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curs_touch 3x 2025-01-18 ncurses 6.5 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.