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1 .TH "SDL_LockSurface" "3" "Mon 12 Mar 2001, 01:04" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_LockSurface\- Lock a surface for directly access\&.
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4 .SH "SYNOPSIS"
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5 .PP
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6 \fB#include "SDL\&.h"
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7 .sp
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8 \fBint \fBSDL_LockSurface\fP\fR(\fBSDL_Surface *surface\fR);
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9 .SH "DESCRIPTION"
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10 .PP
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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\&.
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12 .PP
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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\&.
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14 .PP
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15 No operating system or library calls should be made between lock/unlock pairs, as critical system locks may be held during this time\&.
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16 .PP
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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\&.
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18 .PP
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19 .nf
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20 \f(CW \&.
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21 \&.
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22 SDL_LockSurface( surface );
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23 \&.
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24 /* Surface is locked */
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25 /* Direct pixel access on surface here */
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26 \&.
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27 SDL_LockSurface( surface );
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28 \&.
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29 /* More direct pixel access on surface */
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30 \&.
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31 SDL_UnlockSurface( surface );
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32 /* Surface is still locked */
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33 /* Note: Is versions < 1\&.1\&.8, the surface would have been */
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34 /* no longer locked at this stage */
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35 \&.
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36 SDL_UnlockSurface( surface );
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37 /* Surface is now unlocked */
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38 \&.
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39 \&.\fR
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40 .fi
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41 .PP
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42
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43 .SH "RETURN VALUE"
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44 .PP
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45 \fBSDL_LockSurface\fP returns \fB0\fR, or \fB-1\fR if the surface couldn\&'t be locked\&.
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46 .SH "SEE ALSO"
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47 .PP
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48 \fI\fBSDL_UnlockSurface\fP\fR
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49 ...\" created by instant / docbook-to-man, Mon 12 Mar 2001, 01:04
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