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 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-
tion.
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
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 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
curses).
resizeterm(3x)