1<HTML 2><HEAD 3><TITLE 4>SDL_DisplayFormatAlpha</TITLE 5><META 6NAME="GENERATOR" 7CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ 8"><LINK 9REL="HOME" 10TITLE="SDL Library Documentation" 11HREF="index.html"><LINK 12REL="UP" 13TITLE="Video" 14HREF="video.html"><LINK 15REL="PREVIOUS" 16TITLE="SDL_DisplayFormat" 17HREF="sdldisplayformat.html"><LINK 18REL="NEXT" 19TITLE="SDL_WarpMouse" 20HREF="sdlwarpmouse.html"></HEAD 21><BODY 22CLASS="REFENTRY" 23BGCOLOR="#FFF8DC" 24TEXT="#000000" 25LINK="#0000ee" 26VLINK="#551a8b" 27ALINK="#ff0000" 28><DIV 29CLASS="NAVHEADER" 30><TABLE 31SUMMARY="Header navigation table" 32WIDTH="100%" 33BORDER="0" 34CELLPADDING="0" 35CELLSPACING="0" 36><TR 37><TH 38COLSPAN="3" 39ALIGN="center" 40>SDL Library Documentation</TH 41></TR 42><TR 43><TD 44WIDTH="10%" 45ALIGN="left" 46VALIGN="bottom" 47><A 48HREF="sdldisplayformat.html" 49ACCESSKEY="P" 50>Prev</A 51></TD 52><TD 53WIDTH="80%" 54ALIGN="center" 55VALIGN="bottom" 56></TD 57><TD 58WIDTH="10%" 59ALIGN="right" 60VALIGN="bottom" 61><A 62HREF="sdlwarpmouse.html" 63ACCESSKEY="N" 64>Next</A 65></TD 66></TR 67></TABLE 68><HR 69ALIGN="LEFT" 70WIDTH="100%"></DIV 71><H1 72><A 73NAME="SDLDISPLAYFORMATALPHA" 74></A 75>SDL_DisplayFormatAlpha</H1 76><DIV 77CLASS="REFNAMEDIV" 78><A 79NAME="AEN2432" 80></A 81><H2 82>Name</H2 83>SDL_DisplayFormatAlpha -- Convert a surface to the display format</DIV 84><DIV 85CLASS="REFSYNOPSISDIV" 86><A 87NAME="AEN2435" 88></A 89><H2 90>Synopsis</H2 91><DIV 92CLASS="FUNCSYNOPSIS" 93><A 94NAME="AEN2436" 95></A 96><P 97></P 98><PRE 99CLASS="FUNCSYNOPSISINFO" 100>#include "SDL.h"</PRE 101><P 102><CODE 103><CODE 104CLASS="FUNCDEF" 105>SDL_Surface *<B 106CLASS="FSFUNC" 107>SDL_DisplayFormatAlpha</B 108></CODE 109>(SDL_Surface *surface);</CODE 110></P 111><P 112></P 113></DIV 114></DIV 115><DIV 116CLASS="REFSECT1" 117><A 118NAME="AEN2442" 119></A 120><H2 121>Description</H2 122><P 123>This function takes a surface and copies it to a new surface of the 124pixel format and colors of the video framebuffer plus an alpha channel, 125suitable for fast blitting onto the display surface. It calls 126<A 127HREF="sdlconvertsurface.html" 128>SDL_ConvertSurface</A 129></P 130><P 131>If you want to take advantage of hardware colorkey or alpha blit 132acceleration, you should set the colorkey and alpha value before 133calling this function.</P 134><P 135>This function can be used to convert a colourkey to an alpha channel, 136if the <TT 137CLASS="LITERAL" 138>SDL_SRCCOLORKEY</TT 139> flag is set on the surface. 140The generated surface will then be transparent (alpha=0) where the 141pixels match the colourkey, and opaque (alpha=255) elsewhere.</P 142></DIV 143><DIV 144CLASS="REFSECT1" 145><A 146NAME="AEN2449" 147></A 148><H2 149>Return Value</H2 150><P 151>If the conversion fails or runs out of memory, it returns 152<SPAN 153CLASS="RETURNVALUE" 154>NULL</SPAN 155></P 156></DIV 157><DIV 158CLASS="REFSECT1" 159><A 160NAME="AEN2453" 161></A 162><H2 163>See Also</H2 164><P 165><A 166HREF="sdlconvertsurface.html" 167>SDL_ConvertSurface</A 168>, 169<A 170HREF="sdlsetalpha.html" 171>SDL_SetAlpha</A 172>, 173<A 174HREF="sdlsetcolorkey.html" 175>SDL_SetColorKey</A 176>, 177<A 178HREF="sdldisplayformat.html" 179>SDL_DisplayFormat</A 180>, 181<A 182HREF="sdlsurface.html" 183>SDL_Surface</A 184></P 185></DIV 186><DIV 187CLASS="NAVFOOTER" 188><HR 189ALIGN="LEFT" 190WIDTH="100%"><TABLE 191SUMMARY="Footer navigation table" 192WIDTH="100%" 193BORDER="0" 194CELLPADDING="0" 195CELLSPACING="0" 196><TR 197><TD 198WIDTH="33%" 199ALIGN="left" 200VALIGN="top" 201><A 202HREF="sdldisplayformat.html" 203ACCESSKEY="P" 204>Prev</A 205></TD 206><TD 207WIDTH="34%" 208ALIGN="center" 209VALIGN="top" 210><A 211HREF="index.html" 212ACCESSKEY="H" 213>Home</A 214></TD 215><TD 216WIDTH="33%" 217ALIGN="right" 218VALIGN="top" 219><A 220HREF="sdlwarpmouse.html" 221ACCESSKEY="N" 222>Next</A 223></TD 224></TR 225><TR 226><TD 227WIDTH="33%" 228ALIGN="left" 229VALIGN="top" 230>SDL_DisplayFormat</TD 231><TD 232WIDTH="34%" 233ALIGN="center" 234VALIGN="top" 235><A 236HREF="video.html" 237ACCESSKEY="U" 238>Up</A 239></TD 240><TD 241WIDTH="33%" 242ALIGN="right" 243VALIGN="top" 244>SDL_WarpMouse</TD 245></TR 246></TABLE 247></DIV 248></BODY 249></HTML 250>