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  75 >SDL_DisplayFormatAlpha</H1
  76 ><DIV
  77 CLASS="REFNAMEDIV"
  78 ><A
  79 NAME="AEN2432"
  80 ></A
  81 ><H2
  82 >Name</H2
  83 >SDL_DisplayFormatAlpha&nbsp;--&nbsp;Convert a surface to the display format</DIV
  84 ><DIV
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  87 NAME="AEN2435"
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  90 >Synopsis</H2
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  98 ><PRE
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 100 >#include "SDL.h"</PRE
 101 ><P
 102 ><CODE
 103 ><CODE
 104 CLASS="FUNCDEF"
 105 >SDL_Surface *<B
 106 CLASS="FSFUNC"
 107 >SDL_DisplayFormatAlpha</B
 108 ></CODE
 109 >(SDL_Surface *surface);</CODE
 110 ></P
 111 ><P
 112 ></P
 113 ></DIV
 114 ></DIV
 115 ><DIV
 116 CLASS="REFSECT1"
 117 ><A
 118 NAME="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
 124 pixel format and colors of the video framebuffer plus an alpha channel,
 125 suitable for fast blitting onto the display surface.  It calls
 126 <A
 127 HREF="sdlconvertsurface.html"
 128 >SDL_ConvertSurface</A
 129 ></P
 130 ><P
 131 >If you want to take advantage of hardware colorkey or alpha blit
 132 acceleration, you should set the colorkey and alpha value before
 133 calling this function.</P
 134 ><P
 135 >This function can be used to convert a colourkey to an alpha channel,
 136 if the <TT
 137 CLASS="LITERAL"
 138 >SDL_SRCCOLORKEY</TT
 139 > flag is set on the surface.
 140 The generated surface will then be transparent (alpha=0) where the
 141 pixels match the colourkey, and opaque (alpha=255) elsewhere.</P
 142 ></DIV
 143 ><DIV
 144 CLASS="REFSECT1"
 145 ><A
 146 NAME="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
 153 CLASS="RETURNVALUE"
 154 >NULL</SPAN
 155 ></P
 156 ></DIV
 157 ><DIV
 158 CLASS="REFSECT1"
 159 ><A
 160 NAME="AEN2453"
 161 ></A
 162 ><H2
 163 >See Also</H2
 164 ><P
 165 ><A
 166 HREF="sdlconvertsurface.html"
 167 >SDL_ConvertSurface</A
 168 >,
 169 <A
 170 HREF="sdlsetalpha.html"
 171 >SDL_SetAlpha</A
 172 >,
 173 <A
 174 HREF="sdlsetcolorkey.html"
 175 >SDL_SetColorKey</A
 176 >,
 177 <A
 178 HREF="sdldisplayformat.html"
 179 >SDL_DisplayFormat</A
 180 >,
 181 <A
 182 HREF="sdlsurface.html"
 183 >SDL_Surface</A
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