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     72 ><A
     73 NAME="SDLDISPLAYFORMATALPHA"
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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
     85 CLASS="REFSYNOPSISDIV"
     86 ><A
     87 NAME="AEN2435"
     88 ></A
     89 ><H2
     90 >Synopsis</H2
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     92 CLASS="FUNCSYNOPSIS"
     93 ><A
     94 NAME="AEN2436"
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     96 ><P
     97 ></P
     98 ><PRE
     99 CLASS="FUNCSYNOPSISINFO"
    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
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    115 ><DIV
    116 CLASS="REFSECT1"
    117 ><A
    118 NAME="AEN2442"
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    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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