view docs/html/sdladdtimer.html @ 4215:d83830711a5b SDL-1.2

Fixed bug #615 Scott McCreary 2008-08-21 10:48:14 PDT This patch adds support for Haiku. http://ports.haiku-files.org/browser/haikuports/trunk/media-libs/libsdl/SDL-1.2.13-haiku.diff Haiku is an open-source recreation of BeOS. It has better POSIX compliance than beOS did, and other improved features, which in some cases causes us to have to "undo" previous BeOS workarounds. Here's our port log entry for it, showing the steps to force the changes into configure and Makefile: http://ports.haiku-files.org/wiki/media-libs/libsdl/1.2.13/1 Note that this was only tried on 1.2.13 stable so far. Haiku is using a newer config.guess / config.sub that doesn't yet seem to be in the released libtool, so we are having to copy it in for now. http://haiku-files.org/files/optional-packages/
author Sam Lantinga <slouken@libsdl.org>
date Mon, 21 Sep 2009 09:18:42 +0000
parents 355632dca928
children
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><H1
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>SDL_AddTimer</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8482"
></A
><H2
>Name</H2
>SDL_AddTimer&nbsp;--&nbsp;Add a timer which will call a callback after the specified number of milliseconds has
elapsed.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
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NAME="AEN8485"
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><H2
>Synopsis</H2
><DIV
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><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_TimerID <B
CLASS="FSFUNC"
>SDL_AddTimer</B
></CODE
>(Uint32 interval, SDL_NewTimerCallback callback, void *param);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SDLNEWTIMERCALLBACK"
></A
><H2
>Callback</H2
><PRE
CLASS="PROGRAMLISTING"
>/* type definition for the "new" timer callback function */
typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8495"
></A
><H2
>Description</H2
><P
>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
<TT
CLASS="FUNCTION"
>SDL_AddTimer</TT
> 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.</P
><P
>To cancel a currently running timer call
<A
HREF="sdlremovetimer.html"
>SDL_RemoveTimer</A
> with the
timer ID returned from
<TT
CLASS="FUNCTION"
>SDL_AddTimer</TT
>.</P
><P
>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 <A
HREF="sdlpushevent.html"
>SDL_PushEvent</A
>, however.</P
><P
>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 <TT
CLASS="LITERAL"
>SDL_INIT_TIMER</TT
>
to <A
HREF="sdlinit.html"
>SDL_Init</A
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8507"
></A
><H2
>Return Value</H2
><P
>Returns an ID value for the added timer or
<SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
> if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8511"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>my_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);</PRE
></P
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><A
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></A
><H2
>See Also</H2
><P
><A
HREF="sdlremovetimer.html"
><TT
CLASS="FUNCTION"
>SDL_RemoveTimer</TT
></A
>,
<A
HREF="sdlpushevent.html"
><TT
CLASS="FUNCTION"
>SDL_PushEvent</TT
></A
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