# curs_touch 3x 2025-01-18 ncurses 6.6 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

           Functions  returning  integers  return  ERR  upon  failure  and OK upon
           success.

           In ncurses,

              is_linetouched
                   returns ERR 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  ERR  if  the  window  pointer  is null, or if the line
                   number is outside the window boundaries.

## NOTES

           All of these functions except wtouchln may be implemented as macros.

## PORTABILITY

           X/Open Curses Issue 4 describes these functions.  It specifies no error
           conditions for them.

           SVr4 describes a successful return value except where "otherwise noted"
           as "an integer value other than ERR".

           SVr4 does not check win to ensure that it is not a null pointer.

## HISTORY

           SVr2 (1984) introduced touchwin,

           SVr3  (1987)  added  touchline.   SVr3.1  later  that   year   supplied
           is_linetouched, is_wintouched, untouchwin, and wtouchln.

## SEE ALSO

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

    ncurses 6.6                       2025-01-18                    curs_touch(3x)