- The getsyx routine returns the current coordinates of the virtual
- screen cursor in y and x. If leaveok is currently TRUE, then -1,-1 is
- returned. If lines have been removed from the top of the screen, using
- ripoffline, y and x include these lines; therefore, y and x should be
- used only as arguments for setsyx.
+ getsyx stores the coordinates of virtual screen (newscr) cursor in y
+ and x. If newscr's leaveok(3x) output option is TRUE, getsyx stores -1
+ in both y and x. If lines have been removed from the top of the screen
+ using ripoffline, y includes these lines; therefore, y and x populated
+ by getsyx should be used only as arguments for setsyx.
- Few applications will use this feature, most use getyx instead.
+ Few applications use this feature; most call getyx(3x) instead.
- The setsyx routine sets the virtualscreen cursor to y, x. If y and x
- are both -1, then leaveok is set. The two routines getsyx and setsyx
- are designed to be used by a library routine, which manipulates curses
- windows but does not want to change the current position of the
- program's cursor. The library routine would call getsyx at the
- beginning, do its manipulation of its own windows, do a wnoutrefresh on
- its windows, call setsyx, and then call doupdate.
+ setsyx sets the virtual screen (newscr) cursor location to (y, x).
+ setsyx(-1,-1) is equivalent to leaveok(newscr,TRUE).
+
+ getsyx and setsyx are designed to be used by a function that
+ manipulates curses windows but seeks to avoid changing the cursor
+ position. Such a function would first call getsyx, modify its windows'
+ content, call wnoutrefresh(3x) on them, call setsyx, then call
+ doupdate(3x).
+
+ Few applications use this feature; most call wmove(3x) instead.
+
- Few applications will use this feature, most use wmove instead.
+
+ The curs_set routine sets the cursor state to invisible, normal, or
+ very visible for visibility equal to 0, 1, or 2 respectively. If the
+ terminal supports the visibility requested, the previous cursor state
+ is returned; otherwise, ERR is returned.
+
+
+
+ mvcur provides low-level cursor motion. It takes effect immediately,
+ rather than at the next refresh. Unlike the other low-level output
+ functions, which either write to the standard output stream or are
+ passed a function pointer to perform output, mvcur uses a file
+ descriptor derived from the output stream parameter of newterm(3x).
+
+ One application of mvcur accompanies the temporary use of another
+ program to write to the terminal screen. For example, first call
+ refresh(3x) to ensure that the screen and the library's model of it is
+ up to date; then call reset_shell_mode; write to the screen with the
+ external application; call reset_prog_mode; and finally call mvcur to
+ set the cursor's location to where curses thinks it is, since the
+ library has no knowledge of how the external application moved it.
+
+
+
- ripoffline provides access to the same facility that slk_init(3x) uses
- to reduce the size of the screen. ripoffline must be called before
+ ripoffline provides access to the same facility that slk_init(3x) uses
+ to reduce the size of the screen. ripoffline must be called before
initscr or newterm is called, to prepare these initial actions:
o If line is positive, a line is removed from the top of stdscr.
o if line is negative, a line is removed from the bottom.
- When the resulting initialization is done inside initscr, the routine
+ When the resulting initialization is done inside initscr, the routine
init (supplied by the user) is called with two arguments:
o a window pointer to the one-line window that has been allocated and
o an integer with the number of columns in the window.
- Inside this initialization routine, the integer variables LINES and
- COLS (defined in <curses.h>) are not guaranteed to be accurate and
- wrefresh or doupdate must not be called. It is allowable to call
+ Inside this initialization routine, the integer variables LINES and
+ COLS (defined in <curses.h>) are not guaranteed to be accurate and
+ wrefresh or doupdate must not be called. It is allowable to call
wnoutrefresh during the initialization routine.
- ripoffline can be called up to five times before calling initscr or
+ ripoffline can be called up to five times before calling initscr or
newterm.
-
- The curs_set routine sets the cursor state to invisible, normal, or
- very visible for visibility equal to 0, 1, or 2 respectively. If the
- terminal supports the visibility requested, the previous cursor state
- is returned; otherwise, ERR is returned.
-
-
-
Except for curs_set, these routines always return OK.
- curs_set returns the previous cursor state, or ERR if the requested
+ curs_set returns the previous cursor state, or ERR if the requested
visibility is not supported.
X/Open defines no error conditions. In this implementation
def_prog_mode, def_shell_mode, reset_prog_mode, reset_shell_mode
- return an error if the terminal was not initialized, or if the I/O
- call to obtain the terminal settings fails.
+ return ERR if the terminal was not initialized, or if the I/O call
+ to obtain the terminal settings fails.
ripoffline
- returns an error if the maximum number of ripped-off lines exceeds
- the maximum (5).
+ returns ERR if the maximum number of ripped-off lines exceeds the
+ maximum (5).
Note that getsyx is a macro, so & is not necessary before the variables
y and x.
- Older SVr4 man pages warn that the return value of curs_set "is
+ Older SVr4 man pages warn that the return value of curs_set "is
currently incorrect". This implementation gets it right, but it may be
unwise to count on the correctness of the return value anywhere else.
Both ncurses and SVr4 will call curs_set in endwin if curs_set has been
- called to make the cursor other than normal, i.e., either invisible or
- very visible. There is no way for ncurses to determine the initial
+ called to make the cursor other than normal, i.e., either invisible or
+ very visible. There is no way for ncurses to determine the initial
cursor state to restore that.
+
+ In ncurses, mvcur accepts -1 for either or both old coordinates. This
+ value tells ncurses that the old location is unknown, and that it must
+ use only absolute motion, as with the cursor_address (cup) capability,
+ rather than the least costly combination of absolute and relative
+ motion.
+
+
+ Applications employing ncurses extensions should condition their use on
+ the visibility of the NCURSES_VERSION preprocessor macro.
+
The virtualscreen functions setsyx and getsyx are not described in
X/Open Curses, Issue 4. All other functions are as described in X/Open
Curses.
@@ -198,6 +227,18 @@
type int. This is misleading, as they are macros with no documented
semantics for the return value.
+ X/Open Curses notes:
+
+ "After use of mvcur(), the model Curses maintains of the state
+ of the terminal might not match the actual state of the
+ terminal. An application should touch and refresh the window
+ before resuming conventional use of Curses."
+
+ Both ncurses and SVr4 curses implement mvcur using the SCREEN data
+ allocated in either initscr(3x) or newterm(3x). X/Open Curses states
+ that the old location must be given for mvcur to accommodate terminals
+ that lack absolute cursor positioning.
+
If interrupted, ncurses restarts napms. That, and the limitation to 30
seconds, are different from other implementations.
@@ -208,7 +249,7 @@
-ncurses 6.5 2024-04-20 curs_kernel(3x)
+ncurses 6.5 2024-06-08 curs_kernel(3x)