curs_inopts(3X) curs_inopts(3X)
NAME
cursinopts: cbreak, nocbreak, echo, noecho, halfdelay, intrflush,
keypad, meta, nodelay, notimeout, raw, noraw, noqiflush, qiflush,
timeout, wtimeout, typeahead - curses terminal input option control
routines
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 notimeout(WINDOW *win, bool bf);
int raw(void);
int noraw(void);
void noqiflush(void);
void qiflush(void);
void timeout(int delay);
void wtimeout(WINDOW *win, int delay);
int typeahead(int fd);
DESCRIPTION
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.]
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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 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 KEYLEFT. 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.
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.
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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.
RETURN VALUE
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.
NOTES
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.
SEE ALSO
curses(3X), cursgetch(3X), cursinitscr(3X), termio(7).
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