author Sam Lantinga <>
Thu, 26 Apr 2001 16:45:43 +0000
changeset 0 74212992fb08
child 55 55f1f1b3e27d
permissions -rw-r--r--
Initial revision
     1 .TH "SDL_AddTimer" "3" "Mon 12 Mar 2001, 01:04" "SDL" "SDL API Reference" 
     2 .SH "NAME"
     3 SDL_AddTimer\- Add a timer which will call a callback after the specified number of milliseconds has elapsed\&.
     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
    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
    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\&.
    23 .PP
    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\&.
    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
    37 \fI\fBSDL_RemoveTimer\fP\fR
    38 ...\" created by instant / docbook-to-man, Mon 12 Mar 2001, 01:04