# curs_window 3x 2024-04-20 ncurses 6.5 Library calls

    curs_window(3x)                  Library calls                 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 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.

## PORTABILITY

           X/Open Curses, 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.

## BUGS

           The subwindow functions subwin, derwin, mvderwin,  wsyncup,  wsyncdown,
           wcursyncup,  and  syncok  are  flaky, incompletely implemented, and not
           well tested.

           System V's 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 language here, and behavior of 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)

    ncurses 6.5                       2024-04-20                   curs_window(3x)