window(3NCURSES) Library calls window(3NCURSES)
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). Subwin-
dows 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 po-
sition (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 sub-
window.
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 win-
dow.
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
Functions that return integers return ERR upon failure and OK upon suc-
cess.
Functions that return pointers return NULL on error.
ncurses defines several error conditions.
• 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.
• derwin returns ERR if orig is a null pointer, or if any of the ordi-
nate or dimension arguments is negative, or if the resulting window
does not fit inside the parent window.
• dupwin returns ERR if win is a null pointer.
• mvderwin returns ERR if win is a null pointer, or if any part of the
window would be placed off-screen.
• 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.
• newwin returns ERR if any of its arguments is negative.
• subwin returns ERR if orig is a null pointer, or if any of the ordi-
nate or dimension arguments is negative, or if the resulting window
does not fit inside the parent window.
• 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(3NCURSES) or newterm(3NCURSES).
NOTES
syncok may be implemented as a macro.
Calling syncup on a window and making many small changes to it could de-
grade performance.
PORTABILITY
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 suc-
cessful 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.
SEE ALSO
ncurses(3NCURSES), initscr(3NCURSES), refresh(3NCURSES),
touch(3NCURSES), curses_variables(3NCURSES)
ncurses 6.5 2025-02-01 window(3NCURSES)
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