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

       ncurses(3NCURSES), refresh(3NCURSES), curses_variables(3NCURSES)