resizeterm 3x

resizeterm(3x)                                                  resizeterm(3x)


       is_term_resized,  resize_term,  resizeterm - change the curses terminal


       #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 windows, primarily for use by pro-
       grams 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 variables.


       Most  of the work is done by the inner function resize_term.  The outer
       function resizeterm adds bookkeeping 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
       appropriate data.  The resize_term function attempts to resize all win-
       dows.  However, due to the calling convention of pads, it is not possi-
       ble  to  resize  these without additional interaction with the applica-


       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.


       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  mem-
       ory for the windows.


       While  these functions are intended to be used to support a signal han-
       dler (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,

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

       o   which is tested in wgetch(3x) 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

           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  sys-
       tem.   Thus,  even if a SIGWINCH 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