curs_kernel(3) Library calls curs_kernel(3)
NAME
def_prog_mode, def_shell_mode, reset_prog_mode, reset_shell_mode,
resetty, savetty, getsyx, setsyx, ripoffline, curs_set, napms - low-
level curses routines
SYNOPSIS
#include <curses.h>
int def_prog_mode(void);
int def_shell_mode(void);
int reset_prog_mode(void);
int reset_shell_mode(void);
int resetty(void);
int savetty(void);
void getsyx(int y, int x);
void setsyx(int y, int x);
int ripoffline(int line, int (*init)(WINDOW *, int));
int curs_set(int visibility);
int napms(int ms);
DESCRIPTION
The following routines give low-level access to various curses
capabilities. These routines typically are used inside library
routines.
def_prog_mode, def_shell_mode
The def_prog_mode and def_shell_mode routines save the current terminal
modes as the "program" (in curses) or "shell" (not in curses) state for
use by the reset_prog_mode and reset_shell_mode routines. This is done
automatically by initscr. There is one such save area for each screen
context allocated by newterm.
reset_prog_mode, reset_shell_mode
The reset_prog_mode and reset_shell_mode routines restore the terminal
to "program" (in curses) or "shell" (out of curses) state. These are
done automatically by endwin(3X) and, after an endwin, by doupdate, so
they normally are not called.
resetty, savetty
The resetty and savetty routines save and restore the state of the
terminal modes. savetty saves the current state in a buffer and
resetty restores the state to what it was at the last call to savetty.
getsyx
The getsyx routine returns the current coordinates of the virtual
screen cursor in y and x. If leaveok is currently TRUE, then -1,-1 is
returned. If lines have been removed from the top of the screen, using
ripoffline, y and x include these lines; therefore, y and x should be
used only as arguments for setsyx.
Few applications will use this feature, most use getyx instead.
setsyx
The setsyx routine sets the virtual screen cursor to y, x. If y and x
are both -1, then leaveok is set. The two routines getsyx and setsyx
are designed to be used by a library routine, which manipulates curses
windows but does not want to change the current position of the
program's cursor. The library routine would call getsyx at the
beginning, do its manipulation of its own windows, do a wnoutrefresh on
its windows, call setsyx, and then call doupdate.
Few applications will use this feature, most use wmove instead.
ripoffline
ripoffline provides access to the same facility that slk_init(3X) uses
to reduce the size of the screen. ripoffline must be called before
initscr or newterm is called, to prepare these initial actions:
o If line is positive, a line is removed from the top of stdscr.
o if line is negative, a line is removed from the bottom.
When the resulting initialization is done inside initscr, the routine
init (supplied by the user) is called with two arguments:
o a window pointer to the one-line window that has been allocated and
o an integer with the number of columns in the window.
Inside this initialization routine, the integer variables LINES and
COLS (defined in <curses.h>) are not guaranteed to be accurate and
wrefresh or doupdate must not be called. It is allowable to call
wnoutrefresh during the initialization routine.
ripoffline can be called up to five times before calling initscr or
newterm.
curs_set
The curs_set routine sets the cursor state to invisible, normal, or
very visible for visibility equal to 0, 1, or 2 respectively. If the
terminal supports the visibility requested, the previous cursor state
is returned; otherwise, ERR is returned.
napms
napms sleeps for ms milliseconds. If ms exceeds 30,000 (thirty
seconds), it is capped at that value.
RETURN VALUE
Except for curs_set, these routines always return OK.
curs_set returns the previous cursor state, or ERR if the requested
visibility is not supported.
X/Open defines no error conditions. In this implementation
def_prog_mode, def_shell_mode, reset_prog_mode, reset_shell_mode
return an error if the terminal was not initialized, or if the I/O
call to obtain the terminal settings fails.
ripoffline
returns an error if the maximum number of ripped-off lines exceeds
the maximum (5).
NOTES
Note that getsyx is a macro, so & is not necessary before the variables
y and x.
Older SVr4 man pages warn that the return value of curs_set "is
currently incorrect". This implementation gets it right, but it may be
unwise to count on the correctness of the return value anywhere else.
Both ncurses and SVr4 will call curs_set in endwin if curs_set has been
called to make the cursor other than normal, i.e., either invisible or
very visible. There is no way for ncurses to determine the initial
cursor state to restore that.
PORTABILITY
The virtual screen functions setsyx and getsyx are not described in
X/Open Curses, Issue 4. All other functions are as described in X/Open
Curses.
The SVr4 documentation describes setsyx and getsyx as having return
type int. This is misleading, as they are macros with no documented
semantics for the return value.
If interrupted, ncurses restarts napms. That, and the limitation to 30
seconds, are different from other implementations.
SEE ALSO
curses(3X), curs_initscr(3X), curs_outopts(3X), curs_refresh(3X),
curs_scr_dump(3X), curs_slk(3X), curs_variables(3X)
ncurses 6.5 2024-04-20 curs_kernel(3)
ncurses 6.5 - Generated Wed May 1 13:57:52 CDT 2024