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vga_flip(3) [centos man page]

vga_flip(3)							Svgalib User Manual						       vga_flip(3)

NAME

       vga_flip - toggle between text and graphics mode

SYNOPSIS

       #include <vga.h>

       int vga_flip(void);

DESCRIPTION

       switches  between  graphics  and  text mode without destroying the screen contents. This makes it possible for your application to use both
       text and graphics output.

       However, This is an old vgalib function. You should really only use it for debugging as it runs extremely unstable because svgalib now does
       its  own  virtual  console  management. If you want to perform a similar action, save the current screen contents with ordinary memory copy
       operation to the frame buffer or gl_getbox(3), set vga_setmode(TEXT), then call vga_setmode(3) to return to graphics operation and  restore
       the screen contents with memory or gl_putbox(3).

       One could also use vga_drawscansegment(3) and vga_getscansegment(3) calls.

       However, avoid any calls to vga_flip() in your applications.

       The function always returns 0, a fact on which you shouldn't rely.

       It  might  be  useful if you are debugging one of your svgalib applications though.  If your program reaches a breakpoint while in graphics
       mode, you can switch to text mode with the gdb command

       print vga_flip()

       and later restore the graphics screen contents with the same command.  It is useful to define the following alias in gdb:

       define flip <Return> print vga_flip() <Return> end <Return>

SEE ALSO

       svgalib(7), vgagl(7),  libvga.config(5),  vga_init(3),  vga_setflipchar(3),  vga_drawscanline(3),  vga_drawscansegment(3),  vga_getscanseg-
       ment(3), gl_getbox(3), gl_putbox(3)

AUTHOR

       This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the referenced function as well as of the
       original documentation is unknown.

       It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.

       Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or  corrections
       to this first version of the svgalib manual.

Svgalib (>;= 1.2.11)						   27 July 1997 						       vga_flip(3)

Check Out this Related Man Page

vga_safety_fork(3)						Svgalib User Manual						vga_safety_fork(3)

NAME

       vga_safety_fork - start a parallel process to restore the console at a crash

SYNOPSIS

       #include <vga.h>

       void vga_safety_fork(void (*shutdown_routine)(void))

DESCRIPTION

       Calling	this  at the start of a program results in a better chance of textmode being restored in case of a crash.  However it has to raise
       the iopl level to 3 to work. This is a small security breach as it is inherited to any programs you fork of. However, some SVGA card  driv-
       ers have to use iopl(3) anyway.	If you use it call that function as the very first vga_ function. Call it right before vga_init (3).  Note
       that vga_safety_fork() will already enter a graphicsmode. (For font and grafix state saving).  Don't overestimate the power of  this  func-
       tion.  Your application will continue to run in background while a foreground application will restore a usable screen and graphics mode in
       case of a crash.

       The forktest(6) demo shows the principal operation.  (*shutdown_routine)() is called when the system crashes.  However,	realize  that  the
       call will take in a forked copy of your program, you'll not have access to any globals modified after the vga_safety_fork() call!

SEE ALSO

       svgalib(7), vgagl(7), libvga.config(5), forktest(6), vga_init(3),

AUTHOR

       This manual page was edited by Michael Weller <eowmob@exp-math.uni-essen.de>. The exact source of the referenced function as well as of the
       original documentation is unknown.

       It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.

       Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or  corrections
       to this first version of the svgalib manual.

Svgalib (>;= 1.2.11)						   27 July 1997 						vga_safety_fork(3)
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