Mercurial > sdl-ios-xcode
annotate docs/html/sdlmaprgba.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_MapRGBA</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="Video" | |
| 14 HREF="video.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_MapRGB" | |
| 17 HREF="sdlmaprgb.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_GetRGB" | |
| 20 HREF="sdlgetrgb.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="sdlmaprgb.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="sdlgetrgb.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="SDLMAPRGBA" | |
| 71 >SDL_MapRGBA</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN1303" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_MapRGBA -- Map a RGBA color value to a pixel format.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN1306" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN1307" |
| 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 >Uint32 <B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_MapRGBA</B | |
| 105 ></CODE | |
| 106 >(SDL_PixelFormat *fmt, Uint8 r, Uint8 g, Uint8 b, Uint8 a);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN1313" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 >Maps the RGBA color value to the specified pixel format and returns the | |
| 121 pixel value as a 32-bit int.</P | |
| 122 ><P | |
| 123 >If the format has a palette (8-bit) the index of the closest matching | |
| 124 color in the palette will be returned.</P | |
| 125 ><P | |
| 126 >If the specified pixel format has no alpha component the alpha value | |
| 127 will be ignored (as it will be in formats with a palette).</P | |
| 128 ></DIV | |
| 129 ><DIV | |
| 130 CLASS="REFSECT1" | |
| 131 ><A | |
|
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132 NAME="AEN1318" |
| 0 | 133 ></A |
| 134 ><H2 | |
| 135 >Return Value</H2 | |
| 136 ><P | |
| 137 >A pixel value best approximating the given RGBA color value for a given | |
| 138 pixel format. If the pixel format bpp (color depth) is less than 32-bpp | |
| 139 then the unused upper bits of the return value can safely be ignored | |
| 140 (e.g., with a 16-bpp format the return value can be assigned to a | |
| 141 <SPAN | |
| 142 CLASS="TYPE" | |
| 143 >Uint16</SPAN | |
| 144 >, and similarly a <SPAN | |
| 145 CLASS="TYPE" | |
| 146 >Uint8</SPAN | |
| 147 > for an 8-bpp | |
| 148 format).</P | |
| 149 ></DIV | |
| 150 ><DIV | |
| 151 CLASS="REFSECT1" | |
| 152 ><A | |
|
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153 NAME="AEN1323" |
| 0 | 154 ></A |
| 155 ><H2 | |
| 156 >See Also</H2 | |
| 157 ><P | |
| 158 ><A | |
| 159 HREF="sdlgetrgb.html" | |
| 160 >SDL_GetRGB</A | |
| 161 >, | |
| 162 <A | |
| 163 HREF="sdlgetrgba.html" | |
| 164 >SDL_GetRGBA</A | |
| 165 >, | |
| 166 <A | |
| 167 HREF="sdlmaprgb.html" | |
| 168 >SDL_MapRGB</A | |
| 169 >, | |
| 170 <A | |
| 171 HREF="sdlpixelformat.html" | |
| 172 >SDL_PixelFormat</A | |
| 173 ></P | |
| 174 ></DIV | |
| 175 ><DIV | |
| 176 CLASS="NAVFOOTER" | |
| 177 ><HR | |
| 178 ALIGN="LEFT" | |
| 179 WIDTH="100%"><TABLE | |
| 180 WIDTH="100%" | |
| 181 BORDER="0" | |
| 182 CELLPADDING="0" | |
| 183 CELLSPACING="0" | |
| 184 ><TR | |
| 185 ><TD | |
| 186 WIDTH="33%" | |
| 187 ALIGN="left" | |
| 188 VALIGN="top" | |
| 189 ><A | |
| 190 HREF="sdlmaprgb.html" | |
| 191 >Prev</A | |
| 192 ></TD | |
| 193 ><TD | |
| 194 WIDTH="34%" | |
| 195 ALIGN="center" | |
| 196 VALIGN="top" | |
| 197 ><A | |
| 198 HREF="index.html" | |
| 199 >Home</A | |
| 200 ></TD | |
| 201 ><TD | |
| 202 WIDTH="33%" | |
| 203 ALIGN="right" | |
| 204 VALIGN="top" | |
| 205 ><A | |
| 206 HREF="sdlgetrgb.html" | |
| 207 >Next</A | |
| 208 ></TD | |
| 209 ></TR | |
| 210 ><TR | |
| 211 ><TD | |
| 212 WIDTH="33%" | |
| 213 ALIGN="left" | |
| 214 VALIGN="top" | |
| 215 >SDL_MapRGB</TD | |
| 216 ><TD | |
| 217 WIDTH="34%" | |
| 218 ALIGN="center" | |
| 219 VALIGN="top" | |
| 220 ><A | |
| 221 HREF="video.html" | |
| 222 >Up</A | |
| 223 ></TD | |
| 224 ><TD | |
| 225 WIDTH="33%" | |
| 226 ALIGN="right" | |
| 227 VALIGN="top" | |
| 228 >SDL_GetRGB</TD | |
| 229 ></TR | |
| 230 ></TABLE | |
| 231 ></DIV | |
| 232 ></BODY | |
| 233 ></HTML | |
| 234 > |