view docs/html/sdldisplayformatalpha.html @ 1643:51038e80ae59

More general fix for bug #189 The clipping is done at a higher level, and the low level functions are passed clipped rectangles. Drivers which don't support source clipping have not been changed, so the image will be squished instead of clipped, but at least they will no longer crash when the destination rect was out of bounds.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 17 Apr 2006 06:47:23 +0000
parents 355632dca928
children
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>SDL_DisplayFormatAlpha</H1
><DIV
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><H2
>Name</H2
>SDL_DisplayFormatAlpha&nbsp;--&nbsp;Convert a surface to the display format</DIV
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>Synopsis</H2
><DIV
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><P
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_Surface *<B
CLASS="FSFUNC"
>SDL_DisplayFormatAlpha</B
></CODE
>(SDL_Surface *surface);</CODE
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><H2
>Description</H2
><P
>This function takes a surface and copies it to a new surface of the
pixel format and colors of the video framebuffer plus an alpha channel,
suitable for fast blitting onto the display surface.  It calls
<A
HREF="sdlconvertsurface.html"
>SDL_ConvertSurface</A
></P
><P
>If you want to take advantage of hardware colorkey or alpha blit
acceleration, you should set the colorkey and alpha value before
calling this function.</P
><P
>This function can be used to convert a colourkey to an alpha channel,
if the <TT
CLASS="LITERAL"
>SDL_SRCCOLORKEY</TT
> flag is set on the surface.
The generated surface will then be transparent (alpha=0) where the
pixels match the colourkey, and opaque (alpha=255) elsewhere.</P
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><H2
>Return Value</H2
><P
>If the conversion fails or runs out of memory, it returns
<SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
></P
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>See Also</H2
><P
><A
HREF="sdlconvertsurface.html"
>SDL_ConvertSurface</A
>,
<A
HREF="sdlsetalpha.html"
>SDL_SetAlpha</A
>,
<A
HREF="sdlsetcolorkey.html"
>SDL_SetColorKey</A
>,
<A
HREF="sdldisplayformat.html"
>SDL_DisplayFormat</A
>,
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>SDL_Surface</A
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