Mercurial > sdl-ios-xcode
view docs/html/sdladdtimer.html @ 1621:f12379c41042
Fixes bug #195:
The proper name of Apple's operating system is "Mac OS X" not "MacOS X", as can
bee seen in many places, for example http://www.apple.com/macosx/). This
contrasts the naming of the old operating system, which was called "MacOS" and
today is often refered to as "MacOS Classic".
The attached patches fixes the misuse of the name "MacOS X" in both the SDL12
and sdlweb CVS modules.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Thu, 13 Apr 2006 13:08:26 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_AddTimer</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Time" HREF="time.html"><LINK REL="PREVIOUS" TITLE="SDL_Delay" HREF="sdldelay.html"><LINK REL="NEXT" TITLE="SDL_RemoveTimer" HREF="sdlremovetimer.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdldelay.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlremovetimer.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLADDTIMER" ></A >SDL_AddTimer</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN8482" ></A ><H2 >Name</H2 >SDL_AddTimer -- Add a timer which will call a callback after the specified number of milliseconds has elapsed.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN8485" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN8486" ></A ><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 ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN8515" ></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 ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdldelay.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlremovetimer.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_Delay</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="time.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_RemoveTimer</TD ></TR ></TABLE ></DIV ></BODY ></HTML >