https://invisible-island.net/ncurses/man/
curs_window(3x) Library calls curs_window(3x)
newwin, delwin, mvwin, subwin, derwin, mvderwin, dupwin, wsyncup,
syncok, wcursyncup, wsyncdown - create and manipulate curses windows
#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);
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.
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.
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.
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.
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.
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.
Calling dupwin creates an exact duplicate of the window win.
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.
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.
The routine wcursyncup updates the current cursor position of all the
ancestors of the window to reflect the current cursor position of the
window.
Functions that return integers return ERR upon failure and OK upon
success.
Functions that return pointers return NULL on error.
ncurses defines several error conditions.
o delwin returns ERR if win is a null pointer, or if it is the parent
of another window.
ncurses maintains a list of windows, and checks that the pointer
passed to delwin is one that it created, returning ERR if it was
not.
o derwin returns ERR if orig is a null pointer, or if any of the
ordinate or dimension arguments is negative, or if the resulting
window does not fit inside the parent window.
o dupwin returns ERR if win is a null pointer.
o mvderwin returns ERR if win is a null pointer, or if any part of
the window would be placed off-screen.
o mvwin returns ERR if win is a null pointer, if win is a pad, or if
any part of the window would be placed off-screen.
o newwin returns ERR if any of its arguments is negative.
o subwin returns ERR if orig is a null pointer, or if any of the
ordinate or dimension arguments is negative, or if the resulting
window does not fit inside the parent window.
o syncok returns ERR if win is a null pointer.
Functions that return a window pointer fail if memory allocation for
their data structures fails.
All of these functions fail if the screen has not been initialized; see
initscr(3x) or newterm(3x).
syncok may be implemented as a macro.
Calling syncup on a window and making many small changes to it could
degrade performance.
X/Open Curses Issue 4 describes these functions. It specifies no error
conditions for delwin, derwin, dupwin, newwin, mvderwin, or syncok.
For functions returning integers (except delwin), SVr4 describes a
successful return value only as "an integer value other than ERR".
Regarding delwin, X/Open Curses states that
[t]he application must delete subwindows before deleting the
main window.
If delwin is asked to delete a parent window, it can succeed only if
the curses library keeps a list of its 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
(xcurses) does not make even that check, and will delete a parent
window that still has subwindows. PDCurses also behaves this way.
ncurses 4.0 (1996) and later maintains a list of windows for each
screen to ensure that a window has no subwindows before allowing its
deletion. NetBSD curses has followed suit since 2003.
SVr4 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
description and behavior of these functions in ncurses is patterned on
the X/Open Curses standard; this approach may result in slower updates.
curses(3x), curs_initscr(3x), curs_refresh(3x), curs_touch(3x),
curs_variables(3x)
ncurses 6.5 2025-01-18 curs_window(3x)