docs/man3/SDL_LockSurface.3
changeset 3352 6dc250ebdd80
parent 3351 8e0182c236d8
child 3353 6b14223dd5c7
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3351:8e0182c236d8 3352:6dc250ebdd80
     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