Mercurial > sdl-ios-xcode
annotate docs/html/sdlgetrgba.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_GetRGBA</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_GetRGB" | |
| 17 HREF="sdlgetrgb.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_CreateRGBSurface" | |
| 20 HREF="sdlcreatergbsurface.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="sdlgetrgb.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="sdlcreatergbsurface.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="SDLGETRGBA" | |
| 71 >SDL_GetRGBA</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN1363" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_GetRGBA -- Get RGBA values from a pixel in the specified pixel format.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN1366" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN1367" |
| 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 >void <B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_GetRGBA</B | |
| 105 ></CODE | |
| 106 >(Uint32 pixel, 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="AEN1373" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 >Get RGBA component values from a pixel stored in the specified pixel format.</P | |
| 121 ><P | |
| 122 >This function uses the entire 8-bit [0..255] range when converting color | |
| 123 components from pixel formats with less than 8-bits per RGB component | |
| 124 (e.g., a completely white pixel in 16-bit RGB565 format would return | |
| 125 [0xff, 0xff, 0xff] not [0xf8, 0xfc, 0xf8]).</P | |
| 126 ><P | |
| 127 >If the surface has no alpha component, the alpha will be returned as 0xff | |
| 128 (100% opaque).</P | |
| 129 ></DIV | |
| 130 ><DIV | |
| 131 CLASS="REFSECT1" | |
| 132 ><A | |
|
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133 NAME="AEN1378" |
| 0 | 134 ></A |
| 135 ><H2 | |
| 136 >See Also</H2 | |
| 137 ><P | |
| 138 ><A | |
| 139 HREF="sdlgetrgb.html" | |
| 140 >SDL_GetRGB</A | |
| 141 >, | |
| 142 <A | |
| 143 HREF="sdlmaprgb.html" | |
| 144 >SDL_MapRGB</A | |
| 145 >, | |
| 146 <A | |
| 147 HREF="sdlmaprgba.html" | |
| 148 >SDL_MapRGBA</A | |
| 149 >, | |
| 150 <A | |
| 151 HREF="sdlpixelformat.html" | |
| 152 >SDL_PixelFormat</A | |
| 153 ></P | |
| 154 ></DIV | |
| 155 ><DIV | |
| 156 CLASS="NAVFOOTER" | |
| 157 ><HR | |
| 158 ALIGN="LEFT" | |
| 159 WIDTH="100%"><TABLE | |
| 160 WIDTH="100%" | |
| 161 BORDER="0" | |
| 162 CELLPADDING="0" | |
| 163 CELLSPACING="0" | |
| 164 ><TR | |
| 165 ><TD | |
| 166 WIDTH="33%" | |
| 167 ALIGN="left" | |
| 168 VALIGN="top" | |
| 169 ><A | |
| 170 HREF="sdlgetrgb.html" | |
| 171 >Prev</A | |
| 172 ></TD | |
| 173 ><TD | |
| 174 WIDTH="34%" | |
| 175 ALIGN="center" | |
| 176 VALIGN="top" | |
| 177 ><A | |
| 178 HREF="index.html" | |
| 179 >Home</A | |
| 180 ></TD | |
| 181 ><TD | |
| 182 WIDTH="33%" | |
| 183 ALIGN="right" | |
| 184 VALIGN="top" | |
| 185 ><A | |
| 186 HREF="sdlcreatergbsurface.html" | |
| 187 >Next</A | |
| 188 ></TD | |
| 189 ></TR | |
| 190 ><TR | |
| 191 ><TD | |
| 192 WIDTH="33%" | |
| 193 ALIGN="left" | |
| 194 VALIGN="top" | |
| 195 >SDL_GetRGB</TD | |
| 196 ><TD | |
| 197 WIDTH="34%" | |
| 198 ALIGN="center" | |
| 199 VALIGN="top" | |
| 200 ><A | |
| 201 HREF="video.html" | |
| 202 >Up</A | |
| 203 ></TD | |
| 204 ><TD | |
| 205 WIDTH="33%" | |
| 206 ALIGN="right" | |
| 207 VALIGN="top" | |
| 208 >SDL_CreateRGBSurface</TD | |
| 209 ></TR | |
| 210 ></TABLE | |
| 211 ></DIV | |
| 212 ></BODY | |
| 213 ></HTML | |
| 214 > |