- 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 unaf-
- fected), 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 as they are typed.
- Echoing by the tty driver is always disabled, but ini-
- tially 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
- 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.
-
- If the intrflush option is enabled, (bf is TRUE), when 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 (bf is FALSE), the
- option prevents the flush. The default for the option is
- inherited from the tty driver settings. The window argu-
- ment is ignored.
-
- 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 returns a sin-
- gle 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 key-
- pad to be turned on when wgetch 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
- 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 equiva-
- lent, under POSIX, to setting the CS8 flag on the termi-
- nal. 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 sets a
- timer while waiting for the next character. If notime-
- out(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 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.
-
- 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
- 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 rou-
- tines 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 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 fail-
- ure and OK (SVr4 specifies only "an integer value other
- than ERR") upon successful completion, unless otherwise
- noted in the preceding routine descriptions.
-
-
-
-
PORTABILITY
- 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 portabil-
- ity, set echo or noecho explicitly just after initializa-
- tion, even if your program remains in cooked mode.
-
-
-
-
NOTES
- 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
- recommended.
-
-
-
+ 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
+ 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 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.
+
+
+
+ When interpreting an 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-
+ tions.
+
+ 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,
+
+ halfdelay
+ returns an error if its parameter is outside the range 1..255.
+
+
+
+ This implementation provides four functions which may be used to detect
+ if the corresponding flags were set or reset:
+
+ QuerySetReset
+ ------------------------------
+ is_cbreak cbreak nocbreak
+ is_echo echo noecho
+ is_nl nl nonl
+ is_raw raw noraw
+
+ In each case, the function returns
+
+ 1 if the flag is set,
+
+ 0 if the flag is reset, or
+
+ -1 if the curses library was not initialized.
+
+ These routines are specific to ncurses. They were not supported on
+ Version 7, BSD or System V implementations. It is recommended that any
+ code depending on ncurses extensions be conditioned using NCURSES_VER-
+ SION.
+
+
+
+ Except as noted in the section on extensions, these functions are de-
+ scribed 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.
+
+ The XSI Curses standard is ambiguous on the question of whether raw
+ should disable the CRLF translations controlled by nl and nonl. BSD
+ curses did turn off these translations; AT&T curses (at least as late
+ as SVr1) did not. We chose to do so, on the theory that a programmer
+ requesting raw input wants a clean (ideally 8-bit clean) connection
+ that the operating system will not alter.
+
+ 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, nl, nonl, 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.
+