resizeterm(3x) — Linux manual page


resizeterm(3X)                                            resizeterm(3X)

NAME         top

       is_term_resized, resize_term, resizeterm - change the curses
       terminal size

SYNOPSIS         top

       #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         top

       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.,

       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.

       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

       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

       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.

       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         top

       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         top

       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         top

       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         top

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

AUTHOR         top

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

COLOPHON         top

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