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.
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 ERR if the window pointer is null, or if the window is the
parent of another window.
derwin
returns ERR 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 ERR 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 ERR if the window pointer is null, or if some part of the
window would be placed off-screen.
mvwin
returns ERR 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 ERR if the window pointer is null.
subwin
returns ERR 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.
If many small changes are made to the window, the wsyncup option could
degrade performance.
Note that syncok may be a macro.
X/Open Curses, Issue 4 describes these functions.
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 2024-09-14 curs_window(3x)