intrflush(3ncurses)

NAME

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

SYNOPSIS

   #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);

DESCRIPTION

   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.   Others  apply  only to a specific window.
   Window-specific settings  are  not  automatically  applied  to  new  or
   derived  windows.   An  application must apply these to each window, if
   the same behavior is needed.

   cbreak
   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-processing  (interrupt  and   flow   control
   characters  are  unaffected),  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 overrides  raw.   [See  getch(3NCURSES)  for  a
   discussion of how these routines interact with echo and noecho.]

   echo/noecho
   The  echo  and  noecho routines control whether characters typed by the
   user are echoed by getch 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  getch(3NCURSES)
   for  a  discussion  of  how  these  routines  interact  with cbreak and
   nocbreak.]

   halfdelay
   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  returned  if  nothing  has been typed.  The value of
   tenths must be a number between 1 and 255.  Use nocbreak to leave half-
   delay mode.

   intrflush
   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 interrupt, but causing curses to have the wrong idea of what  is
   on  the screen.  Disabling the option (bf is FALSE) prevents the flush.
   The default for the option is inherited from the tty  driver  settings.
   The window argument is ignored.

   keypad
   The  keypad  option  enables  the  keypad  of  the user's terminal.  If
   enabled (bf is TRUE), the user can press a function  key  (such  as  an
   arrow  key) and wgetch 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 interpret 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 terminal keypad to be turned on when wgetch is called.   The
   default value for keypad is FALSE.

   meta
   Initially,  whether  the  terminal  returns  7 or 8 significant bits on
   input depends on the control mode of the tty  driver  [see  termio(7)].
   To  force  8  bits  to  be  returned,  invoke  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.

   nodelay
   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 sets a timer  while
   waiting  for  the  next  character.  If notimeout(win, TRUE) is called,
   then wgetch does not set a timer.  The purpose of  the  timeout  is  to
   differentiate  between sequences received from a function key and those
   typed by a user.

   raw/noraw
   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 user program.   The  differences  are
   that  in  raw  mode,  the  interrupt,  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.

   noqiflush
   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.

   timeout/wtimeout
   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  input).   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  routines  provide  the  same
   functionality  as nodelay, plus the additional capability of being able
   to block for only delay milliseconds (where delay is positive).

   typeahead
   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  or  doupdate  is called again.  This allows faster response to
   commands 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 typeahead 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.

RETURN VALUE

   All routines that return an integer return  ERR  upon  failure  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 implementation,
   functions with a window parameter will return an error if it  is  null.
   Any  function  will  also  return  an  error  if  the  terminal was not
   initialized.  Also,

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

PORTABILITY

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

   The ncurses library obeys the XPG4 standard and the historical 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 portability, set
   echo or noecho explicitly  just  after  initialization,  even  if  your
   program remains in cooked mode.

   When keypad is first enabled, ncurses loads the key-definitions for the
   current terminal description.  If  the  terminal  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 (depending 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 definition of any
   particular  string capability.  Higher-level applications which use the
   curses wgetch and similar functions 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  determines 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 used.

NOTES

   Note that echo, noecho, halfdelay, intrflush, meta, nodelay, 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
   recommended.

SEE ALSO

   ncurses(3NCURSES), getch(3NCURSES), initscr(3NCURSES),  util(3NCURSES),
   define_key(3NCURSES), termios(3)

                                                          inopts(3NCURSES)

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