# curs_touch 3x 2023-11-25 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 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.

## 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.

           The XSI Curses standard, Issue 4 describes these functions, but defines
           no error conditions.

## SEE ALSO

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

    ncurses 6.4                       2023-11-25                    curs_touch(3x)