curs_window(3) Library calls curs_window(3)
NAME
newwin, delwin, mvwin, subwin, derwin, mvderwin, dupwin, wsyncup,
syncok, wcursyncup, wsyncdown - create and manipulate curses windows
SYNOPSIS
#include <curses.h>
WINDOW *newwin(
int nlines, int ncols,
int begin_y, int begin_x);
int delwin(WINDOW *win);
int mvwin(WINDOW *win, int y, int x);
WINDOW *subwin(WINDOW *orig,
int nlines, int ncols,
int begin_y, int begin_x);
WINDOW *derwin(WINDOW *orig,
int nlines, int ncols,
int begin_y, int begin_x);
int mvderwin(WINDOW *win, int par_y, int par_x);
WINDOW *dupwin(WINDOW *win);
void wsyncup(WINDOW *win);
int syncok(WINDOW *win, bool bf);
void wcursyncup(WINDOW *win);
void wsyncdown(WINDOW *win);
DESCRIPTION
newwin
Calling newwin creates and returns a pointer to a new window with the
given number of lines and columns. The upper left-hand corner of the
window is at
line begin_y,
column begin_x
If either nlines or ncols is zero, they default to
LINES - begin_y and
COLS - begin_x.
A new full-screen window is created by calling newwin(0,0,0,0).
Regardless of the function used for creating a new window (e.g.,
newwin, subwin, derwin, newpad), rather than a duplicate (with dupwin),
all of the window modes are initialized to the default values. These
functions set window modes after a window is created:
idcok idlok immedok keypad leaveok nodelay scrollok setscrreg
syncok wbkgdset wbkgrndset and wtimeout.
delwin
Calling delwin deletes the named window, freeing all memory associated
with it (it does not actually erase the window's screen image).
Subwindows must be deleted before the main window can be deleted.
mvwin
Calling mvwin moves the window so that the upper left-hand corner is at
position (x, y). If the move would cause the window to be off the
screen, it is an error and the window is not moved. Moving subwindows
is allowed, but should be avoided.
subwin
Calling subwin creates and returns a pointer to a new window with the
given number of lines, nlines, and columns, ncols. The window is at
position (begin_y, begin_x) on the screen. The subwindow shares memory
with the window orig, its ancestor, so that changes made to one window
will affect both windows. When using this routine, it is necessary to
call touchwin or touchline on orig before calling wrefresh on the
subwindow.
derwin
Calling derwin is the same as calling subwin, except that begin_y and
begin_x are relative to the origin of the window orig rather than the
screen. There is no difference between the subwindows and the derived
windows.
mvderwin
Calling mvderwin moves a derived window (or subwindow) inside its
parent window. The screen-relative parameters of the window are not
changed. This routine is used to display different parts of the parent
window at the same physical position on the screen.
dupwin
Calling dupwin creates an exact duplicate of the window win.
wsyncup
Calling wsyncup touches all locations in ancestors of win that are
changed in win. If syncok is called with second argument TRUE then
wsyncup is called automatically whenever there is a change in the
window.
wsyncdown
The wsyncdown routine touches each location in win that has been
touched in any of its ancestor windows. This routine is called by
wrefresh, so it should almost never be necessary to call it manually.
wcursyncup
The routine wcursyncup updates the current cursor position of all the
ancestors of the window to reflect the current cursor position of the
window.
RETURN VALUE
Routines that return an integer return the integer ERR upon failure and
OK (SVr4 only specifies "an integer value other than ERR") upon
successful completion.
Routines that return pointers return NULL on error.
X/Open defines no error conditions. In this implementation
delwin
returns an error if the window pointer is null, or if the window
is the parent of another window.
derwin
returns an error if the parent window pointer is null, or if any
of its ordinates or dimensions is negative, or if the resulting
window does not fit inside the parent window.
dupwin
returns an error if the window pointer is null.
This implementation also maintains a list of windows, and checks
that the pointer passed to delwin is one that it created,
returning an error if it was not..
mvderwin
returns an error if the window pointer is null, or if some part of
the window would be placed off-screen.
mvwin
returns an error if the window pointer is null, or if the window
is really a pad, or if some part of the window would be placed
off-screen.
newwin
will fail if either of its beginning ordinates is negative, or if
either the number of lines or columns is negative.
syncok
returns an error if the window pointer is null.
subwin
returns an error if the parent window pointer is null, or if any
of its ordinates or dimensions is negative, or if the resulting
window does not fit inside the parent window.
The functions which return a window pointer may also fail if there is
insufficient memory for its data structures. Any of these functions
will fail if the screen has not been initialized, i.e., with initscr or
newterm.
NOTES
If many small changes are made to the window, the wsyncup option could
degrade performance.
Note that syncok may be a macro.
PORTABILITY
X/Open Curses, Issue 4 describes these functions.
X/Open Curses states regarding delwin:
o It must delete subwindows before deleting their parent.
o If delwin is asked to delete a parent window, it can only succeed
if the curses library keeps a list of the subwindows. SVr4 curses
kept a count of the number of subwindows rather than a list. It
simply returned ERR when asked to delete a subwindow. Solaris
X/Open curses does not even make that check, and will delete a
parent window which still has subwindows.
o Since release 4.0 (1996), ncurses maintains a list of windows for
each screen, to ensure that a window has no subwindows before
allowing deletion.
o NetBSD copied this feature of ncurses in 2003.
PDCurses follows the scheme used in Solaris X/Open curses.
BUGS
The subwindow functions subwin, derwin, mvderwin, wsyncup, wsyncdown,
wcursyncup, and syncok are flaky, incompletely implemented, and not
well tested.
System V's curses documentation is unclear about what wsyncup and
wsyncdown actually do. It seems to imply that they are supposed to
touch only those lines that are affected by changes to a window's
ancestors. The language here, and behavior of ncurses, is patterned on
the X/Open Curses standard; this approach may result in slower updates.
SEE ALSO
curses(3X), curs_initscr(3X), curs_refresh(3X), curs_touch(3X),
curs_variables(3X)
ncurses 6.5 2024-04-20 curs_window(3)
ncurses 6.5 - Generated Sun May 5 16:03:38 CDT 2024