Mercurial > sdl-ios-xcode
view docs/man3/SDL_CreateYUVOverlay.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_CreateYUVOverlay" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_CreateYUVOverlay\- Create a YUV video overlay .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_Overlay *\fBSDL_CreateYUVOverlay\fP\fR(\fBint width, int height, Uint32 format, SDL_Surface *display\fR); .SH "DESCRIPTION" .PP \fBSDL_CreateYUVOverlay\fP creates a YUV overlay of the specified \fBwidth\fR, \fBheight\fR and \fBformat\fR (see \fI\fBSDL_Overlay\fR\fR for a list of available formats), for the provided \fBdisplay\fR\&. A \fI\fBSDL_Overlay\fR\fR structure is returned\&. .PP The term \&'overlay\&' is a misnomer since, unless the overlay is created in hardware, the contents for the display surface underneath the area where the overlay is shown will be overwritten when the overlay is displayed\&. .SH "SEE ALSO" .PP \fI\fBSDL_Overlay\fR\fR, \fI\fBSDL_DisplayYUVOverlay\fP\fR, \fI\fBSDL_FreeYUVOverlay\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01