Mercurial > sdl-ios-xcode
annotate docs/html/sdlgetrgba.html @ 968:4675910b0b7b
Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST)
From: Hannu Savolainen
Subject: Re: SDL uses obsolete OSS features
I did some work on getting OSS to work better with SDL. There have been
some problems with select which should be fixed now.
I'm having some problems in understanding what is the purpose of the
DSP_WaitAudio() routine. I added a return to the very beginning of this
routine and commendted out the define for USE_BLOCKING_WRITES. At least
lbreakout2 seems to work as well as earlier. The latencies are the same.
An ordinary blocking write does exactly the same thing than DSP_WaitAudio
does. So I would recommend using the USE_BLOCKING_WRITES approach and
removing everything from the DSP_WaitAudio routine. Also enabling
USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because
you don't need to handle the partial writes (the do-while loop).
Attached is a patch against SDL-1.2.7. After these changes SDL will use
OSS as it's designed to be used (make it as simple as possible). This code
should work with all OSS implementations because it uses only the very
fundamental features that have been there since the jurassic times.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Fri, 12 Nov 2004 21:39:04 +0000 |
parents | 355632dca928 |
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rev | line source |
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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 1.76b+ |
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 | |
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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="sdlgetrgb.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="sdlcreatergbsurface.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="SDLGETRGBA" | |
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74 ></A |
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75 >SDL_GetRGBA</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN1747" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_GetRGBA -- Get RGBA values from a pixel in the specified pixel format.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN1750" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN1751" |
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 >void <B | |
106 CLASS="FSFUNC" | |
107 >SDL_GetRGBA</B | |
108 ></CODE | |
109 >(Uint32 pixel, SDL_PixelFormat *fmt, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a);</CODE | |
110 ></P | |
111 ><P | |
112 ></P | |
113 ></DIV | |
114 ></DIV | |
115 ><DIV | |
116 CLASS="REFSECT1" | |
117 ><A | |
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118 NAME="AEN1757" |
0 | 119 ></A |
120 ><H2 | |
121 >Description</H2 | |
122 ><P | |
123 >Get RGBA component values from a pixel stored in the specified pixel format.</P | |
124 ><P | |
125 >This function uses the entire 8-bit [0..255] range when converting color | |
126 components from pixel formats with less than 8-bits per RGB component | |
127 (e.g., a completely white pixel in 16-bit RGB565 format would return | |
128 [0xff, 0xff, 0xff] not [0xf8, 0xfc, 0xf8]).</P | |
129 ><P | |
130 >If the surface has no alpha component, the alpha will be returned as 0xff | |
131 (100% opaque).</P | |
132 ></DIV | |
133 ><DIV | |
134 CLASS="REFSECT1" | |
135 ><A | |
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136 NAME="AEN1762" |
0 | 137 ></A |
138 ><H2 | |
139 >See Also</H2 | |
140 ><P | |
141 ><A | |
142 HREF="sdlgetrgb.html" | |
143 >SDL_GetRGB</A | |
144 >, | |
145 <A | |
146 HREF="sdlmaprgb.html" | |
147 >SDL_MapRGB</A | |
148 >, | |
149 <A | |
150 HREF="sdlmaprgba.html" | |
151 >SDL_MapRGBA</A | |
152 >, | |
153 <A | |
154 HREF="sdlpixelformat.html" | |
155 >SDL_PixelFormat</A | |
156 ></P | |
157 ></DIV | |
158 ><DIV | |
159 CLASS="NAVFOOTER" | |
160 ><HR | |
161 ALIGN="LEFT" | |
162 WIDTH="100%"><TABLE | |
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163 SUMMARY="Footer navigation table" |
0 | 164 WIDTH="100%" |
165 BORDER="0" | |
166 CELLPADDING="0" | |
167 CELLSPACING="0" | |
168 ><TR | |
169 ><TD | |
170 WIDTH="33%" | |
171 ALIGN="left" | |
172 VALIGN="top" | |
173 ><A | |
174 HREF="sdlgetrgb.html" | |
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175 ACCESSKEY="P" |
0 | 176 >Prev</A |
177 ></TD | |
178 ><TD | |
179 WIDTH="34%" | |
180 ALIGN="center" | |
181 VALIGN="top" | |
182 ><A | |
183 HREF="index.html" | |
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184 ACCESSKEY="H" |
0 | 185 >Home</A |
186 ></TD | |
187 ><TD | |
188 WIDTH="33%" | |
189 ALIGN="right" | |
190 VALIGN="top" | |
191 ><A | |
192 HREF="sdlcreatergbsurface.html" | |
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193 ACCESSKEY="N" |
0 | 194 >Next</A |
195 ></TD | |
196 ></TR | |
197 ><TR | |
198 ><TD | |
199 WIDTH="33%" | |
200 ALIGN="left" | |
201 VALIGN="top" | |
202 >SDL_GetRGB</TD | |
203 ><TD | |
204 WIDTH="34%" | |
205 ALIGN="center" | |
206 VALIGN="top" | |
207 ><A | |
208 HREF="video.html" | |
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209 ACCESSKEY="U" |
0 | 210 >Up</A |
211 ></TD | |
212 ><TD | |
213 WIDTH="33%" | |
214 ALIGN="right" | |
215 VALIGN="top" | |
216 >SDL_CreateRGBSurface</TD | |
217 ></TR | |
218 ></TABLE | |
219 ></DIV | |
220 ></BODY | |
221 ></HTML | |
222 > |