newwin, delwin, mvwin, subwin, derwin,
mvderwin, dupwin, wsyncup, syncok,
wcursyncup, wsyncdown - create curses windows
#include <ncurses/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, 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 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.
If many small changes are made to the window, the wsyncup option could
degrade performance.
Note that syncok may be a macro.
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.
The XSI Curses standard, Issue 4 describes these functions.
X/Open Curses states regarding delwin:
- It must delete subwindows before deleting their parent.
- 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.
- 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.
- NetBSD copied this feature of ncurses in 2003.
PDCurses follows the scheme used in Solaris X/Open curses.