Mercurial > sdl-ios-xcode
annotate docs/html/sdladdtimer.html @ 1157:baf35853ad54
Date: Mon, 10 Oct 2005 13:09:32 +0300
From: Tommi Kyntola <tommi.kyntola@ray.fi>
To: sdl@libsdl.org
Subject: [SDL] [RFC] get_ticks broken on linux
It uses gettimeofday to calculate the timedifference.
Gettimeofday returns current time which is seldom monotonous.
This breaks SDL timer subsystem. (time callbacks and all that
get borked when the time difference ms is suddenly ~ 2^32)
I posted a message about this earlier but got no response.
Some thoughts on this matter would be appreciated.
(Or even an explanation for the lack of interest.)
A patch below would use the posix timers that have been around
since posix 93 and do provide a good source of monotonous time
on linux boxes (and on few others too).
The following patch is also availabe at:
http://www.hut.fi/u/tkyntola/SDL-1.2.9-clockfix.patch
It's against 1.2.9, but I can easily rediffit against
the cvs branch is needed.
cheers,
Tommi Kyntola tommi.kyntola@ray.fi
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Tue, 11 Oct 2005 18:16:12 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_AddTimer</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
74 ></A |
|
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
75 >SDL_AddTimer</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
88 NAME="AEN8485" |
| 0 | 89 ></A |
| 90 ><H2 | |
| 91 >Synopsis</H2 | |
| 92 ><DIV | |
| 93 CLASS="FUNCSYNOPSIS" | |
| 94 ><A | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
159 main program, and so shouldn't call any functions from within itself. |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
160 You may always call <A |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
161 HREF="sdlpushevent.html" |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
162 >SDL_PushEvent</A |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
163 >, however.</P |
| 0 | 164 ><P |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
165 >The granularity of the timer is platform-dependent, but you should count |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
166 on it being at least 10 ms as this is the most common number. |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 | |
|
55
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
223 >, |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
224 <A |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
225 HREF="sdlpushevent.html" |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
226 ><TT |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
227 CLASS="FUNCTION" |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
228 >SDL_PushEvent</TT |
|
55f1f1b3e27d
Added new docs for SDL 1.2.1
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
229 ></A |
| 0 | 230 ></P |
| 231 ></DIV | |
| 232 ><DIV | |
| 233 CLASS="NAVFOOTER" | |
| 234 ><HR | |
| 235 ALIGN="LEFT" | |
| 236 WIDTH="100%"><TABLE | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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" | |
|
803
355632dca928
Updated SDL HTML documentation
Sam Lantinga <slouken@libsdl.org>
parents:
181
diff
changeset
|
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 > |