Mercurial > sdl-ios-xcode
annotate docs/html/sdljoystickgetball.html @ 896:b56dc586a5ef
Date: Tue, 16 Mar 2004 12:40:33 +0000
From: Alan Swanson
Subject: [SDL] [PATCH] Linux joystick evdev axis count fix
The event device configuration under Linux does not check the returned
ioctl value when reading the axis information. This means extra
undefined axes are returned.
Note, in EV_HandleEvents, the default for case EV_ABS is to return any
axis information which is fine as we have already checked for all valid
absolute axes. No new axes should be returned after opening the device.
(Unless, of course, the evdev allows closing and reassigning a new
device while in use and I can't believe that happens.)
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 16 May 2004 22:48:06 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_JoystickGetBall</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="Joystick" | |
| 14 HREF="joystick.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_JoystickGetButton" | |
| 17 HREF="sdljoystickgetbutton.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_JoystickClose" | |
| 20 HREF="sdljoystickclose.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="sdljoystickgetbutton.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="sdljoystickclose.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="SDLJOYSTICKGETBALL" | |
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74 ></A |
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75 >SDL_JoystickGetBall</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN6433" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_JoystickGetBall -- Get relative trackball motion</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN6436" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN6437" |
| 0 | 95 ></A |
| 96 ><P | |
| 97 ></P | |
| 98 ><PRE | |
| 99 CLASS="FUNCSYNOPSISINFO" | |
| 100 >#include "SDL.h"</PRE | |
| 101 ><P | |
| 102 ><CODE | |
| 103 ><CODE | |
| 104 CLASS="FUNCDEF" | |
| 105 >int <B | |
| 106 CLASS="FSFUNC" | |
| 107 >SDL_JoystickGetBall</B | |
| 108 ></CODE | |
| 109 >(SDL_Joystick *joystick, int ball, int *dx, int *dy);</CODE | |
| 110 ></P | |
| 111 ><P | |
| 112 ></P | |
| 113 ></DIV | |
| 114 ></DIV | |
| 115 ><DIV | |
| 116 CLASS="REFSECT1" | |
| 117 ><A | |
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118 NAME="AEN6443" |
| 0 | 119 ></A |
| 120 ><H2 | |
| 121 >Description</H2 | |
| 122 ><P | |
| 123 >Get the <TT | |
| 124 CLASS="PARAMETER" | |
| 125 ><I | |
| 126 >ball</I | |
| 127 ></TT | |
| 128 > axis change.</P | |
| 129 ><P | |
| 130 >Trackballs can only return relative motion since the last call to <TT | |
| 131 CLASS="FUNCTION" | |
| 132 >SDL_JoystickGetBall</TT | |
| 133 >, these motion deltas a placed into <TT | |
| 134 CLASS="PARAMETER" | |
| 135 ><I | |
| 136 >dx</I | |
| 137 ></TT | |
| 138 > and <TT | |
| 139 CLASS="PARAMETER" | |
| 140 ><I | |
| 141 >dy</I | |
| 142 ></TT | |
| 143 >.</P | |
| 144 ></DIV | |
| 145 ><DIV | |
| 146 CLASS="REFSECT1" | |
| 147 ><A | |
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148 NAME="AEN6451" |
| 0 | 149 ></A |
| 150 ><H2 | |
| 151 >Return Value</H2 | |
| 152 ><P | |
| 153 >Returns <SPAN | |
| 154 CLASS="RETURNVALUE" | |
| 155 >0</SPAN | |
| 156 > on success or <SPAN | |
| 157 CLASS="RETURNVALUE" | |
| 158 >-1</SPAN | |
| 159 > on failure</P | |
| 160 ></DIV | |
| 161 ><DIV | |
| 162 CLASS="REFSECT1" | |
| 163 ><A | |
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164 NAME="AEN6456" |
| 0 | 165 ></A |
| 166 ><H2 | |
| 167 >Examples</H2 | |
| 168 ><P | |
| 169 ><PRE | |
| 170 CLASS="PROGRAMLISTING" | |
| 171 >int delta_x, delta_y; | |
| 172 SDL_Joystick *joy; | |
| 173 . | |
| 174 . | |
| 175 . | |
| 176 SDL_JoystickUpdate(); | |
| 177 if(SDL_JoystickGetBall(joy, 0, &delta_x, &delta_y)==-1) | |
| 178 printf("TrackBall Read Error!\n"); | |
| 179 printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);</PRE | |
| 180 ></P | |
| 181 ></DIV | |
| 182 ><DIV | |
| 183 CLASS="REFSECT1" | |
| 184 ><A | |
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185 NAME="AEN6460" |
| 0 | 186 ></A |
| 187 ><H2 | |
| 188 >See Also</H2 | |
| 189 ><P | |
| 190 ><A | |
| 191 HREF="sdljoysticknumballs.html" | |
| 192 ><TT | |
| 193 CLASS="FUNCTION" | |
| 194 >SDL_JoystickNumBalls</TT | |
| 195 ></A | |
| 196 ></P | |
| 197 ></DIV | |
| 198 ><DIV | |
| 199 CLASS="NAVFOOTER" | |
| 200 ><HR | |
| 201 ALIGN="LEFT" | |
| 202 WIDTH="100%"><TABLE | |
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203 SUMMARY="Footer navigation table" |
| 0 | 204 WIDTH="100%" |
| 205 BORDER="0" | |
| 206 CELLPADDING="0" | |
| 207 CELLSPACING="0" | |
| 208 ><TR | |
| 209 ><TD | |
| 210 WIDTH="33%" | |
| 211 ALIGN="left" | |
| 212 VALIGN="top" | |
| 213 ><A | |
| 214 HREF="sdljoystickgetbutton.html" | |
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215 ACCESSKEY="P" |
| 0 | 216 >Prev</A |
| 217 ></TD | |
| 218 ><TD | |
| 219 WIDTH="34%" | |
| 220 ALIGN="center" | |
| 221 VALIGN="top" | |
| 222 ><A | |
| 223 HREF="index.html" | |
|
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224 ACCESSKEY="H" |
| 0 | 225 >Home</A |
| 226 ></TD | |
| 227 ><TD | |
| 228 WIDTH="33%" | |
| 229 ALIGN="right" | |
| 230 VALIGN="top" | |
| 231 ><A | |
| 232 HREF="sdljoystickclose.html" | |
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233 ACCESSKEY="N" |
| 0 | 234 >Next</A |
| 235 ></TD | |
| 236 ></TR | |
| 237 ><TR | |
| 238 ><TD | |
| 239 WIDTH="33%" | |
| 240 ALIGN="left" | |
| 241 VALIGN="top" | |
| 242 >SDL_JoystickGetButton</TD | |
| 243 ><TD | |
| 244 WIDTH="34%" | |
| 245 ALIGN="center" | |
| 246 VALIGN="top" | |
| 247 ><A | |
| 248 HREF="joystick.html" | |
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249 ACCESSKEY="U" |
| 0 | 250 >Up</A |
| 251 ></TD | |
| 252 ><TD | |
| 253 WIDTH="33%" | |
| 254 ALIGN="right" | |
| 255 VALIGN="top" | |
| 256 >SDL_JoystickClose</TD | |
| 257 ></TR | |
| 258 ></TABLE | |
| 259 ></DIV | |
| 260 ></BODY | |
| 261 ></HTML | |
| 262 > |