Mercurial > sdl-ios-xcode
annotate docs/html/sdlblitsurface.html @ 102:9162d62280b5
Don't crash if freeing a hardware surface after the video mode has been
reset. Fortunately we keep track of the video memory internally.
| author | Sam Lantinga <slouken@lokigames.com> |
|---|---|
| date | Thu, 12 Jul 2001 23:34:44 +0000 |
| parents | 55f1f1b3e27d |
| children | e5bc29de3f0a |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_BlitSurface</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_ConvertSurface" | |
| 17 HREF="sdlconvertsurface.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_FillRect" | |
| 20 HREF="sdlfillrect.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="sdlconvertsurface.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="sdlfillrect.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="SDLBLITSURFACE" | |
| 71 >SDL_BlitSurface</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN1883" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_BlitSurface -- This performs a fast blit from the source surface to the destination surface.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN1886" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN1887" |
| 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_BlitSurface</B | |
| 105 ></CODE | |
| 106 >(SDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN1893" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 >This performs a fast blit from the source surface to the destination surface.</P | |
| 121 ><P | |
| 122 >Only the position is used in the <TT | |
| 123 CLASS="PARAMETER" | |
| 124 ><I | |
| 125 >dstrect</I | |
| 126 ></TT | |
| 127 > (the | |
| 128 width and height are ignored).</P | |
| 129 ><P | |
| 130 >If either <TT | |
| 131 CLASS="PARAMETER" | |
| 132 ><I | |
| 133 >srcrect</I | |
| 134 ></TT | |
| 135 > or | |
| 136 <TT | |
| 137 CLASS="PARAMETER" | |
| 138 ><I | |
| 139 >dstrect</I | |
| 140 ></TT | |
| 141 > are <TT | |
| 142 CLASS="LITERAL" | |
| 143 >NULL</TT | |
| 144 >, the entire | |
| 145 surface (<TT | |
| 146 CLASS="PARAMETER" | |
| 147 ><I | |
| 148 >src</I | |
| 149 ></TT | |
| 150 > or <TT | |
| 151 CLASS="PARAMETER" | |
| 152 ><I | |
| 153 >dst</I | |
| 154 ></TT | |
| 155 >) is | |
| 156 copied.</P | |
| 157 ><P | |
| 158 >The final blit rectangle is saved in | |
| 159 <TT | |
| 160 CLASS="PARAMETER" | |
| 161 ><I | |
| 162 >dstrect</I | |
| 163 ></TT | |
| 164 > after all clipping is performed | |
| 165 (<TT | |
| 166 CLASS="PARAMETER" | |
| 167 ><I | |
| 168 >srcrect</I | |
| 169 ></TT | |
| 170 > is not modified).</P | |
| 171 ><P | |
| 172 >The blit function should not be called on a locked surface.</P | |
| 173 ><P | |
| 174 >The results of blitting operations vary greatly depending on whether <TT | |
| 175 CLASS="LITERAL" | |
| 176 >SDL_SRCAPLHA</TT | |
| 177 > is set or not. See <A | |
| 178 HREF="sdlsetalpha.html" | |
| 179 >SDL_SetAlpha</A | |
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180 > for an explaination of how this affects your results. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully explain. |
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181 <PRE |
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182 CLASS="PROGRAMLISTING" |
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183 >if (source surface has SDL_SRCALPHA set) { |
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184 if (source surface has alpha channel (that is, format->Amask != 0)) |
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185 blit using per-pixel alpha, ignoring any colour key |
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186 else { |
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187 if (source surface has SDL_SRCCOLORKEY set) |
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188 blit using the colour key AND the per-surface alpha value |
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189 else |
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190 blit using the per-surface alpha value |
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191 } |
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192 } else { |
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193 if (source surface has SDL_SRCCOLORKEY set) |
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194 blit using the colour key |
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195 else |
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196 ordinary opaque rectangular blit |
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197 }</PRE |
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198 ></P |
| 0 | 199 ></DIV |
| 200 ><DIV | |
| 201 CLASS="REFSECT1" | |
| 202 ><A | |
|
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203 NAME="AEN1912" |
| 0 | 204 ></A |
| 205 ><H2 | |
| 206 >Return Value</H2 | |
| 207 ><P | |
| 208 >If the blit is successful, it returns <SPAN | |
| 209 CLASS="RETURNVALUE" | |
| 210 >0</SPAN | |
| 211 >, | |
| 212 otherwise it returns <SPAN | |
| 213 CLASS="RETURNVALUE" | |
| 214 >-1</SPAN | |
| 215 >.</P | |
| 216 ><P | |
| 217 >If either of the surfaces were in video memory, and the blit returns | |
| 218 <SPAN | |
| 219 CLASS="RETURNVALUE" | |
| 220 >-2</SPAN | |
| 221 >, the video memory was lost, so it should be | |
| 222 reloaded with artwork and re-blitted: | |
| 223 <PRE | |
| 224 CLASS="PROGRAMLISTING" | |
| 225 > while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) { | |
| 226 while ( SDL_LockSurface(image)) < 0 ) | |
| 227 Sleep(10); | |
| 228 -- Write image pixels to image->pixels -- | |
| 229 SDL_UnlockSurface(image); | |
| 230 }</PRE | |
| 231 > | |
| 232 This happens under DirectX 5.0 when the system switches away from your | |
| 233 fullscreen application. Locking the surface will also fail until you | |
| 234 have access to the video memory again.</P | |
| 235 ></DIV | |
| 236 ><DIV | |
| 237 CLASS="REFSECT1" | |
| 238 ><A | |
|
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239 NAME="AEN1920" |
| 0 | 240 ></A |
| 241 ><H2 | |
| 242 >See Also</H2 | |
| 243 ><P | |
| 244 ><A | |
| 245 HREF="sdllocksurface.html" | |
| 246 ><TT | |
| 247 CLASS="FUNCTION" | |
| 248 >SDL_LockSurface</TT | |
| 249 ></A | |
| 250 >, | |
| 251 <A | |
| 252 HREF="sdlfillrect.html" | |
| 253 ><TT | |
| 254 CLASS="FUNCTION" | |
| 255 >SDL_FillRect</TT | |
| 256 ></A | |
| 257 >, | |
| 258 <A | |
| 259 HREF="sdlsurface.html" | |
| 260 ><SPAN | |
| 261 CLASS="STRUCTNAME" | |
| 262 >SDL_Surface</SPAN | |
| 263 ></A | |
| 264 >, | |
| 265 <A | |
| 266 HREF="sdlrect.html" | |
| 267 ><SPAN | |
| 268 CLASS="STRUCTNAME" | |
| 269 >SDL_Rect</SPAN | |
| 270 ></A | |
| 271 ></P | |
| 272 ></DIV | |
| 273 ><DIV | |
| 274 CLASS="NAVFOOTER" | |
| 275 ><HR | |
| 276 ALIGN="LEFT" | |
| 277 WIDTH="100%"><TABLE | |
| 278 WIDTH="100%" | |
| 279 BORDER="0" | |
| 280 CELLPADDING="0" | |
| 281 CELLSPACING="0" | |
| 282 ><TR | |
| 283 ><TD | |
| 284 WIDTH="33%" | |
| 285 ALIGN="left" | |
| 286 VALIGN="top" | |
| 287 ><A | |
| 288 HREF="sdlconvertsurface.html" | |
| 289 >Prev</A | |
| 290 ></TD | |
| 291 ><TD | |
| 292 WIDTH="34%" | |
| 293 ALIGN="center" | |
| 294 VALIGN="top" | |
| 295 ><A | |
| 296 HREF="index.html" | |
| 297 >Home</A | |
| 298 ></TD | |
| 299 ><TD | |
| 300 WIDTH="33%" | |
| 301 ALIGN="right" | |
| 302 VALIGN="top" | |
| 303 ><A | |
| 304 HREF="sdlfillrect.html" | |
| 305 >Next</A | |
| 306 ></TD | |
| 307 ></TR | |
| 308 ><TR | |
| 309 ><TD | |
| 310 WIDTH="33%" | |
| 311 ALIGN="left" | |
| 312 VALIGN="top" | |
| 313 >SDL_ConvertSurface</TD | |
| 314 ><TD | |
| 315 WIDTH="34%" | |
| 316 ALIGN="center" | |
| 317 VALIGN="top" | |
| 318 ><A | |
| 319 HREF="video.html" | |
| 320 >Up</A | |
| 321 ></TD | |
| 322 ><TD | |
| 323 WIDTH="33%" | |
| 324 ALIGN="right" | |
| 325 VALIGN="top" | |
| 326 >SDL_FillRect</TD | |
| 327 ></TR | |
| 328 ></TABLE | |
| 329 ></DIV | |
| 330 ></BODY | |
| 331 ></HTML | |
| 332 > |