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view docs/html/sdlcreateyuvoverlay.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 >SDL_CreateYUVOverlay</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="Video" HREF="video.html"><LINK REL="PREVIOUS" TITLE="SDL_GL_SwapBuffers" HREF="sdlglswapbuffers.html"><LINK REL="NEXT" TITLE="SDL_LockYUVOverlay" HREF="sdllockyuvoverlay.html"></HEAD ><BODY CLASS="REFENTRY" 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="sdlglswapbuffers.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdllockyuvoverlay.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLCREATEYUVOVERLAY" ></A >SDL_CreateYUVOverlay</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN2808" ></A ><H2 >Name</H2 >SDL_CreateYUVOverlay -- Create a YUV video overlay</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN2811" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN2812" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_Overlay *<B CLASS="FSFUNC" >SDL_CreateYUVOverlay</B ></CODE >(int width, int height, Uint32 format, SDL_Surface *display);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2818" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_CreateYUVOverlay</TT > creates a YUV overlay of the specified <TT CLASS="PARAMETER" ><I >width</I ></TT >, <TT CLASS="PARAMETER" ><I >height</I ></TT > and <TT CLASS="PARAMETER" ><I >format</I ></TT > (see <A HREF="sdloverlay.html" ><SPAN CLASS="STRUCTNAME" >SDL_Overlay</SPAN ></A > for a list of available formats), for the provided <TT CLASS="PARAMETER" ><I >display</I ></TT >. A <A HREF="sdloverlay.html" ><SPAN CLASS="STRUCTNAME" >SDL_Overlay</SPAN ></A > structure is returned.</P ><P >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.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2831" ></A ><H2 >See Also</H2 ><P ><A HREF="sdloverlay.html" ><SPAN CLASS="STRUCTNAME" >SDL_Overlay</SPAN ></A >, <A HREF="sdldisplayyuvoverlay.html" ><TT CLASS="FUNCTION" >SDL_DisplayYUVOverlay</TT ></A >, <A HREF="sdlfreeyuvoverlay.html" ><TT CLASS="FUNCTION" >SDL_FreeYUVOverlay</TT ></A ></P ></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="sdlglswapbuffers.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="sdllockyuvoverlay.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_GL_SwapBuffers</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="video.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_LockYUVOverlay</TD ></TR ></TABLE ></DIV ></BODY ></HTML >