[sdl_omap.git] / docs / man3 / SDL_LockSurface.3

.TH "SDL_LockSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_LockSurface \- Lock a surface for directly access\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
.sp
\fBint \fBSDL_LockSurface\fP\fR(\fBSDL_Surface *surface\fR);
.SH "DESCRIPTION"
.PP
\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\&.
.PP
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\&. 
.PP
No operating system or library calls should be made between lock/unlock pairs, as critical system locks may be held during this time\&.
.PP
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\&. 
.PP
.nf
\f(CW    \&.
    \&.
    SDL_LockSurface( surface );
    \&.
    /* Surface is locked */
    /* Direct pixel access on surface here */
    \&.
    SDL_LockSurface( surface );
    \&.
    /* More direct pixel access on surface */
    \&.
    SDL_UnlockSurface( surface );
    /* Surface is still locked */
    /* Note: Is versions < 1\&.1\&.8, the surface would have been */
    /* no longer locked at this stage                         */
    \&.
    SDL_UnlockSurface( surface );
    /* Surface is now unlocked */
    \&.
    \&.\fR
.fi
.PP
.SH "RETURN VALUE"
.PP
\fBSDL_LockSurface\fP returns \fB0\fR, or \fB-1\fR if the surface couldn\&'t be locked\&.
.SH "SEE ALSO"
.PP
\fI\fBSDL_UnlockSurface\fP\fR
.\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01
Commit	Line	Data
e14743d1	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