curs_inopts(3) UNIX Programmer's Manual curs_inopts(3)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
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), mak-
ing 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(3) 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. Au-
thors 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(3) for a discussion of how these routines in-
teract 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 KEY_LEFT. If disabled
(bf is FALSE), curses does not treat function keys specially
and the program has to interpret the escape sequences it-
self. 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); this is equivalent, under POSIX, to setting
the CS8 flag on the terminal. To force 7 bits to be re-
turned, 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 capabili-
ties 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.
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The raw and noraw routines place the terminal into or out of
raw mode. Raw mode is similar to cbreak mode, in that char-
acters typed are immediately passed through to the user pro-
gram. 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 routines provide the
same functionality as nodelay, plus the additional capabili-
ty 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 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 imple-
mentation, 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
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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 histori-
cal 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.
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 recommend-
ed.
SEE ALSOcurses(3), curs_getch(3), curs_initscr(3), termio(7)MirOS BSD #10-current Printed 18.8.2011 4
