# curs_touch 3x 2024-04-20 ncurses 6.4 Library calls

    curs_touch(3x)                   Library calls                  curs_touch(3x)

## NAME

           touchwin,     touchline,    untouchwin,    wtouchln,    is_linetouched,
           is_wintouched - control terminal output refresh in a curses window

## 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   Curses  does  not  specify  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 boundaries.

                   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 boundaries.

## NOTES

           All of these routines except wtouchln may be macros.

## 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.

           X/Open  Curses, Issue 4 describes these functions, but defines no error
           conditions.

## SEE ALSO

           curses(3x), curs_refresh(3x), curs_variables(3x)

    ncurses 6.4                       2024-04-20                    curs_touch(3x)