Mercurial > sdl-ios-xcode
annotate docs/html/sdllocksurface.html @ 2328:91e601d9df8b
re: bug#563. checking in some commented out trace code and a fix so that the in testalpha.c the background only flashes when alpha == 255. The problem that is being
fixed is caused by clearing SDL_COPY_RLE_COLORKEY without setting SDL_COPY_RLE_DESIRED in SDL_UnRELSurface.
author | Bob Pendleton <bob@pendleton.com> |
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date | Fri, 14 Mar 2008 18:17:49 +0000 |
parents | 355632dca928 |
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rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_LockSurface</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_FreeSurface" | |
17 HREF="sdlfreesurface.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_UnlockSurface" | |
20 HREF="sdlunlocksurface.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="sdlfreesurface.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="sdlunlocksurface.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="SDLLOCKSURFACE" | |
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74 ></A |
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75 >SDL_LockSurface</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN1919" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_LockSurface -- Lock a surface for directly access.</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN1922" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN1923" |
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 >int <B | |
106 CLASS="FSFUNC" | |
107 >SDL_LockSurface</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="AEN1929" |
0 | 119 ></A |
120 ><H2 | |
121 >Description</H2 | |
122 ><P | |
123 ><TT | |
124 CLASS="FUNCTION" | |
125 >SDL_LockSurface</TT | |
126 > sets up a surface for directly | |
127 accessing the pixels. Between calls to <TT | |
128 CLASS="FUNCTION" | |
129 >SDL_LockSurface</TT | |
130 > | |
131 and <TT | |
132 CLASS="FUNCTION" | |
133 >SDL_UnlockSurface</TT | |
134 >, you can write to and read from | |
135 <TT | |
136 CLASS="PARAMETER" | |
137 ><I | |
138 >surface-><TT | |
139 CLASS="STRUCTFIELD" | |
140 ><I | |
141 >pixels</I | |
142 ></TT | |
143 ></I | |
144 ></TT | |
145 >, using the pixel format stored in | |
146 <TT | |
147 CLASS="PARAMETER" | |
148 ><I | |
149 >surface-><TT | |
150 CLASS="STRUCTFIELD" | |
151 ><I | |
152 >format</I | |
153 ></TT | |
154 ></I | |
155 ></TT | |
156 >. Once you are done accessing the | |
157 surface, you should use <TT | |
158 CLASS="FUNCTION" | |
159 >SDL_UnlockSurface</TT | |
160 > to release it.</P | |
161 ><P | |
162 >Not all surfaces require locking. | |
163 If <TT | |
164 CLASS="LITERAL" | |
165 >SDL_MUSTLOCK</TT | |
166 >(<TT | |
167 CLASS="PARAMETER" | |
168 ><I | |
169 >surface</I | |
170 ></TT | |
171 >) | |
172 evaluates to <SPAN | |
173 CLASS="RETURNVALUE" | |
174 >0</SPAN | |
175 >, then you can read and write to the | |
176 surface at any time, and the pixel format of the surface will not change. </P | |
177 ><P | |
178 >No operating system or library calls should be made between lock/unlock | |
179 pairs, as critical system locks may be held during this time.</P | |
180 ><P | |
181 >It should be noted, that since SDL 1.1.8 surface locks are recursive. This means that you can lock a surface multiple times, but each lock must have a match unlock. | |
182 <PRE | |
183 CLASS="PROGRAMLISTING" | |
184 > . | |
185 . | |
186 SDL_LockSurface( surface ); | |
187 . | |
188 /* Surface is locked */ | |
189 /* Direct pixel access on surface here */ | |
190 . | |
191 SDL_LockSurface( surface ); | |
192 . | |
193 /* More direct pixel access on surface */ | |
194 . | |
195 SDL_UnlockSurface( surface ); | |
196 /* Surface is still locked */ | |
197 /* Note: Is versions < 1.1.8, the surface would have been */ | |
198 /* no longer locked at this stage */ | |
199 . | |
200 SDL_UnlockSurface( surface ); | |
201 /* Surface is now unlocked */ | |
202 . | |
203 .</PRE | |
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204 ></P |
0 | 205 ></DIV |
206 ><DIV | |
207 CLASS="REFSECT1" | |
208 ><A | |
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209 NAME="AEN1947" |
0 | 210 ></A |
211 ><H2 | |
212 >Return Value</H2 | |
213 ><P | |
214 ><TT | |
215 CLASS="FUNCTION" | |
216 >SDL_LockSurface</TT | |
217 > returns <SPAN | |
218 CLASS="RETURNVALUE" | |
219 >0</SPAN | |
220 >, | |
221 or <SPAN | |
222 CLASS="RETURNVALUE" | |
223 >-1</SPAN | |
224 > if the surface couldn't be locked.</P | |
225 ></DIV | |
226 ><DIV | |
227 CLASS="REFSECT1" | |
228 ><A | |
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229 NAME="AEN1953" |
0 | 230 ></A |
231 ><H2 | |
232 >See Also</H2 | |
233 ><P | |
234 ><A | |
235 HREF="sdlunlocksurface.html" | |
236 ><TT | |
237 CLASS="FUNCTION" | |
238 >SDL_UnlockSurface</TT | |
239 ></A | |
240 ></P | |
241 ></DIV | |
242 ><DIV | |
243 CLASS="NAVFOOTER" | |
244 ><HR | |
245 ALIGN="LEFT" | |
246 WIDTH="100%"><TABLE | |
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247 SUMMARY="Footer navigation table" |
0 | 248 WIDTH="100%" |
249 BORDER="0" | |
250 CELLPADDING="0" | |
251 CELLSPACING="0" | |
252 ><TR | |
253 ><TD | |
254 WIDTH="33%" | |
255 ALIGN="left" | |
256 VALIGN="top" | |
257 ><A | |
258 HREF="sdlfreesurface.html" | |
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259 ACCESSKEY="P" |
0 | 260 >Prev</A |
261 ></TD | |
262 ><TD | |
263 WIDTH="34%" | |
264 ALIGN="center" | |
265 VALIGN="top" | |
266 ><A | |
267 HREF="index.html" | |
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268 ACCESSKEY="H" |
0 | 269 >Home</A |
270 ></TD | |
271 ><TD | |
272 WIDTH="33%" | |
273 ALIGN="right" | |
274 VALIGN="top" | |
275 ><A | |
276 HREF="sdlunlocksurface.html" | |
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277 ACCESSKEY="N" |
0 | 278 >Next</A |
279 ></TD | |
280 ></TR | |
281 ><TR | |
282 ><TD | |
283 WIDTH="33%" | |
284 ALIGN="left" | |
285 VALIGN="top" | |
286 >SDL_FreeSurface</TD | |
287 ><TD | |
288 WIDTH="34%" | |
289 ALIGN="center" | |
290 VALIGN="top" | |
291 ><A | |
292 HREF="video.html" | |
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293 ACCESSKEY="U" |
0 | 294 >Up</A |
295 ></TD | |
296 ><TD | |
297 WIDTH="33%" | |
298 ALIGN="right" | |
299 VALIGN="top" | |
300 >SDL_UnlockSurface</TD | |
301 ></TR | |
302 ></TABLE | |
303 ></DIV | |
304 ></BODY | |
305 ></HTML | |
306 > |