wsyncdown – create curses windows
WINDOW *newwin(int nlines, int ncols, int begin_y,
int delwin(WINDOW *win);
int mvwin(WINDOW *win, int y, int x);
WINDOW *subwin(WINDOW *orig, int nlines, int ncols,
int begin_y, int begin_x);
WINDOW *derwin(WINDOW *orig, int nlines, int ncols,
int begin_y, int begin_x);
int mvderwin(WINDOW *win, int par_y, int par_x);
WINDOW *dupwin(WINDOW *win);
void wsyncup(WINDOW *win);
int syncok(WINDOW *win, bool bf);
void wcursyncup(WINDOW *win);
void wsyncdown(WINDOW *win);
Calling newwin creates and returns a pointer to a new window with the
given number of lines and columns. The upper left-hand corner of the window is
at line begin_y, column begin_x. If either
nlines or ncols is zero, they default to LINES -
begin_y and COLS - begin_x. A new full-screen
window is created by calling newwin(0,0,0,0).
Calling delwin deletes the named window, freeing all memory
associated with it (it does not actually erase the window’s screen
image). Subwindows must be deleted before the main window can be
Calling mvwin moves the window so that the upper left-hand
corner is at position (x, y). If the move would cause the
window to be off the screen, it is an error and the window is not
moved. Moving subwindows is allowed, but should be avoided.
Calling subwin creates and returns a pointer to a new window
with the given number of lines, nlines, and columns,
ncols. The window is at position (begin_y,
begin_x) on the screen. (This position is relative to the
screen, and not to the window orig.) The window is made in the
middle of the window orig, so that changes made to one window
will affect both windows. The subwindow shares memory with the window
orig. When using this routine, it is necessary to call
touchwin or touchline on orig before calling
wrefresh on the subwindow.
Calling derwin is the same as calling subwin, except that
begin_y and begin_x are relative to the origin
of the window orig rather than the screen. There is no
difference between the subwindows and the derived windows.
Calling mvderwin moves a derived window (or subwindow)
inside its parent window. The screen-relative parameters of the
window are not changed. This routine is used to display different
parts of the parent window at the same physical position on the
Calling dupwin creates an exact duplicate of the window win.
Calling wsyncup touches all locations in ancestors of win that are
changed in win. If syncok is called with second argument
TRUE then wsyncup is called automatically whenever there is a
change in the window.
The wsyncdown routine touches each location in win that has been
touched in any of its ancestor windows. This routine is called by
wrefresh, so it should almost never be necessary to call it manually.
Routines that return an integer return the integer ERR upon failure and
OK (SVr4 only specifies "an integer value other than ERR") upon
Routines that return pointers return NULL on error.
X/Open defines no error conditions.
In this implementation
If many small changes are made to the window, the wsyncup option could
The subwindow functions (subwin, derwin, mvderwin,
wsyncup, wsyncdown, wcursyncup, syncok) are flaky,
incompletely implemented, and not well tested.
The System V curses documentation is very unclear about what wsyncup
and wsyncdown actually do. It seems to imply that they are only
supposed to touch exactly those lines that are affected by ancestor changes.
The language here, and the behavior of the curses implementation,
is patterned on the XPG4 curses standard. The weaker XPG4 spec may result
in slower updates.