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view docs/html/joystick.html @ 997:3bf4103b2b89
Date: Sat, 27 Nov 2004 13:35:43 +0100
From: "Martin Bickel"
Subject: [SDL] Patch: fixing uninitilized palette
while running Valgrind over my application I found the following
problem in SDL:
The function MapNto1 allocates SDL_Color colors[256] but does not
initialize it.
SDL_DitherColors is then called which initialized the r, g and b
component, but not the 'unused' component of each color.
When Map1to1 is called from MapNto1, it runs a memcmp on the colors,
which also evaluates the unused component and therefor returns
differences much more often than necessary.
So the 'unused' component of SDL_Color should be initialized. This
patch does this by calling memset for the whole array in MapNto1 .
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Tue, 30 Nov 2004 14:28:20 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >Joystick</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="SDL Reference" HREF="reference.html"><LINK REL="PREVIOUS" TITLE="SDL_JoystickEventState" HREF="sdljoystickeventstate.html"><LINK REL="NEXT" TITLE="SDL_NumJoysticks" HREF="sdlnumjoysticks.html"><META NAME="KEYWORD" CONTENT="joystick"><META NAME="KEYWORD" CONTENT="function"></HEAD ><BODY CLASS="CHAPTER" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation 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="sdljoystickeventstate.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlnumjoysticks.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="JOYSTICK" ></A >Chapter 9. Joystick</H1 ><DIV CLASS="TOC" ><DL ><DT ><B >Table of Contents</B ></DT ><DT ><A HREF="sdlnumjoysticks.html" >SDL_NumJoysticks</A > -- Count available joysticks.</DT ><DT ><A HREF="sdljoystickname.html" >SDL_JoystickName</A > -- Get joystick name.</DT ><DT ><A HREF="sdljoystickopen.html" >SDL_JoystickOpen</A > -- Opens a joystick for use.</DT ><DT ><A HREF="sdljoystickopened.html" >SDL_JoystickOpened</A > -- Determine if a joystick has been opened</DT ><DT ><A HREF="sdljoystickindex.html" >SDL_JoystickIndex</A > -- Get the index of an SDL_Joystick.</DT ><DT ><A HREF="sdljoysticknumaxes.html" >SDL_JoystickNumAxes</A > -- Get the number of joystick axes</DT ><DT ><A HREF="sdljoysticknumballs.html" >SDL_JoystickNumBalls</A > -- Get the number of joystick trackballs</DT ><DT ><A HREF="sdljoysticknumhats.html" >SDL_JoystickNumHats</A > -- Get the number of joystick hats</DT ><DT ><A HREF="sdljoysticknumbuttons.html" >SDL_JoystickNumButtons</A > -- Get the number of joysitck buttons</DT ><DT ><A HREF="sdljoystickupdate.html" >SDL_JoystickUpdate</A > -- Updates the state of all joysticks</DT ><DT ><A HREF="sdljoystickgetaxis.html" >SDL_JoystickGetAxis</A > -- Get the current state of an axis</DT ><DT ><A HREF="sdljoystickgethat.html" >SDL_JoystickGetHat</A > -- Get the current state of a joystick hat</DT ><DT ><A HREF="sdljoystickgetbutton.html" >SDL_JoystickGetButton</A > -- Get the current state of a given button on a given joystick</DT ><DT ><A HREF="sdljoystickgetball.html" >SDL_JoystickGetBall</A > -- Get relative trackball motion</DT ><DT ><A HREF="sdljoystickclose.html" >SDL_JoystickClose</A > -- Closes a previously opened joystick</DT ></DL ></DIV ><P >Joysticks, and other similar input devices, have a very strong role in game playing and SDL provides comprehensive support for them. Axes, Buttons, POV Hats and trackballs are all supported.</P ><P >Joystick support is initialized by passed the <TT CLASS="LITERAL" >SDL_INIT_JOYSTICK</TT > flag to <A HREF="sdlinit.html" ><TT CLASS="FUNCTION" >SDL_Init</TT ></A >. Once initilized joysticks must be opened using <A HREF="sdljoystickopen.html" ><TT CLASS="FUNCTION" >SDL_JoystickOpen</TT ></A >.</P ><P >While using the functions describe in this secton may seem like the best way to access and read from joysticks, in most cases they aren't. Ideally joysticks should be read using the <A HREF="event.html" >event</A > system. To enable this, you must set the joystick event processing state with <A HREF="sdljoystickeventstate.html" ><TT CLASS="FUNCTION" >SDL_JoystickEventState</TT ></A >. Joysticks must be <A HREF="sdljoystickopen.html" >opened</A > before they can be used of course.</P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B >If you are <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >not</I ></SPAN > handling the joystick via the event queue then you must explicitly request a joystick update by calling <A HREF="sdljoystickupdate.html" ><TT CLASS="FUNCTION" >SDL_JoystickUpdate</TT ></A >.</P ></BLOCKQUOTE ></DIV ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B >Force Feedback is not yet support. Sam (slouken@libsdl.org) is soliciting suggestions from people with force-feedback experience on the best wat to desgin the API.</P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdljoystickeventstate.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlnumjoysticks.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_JoystickEventState</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="reference.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_NumJoysticks</TD ></TR ></TABLE ></DIV ></BODY ></HTML >