1curs_inopts(3X) curs_inopts(3X)
2
6 cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad, meta,
7 nodelay, notimeout, raw, noraw, noqiflush, qiflush, timeout, wtimeout,
8 typeahead - curses input options
9
11 #include <curses.h>
12 int cbreak(void);
14 int nocbreak(void);
15 int echo(void);
16 int noecho(void);
17 int halfdelay(int tenths);
18 int intrflush(WINDOW *win, bool bf);
19 int keypad(WINDOW *win, bool bf);
20 int meta(WINDOW *win, bool bf);
21 int nodelay(WINDOW *win, bool bf);
22 int raw(void);
23 int noraw(void);
24 void noqiflush(void);
25 void qiflush(void);
26 int notimeout(WINDOW *win, bool bf);
27 void timeout(int delay);
28 void wtimeout(WINDOW *win, int delay);
29 int typeahead(int fd);
30
32 Normally, the tty driver buffers typed characters until a newline or
33 carriage return is typed. The cbreak routine disables line buffering
34 and erase/kill character-processing (interrupt and flow control charac‐
35 ters are unaffected), making characters typed by the user immediately
36 available to the program. The nocbreak routine returns the terminal to
37 normal (cooked) mode.
38 Initially the terminal may or may not be in cbreak mode, as the mode is
40 inherited; therefore, a program should call cbreak or nocbreak explic‐
41 itly. Most interactive programs using curses set the cbreak mode.
42 Note that cbreak overrides raw. [See curs_getch(3X) for a discussion
43 of how these routines interact with echo and noecho.]
44 The echo and noecho routines control whether characters typed by the
46 user are echoed by getch as they are typed. Echoing by the tty driver
47 is always disabled, but initially getch is in echo mode, so characters
48 typed are echoed. Authors of most interactive programs prefer to do
49 their own echoing in a controlled area of the screen, or not to echo at
50 all, so they disable echoing by calling noecho. [See curs_getch(3X)
51 for a discussion of how these routines interact with cbreak and
52 nocbreak.]
53 The halfdelay routine is used for half-delay mode, which is similar to
55 cbreak mode in that characters typed by the user are immediately avail‐
56 able to the program. However, after blocking for tenths tenths of sec‐
57 onds, ERR is returned if nothing has been typed. The value of tenths
58 must be a number between 1 and 255. Use nocbreak to leave half-delay
59 mode.
60 If the intrflush option is enabled, (bf is TRUE), when an interrupt key
62 is pressed on the keyboard (interrupt, break, quit) all output in the
63 tty driver queue will be flushed, giving the effect of faster response
64 to the interrupt, but causing curses to have the wrong idea of what is
65 on the screen. Disabling (bf is FALSE), the option prevents the flush.
66 The default for the option is inherited from the tty driver settings.
67 The window argument is ignored.
68 The keypad option enables the keypad of the user's terminal. If en‐
70 abled (bf is TRUE), the user can press a function key (such as an arrow
71 key) and wgetch returns a single value representing the function key,
72 as in KEY_LEFT. If disabled (bf is FALSE), curses does not treat func‐
73 tion keys specially and the program has to interpret the escape se‐
74 quences itself. If the keypad in the terminal can be turned on (made
75 to transmit) and off (made to work locally), turning on this option
76 causes the terminal keypad to be turned on when wgetch is called. The
77 default value for keypad is false.
78 Initially, whether the terminal returns 7 or 8 significant bits on in‐
80 put depends on the control mode of the tty driver [see termio(7)]. To
81 force 8 bits to be returned, invoke meta(win, TRUE); this is equiva‐
82 lent, under POSIX, to setting the CS8 flag on the terminal. To force 7
83 bits to be returned, invoke meta(win, FALSE); this is equivalent, under
84 POSIX, to setting the CS7 flag on the terminal. The window argument,
85 win, is always ignored. If the terminfo capabilities smm (meta_on) and
86 rmm (meta_off) are defined for the terminal, smm is sent to the termi‐
87 nal when meta(win, TRUE) is called and rmm is sent when meta(win,
88 FALSE) is called.
89 The nodelay option causes getch to be a non-blocking call. If no input
91 is ready, getch returns ERR. If disabled (bf is FALSE), getch waits
92 until a key is pressed.
93 While interpreting an input escape sequence, wgetch sets a timer while
95 waiting for the next character. If notimeout(win, TRUE) is called,
96 then wgetch does not set a timer. The purpose of the timeout is to
97 differentiate between sequences received from a function key and those
98 typed by a user.
99 The raw and noraw routines place the terminal into or out of raw mode.
101 Raw mode is similar to cbreak mode, in that characters typed are imme‐
102 diately passed through to the user program. The differences are that
103 in raw mode, the interrupt, quit, suspend, and flow control characters
104 are all passed through uninterpreted, instead of generating a signal.
105 The behavior of the BREAK key depends on other bits in the tty driver
106 that are not set by curses.
107 When the noqiflush routine is used, normal flush of input and output
109 queues associated with the INTR, QUIT and SUSP characters will not be
110 done [see termio(7)]. When qiflush is called, the queues will be
111 flushed when these control characters are read. You may want to call
112 noqiflush() in a signal handler if you want output to continue as
113 though the interrupt had not occurred, after the handler exits.
114 The timeout and wtimeout routines set blocking or non-blocking read for
116 a given window. If delay is negative, blocking read is used (i.e.,
117 waits indefinitely for input). If delay is zero, then non-blocking
118 read is used (i.e., read returns ERR if no input is waiting). If delay
119 is positive, then read blocks for delay milliseconds, and returns ERR
120 if there is still no input. Hence, these routines provide the same
121 functionality as nodelay, plus the additional capability of being able
122 to block for only delay milliseconds (where delay is positive).
123 The curses library does ``line-breakout optimization'' by looking for
125 typeahead periodically while updating the screen. If input is found,
126 and it is coming from a tty, the current update is postponed until re‐
127 fresh or doupdate is called again. This allows faster response to com‐
128 mands typed in advance. Normally, the input FILE pointer passed to
129 newterm, or stdin in the case that initscr was used, will be used to do
130 this typeahead checking. The typeahead routine specifies that the file
131 descriptor fd is to be used to check for typeahead instead. If fd is
132 -1, then no typeahead checking is done.
133
135 All routines that return an integer return ERR upon failure and OK
136 (SVr4 specifies only "an integer value other than ERR") upon successful
137 completion, unless otherwise noted in the preceding routine descrip‐
138 tions.
139 X/Open does not define any error conditions. In this implementation,
141 functions with a window parameter will return an error if it is null.
142 Any function will also return an error if the terminal was not initial‐
143 ized. Also,
144 halfdelay
146 returns an error if its parameter is outside the range
147 1..255.
148
150 These functions are described in the XSI Curses standard, Issue 4.
151 The ncurses library obeys the XPG4 standard and the historical practice
153 of the AT&T curses implementations, in that the echo bit is cleared
154 when curses initializes the terminal state. BSD curses differed from
155 this slightly; it left the echo bit on at initialization, but the BSD
156 raw call turned it off as a side-effect. For best portability, set
157 echo or noecho explicitly just after initialization, even if your pro‐
158 gram remains in cooked mode.
159
161 Note that echo, noecho, halfdelay, intrflush, meta, nodelay, notimeout,
162 noqiflush, qiflush, timeout, and wtimeout may be macros.
163 The noraw and nocbreak calls follow historical practice in that they
165 attempt to restore to normal (`cooked') mode from raw and cbreak modes
166 respectively. Mixing raw/noraw and cbreak/nocbreak calls leads to tty
167 driver control states that are hard to predict or understand; it is not
168 recommended.
169
171 curses(3X), curs_getch(3X), curs_initscr(3X), termio(7)
172 curs_inopts(3X)