299 lines
4.3 KiB
HTML
299 lines
4.3 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>SDL_LockSurface</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.64
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"><LINK
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REL="HOME"
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TITLE="SDL Library Documentation"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Video"
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HREF="video.html"><LINK
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REL="PREVIOUS"
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TITLE="SDL_FreeSurface"
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HREF="sdlfreesurface.html"><LINK
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REL="NEXT"
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TITLE="SDL_UnlockSurface"
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HREF="sdlunlocksurface.html"></HEAD
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><BODY
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CLASS="REFENTRY"
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BGCOLOR="#FFF8DC"
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TEXT="#000000"
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LINK="#0000ee"
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VLINK="#551a8b"
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ALINK="#ff0000"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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WIDTH="100%"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>SDL Library Documentation</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="sdlfreesurface.html"
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>Prev</A
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></TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="sdlunlocksurface.html"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><H1
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><A
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NAME="SDLLOCKSURFACE"
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>SDL_LockSurface</A
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></H1
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><DIV
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CLASS="REFNAMEDIV"
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><A
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NAME="AEN1504"
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></A
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><H2
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>Name</H2
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>SDL_LockSurface -- Lock a surface for directly access.</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN1507"
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></A
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><H2
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>Synopsis</H2
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><DIV
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CLASS="FUNCSYNOPSIS"
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><A
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NAME="AEN1508"
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></A
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><P
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></P
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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>#include "SDL.h"</PRE
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>int <B
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CLASS="FSFUNC"
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>SDL_LockSurface</B
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></CODE
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>(SDL_Surface *surface);</CODE
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></P
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><P
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></P
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></DIV
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN1514"
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></A
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><H2
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>Description</H2
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><P
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><TT
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CLASS="FUNCTION"
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>SDL_LockSurface</TT
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> sets up a surface for directly
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accessing the pixels. Between calls to <TT
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CLASS="FUNCTION"
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>SDL_LockSurface</TT
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>
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and <TT
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CLASS="FUNCTION"
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>SDL_UnlockSurface</TT
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>, you can write to and read from
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<TT
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CLASS="PARAMETER"
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><I
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>surface-><TT
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CLASS="STRUCTFIELD"
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><I
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>pixels</I
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></TT
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></I
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></TT
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>, using the pixel format stored in
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<TT
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CLASS="PARAMETER"
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><I
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>surface-><TT
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CLASS="STRUCTFIELD"
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><I
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>format</I
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></TT
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></I
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></TT
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>. Once you are done accessing the
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surface, you should use <TT
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CLASS="FUNCTION"
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>SDL_UnlockSurface</TT
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> to release it.</P
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><P
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>Not all surfaces require locking.
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If <TT
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CLASS="LITERAL"
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>SDL_MUSTLOCK</TT
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>(<TT
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CLASS="PARAMETER"
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><I
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>surface</I
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></TT
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>)
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evaluates to <SPAN
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CLASS="RETURNVALUE"
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>0</SPAN
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>, then you can read and write to the
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surface at any time, and the pixel format of the surface will not change. </P
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><P
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>No operating system or library calls should be made between lock/unlock
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pairs, as critical system locks may be held during this time.</P
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><P
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>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.
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<PRE
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CLASS="PROGRAMLISTING"
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> .
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.
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SDL_LockSurface( surface );
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.
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/* Surface is locked */
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/* Direct pixel access on surface here */
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.
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SDL_LockSurface( surface );
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.
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/* More direct pixel access on surface */
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.
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SDL_UnlockSurface( surface );
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/* Surface is still locked */
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/* Note: Is versions < 1.1.8, the surface would have been */
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/* no longer locked at this stage */
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.
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SDL_UnlockSurface( surface );
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/* Surface is now unlocked */
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.
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.</PRE
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>
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</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN1532"
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></A
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><H2
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>Return Value</H2
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><P
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><TT
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CLASS="FUNCTION"
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>SDL_LockSurface</TT
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> returns <SPAN
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CLASS="RETURNVALUE"
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>0</SPAN
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>,
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or <SPAN
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CLASS="RETURNVALUE"
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>-1</SPAN
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> if the surface couldn't be locked.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN1538"
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></A
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><H2
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>See Also</H2
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><P
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><A
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HREF="sdlunlocksurface.html"
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><TT
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CLASS="FUNCTION"
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>SDL_UnlockSurface</TT
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></A
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></P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
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VALIGN="top"
|
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><A
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HREF="sdlfreesurface.html"
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>Prev</A
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></TD
|
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
|
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><A
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HREF="index.html"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="sdlunlocksurface.html"
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>Next</A
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></TD
|
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></TR
|
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><TR
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><TD
|
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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>SDL_FreeSurface</TD
|
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><TD
|
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
|
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HREF="video.html"
|
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>Up</A
|
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></TD
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>SDL_UnlockSurface</TD
|
|
></TR
|
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></TABLE
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></DIV
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></BODY
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></HTML
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> |