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view docs/man3/SDL_ConvertSurface.3 @ 1543:98f9b16f565c
From: "Alex Volkov"
Date: Thu, 10 Nov 2005 21:53:40 -0500
Subject: [SDL] BUG[?]: 32bpp RGBA->RGB colorkey blit, no SDL_SRCALPHA
It seems there is either a documentation vs. reality mismatch or a real bug
in SDL_blit_N.c:BlitNtoNKey().
The exact blit in question is a 32bpp RGBA->RGB, where RGBA has SDL_COLORKEY
and *no* SDL_SRCALPHA flags. The doc in SDL_video.h states:
* RGBA->RGB:
* SDL_SRCALPHA not set:
* copy RGB.
* if SDL_SRCCOLORKEY set, only copy the pixels matching the
* RGB values of the source colour key, ignoring alpha in the
* comparison.
BlitNtoNKey(), however, forgets to "ignore alpha in the comparison". The
documentation makes perfect sense, so I think it is the code that is faulty.
The attached patch corrects the code.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 15 Mar 2006 15:43:15 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_ConvertSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_ConvertSurface\- Converts a surface to the same format as another surface\&. .SH "SYNOPSIS" .PP \fB#include "SDL/SDL\&.h" .sp \fBSDL_Surface *\fBSDL_ConvertSurface\fP\fR(\fBSDL_Surface *src, SDL_PixelFormat *fmt, Uint32 flags\fR); .SH "DESCRIPTION" .PP Creates a new surface of the specified format, and then copies and maps the given surface to it\&. If this function fails, it returns \fBNULL\fP\&. .PP The \fBflags\fR parameter is passed to \fI\fBSDL_CreateRGBSurface\fP\fR and has those semantics\&. .PP This function is used internally by \fI\fBSDL_DisplayFormat\fP\fR\&. .PP This function can only be called after SDL_Init\&. .SH "RETURN VALUE" .PP Returns either a pointer to the new surface, or \fBNULL\fP on error\&. .SH "SEE ALSO" .PP \fI\fBSDL_CreateRGBSurface\fP\fR, \fI\fBSDL_DisplayFormat\fP\fR, \fI\fBSDL_PixelFormat\fR\fR, \fI\fBSDL_Surface\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01