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view docs/html/sdljoystickgethat.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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<HTML ><HEAD ><TITLE >SDL_JoystickGetHat</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Joystick" HREF="joystick.html"><LINK REL="PREVIOUS" TITLE="SDL_JoystickGetAxis" HREF="sdljoystickgetaxis.html"><LINK REL="NEXT" TITLE="SDL_JoystickGetButton" HREF="sdljoystickgetbutton.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdljoystickgetaxis.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdljoystickgetbutton.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLJOYSTICKGETHAT" >SDL_JoystickGetHat</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN5970" ></A ><H2 >Name</H2 >SDL_JoystickGetHat -- Get the current state of a joystick hat</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN5973" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN5974" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >Uint8 <B CLASS="FSFUNC" >SDL_JoystickGetHat</B ></CODE >(SDL_Joystick *joystick, int hat);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5980" ></A ><H2 >Description</H2 ><P >SDL_JoystickGetHat returns the current state of the given <TT CLASS="PARAMETER" ><I >hat</I ></TT > on the given <TT CLASS="PARAMETER" ><I >joystick</I ></TT >.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5985" ></A ><H2 >Return Value</H2 ><P >The current state is returned as a Uint8 which is defined as an OR'd combination of one or more of the following</P ><P ></P ><TABLE BORDER="0" ><TBODY ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_CENTERED</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_UP</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_RIGHT</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_DOWN</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_LEFT</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_RIGHTUP</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_RIGHTDOWN</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_LEFTUP</TT ></TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >SDL_HAT_LEFTDOWN</TT ></TD ></TR ></TBODY ></TABLE ><P ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6007" ></A ><H2 >See Also</H2 ><P ><A HREF="sdljoysticknumhats.html" ><TT CLASS="FUNCTION" >SDL_JoystickNumHats</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdljoystickgetaxis.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdljoystickgetbutton.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_JoystickGetAxis</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="joystick.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_JoystickGetButton</TD ></TR ></TABLE ></DIV ></BODY ></HTML >