- 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 dimen-
- sions, and adjusts other bookkeeping data used by the
- ncurses library that record the window dimensions.
-
- 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.
+
+ 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) when the
+ terminal's screen size is changed by the user:
+ ocurses windows cannot extend outside the screen. If the terminal
+ is shrunk, curses windows must be shrunk to fit.
-
-
RETURN VALUE
- Except as notes, these function 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.
+ o If the terminal is stretched, rows and/or columns can be added to
+ existing windows. The added cells should match the current
+ attributes of the windows.
+ If the calling program has not set up a handler for SIGWINCH when it
+ initializes ncurses (e.g., using initscr(3x) or newterm(3x)), then
+ ncurses sets a handler for SIGWINCH which notifies the library when a
+ window-size event has occurred. The library checks for this
+ notification
-
-
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 real-
- loc may have been interrupted, since it uses those func-
- tions.
-
- If ncurses is configured to supply its own SIGWINCH han-
- dler, the resizeterm function ungetch's a KEY_RESIZE which
- will be read on the next call to getch. This is used to
- alert an application that the screen size has changed, and
- that it should repaint special features such as pads that
- cannot be done automatically.
-
- 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.
- In that case, no KEY_RESIZE is queued for the next call to
- getch; an ERR will be returned instead.
+ o when reading input data,
+ o when implicitly resuming program mode (e.g., between endwin(3x) and
+ wrefresh(3x)), and
-
-
SEE ALSO
- curs_variables(3x), wresize(3x).
+ o when explicitly resuming program mode in restartterm(3x).
+ When the library has found that the terminal's window-size has changed,
+ it calls resizeterm to update its data structures.
-
-
AUTHOR
- Thomas Dickey (from an equivalent function written in 1988
- for BSD curses).
+ An application which establishes its own SIGWINCH handler can call
+ resizeterm, but in that case, the library will not see SIGWINCH, and
+ proper layout will rely upon the application.
+
+
+
+ The function resizeterm resizes the standard and current windows (i.e.,
+ stdscr and curscr) 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 for resizeterm 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)).
+
+ The resize_term function attempts to resize all windows. This helps
+ with simple applications. However:
+
+ o It is not possible to automatically resize pads.
+
+ o Applications which have complicated layouts should check for
+ KEY_RESIZE returned from wgetch, and adjust their layout, e.g.,
+ using wresize and mvwin, or by recreating the windows.
+
+ 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.
+
+
+
+ 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 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), doupdate(3x) and restartterm(3x),
+
+ 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
+ system. 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).
+
+
+