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view docs/man3/SDL_CreateYUVOverlay.3 @ 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 | 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