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> |
|---|---|
| date | Fri, 14 Mar 2008 18:17:49 +0000 |
| parents | 355632dca928 |
| children |
| 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 > |