise a new alarm is scheduled\&. | |
| 19 .PP | |
| 20 To cancel a currently running timer call \fISDL_RemoveTimer\fR with the timer ID returned from \fBSDL_AddTimer\fP\&. | |
| 21 .PP | |
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22 The timer callback function may run in a different thread than your main program, and so shouldn\&'t call any functions from within itself\&. You may always call \fISDL_PushEvent\fR, however\&. |
| 0 | 23 .PP |
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24 The granularity of the timer is platform-dependent, but you should count on it being at least 10 ms as this is the most common number\&. This means that if you request a 16 ms timer, your callback will run approximately 20 ms later on an unloaded system\&. If you wanted to set a flag signaling a frame update at 30 frames per second (every 33 ms), you might set a timer for 30 ms (see example below)\&. If you use this function, you need to pass \fBSDL_INIT_TIMER\fP to \fISDL_Init\fR\&. |
| 0 | 25 .SH "RETURN VALUE" |
| 26 .PP | |
| 27 Returns an ID value for the added timer or \fBNULL\fR if there was an error\&. | |
| 28 .SH "EXAMPLES" | |
| 29 .PP | |
| 30 .PP | |
| 31 .nf | |
| 32 \f(CWmy_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);\fR | |
| 33 .fi | |
| 34 .PP | |
| 35 .SH "SEE ALSO" | |
| 36 .PP | |
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37 \fI\fBSDL_RemoveTimer\fP\fR, \fI\fBSDL_PushEvent\fP\fR |
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38 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |