curs_inopts 3x

curs_inopts(3x)                                         curs_inopts(3x)


       cbreak, nocbreak, echo, noecho, halfdelay, intrflush,
       keypad, meta, nodelay, notimeout, raw, noraw, noqiflush,
       qiflush, timeout, wtimeout, typeahead - curses input


       #include <curses.h>

       int cbreak(void);
       int nocbreak(void);
       int echo(void);
       int noecho(void);
       int halfdelay(int tenths);
       int intrflush(WINDOW *win, bool bf);
       int keypad(WINDOW *win, bool bf);
       int meta(WINDOW *win, bool bf);
       int nodelay(WINDOW *win, bool bf);
       int raw(void);
       int noraw(void);
       void noqiflush(void);
       void qiflush(void);
       int notimeout(WINDOW *win, bool bf);
       void timeout(int delay);
       void wtimeout(WINDOW *win, int delay);
       int typeahead(int fd);


       The ncurses library provides several functions  which  let
       an  application  change the way input from the terminal is
       handled.  Some are global, applying to all windows.   Oth-
       ers apply only to a specific window.  Window-specific set-
       tings are not automatically applied to new or derived win-
       dows.   An application must apply these to each window, if
       the same behavior is needed.


       Normally, the tty driver buffers typed characters until  a
       newline  or  carriage return is typed.  The cbreak routine
       disables line buffering and erase/kill  character-process-
       ing  (interrupt  and flow control characters are unaffect-
       ed), making  characters  typed  by  the  user  immediately
       available  to  the  program.  The nocbreak routine returns
       the terminal to normal (cooked) mode.

       Initially the terminal may or may not be in  cbreak  mode,
       as the mode is inherited; therefore, a program should call
       cbreak or nocbreak explicitly.  Most interactive  programs
       using  curses set the cbreak mode.  Note that cbreak over-
       rides raw.  [See curs_getch(3x) for a  discussion  of  how
       these routines interact with echo and noecho.]


       The  echo  and  noecho routines control whether characters
       typed by the user are echoed  by  getch(3x)  as  they  are
       typed.   Echoing by the tty driver is always disabled, but
       initially getch is in echo mode, so characters  typed  are
       echoed.  Authors of most interactive programs prefer to do
       their own echoing in a controlled area of the  screen,  or
       not  to  echo  at  all, so they disable echoing by calling
       noecho.  [See curs_getch(3x) for a discussion of how these
       routines interact with cbreak and nocbreak.]


       The  halfdelay  routine is used for half-delay mode, which
       is similar to cbreak mode in that characters typed by  the
       user  are  immediately available to the program.  However,
       after blocking for tenths tenths of seconds,  ERR  is  re-
       turned  if  nothing  has  been typed.  The value of tenths
       must be a number between 1 and 255.  Use nocbreak to leave
       half-delay mode.


       If  the  intrflush  option is enabled (bf is TRUE), and an
       interrupt key  is  pressed  on  the  keyboard  (interrupt,
       break,  quit),  all output in the tty driver queue will be
       flushed, giving the effect of faster response to  the  in-
       terrupt, but causing curses to have the wrong idea of what
       is on the screen.  Disabling the option (bf is FALSE) pre-
       vents  the flush.  The default for the option is inherited
       from the tty driver settings.  The window argument is  ig-


       The  keypad option enables the keypad of the user's termi-
       nal.  If enabled (bf is TRUE), the user can press a  func-
       tion  key  (such as an arrow key) and wgetch(3x) returns a
       single  value  representing  the  function  key,   as   in
       KEY_LEFT.   If  disabled  (bf  is  FALSE), curses does not
       treat function keys specially and the program has  to  in-
       terpret the escape sequences itself.  If the keypad in the
       terminal can be turned on (made to transmit) and off (made
       to work locally), turning on this option causes the termi-
       nal keypad to be turned on when wgetch(3x) is called.  The
       default value for keypad is FALSE.


       Initially, whether the terminal returns 7 or 8 significant
       bits on input depends on the control mode of the tty driv-
       er  [see  termio(7)].  To force 8 bits to be returned, in-
       voke meta(win, TRUE); this is equivalent, under POSIX,  to
       setting  the CS8 flag on the terminal.  To force 7 bits to
       be returned, invoke meta(win, FALSE); this is  equivalent,
       under POSIX, to setting the CS7 flag on the terminal.  The
       window argument, win, is always ignored.  If the  terminfo
       capabilities  smm (meta_on) and rmm (meta_off) are defined
       for the  terminal,  smm  is  sent  to  the  terminal  when
       meta(win,  TRUE)  is called and rmm is sent when meta(win,
       FALSE) is called.


       The nodelay option causes getch to be a non-blocking call.
       If  no input is ready, getch returns ERR.  If disabled (bf
       is FALSE), getch waits until a key is pressed.

       While interpreting an input  escape  sequence,  wgetch(3x)
       sets a timer while waiting for the next character.  If no-
       timeout(win, TRUE) is called, then wgetch does not  set  a
       timer.  The purpose of the timeout is to differentiate be-
       tween sequences received from a  function  key  and  those
       typed by a user.


       The  raw and noraw routines place the terminal into or out
       of raw mode.  Raw mode is similar to cbreak mode, in  that
       characters typed are immediately passed through to the us-
       er program.  The differences are that in raw mode, the in-
       terrupt,  quit,  suspend,  and flow control characters are
       all passed through uninterpreted, instead of generating  a
       signal.   The  behavior  of the BREAK key depends on other
       bits in the tty driver that are not set by curses.


       When the noqiflush routine is used, normal flush of  input
       and  output queues associated with the INTR, QUIT and SUSP
       characters will not be done [see termio(7)].  When qiflush
       is  called,  the queues will be flushed when these control
       characters are read.  You may want to call noqiflush in  a
       signal  handler  if  you want output to continue as though
       the interrupt had not occurred, after the handler exits.


       The timeout and wtimeout routines  set  blocking  or  non-
       blocking  read  for a given window.  If delay is negative,
       blocking read is used (i.e., waits  indefinitely  for  in-
       put).   If  delay  is zero, then non-blocking read is used
       (i.e., read returns ERR if no input is waiting).  If delay
       is  positive, then read blocks for delay milliseconds, and
       returns ERR if there is still no input.  Hence, these rou-
       tines  provide the same functionality as nodelay, plus the
       additional capability of being able to block for only  de-
       lay milliseconds (where delay is positive).


       The  curses  library  does "line-breakout optimization" by
       looking for  typeahead  periodically  while  updating  the
       screen.   If  input is found, and it is coming from a tty,
       the current update is postponed until refresh(3x) or doup-
       date is called again.  This allows faster response to com-
       mands typed in advance.  Normally, the input FILE  pointer
       passed  to  newterm, or stdin in the case that initscr was
       used, will be used to do this typeahead checking.  The ty-
       peahead  routine  specifies that the file descriptor fd is
       to be used to check for typeahead instead.  If fd  is  -1,
       then no typeahead checking is done.


       All  routines that return an integer return ERR upon fail-
       ure and OK (SVr4 specifies only "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  im-
       plementation,  functions  with a window parameter will re-
       turn an error if it is null.  Any function will  also  re-
       turn an error if the terminal was not initialized.  Also,

                   returns  an  error if its parameter is outside
                   the range 1..255.


       These functions are described in the XSI Curses  standard,
       Issue 4.

       The  ncurses  library obeys the XPG4 standard and the his-
       torical practice of the AT&T  curses  implementations,  in
       that  the  echo bit is cleared when curses initializes the
       terminal state.  BSD curses differed from  this  slightly;
       it left the echo bit on at initialization, but the BSD raw
       call turned it off as a side-effect.  For best  portabili-
       ty,  set  echo or noecho explicitly just after initializa-
       tion, even if your program remains in cooked mode.

       When keypad is first enabled, ncurses loads the  key-defi-
       nitions for the current terminal description.  If the ter-
       minal description includes extended  string  capabilities,
       e.g.,  from  using the -x option of tic, then ncurses also
       defines keys for the capabilities whose names  begin  with
       "k".   The  corresponding  keycodes are generated and (de-
       pending on previous loads of  terminal  descriptions)  may
       differ  from  one execution of a program to the next.  The
       generated keycodes are recognized by the keyname  function
       (which will then return a name beginning with "k" denoting
       the terminfo capability name rather  than  "K",  used  for
       curses  key-names).  On the other hand, an application can
       use define_key to establish a specific keycode for a given
       string.   This  makes  it  possible  for an application to
       check for an extended capability's presence with tigetstr,
       and reassign the keycode to match its own needs.

       Low-level applications can use tigetstr to obtain the def-
       inition of any particular string capability.  Higher-level
       applications which use the curses wgetch and similar func-
       tions to return keycodes rely upon the order in which  the
       strings  are  loaded.  If more than one key definition has
       the same string value, then wgetch  can  return  only  one
       keycode.   Most curses implementations (including ncurses)
       load key definitions in the order defined by the array  of
       string capability names.  The last key to be loaded deter-
       mines the keycode which will be returned.  In ncurses, you
       may  also  have  extended  capabilities interpreted as key
       definitions.  These are loaded after the predefined  keys,
       and  if  a capability's value is the same as a previously-
       loaded key definition, the later  definition  is  the  one


       Note  that echo, noecho, halfdelay, intrflush, meta, node-
       lay, notimeout, noqiflush, qiflush, timeout, and  wtimeout
       may be macros.

       The noraw and nocbreak calls follow historical practice in
       that they attempt to restore  to  normal  ("cooked")  mode
       from  raw and cbreak modes respectively.  Mixing raw/noraw
       and cbreak/nocbreak calls  leads  to  tty  driver  control
       states  that  are hard to predict or understand; it is not


       curses(3x),       curs_getch(3x),        curs_initscr(3x),
       curs_util(3x), define_key(3x), termio(7)