curs_window(3X)

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). 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, 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.

  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 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 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.

NOTES
If many small changes are made to the window, the wsyncup option could degrade performance.

Note that syncok may be a macro.

PORTABILITY
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.

SEE ALSO
curses(3X), curs_initscr(3X), curs_refresh(3X), curs_touch(3X), curs_variables(3X)