view docs/html/sdlconvertsurface.html @ 688:c0522010bb6d

Date: Tue, 12 Aug 2003 14:26:19 +0200 (MEST) From: "Mattias Engdeg?rd" Subject: bug in SDL_GetRGB/GetRGBA There's an embarrassing bug in GetRGB/GetRGBA which apparently has been there for years. It incorrectly converts colours with < 8 bits/channel. It came to my attention today in #sdl. What it does now is (for each channel): rv = (pixel & fmt->Rmask) >> fmt->Rshift; *r = (rv << fmt->Rloss) + (rv >> (8 - fmt->Rloss)); which is wrong; the last line should be *r = (rv << fmt->Rloss) + (rv >> (8 - (fmt->Rloss << 1)));
author Sam Lantinga <slouken@libsdl.org>
date Tue, 12 Aug 2003 15:17:20 +0000
parents e5bc29de3f0a
children 355632dca928
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>SDL_ConvertSurface</A
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><H2
>Name</H2
>SDL_ConvertSurface&nbsp;--&nbsp;Converts a surface to the same format as another surface.</DIV
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>Synopsis</H2
><DIV
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL/SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_Surface *<B
CLASS="FSFUNC"
>SDL_ConvertSurface</B
></CODE
>(SDL_Surface *src, SDL_PixelFormat *fmt, Uint32 flags);</CODE
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><H2
>Description</H2
><P
>Creates a new surface of the specified format, and then copies and maps
the given surface to it.  If this function fails, it returns
<TT
CLASS="LITERAL"
>NULL</TT
>.</P
><P
>The <TT
CLASS="PARAMETER"
><I
>flags</I
></TT
> parameter is passed to 
<A
HREF="sdlcreatergbsurface.html"
><TT
CLASS="FUNCTION"
>SDL_CreateRGBSurface</TT
></A
>
and has those semantics.</P
><P
>This function is used internally by 
<A
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><TT
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>SDL_DisplayFormat</TT
></A
>.</P
><P
>This function can only be called after SDL_Init.</P
></DIV
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><A
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><H2
>Return Value</H2
><P
>Returns either a pointer to the new surface, or
<TT
CLASS="LITERAL"
>NULL</TT
> on error.</P
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><P
><A
HREF="sdlcreatergbsurface.html"
><TT
CLASS="FUNCTION"
>SDL_CreateRGBSurface</TT
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>SDL_DisplayFormat</TT
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>SDL_PixelFormat</SPAN
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>SDL_Surface</SPAN
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