docs/man3/SDL_LockSurface.3
author Sam Lantinga <slouken@libsdl.org>
Wed, 08 Mar 2006 18:30:12 +0000
changeset 1486 9d77fc9d0ace
parent 181 e5bc29de3f0a
child 2283 546f7c1eb755
permissions -rw-r--r--
Re-added C runtime support for Visual C++ 5,6
     1 .TH "SDL_LockSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" 
     2 .SH "NAME"
     3 SDL_LockSurface\- Lock a surface for directly access\&.
     4 .SH "SYNOPSIS"
     5 .PP
     6 \fB#include "SDL\&.h"
     7 .sp
     8 \fBint \fBSDL_LockSurface\fP\fR(\fBSDL_Surface *surface\fR);
     9 .SH "DESCRIPTION"
    10 .PP
    11 \fBSDL_LockSurface\fP sets up a surface for directly accessing the pixels\&. Between calls to \fBSDL_LockSurface\fP and \fBSDL_UnlockSurface\fP, you can write to and read from \fBsurface->\fBpixels\fR\fR, using the pixel format stored in \fBsurface->\fBformat\fR\fR\&. Once you are done accessing the surface, you should use \fBSDL_UnlockSurface\fP to release it\&.
    12 .PP
    13 Not all surfaces require locking\&. If \fBSDL_MUSTLOCK\fP(\fBsurface\fR) evaluates to \fB0\fR, then you can read and write to the surface at any time, and the pixel format of the surface will not change\&. 
    14 .PP
    15 No operating system or library calls should be made between lock/unlock pairs, as critical system locks may be held during this time\&.
    16 .PP
    17 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\&. 
    18 .PP
    19 .nf
    20 \f(CW    \&.
    21     \&.
    22     SDL_LockSurface( surface );
    23     \&.
    24     /* Surface is locked */
    25     /* Direct pixel access on surface here */
    26     \&.
    27     SDL_LockSurface( surface );
    28     \&.
    29     /* More direct pixel access on surface */
    30     \&.
    31     SDL_UnlockSurface( surface );
    32     /* Surface is still locked */
    33     /* Note: Is versions < 1\&.1\&.8, the surface would have been */
    34     /* no longer locked at this stage                         */
    35     \&.
    36     SDL_UnlockSurface( surface );
    37     /* Surface is now unlocked */
    38     \&.
    39     \&.\fR
    40 .fi
    41 .PP
    42 .SH "RETURN VALUE"
    43 .PP
    44 \fBSDL_LockSurface\fP returns \fB0\fR, or \fB-1\fR if the surface couldn\&'t be locked\&.
    45 .SH "SEE ALSO"
    46 .PP
    47 \fI\fBSDL_UnlockSurface\fP\fR
    48 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01