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 The ncurses library provides several functions which let an application
33 change the way input from the terminal is handled. Some are global,
34 applying to all windows. Others apply only to a specific window. Win‐
35 dow-specific settings are not automatically applied to new or derived
36 windows. An application must apply these to each window, if the same
37 behavior is needed.
38 cbreak
40 Normally, the tty driver buffers typed characters until a newline or
41 carriage return is typed. The cbreak routine disables line buffering
42 and erase/kill character-processing (interrupt and flow control charac‐
43 ters are unaffected), making characters typed by the user immediately
44 available to the program. The nocbreak routine returns the terminal to
45 normal (cooked) mode.
46 Initially the terminal may or may not be in cbreak mode, as the mode is
48 inherited; therefore, a program should call cbreak or nocbreak explic‐
49 itly. Most interactive programs using curses set the cbreak mode.
50 Note that cbreak overrides raw. [See curs_getch(3X) for a discussion
51 of how these routines interact with echo and noecho.]
52 echo/noecho
54 The echo and noecho routines control whether characters typed by the
55 user are echoed by getch(3X) as they are typed. Echoing by the tty
56 driver is always disabled, but initially getch is in echo mode, so
57 characters typed are echoed. Authors of most interactive programs pre‐
58 fer to do their own echoing in a controlled area of the screen, or not
59 to echo at all, so they disable echoing by calling noecho. [See
60 curs_getch(3X) for a discussion of how these routines interact with
61 cbreak and nocbreak.]
62 halfdelay
64 The halfdelay routine is used for half-delay mode, which is similar to
65 cbreak mode in that characters typed by the user are immediately avail‐
66 able to the program. However, after blocking for tenths tenths of sec‐
67 onds, ERR is returned if nothing has been typed. The value of tenths
68 must be a number between 1 and 255. Use nocbreak to leave half-delay
69 mode.
70 intrflush
72 If the intrflush option is enabled (bf is TRUE), and an interrupt key
73 is pressed on the keyboard (interrupt, break, quit), all output in the
74 tty driver queue will be flushed, giving the effect of faster response
75 to the interrupt, but causing curses to have the wrong idea of what is
76 on the screen. Disabling the option (bf is FALSE) prevents the flush.
77 The default for the option is inherited from the tty driver settings.
78 The window argument is ignored.
79 keypad
81 The keypad option enables the keypad of the user's terminal. If en‐
82 abled (bf is TRUE), the user can press a function key (such as an arrow
83 key) and wgetch(3X) returns a single value representing the function
84 key, as in KEY_LEFT. If disabled (bf is FALSE), curses does not treat
85 function keys specially and the program has to interpret the escape se‐
86 quences itself. If the keypad in the terminal can be turned on (made
87 to transmit) and off (made to work locally), turning on this option
88 causes the terminal keypad to be turned on when wgetch(3X) is called.
89 The default value for keypad is FALSE.
90 meta
92 Initially, whether the terminal returns 7 or 8 significant bits on in‐
93 put depends on the control mode of the tty driver [see termio(7)]. To
94 force 8 bits to be returned, invoke meta(win, TRUE); this is equiva‐
95 lent, under POSIX, to setting the CS8 flag on the terminal. To force 7
96 bits to be returned, invoke meta(win, FALSE); this is equivalent, under
97 POSIX, to setting the CS7 flag on the terminal. The window argument,
98 win, is always ignored. If the terminfo capabilities smm (meta_on) and
99 rmm (meta_off) are defined for the terminal, smm is sent to the termi‐
100 nal when meta(win, TRUE) is called and rmm is sent when meta(win,
101 FALSE) is called.
102 nodelay
104 The nodelay option causes getch to be a non-blocking call. If no input
105 is ready, getch returns ERR. If disabled (bf is FALSE), getch waits
106 until a key is pressed.
107 While interpreting an input escape sequence, wgetch(3X) sets a timer
109 while waiting for the next character. If notimeout(win, TRUE) is
110 called, then wgetch does not set a timer. The purpose of the timeout
111 is to differentiate between sequences received from a function key and
112 those typed by a user.
113 raw/noraw
115 The raw and noraw routines place the terminal into or out of raw mode.
116 Raw mode is similar to cbreak mode, in that characters typed are imme‐
117 diately passed through to the user program. The differences are that
118 in raw mode, the interrupt, quit, suspend, and flow control characters
119 are all passed through uninterpreted, instead of generating a signal.
120 The behavior of the BREAK key depends on other bits in the tty driver
121 that are not set by curses.
122 noqiflush
124 When the noqiflush routine is used, normal flush of input and output
125 queues associated with the INTR, QUIT and SUSP characters will not be
126 done [see termio(7)]. When qiflush is called, the queues will be
127 flushed when these control characters are read. You may want to call
128 noqiflush in a signal handler if you want output to continue as though
129 the interrupt had not occurred, after the handler exits.
130 timeout/wtimeout
132 The timeout and wtimeout routines set blocking or non-blocking read for
133 a given window. If delay is negative, blocking read is used (i.e.,
134 waits indefinitely for input). If delay is zero, then non-blocking
135 read is used (i.e., read returns ERR if no input is waiting). If delay
136 is positive, then read blocks for delay milliseconds, and returns ERR
137 if there is still no input. Hence, these routines provide the same
138 functionality as nodelay, plus the additional capability of being able
139 to block for only delay milliseconds (where delay is positive).
140 typeahead
142 The curses library does “line-breakout optimization” by looking for ty‐
143 peahead periodically while updating the screen. If input is found, and
144 it is coming from a tty, the current update is postponed until re‐
145 fresh(3X) or doupdate is called again. This allows faster response to
146 commands typed in advance. Normally, the input FILE pointer passed to
147 newterm, or stdin in the case that initscr was used, will be used to do
148 this typeahead checking. The typeahead routine specifies that the file
149 descriptor fd is to be used to check for typeahead instead. If fd is
150 -1, then no typeahead checking is done.
151
153 All routines that return an integer return ERR upon failure and OK
154 (SVr4 specifies only “an integer value other than ERR”) upon successful
155 completion, unless otherwise noted in the preceding routine descrip‐
156 tions.
157 X/Open does not define any error conditions. In this implementation,
159 functions with a window parameter will return an error if it is null.
160 Any function will also return an error if the terminal was not initial‐
161 ized. Also,
162 halfdelay
164 returns an error if its parameter is outside the range
165 1..255.
166
168 These functions are described in the XSI Curses standard, Issue 4.
169 The ncurses library obeys the XPG4 standard and the historical practice
171 of the AT&T curses implementations, in that the echo bit is cleared
172 when curses initializes the terminal state. BSD curses differed from
173 this slightly; it left the echo bit on at initialization, but the BSD
174 raw call turned it off as a side-effect. For best portability, set
175 echo or noecho explicitly just after initialization, even if your pro‐
176 gram remains in cooked mode.
177 When keypad is first enabled, ncurses loads the key-definitions for the
179 current terminal description. If the terminal description includes ex‐
180 tended string capabilities, e.g., from using the -x option of tic, then
181 ncurses also defines keys for the capabilities whose names begin with
182 “k”. The corresponding keycodes are generated and (depending on previ‐
183 ous loads of terminal descriptions) may differ from one execution of a
184 program to the next. The generated keycodes are recognized by the key‐
185 name function (which will then return a name beginning with “k” denot‐
186 ing the terminfo capability name rather than “K”, used for curses key-
187 names). On the other hand, an application can use define_key to estab‐
188 lish a specific keycode for a given string. This makes it possible for
189 an application to check for an extended capability's presence with
190 tigetstr, and reassign the keycode to match its own needs.
191 Low-level applications can use tigetstr to obtain the definition of any
193 particular string capability. Higher-level applications which use the
194 curses wgetch and similar functions to return keycodes rely upon the
195 order in which the strings are loaded. If more than one key definition
196 has the same string value, then wgetch can return only one keycode.
197 Most curses implementations (including ncurses) load key definitions in
198 the order defined by the array of string capability names. The last
199 key to be loaded determines the keycode which will be returned. In
200 ncurses, you may also have extended capabilities interpreted as key
201 definitions. These are loaded after the predefined keys, and if a ca‐
202 pability's value is the same as a previously-loaded key definition, the
203 later definition is the one used.
204
206 Note that echo, noecho, halfdelay, intrflush, meta, nodelay, notimeout,
207 noqiflush, qiflush, timeout, and wtimeout may be macros.
208 The noraw and nocbreak calls follow historical practice in that they
210 attempt to restore to normal (“cooked”) mode from raw and cbreak modes
211 respectively. Mixing raw/noraw and cbreak/nocbreak calls leads to tty
212 driver control states that are hard to predict or understand; it is not
213 recommended.
214
216 curses(3X), curs_getch(3X), curs_initscr(3X), curs_util(3X), de‐
217 fine_key(3X), termio(7)
218 curs_inopts(3X)