| 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 |