Mercurial > sdl-ios-xcode
annotate docs/html/sdlkeysym.html @ 765:4c2ba6161939
Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 04 Jan 2004 15:40:50 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_keysym</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="SDL Event Structures." | |
| 14 HREF="eventstructures.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_QuitEvent" | |
| 17 HREF="sdlquitevent.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDLKey" | |
| 20 HREF="sdlkey.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="sdlquitevent.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="sdlkey.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="SDLKEYSYM" | |
| 71 >SDL_keysym</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN4275" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_keysym -- Keysym structure</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSECT1" | |
| 83 ><A | |
|
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84 NAME="AEN4278" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Structure Definition</H2 | |
| 88 ><PRE | |
| 89 CLASS="PROGRAMLISTING" | |
| 90 >typedef struct{ | |
| 91 Uint8 scancode; | |
| 92 SDLKey sym; | |
| 93 SDLMod mod; | |
| 94 Uint16 unicode; | |
| 95 } SDL_keysym;</PRE | |
| 96 ></DIV | |
| 97 ><DIV | |
| 98 CLASS="REFSECT1" | |
| 99 ><A | |
|
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100 NAME="AEN4281" |
| 0 | 101 ></A |
| 102 ><H2 | |
| 103 >Structure Data</H2 | |
| 104 ><DIV | |
| 105 CLASS="INFORMALTABLE" | |
| 106 ><A | |
|
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107 NAME="AEN4283" |
| 0 | 108 ></A |
| 109 ><P | |
| 110 ></P | |
| 111 ><TABLE | |
| 112 BORDER="0" | |
| 113 CLASS="CALSTABLE" | |
| 114 ><TBODY | |
| 115 ><TR | |
| 116 ><TD | |
| 117 ALIGN="LEFT" | |
| 118 VALIGN="TOP" | |
| 119 ><TT | |
| 120 CLASS="STRUCTFIELD" | |
| 121 ><I | |
| 122 >scancode</I | |
| 123 ></TT | |
| 124 ></TD | |
| 125 ><TD | |
| 126 ALIGN="LEFT" | |
| 127 VALIGN="TOP" | |
| 128 >Hardware specific scancode</TD | |
| 129 ></TR | |
| 130 ><TR | |
| 131 ><TD | |
| 132 ALIGN="LEFT" | |
| 133 VALIGN="TOP" | |
| 134 ><TT | |
| 135 CLASS="STRUCTFIELD" | |
| 136 ><I | |
| 137 >sym</I | |
| 138 ></TT | |
| 139 ></TD | |
| 140 ><TD | |
| 141 ALIGN="LEFT" | |
| 142 VALIGN="TOP" | |
| 143 >SDL virtual keysym</TD | |
| 144 ></TR | |
| 145 ><TR | |
| 146 ><TD | |
| 147 ALIGN="LEFT" | |
| 148 VALIGN="TOP" | |
| 149 ><TT | |
| 150 CLASS="STRUCTFIELD" | |
| 151 ><I | |
| 152 >mod</I | |
| 153 ></TT | |
| 154 ></TD | |
| 155 ><TD | |
| 156 ALIGN="LEFT" | |
| 157 VALIGN="TOP" | |
| 158 >Current key modifiers</TD | |
| 159 ></TR | |
| 160 ><TR | |
| 161 ><TD | |
| 162 ALIGN="LEFT" | |
| 163 VALIGN="TOP" | |
| 164 ><TT | |
| 165 CLASS="STRUCTFIELD" | |
| 166 ><I | |
| 167 >unicode</I | |
| 168 ></TT | |
| 169 ></TD | |
| 170 ><TD | |
| 171 ALIGN="LEFT" | |
| 172 VALIGN="TOP" | |
| 173 >Translated character</TD | |
| 174 ></TR | |
| 175 ></TBODY | |
| 176 ></TABLE | |
| 177 ><P | |
| 178 ></P | |
| 179 ></DIV | |
| 180 ></DIV | |
| 181 ><DIV | |
| 182 CLASS="REFSECT1" | |
| 183 ><A | |
|
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184 NAME="AEN4302" |
| 0 | 185 ></A |
| 186 ><H2 | |
| 187 >Description</H2 | |
| 188 ><P | |
| 189 >The <SPAN | |
| 190 CLASS="STRUCTNAME" | |
| 191 >SDL_keysym</SPAN | |
| 192 > structure is used by reporting key presses and releases since it is a part of the <A | |
| 193 HREF="sdlkeyboardevent.html" | |
| 194 ><SPAN | |
| 195 CLASS="STRUCTNAME" | |
| 196 >SDL_KeyboardEvent</SPAN | |
| 197 ></A | |
| 198 >.</P | |
| 199 ><P | |
| 200 >The <TT | |
| 201 CLASS="STRUCTFIELD" | |
| 202 ><I | |
| 203 >scancode</I | |
| 204 ></TT | |
| 205 > field should generally be left alone, it is the hardware dependent scancode returned by the keyboard. The <TT | |
| 206 CLASS="STRUCTFIELD" | |
| 207 ><I | |
| 208 >sym</I | |
| 209 ></TT | |
| 210 > field is extremely useful. It is the SDL-defined value of the key (see <A | |
| 211 HREF="sdlkey.html" | |
| 212 >SDL Key Syms</A | |
| 213 >. This field is very useful when you are checking for certain key presses, like so: | |
| 214 <PRE | |
| 215 CLASS="PROGRAMLISTING" | |
| 216 >. | |
| 217 . | |
| 218 while(SDL_PollEvent(&event)){ | |
| 219 switch(event.type){ | |
| 220 case SDL_KEYDOWN: | |
| 221 if(event.key.keysym.sym==SDLK_LEFT) | |
| 222 move_left(); | |
| 223 break; | |
| 224 . | |
| 225 . | |
| 226 . | |
| 227 } | |
| 228 } | |
| 229 . | |
| 230 .</PRE | |
| 231 > | |
| 232 <TT | |
| 233 CLASS="STRUCTFIELD" | |
| 234 ><I | |
| 235 >mod</I | |
| 236 ></TT | |
| 237 > stores the current state of the keyboard modifiers as explained in <A | |
| 238 HREF="sdlgetmodstate.html" | |
| 239 ><TT | |
| 240 CLASS="FUNCTION" | |
| 241 >SDL_GetModState</TT | |
| 242 ></A | |
| 243 >. The <TT | |
| 244 CLASS="STRUCTFIELD" | |
| 245 ><I | |
| 246 >unicode</I | |
| 247 ></TT | |
| 248 > is only used when UNICODE translation is enabled with <A | |
| 249 HREF="sdlenableunicode.html" | |
| 250 ><TT | |
| 251 CLASS="FUNCTION" | |
| 252 >SDL_EnableUNICODE</TT | |
| 253 ></A | |
| 254 >. If <TT | |
| 255 CLASS="STRUCTFIELD" | |
| 256 ><I | |
| 257 >unicode</I | |
| 258 ></TT | |
| 259 > is non-zero then this a the UNICODE character corresponding to the keypress. If the high 9 bits of the character are 0, then this maps to the equivalent ASCII character: | |
| 260 <PRE | |
| 261 CLASS="PROGRAMLISTING" | |
| 262 >char ch; | |
| 263 if ( (keysym.unicode & 0xFF80) == 0 ) { | |
| 264 ch = keysym.unicode & 0x7F; | |
| 265 } | |
| 266 else { | |
| 267 printf("An International Character.\n"); | |
| 268 }</PRE | |
| 269 > | |
| 270 UNICODE translation does have a slight overhead so don't enable it unless its needed.</P | |
| 271 ></DIV | |
| 272 ><DIV | |
| 273 CLASS="REFSECT1" | |
| 274 ><A | |
|
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275 NAME="AEN4321" |
| 0 | 276 ></A |
| 277 ><H2 | |
| 278 >See Also</H2 | |
| 279 ><P | |
| 280 ><A | |
| 281 HREF="sdlkey.html" | |
| 282 ><SPAN | |
| 283 CLASS="STRUCTNAME" | |
| 284 >SDLKey</SPAN | |
| 285 ></A | |
| 286 ></P | |
| 287 ></DIV | |
| 288 ><DIV | |
| 289 CLASS="NAVFOOTER" | |
| 290 ><HR | |
| 291 ALIGN="LEFT" | |
| 292 WIDTH="100%"><TABLE | |
| 293 WIDTH="100%" | |
| 294 BORDER="0" | |
| 295 CELLPADDING="0" | |
| 296 CELLSPACING="0" | |
| 297 ><TR | |
| 298 ><TD | |
| 299 WIDTH="33%" | |
| 300 ALIGN="left" | |
| 301 VALIGN="top" | |
| 302 ><A | |
| 303 HREF="sdlquitevent.html" | |
| 304 >Prev</A | |
| 305 ></TD | |
| 306 ><TD | |
| 307 WIDTH="34%" | |
| 308 ALIGN="center" | |
| 309 VALIGN="top" | |
| 310 ><A | |
| 311 HREF="index.html" | |
| 312 >Home</A | |
| 313 ></TD | |
| 314 ><TD | |
| 315 WIDTH="33%" | |
| 316 ALIGN="right" | |
| 317 VALIGN="top" | |
| 318 ><A | |
| 319 HREF="sdlkey.html" | |
| 320 >Next</A | |
| 321 ></TD | |
| 322 ></TR | |
| 323 ><TR | |
| 324 ><TD | |
| 325 WIDTH="33%" | |
| 326 ALIGN="left" | |
| 327 VALIGN="top" | |
| 328 >SDL_QuitEvent</TD | |
| 329 ><TD | |
| 330 WIDTH="34%" | |
| 331 ALIGN="center" | |
| 332 VALIGN="top" | |
| 333 ><A | |
| 334 HREF="eventstructures.html" | |
| 335 >Up</A | |
| 336 ></TD | |
| 337 ><TD | |
| 338 WIDTH="33%" | |
| 339 ALIGN="right" | |
| 340 VALIGN="top" | |
| 341 >SDLKey</TD | |
| 342 ></TR | |
| 343 ></TABLE | |
| 344 ></DIV | |
| 345 ></BODY | |
| 346 ></HTML | |
| 347 > |