derwin(3ncurses)

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).

   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.

SEE ALSO

   ncurses(3NCURSES),          refresh(3NCURSES),         touch(3NCURSES),
   curses_variables(3NCURSES)

                                                          window(3NCURSES)

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