1 <HTML 2 ><HEAD 3 ><TITLE 4 >SDL_SetTimer</TITLE 5 ><META 6 NAME="GENERATOR" 7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ 8 "><LINK 9 REL="HOME" 10 TITLE="SDL Library Documentation" 11 HREF="index.html"><LINK 12 REL="UP" 13 TITLE="Time" 14 HREF="time.html"><LINK 15 REL="PREVIOUS" 16 TITLE="SDL_RemoveTimer" 17 HREF="sdlremovetimer.html"></HEAD 18 ><BODY 19 CLASS="REFENTRY" 20 BGCOLOR="#FFF8DC" 21 TEXT="#000000" 22 LINK="#0000ee" 23 VLINK="#551a8b" 24 ALINK="#ff0000" 25 ><DIV 26 CLASS="NAVHEADER" 27 ><TABLE 28 SUMMARY="Header navigation table" 29 WIDTH="100%" 30 BORDER="0" 31 CELLPADDING="0" 32 CELLSPACING="0" 33 ><TR 34 ><TH 35 COLSPAN="3" 36 ALIGN="center" 37 >SDL Library Documentation</TH 38 ></TR 39 ><TR 40 ><TD 41 WIDTH="10%" 42 ALIGN="left" 43 VALIGN="bottom" 44 ><A 45 HREF="sdlremovetimer.html" 46 ACCESSKEY="P" 47 >Prev</A 48 ></TD 49 ><TD 50 WIDTH="80%" 51 ALIGN="center" 52 VALIGN="bottom" 53 ></TD 54 ><TD 55 WIDTH="10%" 56 ALIGN="right" 57 VALIGN="bottom" 58 > </TD 59 ></TR 60 ></TABLE 61 ><HR 62 ALIGN="LEFT" 63 WIDTH="100%"></DIV 64 ><H1 65 ><A 66 NAME="SDLSETTIMER" 67 ></A 68 >SDL_SetTimer</H1 69 ><DIV 70 CLASS="REFNAMEDIV" 71 ><A 72 NAME="AEN8557" 73 ></A 74 ><H2 75 >Name</H2 76 >SDL_SetTimer -- Set a callback to run after the specified number of milliseconds has 77 elapsed.</DIV 78 ><DIV 79 CLASS="REFSYNOPSISDIV" 80 ><A 81 NAME="AEN8560" 82 ></A 83 ><H2 84 >Synopsis</H2 85 ><DIV 86 CLASS="FUNCSYNOPSIS" 87 ><A 88 NAME="AEN8561" 89 ></A 90 ><P 91 ></P 92 ><PRE 93 CLASS="FUNCSYNOPSISINFO" 94 >#include "SDL.h"</PRE 95 ><P 96 ><CODE 97 ><CODE 98 CLASS="FUNCDEF" 99 >int <B 100 CLASS="FSFUNC" 101 >SDL_SetTimer</B 102 ></CODE 103 >(Uint32 interval, SDL_TimerCallback callback);</CODE 104 ></P 105 ><P 106 ></P 107 ></DIV 108 ></DIV 109 ><DIV 110 CLASS="REFSECT1" 111 ><A 112 NAME="SDLTIMERCALLBACK" 113 ></A 114 ><H2 115 >Callback</H2 116 ><P 117 >/* Function prototype for the timer callback function */ 118 typedef Uint32 (*SDL_TimerCallback)(Uint32 interval);</P 119 ></DIV 120 ><DIV 121 CLASS="REFSECT1" 122 ><A 123 NAME="AEN8570" 124 ></A 125 ><H2 126 >Description</H2 127 ><P 128 >Set a callback to run after the specified number of milliseconds has 129 elapsed. The callback function is passed the current timer interval 130 and returns the next timer interval. If the returned value is the 131 same as the one passed in, the periodic alarm continues, otherwise a 132 new alarm is scheduled.</P 133 ><P 134 >To cancel a currently running timer, call 135 <TT 136 CLASS="FUNCTION" 137 >SDL_SetTimer(0, NULL);</TT 138 ></P 139 ><P 140 >The timer callback function may run in a different thread than your 141 main constant, and so shouldn't call any functions from within itself.</P 142 ><P 143 >The maximum resolution of this timer is 10 ms, which means that if 144 you request a 16 ms timer, your callback will run approximately 20 ms 145 later on an unloaded system. If you wanted to set a flag signaling 146 a frame update at 30 frames per second (every 33 ms), you might set a 147 timer for 30 ms (see example below).</P 148 ><P 149 >If you use this function, you need to pass <TT 150 CLASS="LITERAL" 151 >SDL_INIT_TIMER</TT 152 > 153 to <TT 154 CLASS="FUNCTION" 155 >SDL_Init()</TT 156 >.</P 157 ><DIV 158 CLASS="NOTE" 159 ><BLOCKQUOTE 160 CLASS="NOTE" 161 ><P 162 ><B 163 >Note: </B 164 >This function is kept for compatibility but has been superseded 165 by the new timer functions 166 <A 167 HREF="sdladdtimer.html" 168 >SDL_AddTimer</A 169 > and 170 <A 171 HREF="sdlremovetimer.html" 172 >SDL_RemoveTimer</A 173 > which support 174 multiple timers.</P 175 ></BLOCKQUOTE 176 ></DIV 177 ></DIV 178 ><DIV 179 CLASS="REFSECT1" 180 ><A 181 NAME="AEN8584" 182 ></A 183 ><H2 184 >Examples</H2 185 ><P 186 ><PRE 187 CLASS="PROGRAMLISTING" 188 >SDL_SetTimer((33/10)*10, my_callback);</PRE 189 ></P 190 ></DIV 191 ><DIV 192 CLASS="REFSECT1" 193 ><A 194 NAME="AEN8588" 195 ></A 196 ><H2 197 >See Also</H2 198 ><P 199 ><A 200 HREF="sdladdtimer.html" 201 ><TT 202 CLASS="FUNCTION" 203 >SDL_AddTimer</TT 204 ></A 205 ></P 206 ></DIV 207 ><DIV 208 CLASS="NAVFOOTER" 209 ><HR 210 ALIGN="LEFT" 211 WIDTH="100%"><TABLE 212 SUMMARY="Footer navigation table" 213 WIDTH="100%" 214 BORDER="0" 215 CELLPADDING="0" 216 CELLSPACING="0" 217 ><TR 218 ><TD 219 WIDTH="33%" 220 ALIGN="left" 221 VALIGN="top" 222 ><A 223 HREF="sdlremovetimer.html" 224 ACCESSKEY="P" 225 >Prev</A 226 ></TD 227 ><TD 228 WIDTH="34%" 229 ALIGN="center" 230 VALIGN="top" 231 ><A 232 HREF="index.html" 233 ACCESSKEY="H" 234 >Home</A 235 ></TD 236 ><TD 237 WIDTH="33%" 238 ALIGN="right" 239 VALIGN="top" 240 > </TD 241 ></TR 242 ><TR 243 ><TD 244 WIDTH="33%" 245 ALIGN="left" 246 VALIGN="top" 247 >SDL_RemoveTimer</TD 248 ><TD 249 WIDTH="34%" 250 ALIGN="center" 251 VALIGN="top" 252 ><A 253 HREF="time.html" 254 ACCESSKEY="U" 255 >Up</A 256 ></TD 257 ><TD 258 WIDTH="33%" 259 ALIGN="right" 260 VALIGN="top" 261 > </TD 262 ></TR 263 ></TABLE 264 ></DIV 265 ></BODY 266 ></HTML 267 >