resizeterm 3x

resizeterm(3x)                                           resizeterm(3x)


       is_term_resized,  resize_term,  resizeterm  -  change  the
       curses terminal size


       #include <curses.h>

       bool is_term_resized(int lines, int columns);
       int resize_term(int lines, int columns);
       int resizeterm(int lines, int columns);


       This is an extension to the curses library.   It  provides
       callers  with  a hook into the ncurses data to resize win-
       dows, primarily for use by programs running in an X Window
       terminal (e.g., xterm).


       The  function  resizeterm resizes the standard and current
       windows to the specified  dimensions,  and  adjusts  other
       bookkeeping  data  used by the ncurses library that record
       the window dimensions such as the  LINES  and  COLS  vari-


       Most   of   the   work  is  done  by  the  inner  function
       resize_term.  The outer function resizeterm adds bookkeep-
       ing  for the SIGWINCH handler.  When resizing the windows,
       resize_term blank-fills the areas that are extended.   The
       calling application should fill in these areas with appro-
       priate data.  The resize_term function attempts to  resize
       all  windows.   However,  due to the calling convention of
       pads, it is not possible to  resize  these  without  addi-
       tional interaction with the application.


       A  support  function  is_term_resized  is provided so that
       applications can check if the resize_term  function  would
       modify the window structures.  It returns TRUE if the win-
       dows would be modified, and FALSE otherwise.


       Except as noted, these functions return  the  integer  ERR
       upon  failure and OK on success.  They will fail if either
       of the dimensions are less than or equal to zero, or if an
       error occurs while (re)allocating memory for the windows.


       While these functions are intended to be used to support a
       signal handler (i.e., for SIGWINCH), care should be  taken
       to  avoid invoking them in a context where malloc or real-
       loc may have been interrupted, since it uses  those  func-

       If  ncurses  is configured to supply its own SIGWINCH han-

       o   on receipt of a SIGWINCH, the handler sets a flag

       o   which is tested in wgetch and doupdate,

       o   in turn, calling the resizeterm function,

       o   which ungetch's a KEY_RESIZE which will be read on the
           next call to wgetch.

           The  KEY_RESIZE  alerts an application that the screen
           size has changed, and that it should  repaint  special
           features  such  as  pads that cannot be done automati-

           Calling resizeterm or resize_term directly from a sig-
           nal  handler  is unsafe.  This indirect method is used
           to provide a safe  way  to  resize  the  ncurses  data

       If  the  environment  variables  LINES or COLUMNS are set,
       this overrides  the  library's  use  of  the  window  size
       obtained  from the operating system.  Thus, even if a SIG-
       WINCH is received, no screen size change may be recorded.


       It is possible to resize the screen with SVr4 curses, by

       o   exiting curses with endwin(3x) and

       o   resuming using refresh(3x).

       Doing that clears the screen and is visually distracting.

       This extension of ncurses was introduced in mid-1995.   It
       was adopted in NetBSD curses (2001) and PDCurses (2003).


       curs_getch(3x), curs_variables(3x), wresize(3x).


       Thomas Dickey (from an equivalent function written in 1988
       for BSD curses).