Mercurial > sdl-ios-xcode
annotate docs/html/sdladdtimer.html @ 4333:55717a755897 SDL-1.2
Switched from setting the period size and count to setting the buffer size directly, based on feedback from the ALSA development list:
http://mailman.alsa-project.org/pipermail/alsa-devel/2009-October/022267.html
This has the nice side effect of reducing latency on my SBLive! card.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 13 Oct 2009 09:56:15 +0000 |
| parents | 355632dca928 |
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| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_AddTimer</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 0 | 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_Delay" | |
| 17 HREF="sdldelay.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_RemoveTimer" | |
| 20 HREF="sdlremovetimer.html"></HEAD | |
| 21 ><BODY | |
| 22 CLASS="REFENTRY" | |
| 23 BGCOLOR="#FFF8DC" | |
| 24 TEXT="#000000" | |
| 25 LINK="#0000ee" | |
| 26 VLINK="#551a8b" | |
| 27 ALINK="#ff0000" | |
| 28 ><DIV | |
| 29 CLASS="NAVHEADER" | |
| 30 ><TABLE | |
|
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31 SUMMARY="Header navigation table" |
| 0 | 32 WIDTH="100%" |
| 33 BORDER="0" | |
| 34 CELLPADDING="0" | |
| 35 CELLSPACING="0" | |
| 36 ><TR | |
| 37 ><TH | |
| 38 COLSPAN="3" | |
| 39 ALIGN="center" | |
| 40 >SDL Library Documentation</TH | |
| 41 ></TR | |
| 42 ><TR | |
| 43 ><TD | |
| 44 WIDTH="10%" | |
| 45 ALIGN="left" | |
| 46 VALIGN="bottom" | |
| 47 ><A | |
| 48 HREF="sdldelay.html" | |
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49 ACCESSKEY="P" |
| 0 | 50 >Prev</A |
| 51 ></TD | |
| 52 ><TD | |
| 53 WIDTH="80%" | |
| 54 ALIGN="center" | |
| 55 VALIGN="bottom" | |
| 56 ></TD | |
| 57 ><TD | |
| 58 WIDTH="10%" | |
| 59 ALIGN="right" | |
| 60 VALIGN="bottom" | |
| 61 ><A | |
| 62 HREF="sdlremovetimer.html" | |
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63 ACCESSKEY="N" |
| 0 | 64 >Next</A |
| 65 ></TD | |
| 66 ></TR | |
| 67 ></TABLE | |
| 68 ><HR | |
| 69 ALIGN="LEFT" | |
| 70 WIDTH="100%"></DIV | |
| 71 ><H1 | |
| 72 ><A | |
| 73 NAME="SDLADDTIMER" | |
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74 ></A |
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75 >SDL_AddTimer</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN8482" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_AddTimer -- Add a timer which will call a callback after the specified number of milliseconds has | |
| 84 elapsed.</DIV | |
| 85 ><DIV | |
| 86 CLASS="REFSYNOPSISDIV" | |
| 87 ><A | |
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88 NAME="AEN8485" |
| 0 | 89 ></A |
| 90 ><H2 | |
| 91 >Synopsis</H2 | |
| 92 ><DIV | |
| 93 CLASS="FUNCSYNOPSIS" | |
| 94 ><A | |
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95 NAME="AEN8486" |
| 0 | 96 ></A |
| 97 ><P | |
| 98 ></P | |
| 99 ><PRE | |
| 100 CLASS="FUNCSYNOPSISINFO" | |
| 101 >#include "SDL.h"</PRE | |
| 102 ><P | |
| 103 ><CODE | |
| 104 ><CODE | |
| 105 CLASS="FUNCDEF" | |
| 106 >SDL_TimerID <B | |
| 107 CLASS="FSFUNC" | |
| 108 >SDL_AddTimer</B | |
| 109 ></CODE | |
| 110 >(Uint32 interval, SDL_NewTimerCallback callback, void *param);</CODE | |
| 111 ></P | |
| 112 ><P | |
| 113 ></P | |
| 114 ></DIV | |
| 115 ></DIV | |
| 116 ><DIV | |
| 117 CLASS="REFSECT1" | |
| 118 ><A | |
| 119 NAME="SDLNEWTIMERCALLBACK" | |
| 120 ></A | |
| 121 ><H2 | |
| 122 >Callback</H2 | |
| 123 ><PRE | |
| 124 CLASS="PROGRAMLISTING" | |
| 125 >/* type definition for the "new" timer callback function */ | |
| 126 typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);</PRE | |
| 127 ></DIV | |
| 128 ><DIV | |
| 129 CLASS="REFSECT1" | |
| 130 ><A | |
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131 NAME="AEN8495" |
| 0 | 132 ></A |
| 133 ><H2 | |
| 134 >Description</H2 | |
| 135 ><P | |
| 136 >Adds a callback function to be run after the specified number of | |
| 137 milliseconds has elapsed. The callback function is passed the current | |
| 138 timer interval and the user supplied parameter from the | |
| 139 <TT | |
| 140 CLASS="FUNCTION" | |
| 141 >SDL_AddTimer</TT | |
| 142 > call and returns the next timer | |
| 143 interval. If the returned value from the callback is the same as the one | |
| 144 passed in, the periodic alarm continues, otherwise a new alarm is | |
| 145 scheduled.</P | |
| 146 ><P | |
| 147 >To cancel a currently running timer call | |
| 148 <A | |
| 149 HREF="sdlremovetimer.html" | |
| 150 >SDL_RemoveTimer</A | |
| 151 > with the | |
| 152 timer ID returned from | |
| 153 <TT | |
| 154 CLASS="FUNCTION" | |
| 155 >SDL_AddTimer</TT | |
| 156 >.</P | |
| 157 ><P | |
| 158 >The timer callback function may run in a different thread than your | |
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159 main program, and so shouldn't call any functions from within itself. |
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160 You may always call <A |
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161 HREF="sdlpushevent.html" |
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162 >SDL_PushEvent</A |
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163 >, however.</P |
| 0 | 164 ><P |
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165 >The granularity of the timer is platform-dependent, but you should count |
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166 on it being at least 10 ms as this is the most common number. |
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167 This means that if |
| 0 | 168 you request a 16 ms timer, your callback will run approximately 20 ms |
| 169 later on an unloaded system. If you wanted to set a flag signaling | |
| 170 a frame update at 30 frames per second (every 33 ms), you might set a | |
| 171 timer for 30 ms (see example below). | |
| 172 | |
| 173 If you use this function, you need to pass <TT | |
| 174 CLASS="LITERAL" | |
| 175 >SDL_INIT_TIMER</TT | |
| 176 > | |
| 177 to <A | |
| 178 HREF="sdlinit.html" | |
| 179 >SDL_Init</A | |
| 180 >.</P | |
| 181 ></DIV | |
| 182 ><DIV | |
| 183 CLASS="REFSECT1" | |
| 184 ><A | |
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185 NAME="AEN8507" |
| 0 | 186 ></A |
| 187 ><H2 | |
| 188 >Return Value</H2 | |
| 189 ><P | |
| 190 >Returns an ID value for the added timer or | |
| 191 <SPAN | |
| 192 CLASS="RETURNVALUE" | |
| 193 >NULL</SPAN | |
| 194 > if there was an error.</P | |
| 195 ></DIV | |
| 196 ><DIV | |
| 197 CLASS="REFSECT1" | |
| 198 ><A | |
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199 NAME="AEN8511" |
| 0 | 200 ></A |
| 201 ><H2 | |
| 202 >Examples</H2 | |
| 203 ><P | |
| 204 ><PRE | |
| 205 CLASS="PROGRAMLISTING" | |
| 206 >my_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);</PRE | |
| 207 ></P | |
| 208 ></DIV | |
| 209 ><DIV | |
| 210 CLASS="REFSECT1" | |
| 211 ><A | |
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212 NAME="AEN8515" |
| 0 | 213 ></A |
| 214 ><H2 | |
| 215 >See Also</H2 | |
| 216 ><P | |
| 217 ><A | |
| 218 HREF="sdlremovetimer.html" | |
| 219 ><TT | |
| 220 CLASS="FUNCTION" | |
| 221 >SDL_RemoveTimer</TT | |
| 222 ></A | |
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223 >, |
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224 <A |
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225 HREF="sdlpushevent.html" |
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226 ><TT |
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227 CLASS="FUNCTION" |
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228 >SDL_PushEvent</TT |
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229 ></A |
| 0 | 230 ></P |
| 231 ></DIV | |
| 232 ><DIV | |
| 233 CLASS="NAVFOOTER" | |
| 234 ><HR | |
| 235 ALIGN="LEFT" | |
| 236 WIDTH="100%"><TABLE | |
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237 SUMMARY="Footer navigation table" |
| 0 | 238 WIDTH="100%" |
| 239 BORDER="0" | |
| 240 CELLPADDING="0" | |
| 241 CELLSPACING="0" | |
| 242 ><TR | |
| 243 ><TD | |
| 244 WIDTH="33%" | |
| 245 ALIGN="left" | |
| 246 VALIGN="top" | |
| 247 ><A | |
| 248 HREF="sdldelay.html" | |
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249 ACCESSKEY="P" |
| 0 | 250 >Prev</A |
| 251 ></TD | |
| 252 ><TD | |
| 253 WIDTH="34%" | |
| 254 ALIGN="center" | |
| 255 VALIGN="top" | |
| 256 ><A | |
| 257 HREF="index.html" | |
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258 ACCESSKEY="H" |
| 0 | 259 >Home</A |
| 260 ></TD | |
| 261 ><TD | |
| 262 WIDTH="33%" | |
| 263 ALIGN="right" | |
| 264 VALIGN="top" | |
| 265 ><A | |
| 266 HREF="sdlremovetimer.html" | |
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267 ACCESSKEY="N" |
| 0 | 268 >Next</A |
| 269 ></TD | |
| 270 ></TR | |
| 271 ><TR | |
| 272 ><TD | |
| 273 WIDTH="33%" | |
| 274 ALIGN="left" | |
| 275 VALIGN="top" | |
| 276 >SDL_Delay</TD | |
| 277 ><TD | |
| 278 WIDTH="34%" | |
| 279 ALIGN="center" | |
| 280 VALIGN="top" | |
| 281 ><A | |
| 282 HREF="time.html" | |
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283 ACCESSKEY="U" |
| 0 | 284 >Up</A |
| 285 ></TD | |
| 286 ><TD | |
| 287 WIDTH="33%" | |
| 288 ALIGN="right" | |
| 289 VALIGN="top" | |
| 290 >SDL_RemoveTimer</TD | |
| 291 ></TR | |
| 292 ></TABLE | |
| 293 ></DIV | |
| 294 ></BODY | |
| 295 ></HTML | |
| 296 > |