Mercurial > sdl-ios-xcode
annotate docs/html/sdlgetkeystate.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_GetKeyState</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="Event Functions." | |
| 14 HREF="eventfunctions.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_EventState" | |
| 17 HREF="sdleventstate.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_GetModState" | |
| 20 HREF="sdlgetmodstate.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="sdleventstate.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="sdlgetmodstate.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="SDLGETKEYSTATE" | |
| 71 >SDL_GetKeyState</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN5298" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_GetKeyState -- Get a snapshot of the current keyboard state</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN5301" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN5302" |
| 0 | 92 ></A |
| 93 ><P | |
| 94 ></P | |
| 95 ><PRE | |
| 96 CLASS="FUNCSYNOPSISINFO" | |
| 97 >#include "SDL.h"</PRE | |
| 98 ><P | |
| 99 ><CODE | |
| 100 ><CODE | |
| 101 CLASS="FUNCDEF" | |
| 102 >Uint8 *<B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_GetKeyState</B | |
| 105 ></CODE | |
| 106 >(int *numkeys);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN5308" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 >Gets a snapshot of the current keyboard state. The current state is return as a pointer to an array, the size of this array is stored in <TT | |
| 121 CLASS="PARAMETER" | |
| 122 ><I | |
| 123 >numkeys</I | |
| 124 ></TT | |
| 125 >. The array is indexed by the <A | |
| 126 HREF="sdlkey.html" | |
| 127 ><TT | |
| 128 CLASS="LITERAL" | |
| 129 >SDLK_*</TT | |
| 130 ></A | |
|
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131 > symbols. A value of 1 means the key is pressed and a value of 0 means its not. The pointer returned is a pointer to an internal SDL array and should not be freed by the caller.</P |
| 0 | 132 ><DIV |
| 133 CLASS="NOTE" | |
| 134 ><BLOCKQUOTE | |
| 135 CLASS="NOTE" | |
| 136 ><P | |
| 137 ><B | |
| 138 >Note: </B | |
| 139 >Use <A | |
| 140 HREF="sdlpumpevents.html" | |
| 141 ><TT | |
| 142 CLASS="FUNCTION" | |
| 143 >SDL_PumpEvents</TT | |
| 144 ></A | |
| 145 > to update the state array.</P | |
| 146 ></BLOCKQUOTE | |
| 147 ></DIV | |
| 148 ></DIV | |
| 149 ><DIV | |
| 150 CLASS="REFSECT1" | |
| 151 ><A | |
|
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152 NAME="AEN5318" |
| 0 | 153 ></A |
| 154 ><H2 | |
| 155 >Example</H2 | |
| 156 ><P | |
| 157 ><PRE | |
| 158 CLASS="PROGRAMLISTING" | |
| 159 >Uint8 *keystate = SDL_GetKeyState(NULL); | |
| 160 if ( keystate[SDLK_RETURN] ) printf("Return Key Pressed.\n");</PRE | |
| 161 ></P | |
| 162 ></DIV | |
| 163 ><DIV | |
| 164 CLASS="REFSECT1" | |
| 165 ><A | |
|
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166 NAME="AEN5322" |
| 0 | 167 ></A |
| 168 ><H2 | |
| 169 >See Also</H2 | |
| 170 ><P | |
| 171 ><A | |
| 172 HREF="sdlkey.html" | |
| 173 ><TT | |
| 174 CLASS="LITERAL" | |
| 175 >SDL Key Symbols</TT | |
| 176 ></A | |
| 177 >, | |
| 178 <A | |
| 179 HREF="sdlpumpevents.html" | |
| 180 ><TT | |
| 181 CLASS="FUNCTION" | |
| 182 >SDL_PumpEvents</TT | |
| 183 ></A | |
| 184 ></P | |
| 185 ></DIV | |
| 186 ><DIV | |
| 187 CLASS="NAVFOOTER" | |
| 188 ><HR | |
| 189 ALIGN="LEFT" | |
| 190 WIDTH="100%"><TABLE | |
| 191 WIDTH="100%" | |
| 192 BORDER="0" | |
| 193 CELLPADDING="0" | |
| 194 CELLSPACING="0" | |
| 195 ><TR | |
| 196 ><TD | |
| 197 WIDTH="33%" | |
| 198 ALIGN="left" | |
| 199 VALIGN="top" | |
| 200 ><A | |
| 201 HREF="sdleventstate.html" | |
| 202 >Prev</A | |
| 203 ></TD | |
| 204 ><TD | |
| 205 WIDTH="34%" | |
| 206 ALIGN="center" | |
| 207 VALIGN="top" | |
| 208 ><A | |
| 209 HREF="index.html" | |
| 210 >Home</A | |
| 211 ></TD | |
| 212 ><TD | |
| 213 WIDTH="33%" | |
| 214 ALIGN="right" | |
| 215 VALIGN="top" | |
| 216 ><A | |
| 217 HREF="sdlgetmodstate.html" | |
| 218 >Next</A | |
| 219 ></TD | |
| 220 ></TR | |
| 221 ><TR | |
| 222 ><TD | |
| 223 WIDTH="33%" | |
| 224 ALIGN="left" | |
| 225 VALIGN="top" | |
| 226 >SDL_EventState</TD | |
| 227 ><TD | |
| 228 WIDTH="34%" | |
| 229 ALIGN="center" | |
| 230 VALIGN="top" | |
| 231 ><A | |
| 232 HREF="eventfunctions.html" | |
| 233 >Up</A | |
| 234 ></TD | |
| 235 ><TD | |
| 236 WIDTH="33%" | |
| 237 ALIGN="right" | |
| 238 VALIGN="top" | |
| 239 >SDL_GetModState</TD | |
| 240 ></TR | |
| 241 ></TABLE | |
| 242 ></DIV | |
| 243 ></BODY | |
| 244 ></HTML | |
| 245 > |