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view docs/man3/SDL_AddTimer.3 @ 1180:bdcb8bb4c831
From: Tyler Montbriand <tsm@accesscomm.ca>
To: sdl@libsdl.org
Date: Fri, 30 Sep 2005 02:24:50 -0600
Subject: [SDL] WinCE timers, continued
Here's a strange timer for Windows CE that doesn't ignore time across
suspends. It uses GetSystemTime to keep the time continuous, and GetTicks to
get finer-grained readings than 1 second. It detects the difference between
the GetTicks time and GetSystemTime time on power-on to keep the error within
one second max.
It's not a patch on the current win32 timer code -- took one look at that and
figured it had more than enough #ifdefs already. It's windows-ce specific.
Another thing I've noticed is that the Windows CE 4.0 and newer API has
functions warn processes about suspends. This is something SDL REALLY needs
for audio in particular, because turning it off while it's playing causes
anything that uses audio to hardlock the system on power-on. Unfortunately I
don't have 4.0 to play with. :(
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Tue, 22 Nov 2005 07:10:07 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_AddTimer" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_AddTimer\- Add a timer which will call a callback after the specified number of milliseconds has elapsed\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_TimerID \fBSDL_AddTimer\fP\fR(\fBUint32 interval, SDL_NewTimerCallback callback, void *param\fR); .SH "CALLBACK" .PP .nf \f(CW/* type definition for the "new" timer callback function */ typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);\fR .fi .PP .SH "DESCRIPTION" .PP 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\&. .PP To cancel a currently running timer call \fISDL_RemoveTimer\fR with the timer ID returned from \fBSDL_AddTimer\fP\&. .PP 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\&. .PP 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\&. .SH "RETURN VALUE" .PP Returns an ID value for the added timer or \fBNULL\fR if there was an error\&. .SH "EXAMPLES" .PP .PP .nf \f(CWmy_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_RemoveTimer\fP\fR, \fI\fBSDL_PushEvent\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01