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Date: Sun, 7 May 2006 19:22:33 -0400 From: Mike Frysinger Subject: [SDL] [patch] fix building with DirectFB-0.9.25.1 another DirectFB release, another small bit of API breakage :) this time around, DIKI_ALTGR has been removed and DIKI_ALT_R is supposed to be used ... DIKI_ALT_R is not a new define, so there shouldnt be any need for checking the DirectFB version ... it should work with older DirectFB's as well thanks to Sascha Schwarz for pointing this out on the Gentoo bugzilla: http://bugs.gentoo.org/132571 -mike
author Sam Lantinga <slouken@libsdl.org>
date Mon, 08 May 2006 02:09:34 +0000 (2006-05-08)
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_LockSurface</TITLE
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><H1
><A
NAME="SDLLOCKSURFACE"
></A
>SDL_LockSurface</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN1919"
></A
><H2
>Name</H2
>SDL_LockSurface&nbsp;--&nbsp;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-&#62;<TT
CLASS="STRUCTFIELD"
><I
>pixels</I
></TT
></I
></TT
>, using the pixel format stored in
<TT
CLASS="PARAMETER"
><I
>surface-&#62;<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 &#60; 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
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