Mercurial > sdl-ios-xcode
annotate docs/html/sdldisplayformatalpha.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 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_DisplayFormatAlpha</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_DisplayFormat" | |
17 HREF="sdldisplayformat.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_WarpMouse" | |
20 HREF="sdlwarpmouse.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="sdldisplayformat.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="sdlwarpmouse.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="SDLDISPLAYFORMATALPHA" | |
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74 ></A |
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75 >SDL_DisplayFormatAlpha</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN2432" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_DisplayFormatAlpha -- Convert a surface to the display format</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN2435" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN2436" |
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 >SDL_Surface *<B | |
106 CLASS="FSFUNC" | |
107 >SDL_DisplayFormatAlpha</B | |
108 ></CODE | |
109 >(SDL_Surface *surface);</CODE | |
110 ></P | |
111 ><P | |
112 ></P | |
113 ></DIV | |
114 ></DIV | |
115 ><DIV | |
116 CLASS="REFSECT1" | |
117 ><A | |
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118 NAME="AEN2442" |
0 | 119 ></A |
120 ><H2 | |
121 >Description</H2 | |
122 ><P | |
123 >This function takes a surface and copies it to a new surface of the | |
124 pixel format and colors of the video framebuffer plus an alpha channel, | |
125 suitable for fast blitting onto the display surface. It calls | |
126 <A | |
127 HREF="sdlconvertsurface.html" | |
128 >SDL_ConvertSurface</A | |
129 ></P | |
130 ><P | |
131 >If you want to take advantage of hardware colorkey or alpha blit | |
132 acceleration, you should set the colorkey and alpha value before | |
133 calling this function.</P | |
55
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134 ><P |
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135 >This function can be used to convert a colourkey to an alpha channel, |
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136 if the <TT |
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137 CLASS="LITERAL" |
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138 >SDL_SRCCOLORKEY</TT |
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139 > flag is set on the surface. |
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140 The generated surface will then be transparent (alpha=0) where the |
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141 pixels match the colourkey, and opaque (alpha=255) elsewhere.</P |
0 | 142 ></DIV |
143 ><DIV | |
144 CLASS="REFSECT1" | |
145 ><A | |
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146 NAME="AEN2449" |
0 | 147 ></A |
148 ><H2 | |
149 >Return Value</H2 | |
150 ><P | |
151 >If the conversion fails or runs out of memory, it returns | |
152 <SPAN | |
153 CLASS="RETURNVALUE" | |
154 >NULL</SPAN | |
155 ></P | |
156 ></DIV | |
157 ><DIV | |
158 CLASS="REFSECT1" | |
159 ><A | |
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160 NAME="AEN2453" |
0 | 161 ></A |
162 ><H2 | |
163 >See Also</H2 | |
164 ><P | |
165 ><A | |
166 HREF="sdlconvertsurface.html" | |
167 >SDL_ConvertSurface</A | |
168 >, | |
169 <A | |
170 HREF="sdlsetalpha.html" | |
171 >SDL_SetAlpha</A | |
172 >, | |
173 <A | |
174 HREF="sdlsetcolorkey.html" | |
175 >SDL_SetColorKey</A | |
176 >, | |
177 <A | |
178 HREF="sdldisplayformat.html" | |
179 >SDL_DisplayFormat</A | |
180 >, | |
181 <A | |
182 HREF="sdlsurface.html" | |
183 >SDL_Surface</A | |
184 ></P | |
185 ></DIV | |
186 ><DIV | |
187 CLASS="NAVFOOTER" | |
188 ><HR | |
189 ALIGN="LEFT" | |
190 WIDTH="100%"><TABLE | |
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191 SUMMARY="Footer navigation table" |
0 | 192 WIDTH="100%" |
193 BORDER="0" | |
194 CELLPADDING="0" | |
195 CELLSPACING="0" | |
196 ><TR | |
197 ><TD | |
198 WIDTH="33%" | |
199 ALIGN="left" | |
200 VALIGN="top" | |
201 ><A | |
202 HREF="sdldisplayformat.html" | |
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203 ACCESSKEY="P" |
0 | 204 >Prev</A |
205 ></TD | |
206 ><TD | |
207 WIDTH="34%" | |
208 ALIGN="center" | |
209 VALIGN="top" | |
210 ><A | |
211 HREF="index.html" | |
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212 ACCESSKEY="H" |
0 | 213 >Home</A |
214 ></TD | |
215 ><TD | |
216 WIDTH="33%" | |
217 ALIGN="right" | |
218 VALIGN="top" | |
219 ><A | |
220 HREF="sdlwarpmouse.html" | |
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221 ACCESSKEY="N" |
0 | 222 >Next</A |
223 ></TD | |
224 ></TR | |
225 ><TR | |
226 ><TD | |
227 WIDTH="33%" | |
228 ALIGN="left" | |
229 VALIGN="top" | |
230 >SDL_DisplayFormat</TD | |
231 ><TD | |
232 WIDTH="34%" | |
233 ALIGN="center" | |
234 VALIGN="top" | |
235 ><A | |
236 HREF="video.html" | |
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237 ACCESSKEY="U" |
0 | 238 >Up</A |
239 ></TD | |
240 ><TD | |
241 WIDTH="33%" | |
242 ALIGN="right" | |
243 VALIGN="top" | |
244 >SDL_WarpMouse</TD | |
245 ></TR | |
246 ></TABLE | |
247 ></DIV | |
248 ></BODY | |
249 ></HTML | |
250 > |