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)