Mercurial > sdl-ios-xcode
view docs/html/sdllocksurface.html @ 3261:72b542f34739
The new, cleaner, version of the atomic operations. The dummy code is what you should start working with to port atomic ops.
The linux code appears to be complete and *should* be the base of all Unix and GCC based versions. The macosx and win32 versions
are currently just copies of the dummy code. I will begin working on the windows version as soon as this check in is done. I
need someone to work on the Mac OS X version.
I'm afraid that this check in will break QNX (Sorry!)
author | Bob Pendleton <bob@pendleton.com> |
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date | Thu, 17 Sep 2009 20:35:12 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_LockSurface</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_FreeSurface" HREF="sdlfreesurface.html"><LINK REL="NEXT" TITLE="SDL_UnlockSurface" HREF="sdlunlocksurface.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="sdlfreesurface.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlunlocksurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLLOCKSURFACE" ></A >SDL_LockSurface</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN1919" ></A ><H2 >Name</H2 >SDL_LockSurface -- Lock a surface for directly access.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN1922" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN1923" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_LockSurface</B ></CODE >(SDL_Surface *surface);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1929" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_LockSurface</TT > sets up a surface for directly accessing the pixels. Between calls to <TT CLASS="FUNCTION" >SDL_LockSurface</TT > and <TT CLASS="FUNCTION" >SDL_UnlockSurface</TT >, you can write to and read from <TT CLASS="PARAMETER" ><I >surface-><TT CLASS="STRUCTFIELD" ><I >pixels</I ></TT ></I ></TT >, using the pixel format stored in <TT CLASS="PARAMETER" ><I >surface-><TT CLASS="STRUCTFIELD" ><I >format</I ></TT ></I ></TT >. Once you are done accessing the surface, you should use <TT CLASS="FUNCTION" >SDL_UnlockSurface</TT > to release it.</P ><P >Not all surfaces require locking. If <TT CLASS="LITERAL" >SDL_MUSTLOCK</TT >(<TT CLASS="PARAMETER" ><I >surface</I ></TT >) evaluates to <SPAN CLASS="RETURNVALUE" >0</SPAN >, then you can read and write to the surface at any time, and the pixel format of the surface will not change. </P ><P >No operating system or library calls should be made between lock/unlock pairs, as critical system locks may be held during this time.</P ><P >It should be noted, that since SDL 1.1.8 surface locks are recursive. This means that you can lock a surface multiple times, but each lock must have a match unlock. <PRE CLASS="PROGRAMLISTING" > . . SDL_LockSurface( surface ); . /* Surface is locked */ /* Direct pixel access on surface here */ . SDL_LockSurface( surface ); . /* More direct pixel access on surface */ . SDL_UnlockSurface( surface ); /* Surface is still locked */ /* Note: Is versions < 1.1.8, the surface would have been */ /* no longer locked at this stage */ . SDL_UnlockSurface( surface ); /* Surface is now unlocked */ . .</PRE ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1947" ></A ><H2 >Return Value</H2 ><P ><TT CLASS="FUNCTION" >SDL_LockSurface</TT > returns <SPAN CLASS="RETURNVALUE" >0</SPAN >, or <SPAN CLASS="RETURNVALUE" >-1</SPAN > if the surface couldn't be locked.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1953" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlunlocksurface.html" ><TT CLASS="FUNCTION" >SDL_UnlockSurface</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="sdlfreesurface.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="sdlunlocksurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_FreeSurface</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_UnlockSurface</TD ></TR ></TABLE ></DIV ></BODY ></HTML >