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Date: 28 Jun 2003 22:42:52 +0100 From: Alan Swanson Subject: Re: [SDL] New XFree 4.3 Video Mode Patch I have a wee amendment that moves the qsort in set_best_resolution to only occur after failing to find an exact match only. This would make absolutely sure we get a user set mode. While I've never had any problems for my normal resolutions (1280x1024, 1024x768, 800x600 & 640,480) while closely examining the output from qsort I've noticed it doesn't seem to sort the modes fully. These is one definite wrong at 1152x768 and a few that just look wrong to me. From a program (attached) I made to examine this more easily. X has sorted its mode list using the same method as ours (plus frequency), and our user modes get inserted without any other movement. On the patch I've made I've also changed cmpmodes to sort on vertical resolution and then horizontal. Ie vertical is now most significant bit.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 28 Jun 2003 21:52:26 +0000
parents e5bc29de3f0a
children 355632dca928
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<HTML
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>SDL_LockSurface</TITLE
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><H1
><A
NAME="SDLLOCKSURFACE"
>SDL_LockSurface</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN1535"
></A
><H2
>Name</H2
>SDL_LockSurface&nbsp;--&nbsp;Lock a surface for directly access.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN1538"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN1539"
></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="AEN1545"
></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="AEN1563"
></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="AEN1569"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlunlocksurface.html"
><TT
CLASS="FUNCTION"
>SDL_UnlockSurface</TT
></A
></P
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