Mercurial > sdl-ios-xcode
annotate docs/html/sdllocksurface.html @ 259:80b647695abd
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| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Thu, 20 Dec 2001 22:46:09 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 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 1.64 |
| 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_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 | |
| 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="sdlfreesurface.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="sdlunlocksurface.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="SDLLOCKSURFACE" | |
| 71 >SDL_LockSurface</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN1535" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_LockSurface -- Lock a surface for directly access.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN1538" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
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91 NAME="AEN1539" |
| 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 >int <B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_LockSurface</B | |
| 105 ></CODE | |
| 106 >(SDL_Surface *surface);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN1545" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 ><TT | |
| 121 CLASS="FUNCTION" | |
| 122 >SDL_LockSurface</TT | |
| 123 > sets up a surface for directly | |
| 124 accessing the pixels. Between calls to <TT | |
| 125 CLASS="FUNCTION" | |
| 126 >SDL_LockSurface</TT | |
| 127 > | |
| 128 and <TT | |
| 129 CLASS="FUNCTION" | |
| 130 >SDL_UnlockSurface</TT | |
| 131 >, you can write to and read from | |
| 132 <TT | |
| 133 CLASS="PARAMETER" | |
| 134 ><I | |
| 135 >surface-><TT | |
| 136 CLASS="STRUCTFIELD" | |
| 137 ><I | |
| 138 >pixels</I | |
| 139 ></TT | |
| 140 ></I | |
| 141 ></TT | |
| 142 >, using the pixel format stored in | |
| 143 <TT | |
| 144 CLASS="PARAMETER" | |
| 145 ><I | |
| 146 >surface-><TT | |
| 147 CLASS="STRUCTFIELD" | |
| 148 ><I | |
| 149 >format</I | |
| 150 ></TT | |
| 151 ></I | |
| 152 ></TT | |
| 153 >. Once you are done accessing the | |
| 154 surface, you should use <TT | |
| 155 CLASS="FUNCTION" | |
| 156 >SDL_UnlockSurface</TT | |
| 157 > to release it.</P | |
| 158 ><P | |
| 159 >Not all surfaces require locking. | |
| 160 If <TT | |
| 161 CLASS="LITERAL" | |
| 162 >SDL_MUSTLOCK</TT | |
| 163 >(<TT | |
| 164 CLASS="PARAMETER" | |
| 165 ><I | |
| 166 >surface</I | |
| 167 ></TT | |
| 168 >) | |
| 169 evaluates to <SPAN | |
| 170 CLASS="RETURNVALUE" | |
| 171 >0</SPAN | |
| 172 >, then you can read and write to the | |
| 173 surface at any time, and the pixel format of the surface will not change. </P | |
| 174 ><P | |
| 175 >No operating system or library calls should be made between lock/unlock | |
| 176 pairs, as critical system locks may be held during this time.</P | |
| 177 ><P | |
| 178 >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. | |
| 179 <PRE | |
| 180 CLASS="PROGRAMLISTING" | |
| 181 > . | |
| 182 . | |
| 183 SDL_LockSurface( surface ); | |
| 184 . | |
| 185 /* Surface is locked */ | |
| 186 /* Direct pixel access on surface here */ | |
| 187 . | |
| 188 SDL_LockSurface( surface ); | |
| 189 . | |
| 190 /* More direct pixel access on surface */ | |
| 191 . | |
| 192 SDL_UnlockSurface( surface ); | |
| 193 /* Surface is still locked */ | |
| 194 /* Note: Is versions < 1.1.8, the surface would have been */ | |
| 195 /* no longer locked at this stage */ | |
| 196 . | |
| 197 SDL_UnlockSurface( surface ); | |
| 198 /* Surface is now unlocked */ | |
| 199 . | |
| 200 .</PRE | |
|
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201 ></P |
| 0 | 202 ></DIV |
| 203 ><DIV | |
| 204 CLASS="REFSECT1" | |
| 205 ><A | |
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206 NAME="AEN1563" |
| 0 | 207 ></A |
| 208 ><H2 | |
| 209 >Return Value</H2 | |
| 210 ><P | |
| 211 ><TT | |
| 212 CLASS="FUNCTION" | |
| 213 >SDL_LockSurface</TT | |
| 214 > returns <SPAN | |
| 215 CLASS="RETURNVALUE" | |
| 216 >0</SPAN | |
| 217 >, | |
| 218 or <SPAN | |
| 219 CLASS="RETURNVALUE" | |
| 220 >-1</SPAN | |
| 221 > if the surface couldn't be locked.</P | |
| 222 ></DIV | |
| 223 ><DIV | |
| 224 CLASS="REFSECT1" | |
| 225 ><A | |
|
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226 NAME="AEN1569" |
| 0 | 227 ></A |
| 228 ><H2 | |
| 229 >See Also</H2 | |
| 230 ><P | |
| 231 ><A | |
| 232 HREF="sdlunlocksurface.html" | |
| 233 ><TT | |
| 234 CLASS="FUNCTION" | |
| 235 >SDL_UnlockSurface</TT | |
| 236 ></A | |
| 237 ></P | |
| 238 ></DIV | |
| 239 ><DIV | |
| 240 CLASS="NAVFOOTER" | |
| 241 ><HR | |
| 242 ALIGN="LEFT" | |
| 243 WIDTH="100%"><TABLE | |
| 244 WIDTH="100%" | |
| 245 BORDER="0" | |
| 246 CELLPADDING="0" | |
| 247 CELLSPACING="0" | |
| 248 ><TR | |
| 249 ><TD | |
| 250 WIDTH="33%" | |
| 251 ALIGN="left" | |
| 252 VALIGN="top" | |
| 253 ><A | |
| 254 HREF="sdlfreesurface.html" | |
| 255 >Prev</A | |
| 256 ></TD | |
| 257 ><TD | |
| 258 WIDTH="34%" | |
| 259 ALIGN="center" | |
| 260 VALIGN="top" | |
| 261 ><A | |
| 262 HREF="index.html" | |
| 263 >Home</A | |
| 264 ></TD | |
| 265 ><TD | |
| 266 WIDTH="33%" | |
| 267 ALIGN="right" | |
| 268 VALIGN="top" | |
| 269 ><A | |
| 270 HREF="sdlunlocksurface.html" | |
| 271 >Next</A | |
| 272 ></TD | |
| 273 ></TR | |
| 274 ><TR | |
| 275 ><TD | |
| 276 WIDTH="33%" | |
| 277 ALIGN="left" | |
| 278 VALIGN="top" | |
| 279 >SDL_FreeSurface</TD | |
| 280 ><TD | |
| 281 WIDTH="34%" | |
| 282 ALIGN="center" | |
| 283 VALIGN="top" | |
| 284 ><A | |
| 285 HREF="video.html" | |
| 286 >Up</A | |
| 287 ></TD | |
| 288 ><TD | |
| 289 WIDTH="33%" | |
| 290 ALIGN="right" | |
| 291 VALIGN="top" | |
| 292 >SDL_UnlockSurface</TD | |
| 293 ></TR | |
| 294 ></TABLE | |
| 295 ></DIV | |
| 296 ></BODY | |
| 297 ></HTML | |
| 298 > |