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49 lines
1.9 KiB
Groff
49 lines
1.9 KiB
Groff
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.TH "SDL_LockSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference"
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.SH "NAME"
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SDL_LockSurface \- Lock a surface for directly access\&.
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.SH "SYNOPSIS"
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.PP
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\fB#include "SDL\&.h"
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.sp
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\fBint \fBSDL_LockSurface\fP\fR(\fBSDL_Surface *surface\fR);
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.SH "DESCRIPTION"
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.PP
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\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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.PP
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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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.PP
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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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.PP
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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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.PP
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.nf
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\f(CW \&.
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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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\&.\fR
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.fi
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.PP
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.SH "RETURN VALUE"
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.PP
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\fBSDL_LockSurface\fP returns \fB0\fR, or \fB-1\fR if the surface couldn\&'t be locked\&.
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.SH "SEE ALSO"
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.PP
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\fI\fBSDL_UnlockSurface\fP\fR
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.\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01
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