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 options


       #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.  Others apply only to a specific window.  Win-
       dow-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.


       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 charac-
       ters  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  explic-
       itly.   Most  interactive  programs  using  curses set the cbreak mode.
       Note that cbreak overrides 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 pre-
       fer  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 avail-
       able to the program.  However, after blocking for tenths tenths of sec-
       onds,  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


       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.


       The  keypad  option  enables the keypad of the user's terminal.  If en-
       abled (bf is TRUE), the user can press a function 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 interpret the escape se-
       quences 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(3x)  is  called.
       The default value for keypad is FALSE.


       Initially,  whether the terminal returns 7 or 8 significant bits on in-
       put depends on the control mode of the tty driver [see termios(3)].  To
       force  8  bits  to be returned, invoke meta(win, TRUE); this is equiva-
       lent, 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  termi-
       nal  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 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.


       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 imme-
       diately 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.


       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 termios(3)].  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  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).


       The curses library does "line-breakout optimization" by looking for ty-
       peahead periodically while updating the screen.  If input is found, and
       it is coming from a tty, the current  update  is  postponed  until  re-
       fresh(3x)  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.


       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  descrip-

       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 initial-
       ized.  Also,

                   returns an error if its  parameter  is  outside  the  range


       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  pro-
       gram remains in cooked mode.

       When keypad is first enabled, ncurses loads the key-definitions for the
       current terminal description.  If the terminal description includes ex-
       tended 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 previ-
       ous loads of terminal descriptions) may differ from one execution of  a
       program to the next.  The generated keycodes are recognized by the key-
       name function (which will then return a name beginning with "k"  denot-
       ing  the terminfo capability name rather than "K", used for curses key-
       names).  On the other hand, an application can use define_key to estab-
       lish 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  ca-
       pability's value is the same as a previously-loaded key definition, the
       later definition is the one used.


       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


       curses(3x),   curs_getch(3x),   curs_initscr(3x),   curs_util(3x),  de-
       fine_key(3x), termios(3)