resizeterm(3X)                                                  resizeterm(3X)

NAME
       is_term_resized, resize_term, resizeterm - change the curses terminal
       size

SYNOPSIS
       #include <curses.h>

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

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

   resizeterm
       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 variables.

   resize_term
       Most of the work is done by the inner function resize_term.  The outer
       function resizeterm adds bookkeeping for the SIGWINCH handler, as well
       as repainting the soft-key area (see slk_touch(3X)).

       When resizing the windows, resize_term blank-fills the areas that are
       extended.  The calling application should fill in these areas with
       appropriate 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 additional interaction with the application.

       When resizing windows, resize_term recursively adjusts subwindows,
       keeping them within the updated parent window's limits.  If a top-level
       window happens to extend to the screen's limits, then on resizing the
       window, resize_term will keep the window extending to the corresponding
       limit, regardless of whether the screen has shrunk or grown.

   is_term_resized
       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 windows would be modified, and FALSE otherwise.

RETURN VALUE
       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.

NOTES
       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 realloc may have been interrupted,
       since it uses those functions.

       If ncurses is configured to supply its own SIGWINCH handler,

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

       • which is tested in wgetch(3X) and doupdate,

       • in turn, calling the resizeterm function,

       • 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 automatically.

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

       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 SIGWINCH is received, no screen size change
       may be recorded.

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

       • exiting curses with endwin(3X) and

       • 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).

SEE ALSO
       curs_getch(3X), curs_variables(3X), wresize(3X).

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

                                                                resizeterm(3X)