Mercurial > sdl-ios-xcode

view docs/man3/SDL_LockSurface.3 @ 3162:dc1eb82ffdaa

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Von: Thomas Zimmermann Betreff: [SDL] [PATCH] Make static variables const Datum: Tue, 19 May 2009 19:45:37 +0200 Hi, this is a set of simple changes which make some of SDL's internal static arrays constant. The purpose is to shrink the number of write-able static bytes and thus increase the number of memory pages shared between SDL applications. The patch set is against trunk@4513. Each of the attached patch files is specific to a sub-system. The set is completed by a second mail, because of the list's 40 KiB limit. The files readelf-r4513.txt and readelf-const-patch.txt where made by calling 'readelf -S libSDL.so'. They show the difference in ELF sections without and with the patch. Some numbers measured on my x86-64: Before [13] .rodata PROGBITS 00000000000eaaa0 000eaaa0 0000000000008170 0000000000000000 A 0 0 32 [19] .data.rel.ro PROGBITS 00000000003045e0 001045e0 00000000000023d0 0000000000000000 WA 0 0 32 [23] .data PROGBITS 00000000003076e0 001076e0 0000000000004988 0000000000000000 WA 0 0 32 After [13] .rodata PROGBITS 00000000000eaaa0 000eaaa0 0000000000009a50 0000000000000000 A 0 0 32 [19] .data.rel.ro PROGBITS 0000000000306040 00106040 0000000000002608 0000000000000000 WA 0 0 32 [23] .data PROGBITS 0000000000309360 00109360 0000000000002e88 0000000000000000 WA 0 0 32 The size of the write-able data section decreased considerably. Some entries became const-after-relocation, while most of its content went straight into the read-only data section. Best regards, Thomas
author Sam Lantinga <slouken@libsdl.org>
date Wed, 03 Jun 2009 04:37:27 +0000
parents 546f7c1eb755
children 1238da4a7112
line wrap: on
line source

.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