curs_inopts: cbreak, nocbreak, echo, noecho, halfdelay, intrflush,
keypad, meta, nodelay, notimeout, raw, noraw, noqiflush, qiflush,
timeout, wtimeout, typeahead - curses terminal input option control
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 notimeout(WINDOW *win, bool bf);
void timeout(int delay);
void wtimeout(WINDOW *win, int delay);
int typeahead(int fd);
The cbreak and nocbreak routines put the terminal into and out of cbreak
mode, respectively. In this mode, characters typed by the user are
immediately available to the program, and erase/kill character-processing
is not performed. When out of this mode, the tty driver buffers the
typed characters until a newline or carriage return is typed. Interrupt
and flow control characters are unaffected by this 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 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 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 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), 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 argument is ignored.
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
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). To force 7 bits to be
returned, invoke meta(win, FALSE). 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 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.
With the raw and noraw routines, the terminal is placed 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.
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).
curses 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.
All routines that return an integer return ERR upon failure and an
integer value other than ERR upon successful completion, unless otherwise
noted in the preceding routine descriptions.
The header file <curses.h> automatically includes the header files
<stdio.h> and <unctrl.h>.
Note that echo, noecho, halfdelay, intrflush, meta, nodelay, notimeout,
noqiflush, qiflush, timeout, and wtimeout may be macros.
curses(3X), curs_getch(3X), curs_initscr(3X), termio(7)
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