curs_window(3) curs_window(3)
NAME
newwin, delwin, mvwin, subwin, derwin, mvderwin, dupwin, wsyncup, syncok,
wcursyncup, wsyncdown - create 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, 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.
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.
BUGS
The subwindow functions (subwin, derwin, mvderwin, wsyncup, wsyncdown,
wcursyncup, syncok) are flaky, incompletely implemented, and not well
tested.
The System V curses documentation is very unclear about what wsyncup and
wsyncdown actually do. It seems to imply that they are only supposed to
touch exactly those lines that are affected by ancestor changes. The
language here, and the behavior of the curses implementation, is
patterned on the XPG4 curses standard. The weaker XPG4 spec may result
in slower updates.
PORTABILITY
The XSI Curses standard, 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.
SEE ALSO
curses(3X), curs_initscr(3X), curs_refresh(3X), curs_touch(3X),
curs_variables(3X)
curs_window(3)
ncurses 6.4 - Generated Thu Jan 5 19:02:03 CST 2023