1 <HTML 2 ><HEAD 3 ><TITLE 4 >SDL_SetColorKey</TITLE 5 ><META 6 NAME="GENERATOR" 7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ 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_SaveBMP" 17 HREF="sdlsavebmp.html"><LINK 18 REL="NEXT" 19 TITLE="SDL_SetAlpha" 20 HREF="sdlsetalpha.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 SUMMARY="Header navigation table" 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="sdlsavebmp.html" 49 ACCESSKEY="P" 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="sdlsetalpha.html" 63 ACCESSKEY="N" 64 >Next</A 65 ></TD 66 ></TR 67 ></TABLE 68 ><HR 69 ALIGN="LEFT" 70 WIDTH="100%"></DIV 71 ><H1 72 ><A 73 NAME="SDLSETCOLORKEY" 74 ></A 75 >SDL_SetColorKey</H1 76 ><DIV 77 CLASS="REFNAMEDIV" 78 ><A 79 NAME="AEN2045" 80 ></A 81 ><H2 82 >Name</H2 83 >SDL_SetColorKey -- Sets the color key (transparent pixel) in a blittable surface and 84 RLE acceleration.</DIV 85 ><DIV 86 CLASS="REFSYNOPSISDIV" 87 ><A 88 NAME="AEN2048" 89 ></A 90 ><H2 91 >Synopsis</H2 92 ><DIV 93 CLASS="FUNCSYNOPSIS" 94 ><A 95 NAME="AEN2049" 96 ></A 97 ><P 98 ></P 99 ><PRE 100 CLASS="FUNCSYNOPSISINFO" 101 >#include "SDL.h"</PRE 102 ><P 103 ><CODE 104 ><CODE 105 CLASS="FUNCDEF" 106 >int <B 107 CLASS="FSFUNC" 108 >SDL_SetColorKey</B 109 ></CODE 110 >(SDL_Surface *surface, Uint32 flag, Uint32 key);</CODE 111 ></P 112 ><P 113 ></P 114 ></DIV 115 ></DIV 116 ><DIV 117 CLASS="REFSECT1" 118 ><A 119 NAME="AEN2055" 120 ></A 121 ><H2 122 >Description</H2 123 ><P 124 > Sets the color key (transparent pixel) in a blittable surface and enables or 125 disables RLE blit acceleration.</P 126 ><P 127 >RLE acceleration can substantially speed up blitting of images with large 128 horizontal runs of transparent pixels (i.e., pixels that match the 129 <TT 130 CLASS="PARAMETER" 131 ><I 132 >key</I 133 ></TT 134 > value). The <TT 135 CLASS="PARAMETER" 136 ><I 137 >key</I 138 ></TT 139 > must be of the same pixel format as the <TT 140 CLASS="PARAMETER" 141 ><I 142 >surface</I 143 ></TT 144 >, <A 145 HREF="sdlmaprgb.html" 146 ><TT 147 CLASS="FUNCTION" 148 >SDL_MapRGB</TT 149 ></A 150 > is often useful for obtaining an acceptable value.</P 151 ><P 152 >If <TT 153 CLASS="PARAMETER" 154 ><I 155 >flag</I 156 ></TT 157 > is <TT 158 CLASS="LITERAL" 159 >SDL_SRCCOLORKEY</TT 160 > then 161 <TT 162 CLASS="PARAMETER" 163 ><I 164 >key</I 165 ></TT 166 > is the transparent pixel value in the source image of a 167 blit.</P 168 ><P 169 >If <TT 170 CLASS="PARAMETER" 171 ><I 172 >flag</I 173 ></TT 174 > is OR'd with 175 <TT 176 CLASS="LITERAL" 177 >SDL_RLEACCEL</TT 178 > then the surface will be draw using RLE 179 acceleration when drawn with 180 <A 181 HREF="sdlblitsurface.html" 182 >SDL_BlitSurface</A 183 >. The surface will 184 actually be encoded for RLE acceleration the first time 185 <A 186 HREF="sdlblitsurface.html" 187 >SDL_BlitSurface</A 188 > or 189 <A 190 HREF="sdldisplayformat.html" 191 >SDL_DisplayFormat</A 192 > is called on the 193 surface.</P 194 ><P 195 >If <TT 196 CLASS="PARAMETER" 197 ><I 198 >flag</I 199 ></TT 200 > is 0, this function clears 201 any current color key.</P 202 ></DIV 203 ><DIV 204 CLASS="REFSECT1" 205 ><A 206 NAME="AEN2076" 207 ></A 208 ><H2 209 >Return Value</H2 210 ><P 211 >This function returns <SPAN 212 CLASS="RETURNVALUE" 213 >0</SPAN 214 >, or 215 <SPAN 216 CLASS="RETURNVALUE" 217 >-1</SPAN 218 > if there was an error.</P 219 ></DIV 220 ><DIV 221 CLASS="REFSECT1" 222 ><A 223 NAME="AEN2081" 224 ></A 225 ><H2 226 >See Also</H2 227 ><P 228 ><A 229 HREF="sdlblitsurface.html" 230 ><TT 231 CLASS="FUNCTION" 232 >SDL_BlitSurface</TT 233 ></A 234 >, 235 <A 236 HREF="sdldisplayformat.html" 237 ><TT 238 CLASS="FUNCTION" 239 >SDL_DisplayFormat</TT 240 ></A 241 >, 242 <A 243 HREF="sdlmaprgb.html" 244 ><TT 245 CLASS="FUNCTION" 246 >SDL_MapRGB</TT 247 ></A 248 >, 249 <A 250 HREF="sdlsetalpha.html" 251 ><TT 252 CLASS="FUNCTION" 253 >SDL_SetAlpha</TT 254 ></A 255 ></P 256 ></DIV 257 ><DIV 258 CLASS="NAVFOOTER" 259 ><HR 260 ALIGN="LEFT" 261 WIDTH="100%"><TABLE 262 SUMMARY="Footer navigation table" 263 WIDTH="100%" 264 BORDER="0" 265 CELLPADDING="0" 266 CELLSPACING="0" 267 ><TR 268 ><TD 269 WIDTH="33%" 270 ALIGN="left" 271 VALIGN="top" 272 ><A 273 HREF="sdlsavebmp.html" 274 ACCESSKEY="P" 275 >Prev</A 276 ></TD 277 ><TD 278 WIDTH="34%" 279 ALIGN="center" 280 VALIGN="top" 281 ><A 282 HREF="index.html" 283 ACCESSKEY="H" 284 >Home</A 285 ></TD 286 ><TD 287 WIDTH="33%" 288 ALIGN="right" 289 VALIGN="top" 290 ><A 291 HREF="sdlsetalpha.html" 292 ACCESSKEY="N" 293 >Next</A 294 ></TD 295 ></TR 296 ><TR 297 ><TD 298 WIDTH="33%" 299 ALIGN="left" 300 VALIGN="top" 301 >SDL_SaveBMP</TD 302 ><TD 303 WIDTH="34%" 304 ALIGN="center" 305 VALIGN="top" 306 ><A 307 HREF="video.html" 308 ACCESSKEY="U" 309 >Up</A 310 ></TD 311 ><TD 312 WIDTH="33%" 313 ALIGN="right" 314 VALIGN="top" 315 >SDL_SetAlpha</TD 316 ></TR 317 ></TABLE 318 ></DIV 319 ></BODY 320 ></HTML 321 >