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1 .TH "SDL_AddTimer" "3" "Mon 12 Mar 2001, 01:04" "SDL" "SDL API Reference"
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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\&.
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4 .SH "SYNOPSIS"
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5 .PP
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6 \fB#include "SDL\&.h"
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7 .sp
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8 \fBSDL_TimerID \fBSDL_AddTimer\fP\fR(\fBUint32 interval, SDL_NewTimerCallback callback, void *param\fR);
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9 .SH "CALLBACK"
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10 .PP
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11 .nf
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12 \f(CW/* type definition for the "new" timer callback function */
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13 typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);\fR
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14 .fi
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15 .PP
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16 .SH "DESCRIPTION"
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17 .PP
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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\&.
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19 .PP
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20 To cancel a currently running timer call \fISDL_RemoveTimer\fR with the timer ID returned from \fBSDL_AddTimer\fP\&.
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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\&.
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23 .PP
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24 The maximum resolution of this timer is 10 ms, which 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\&.
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25 .SH "RETURN VALUE"
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26 .PP
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27 Returns an ID value for the added timer or \fBNULL\fR if there was an error\&.
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28 .SH "EXAMPLES"
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29 .PP
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30 .PP
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31 .nf
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32 \f(CWmy_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);\fR
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33 .fi
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34 .PP
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35 .SH "SEE ALSO"
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36 .PP
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37 \fI\fBSDL_RemoveTimer\fP\fR
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38 ...\" created by instant / docbook-to-man, Mon 12 Mar 2001, 01:04
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