curs_inopts(3X) curs_inopts(3X)
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 con-trol control
trol characters 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 pro-gram program
gram 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 rou-tines routines
tines 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 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 func-tion function
tion 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 termi-nal terminal
nal 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 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 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 charac-ter. character.
ter. If notimeout(win, TRUE) is called, then wgetch does not set a timer. The purpose of the time-out timeout
out 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 oth-er other
er 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 han-dler handler
dler if you want output to continue as though the interrupt had not occurred, after the handler ex-its. exits.
its.
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 nonblocking
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 routines
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 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 implementation, functions with a window parame-ter parameter
ter will return an error if it is null. Any function will also return an error if the terminal was
not initialized. Also,
halfdelay
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 historical practice of the AT&T curses implemen-tations, implementations,
tations, in that the echo bit is cleared when curses initializes the terminal state. BSD curses dif-fered differed
fered 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 recommended.
SEE ALSO
curses(3X), curs_getch(3X), curs_initscr(3X), termio(7)
curs_inopts(3X)
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