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view docs/html/sdlpauseaudio.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_PauseAudio</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="Audio" HREF="audio.html"><LINK REL="PREVIOUS" TITLE="SDL_OpenAudio" HREF="sdlopenaudio.html"><LINK REL="NEXT" TITLE="SDL_GetAudioStatus" HREF="sdlgetaudiostatus.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="sdlopenaudio.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlgetaudiostatus.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLPAUSEAUDIO" >SDL_PauseAudio</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN6377" ></A ><H2 >Name</H2 >SDL_PauseAudio -- Pauses and unpauses the audio callback processing</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN6380" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN6381" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >void <B CLASS="FSFUNC" >SDL_PauseAudio</B ></CODE >(int pause_on);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6387" ></A ><H2 >Description</H2 ><P >This function pauses and unpauses the audio callback processing. It should be called with <TT CLASS="PARAMETER" ><I >pause_on</I ></TT >=0 after opening the audio device to start playing sound. This is so you can safely initialize data for your callback function after opening the audio device. Silence will be written to the audio device during the pause.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6391" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlgetaudiostatus.html" ><TT CLASS="FUNCTION" >SDL_GetAudioStatus</TT ></A >, <A HREF="sdlopenaudio.html" ><TT CLASS="FUNCTION" >SDL_OpenAudio</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="sdlopenaudio.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="sdlgetaudiostatus.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_OpenAudio</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="audio.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_GetAudioStatus</TD ></TR ></TABLE ></DIV ></BODY ></HTML >