# curs_touch 3x

    curs_touch(3x)                                                  curs_touch(3x)

## NAME

           touchwin, touchline, untouchwin, wtouchln, is_linetouched,
           is_wintouched - curses refresh control routines

## SYNOPSIS

           #include <curses.h>
           int touchwin(WINDOW *win);
           int touchline(WINDOW *win, int start, int count);
           int untouchwin(WINDOW *win);
           int wtouchln(WINDOW *win, int y, int n, int changed);
           bool is_linetouched(WINDOW *win, int line);
           bool is_wintouched(WINDOW *win);

## DESCRIPTION

           The touchwin and touchline routines throw away all optimization  infor-
           mation 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 speci-
           fied line/window was modified since the last call to  wrefresh;  other-
           wise  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

              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.

              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).

                                                                    curs_touch(3x)