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view docs/man3/SDL_GetGammaRamp.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_GetGammaRamp" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_GetGammaRamp\- Gets the color gamma lookup tables for the display .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBint \fBSDL_GetGammaRamp\fP\fR(\fBUint16 *redtable, Uint16 *greentable, Uint16 *bluetable\fR); .SH "DESCRIPTION" .PP Gets the gamma translation lookup tables currently used by the display\&. Each table is an array of 256 Uint16 values\&. .PP Not all display hardware is able to change gamma\&. .SH "RETURN VALUE" .PP Returns -1 on error\&. .SH "SEE ALSO" .PP \fISDL_SetGamma\fR \fISDL_SetGammaRamp\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01