ncurses/man/curs_touch.3x

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 $Id: curs_touch.3x,v 1.23 2020/10/24 09:51:21 tom Exp $
 curs_touch 3X ""
 NAME
touchwin,
touchline,
untouchwin,
wtouchln,
is_linetouched,
is_wintouched - curses refresh control routines
 SYNOPSIS
#include <curses.h>
int touchline(WINDOW *win, int start, int count);
int touchwin(WINDOW *win);

int wtouchln(WINDOW *win, int y, int n, int changed);
int untouchwin(WINDOW *win);
bool is_linetouched(WINDOW *win, int line);

bool is_wintouched(WINDOW *win);

 DESCRIPTION
The touchwin and touchline routines throw away all
optimization information about which parts of the window have been
touched, by pretending that the entire window has been drawn on.
This
is sometimes necessary when using overlapping windows, since a change
to one window affects the other window, but the records of which lines
have been changed in the other window do not reflect the change.
The
routine touchline only pretends that count lines have been
changed, beginning with line start.

The untouchwin routine marks all lines in the window as unchanged since
the last call to wrefresh.

The wtouchln routine makes n lines in the window, starting
at line y, look as if they have (changed=1) or have
not (changed=0) been changed since the last call to
wrefresh.

The is_linetouched and is_wintouched routines return
TRUE if the specified line/window was modified since the last
call to wrefresh; otherwise they return FALSE. In
addition, is_linetouched returns ERR if line is not
valid for the given window.
 RETURN VALUE
All routines return the integer ERR upon failure and an integer value
other than ERR upon successful completion, unless otherwise noted in the
preceding routine descriptions.

X/Open does not define any error conditions.
In this implementation

 5
is_linetouched
returns an error
if the window pointer is null, or
if the line number is outside the window.
The constant ERR is distinct from TRUE and FALSE,
which are the normal return values of this function.
Because the function returns a bool,
returning ERR (which is neither TRUE nor FALSE)
may not be supported by the compiler.
To provide error-checking and also match the X/Open function prototype,
the ERR is provided by a macro named is_linetouched.
The actual function returns FALSE when it detects an error.
 5
wtouchln
returns an error
if the window pointer is null, or
if the line number is outside the window.

 PORTABILITY

These functions were introduced by SVr4.
The Solaris curses header file,
for instance, defines both an actual function and macro for each.
The macros give the same result as the actual functions.
SVr4 curses does not check the window parameter win to ensure
that it is not NULL;
otherwise this implementation behaves the same as SVr4.

The XSI Curses standard, Issue 4 describes these functions,
but defines no error conditions.
 NOTES
All of these routines except wtouchln may be macros.
 SEE ALSO
curses(3X),
curs_refresh(3X),
curs_variables(3X).