Mercurial > sdl-ios-xcode
annotate docs/html/sdladdtimer.html @ 548:6cd49f896c5a
Open ALSA devices in non-blocking mode (thanks Aleksey!)
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 17 Nov 2002 20:02:26 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| 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 1.64 |
| 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 | |
| 31 WIDTH="100%" | |
| 32 BORDER="0" | |
| 33 CELLPADDING="0" | |
| 34 CELLSPACING="0" | |
| 35 ><TR | |
| 36 ><TH | |
| 37 COLSPAN="3" | |
| 38 ALIGN="center" | |
| 39 >SDL Library Documentation</TH | |
| 40 ></TR | |
| 41 ><TR | |
| 42 ><TD | |
| 43 WIDTH="10%" | |
| 44 ALIGN="left" | |
| 45 VALIGN="bottom" | |
| 46 ><A | |
| 47 HREF="sdldelay.html" | |
| 48 >Prev</A | |
| 49 ></TD | |
| 50 ><TD | |
| 51 WIDTH="80%" | |
| 52 ALIGN="center" | |
| 53 VALIGN="bottom" | |
| 54 ></TD | |
| 55 ><TD | |
| 56 WIDTH="10%" | |
| 57 ALIGN="right" | |
| 58 VALIGN="bottom" | |
| 59 ><A | |
| 60 HREF="sdlremovetimer.html" | |
| 61 >Next</A | |
| 62 ></TD | |
| 63 ></TR | |
| 64 ></TABLE | |
| 65 ><HR | |
| 66 ALIGN="LEFT" | |
| 67 WIDTH="100%"></DIV | |
| 68 ><H1 | |
| 69 ><A | |
| 70 NAME="SDLADDTIMER" | |
| 71 >SDL_AddTimer</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
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76 NAME="AEN8094" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_AddTimer -- Add a timer which will call a callback after the specified number of milliseconds has | |
| 81 elapsed.</DIV | |
| 82 ><DIV | |
| 83 CLASS="REFSYNOPSISDIV" | |
| 84 ><A | |
|
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85 NAME="AEN8097" |
| 0 | 86 ></A |
| 87 ><H2 | |
| 88 >Synopsis</H2 | |
| 89 ><DIV | |
| 90 CLASS="FUNCSYNOPSIS" | |
| 91 ><A | |
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92 NAME="AEN8098" |
| 0 | 93 ></A |
| 94 ><P | |
| 95 ></P | |
| 96 ><PRE | |
| 97 CLASS="FUNCSYNOPSISINFO" | |
| 98 >#include "SDL.h"</PRE | |
| 99 ><P | |
| 100 ><CODE | |
| 101 ><CODE | |
| 102 CLASS="FUNCDEF" | |
| 103 >SDL_TimerID <B | |
| 104 CLASS="FSFUNC" | |
| 105 >SDL_AddTimer</B | |
| 106 ></CODE | |
| 107 >(Uint32 interval, SDL_NewTimerCallback callback, void *param);</CODE | |
| 108 ></P | |
| 109 ><P | |
| 110 ></P | |
| 111 ></DIV | |
| 112 ></DIV | |
| 113 ><DIV | |
| 114 CLASS="REFSECT1" | |
| 115 ><A | |
| 116 NAME="SDLNEWTIMERCALLBACK" | |
| 117 ></A | |
| 118 ><H2 | |
| 119 >Callback</H2 | |
| 120 ><PRE | |
| 121 CLASS="PROGRAMLISTING" | |
| 122 >/* type definition for the "new" timer callback function */ | |
| 123 typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);</PRE | |
| 124 ></DIV | |
| 125 ><DIV | |
| 126 CLASS="REFSECT1" | |
| 127 ><A | |
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128 NAME="AEN8107" |
| 0 | 129 ></A |
| 130 ><H2 | |
| 131 >Description</H2 | |
| 132 ><P | |
| 133 >Adds a callback function to be run after the specified number of | |
| 134 milliseconds has elapsed. The callback function is passed the current | |
| 135 timer interval and the user supplied parameter from the | |
| 136 <TT | |
| 137 CLASS="FUNCTION" | |
| 138 >SDL_AddTimer</TT | |
| 139 > call and returns the next timer | |
| 140 interval. If the returned value from the callback is the same as the one | |
| 141 passed in, the periodic alarm continues, otherwise a new alarm is | |
| 142 scheduled.</P | |
| 143 ><P | |
| 144 >To cancel a currently running timer call | |
| 145 <A | |
| 146 HREF="sdlremovetimer.html" | |
| 147 >SDL_RemoveTimer</A | |
| 148 > with the | |
| 149 timer ID returned from | |
| 150 <TT | |
| 151 CLASS="FUNCTION" | |
| 152 >SDL_AddTimer</TT | |
| 153 >.</P | |
| 154 ><P | |
| 155 >The timer callback function may run in a different thread than your | |
|
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156 main program, and so shouldn't call any functions from within itself. |
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157 You may always call <A |
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158 HREF="sdlpushevent.html" |
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159 >SDL_PushEvent</A |
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160 >, however.</P |
| 0 | 161 ><P |
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162 >The granularity of the timer is platform-dependent, but you should count |
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163 on it being at least 10 ms as this is the most common number. |
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164 This means that if |
| 0 | 165 you request a 16 ms timer, your callback will run approximately 20 ms |
| 166 later on an unloaded system. If you wanted to set a flag signaling | |
| 167 a frame update at 30 frames per second (every 33 ms), you might set a | |
| 168 timer for 30 ms (see example below). | |
| 169 | |
| 170 If you use this function, you need to pass <TT | |
| 171 CLASS="LITERAL" | |
| 172 >SDL_INIT_TIMER</TT | |
| 173 > | |
| 174 to <A | |
| 175 HREF="sdlinit.html" | |
| 176 >SDL_Init</A | |
| 177 >.</P | |
| 178 ></DIV | |
| 179 ><DIV | |
| 180 CLASS="REFSECT1" | |
| 181 ><A | |
|
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182 NAME="AEN8119" |
| 0 | 183 ></A |
| 184 ><H2 | |
| 185 >Return Value</H2 | |
| 186 ><P | |
| 187 >Returns an ID value for the added timer or | |
| 188 <SPAN | |
| 189 CLASS="RETURNVALUE" | |
| 190 >NULL</SPAN | |
| 191 > if there was an error.</P | |
| 192 ></DIV | |
| 193 ><DIV | |
| 194 CLASS="REFSECT1" | |
| 195 ><A | |
|
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196 NAME="AEN8123" |
| 0 | 197 ></A |
| 198 ><H2 | |
| 199 >Examples</H2 | |
| 200 ><P | |
| 201 ><PRE | |
| 202 CLASS="PROGRAMLISTING" | |
| 203 >my_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);</PRE | |
| 204 ></P | |
| 205 ></DIV | |
| 206 ><DIV | |
| 207 CLASS="REFSECT1" | |
| 208 ><A | |
|
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209 NAME="AEN8127" |
| 0 | 210 ></A |
| 211 ><H2 | |
| 212 >See Also</H2 | |
| 213 ><P | |
| 214 ><A | |
| 215 HREF="sdlremovetimer.html" | |
| 216 ><TT | |
| 217 CLASS="FUNCTION" | |
| 218 >SDL_RemoveTimer</TT | |
| 219 ></A | |
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220 >, |
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221 <A |
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222 HREF="sdlpushevent.html" |
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223 ><TT |
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224 CLASS="FUNCTION" |
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225 >SDL_PushEvent</TT |
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226 ></A |
| 0 | 227 ></P |
| 228 ></DIV | |
| 229 ><DIV | |
| 230 CLASS="NAVFOOTER" | |
| 231 ><HR | |
| 232 ALIGN="LEFT" | |
| 233 WIDTH="100%"><TABLE | |
| 234 WIDTH="100%" | |
| 235 BORDER="0" | |
| 236 CELLPADDING="0" | |
| 237 CELLSPACING="0" | |
| 238 ><TR | |
| 239 ><TD | |
| 240 WIDTH="33%" | |
| 241 ALIGN="left" | |
| 242 VALIGN="top" | |
| 243 ><A | |
| 244 HREF="sdldelay.html" | |
| 245 >Prev</A | |
| 246 ></TD | |
| 247 ><TD | |
| 248 WIDTH="34%" | |
| 249 ALIGN="center" | |
| 250 VALIGN="top" | |
| 251 ><A | |
| 252 HREF="index.html" | |
| 253 >Home</A | |
| 254 ></TD | |
| 255 ><TD | |
| 256 WIDTH="33%" | |
| 257 ALIGN="right" | |
| 258 VALIGN="top" | |
| 259 ><A | |
| 260 HREF="sdlremovetimer.html" | |
| 261 >Next</A | |
| 262 ></TD | |
| 263 ></TR | |
| 264 ><TR | |
| 265 ><TD | |
| 266 WIDTH="33%" | |
| 267 ALIGN="left" | |
| 268 VALIGN="top" | |
| 269 >SDL_Delay</TD | |
| 270 ><TD | |
| 271 WIDTH="34%" | |
| 272 ALIGN="center" | |
| 273 VALIGN="top" | |
| 274 ><A | |
| 275 HREF="time.html" | |
| 276 >Up</A | |
| 277 ></TD | |
| 278 ><TD | |
| 279 WIDTH="33%" | |
| 280 ALIGN="right" | |
| 281 VALIGN="top" | |
| 282 >SDL_RemoveTimer</TD | |
| 283 ></TR | |
| 284 ></TABLE | |
| 285 ></DIV | |
| 286 ></BODY | |
| 287 ></HTML | |
| 288 > |