| 1 | <HTML |
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| 3 | ><TITLE |
| 4 | >SDL_BlitSurface</TITLE |
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| 16 | TITLE="SDL_ConvertSurface" |
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| 40 | >SDL Library Documentation</TH |
| 41 | ></TR |
| 42 | ><TR |
| 43 | ><TD |
| 44 | WIDTH="10%" |
| 45 | ALIGN="left" |
| 46 | VALIGN="bottom" |
| 47 | ><A |
| 48 | HREF="sdlconvertsurface.html" |
| 49 | ACCESSKEY="P" |
| 50 | >Prev</A |
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| 60 | VALIGN="bottom" |
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| 62 | HREF="sdlfillrect.html" |
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| 70 | WIDTH="100%"></DIV |
| 71 | ><H1 |
| 72 | ><A |
| 73 | NAME="SDLBLITSURFACE" |
| 74 | ></A |
| 75 | >SDL_BlitSurface</H1 |
| 76 | ><DIV |
| 77 | CLASS="REFNAMEDIV" |
| 78 | ><A |
| 79 | NAME="AEN2299" |
| 80 | ></A |
| 81 | ><H2 |
| 82 | >Name</H2 |
| 83 | >SDL_BlitSurface -- This performs a fast blit from the source surface to the destination surface.</DIV |
| 84 | ><DIV |
| 85 | CLASS="REFSYNOPSISDIV" |
| 86 | ><A |
| 87 | NAME="AEN2302" |
| 88 | ></A |
| 89 | ><H2 |
| 90 | >Synopsis</H2 |
| 91 | ><DIV |
| 92 | CLASS="FUNCSYNOPSIS" |
| 93 | ><A |
| 94 | NAME="AEN2303" |
| 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_BlitSurface</B |
| 108 | ></CODE |
| 109 | >(SDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect);</CODE |
| 110 | ></P |
| 111 | ><P |
| 112 | ></P |
| 113 | ></DIV |
| 114 | ></DIV |
| 115 | ><DIV |
| 116 | CLASS="REFSECT1" |
| 117 | ><A |
| 118 | NAME="AEN2309" |
| 119 | ></A |
| 120 | ><H2 |
| 121 | >Description</H2 |
| 122 | ><P |
| 123 | >This performs a fast blit from the source surface to the destination surface.</P |
| 124 | ><P |
| 125 | >The width and height in <TT |
| 126 | CLASS="PARAMETER" |
| 127 | ><I |
| 128 | >srcrect</I |
| 129 | ></TT |
| 130 | > determine the |
| 131 | size of the copied rectangle. Only the position is used in the |
| 132 | <TT |
| 133 | CLASS="PARAMETER" |
| 134 | ><I |
| 135 | >dstrect</I |
| 136 | ></TT |
| 137 | > (the width and height are ignored).</P |
| 138 | ><P |
| 139 | >If <TT |
| 140 | CLASS="PARAMETER" |
| 141 | ><I |
| 142 | >srcrect</I |
| 143 | ></TT |
| 144 | > is <TT |
| 145 | CLASS="LITERAL" |
| 146 | >NULL</TT |
| 147 | >, the |
| 148 | entire surface is copied. If <TT |
| 149 | CLASS="PARAMETER" |
| 150 | ><I |
| 151 | >dstrect</I |
| 152 | ></TT |
| 153 | > is |
| 154 | <TT |
| 155 | CLASS="LITERAL" |
| 156 | >NULL</TT |
| 157 | >, then the destination position (upper left |
| 158 | corner) is (0, 0).</P |
| 159 | ><P |
| 160 | >The final blit rectangle is saved in |
| 161 | <TT |
| 162 | CLASS="PARAMETER" |
| 163 | ><I |
| 164 | >dstrect</I |
| 165 | ></TT |
| 166 | > after all clipping is performed |
| 167 | (<TT |
| 168 | CLASS="PARAMETER" |
| 169 | ><I |
| 170 | >srcrect</I |
| 171 | ></TT |
| 172 | > is not modified).</P |
| 173 | ><P |
| 174 | >The blit function should not be called on a locked surface.</P |
| 175 | ><P |
| 176 | >The results of blitting operations vary greatly depending on whether <TT |
| 177 | CLASS="LITERAL" |
| 178 | >SDL_SRCAPLHA</TT |
| 179 | > is set or not. See <A |
| 180 | HREF="sdlsetalpha.html" |
| 181 | >SDL_SetAlpha</A |
| 182 | > 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. |
| 183 | <PRE |
| 184 | CLASS="PROGRAMLISTING" |
| 185 | >if (source surface has SDL_SRCALPHA set) { |
| 186 | if (source surface has alpha channel (that is, format->Amask != 0)) |
| 187 | blit using per-pixel alpha, ignoring any colour key |
| 188 | else { |
| 189 | if (source surface has SDL_SRCCOLORKEY set) |
| 190 | blit using the colour key AND the per-surface alpha value |
| 191 | else |
| 192 | blit using the per-surface alpha value |
| 193 | } |
| 194 | } else { |
| 195 | if (source surface has SDL_SRCCOLORKEY set) |
| 196 | blit using the colour key |
| 197 | else |
| 198 | ordinary opaque rectangular blit |
| 199 | }</PRE |
| 200 | ></P |
| 201 | ></DIV |
| 202 | ><DIV |
| 203 | CLASS="REFSECT1" |
| 204 | ><A |
| 205 | NAME="AEN2328" |
| 206 | ></A |
| 207 | ><H2 |
| 208 | >Return Value</H2 |
| 209 | ><P |
| 210 | >If the blit is successful, it returns <SPAN |
| 211 | CLASS="RETURNVALUE" |
| 212 | >0</SPAN |
| 213 | >, |
| 214 | otherwise it returns <SPAN |
| 215 | CLASS="RETURNVALUE" |
| 216 | >-1</SPAN |
| 217 | >.</P |
| 218 | ><P |
| 219 | >If either of the surfaces were in video memory, and the blit returns |
| 220 | <SPAN |
| 221 | CLASS="RETURNVALUE" |
| 222 | >-2</SPAN |
| 223 | >, the video memory was lost, so it should be |
| 224 | reloaded with artwork and re-blitted: |
| 225 | <PRE |
| 226 | CLASS="PROGRAMLISTING" |
| 227 | > while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) { |
| 228 | while ( SDL_LockSurface(image)) < 0 ) |
| 229 | SDL_Delay(10); |
| 230 | -- Write image pixels to image->pixels -- |
| 231 | SDL_UnlockSurface(image); |
| 232 | }</PRE |
| 233 | > |
| 234 | This happens under DirectX 5.0 when the system switches away from your |
| 235 | fullscreen application. Locking the surface will also fail until you |
| 236 | have access to the video memory again.</P |
| 237 | ></DIV |
| 238 | ><DIV |
| 239 | CLASS="REFSECT1" |
| 240 | ><A |
| 241 | NAME="AEN2336" |
| 242 | ></A |
| 243 | ><H2 |
| 244 | >See Also</H2 |
| 245 | ><P |
| 246 | ><A |
| 247 | HREF="sdllocksurface.html" |
| 248 | ><TT |
| 249 | CLASS="FUNCTION" |
| 250 | >SDL_LockSurface</TT |
| 251 | ></A |
| 252 | >, |
| 253 | <A |
| 254 | HREF="sdlfillrect.html" |
| 255 | ><TT |
| 256 | CLASS="FUNCTION" |
| 257 | >SDL_FillRect</TT |
| 258 | ></A |
| 259 | >, |
| 260 | <A |
| 261 | HREF="sdlsurface.html" |
| 262 | ><SPAN |
| 263 | CLASS="STRUCTNAME" |
| 264 | >SDL_Surface</SPAN |
| 265 | ></A |
| 266 | >, |
| 267 | <A |
| 268 | HREF="sdlrect.html" |
| 269 | ><SPAN |
| 270 | CLASS="STRUCTNAME" |
| 271 | >SDL_Rect</SPAN |
| 272 | ></A |
| 273 | ></P |
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| 319 | >SDL_ConvertSurface</TD |
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