+ The ncurses library provides several functions which let
+ an application change the way input from the terminal is
+ handled. Some are global, applying to all windows. Oth-
+ ers apply only to a specific window. Window-specific set-
+ tings are not automatically applied to new or derived win-
+ dows. An application must apply these to each window, if
+ the same behavior is needed.
+
+
+
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-process-
- ing (interrupt and flow control characters are unaf-
- fected), making characters typed by the user immediately
+ ing (interrupt and flow control characters are unaffect-
+ ed), making characters typed by the user immediately
available to the program. The nocbreak routine returns
the terminal to normal (cooked) mode.
@@ -89,34 +104,46 @@
rides 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 ini-
- tially 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.]
+ Echoing by the tty driver is always disabled, but initial-
+ ly 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
+ after blocking for tenths tenths of seconds, ERR is re-
+ turned 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
+
+
+ If the intrflush option is enabled (bf is TRUE), and 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 argu-
- ment is ignored.
+ break, quit), all output in the tty driver queue will be
+ flushed, giving the effect of faster response to the in-
+ terrupt, but causing curses to have the wrong idea of what
+ is on the screen. Disabling the option (bf is FALSE) pre-
+ vents the flush. The default for the option is inherited
+ from the tty driver settings. The window argument is ig-
+ nored.
+
+
The keypad option enables the keypad of the user's termi-
nal. If enabled (bf is TRUE), the user can press a func-
tion key (such as an arrow key) and wgetch returns a sin-
@@ -124,24 +151,30 @@
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 key-
- pad to be turned on when wgetch is called. The default
- value for keypad is false.
+ turned on (made to transmit) and off (made to work local-
+ ly), 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 returned, invoke meta(win, FALSE); this is equiva-
- lent, under POSIX, to setting the CS7 flag on the termi-
- nal. 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
+ bits on input depends on the control mode of the tty driv-
+ er [see termio(7)]. To force 8 bits to be returned, in-
+ voke 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.
@@ -149,39 +182,51 @@
While interpreting an input escape sequence, wgetch sets a
timer while waiting for the next character. If notime-out(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
+ timer. The purpose of the timeout is to differentiate be-
+ tween 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
+ characters typed are immediately passed through to the us-
+ er program. The differences are that in raw mode, the in-
+ terrupt, 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
+ 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
+ blocking read is used (i.e., waits indefinitely for in-
+ put). 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 rou-
tines provide the same functionality as nodelay, plus the
- additional capability of being able to block for only
- delay milliseconds (where delay is positive).
+ additional capability of being able to block for only de-
+ lay milliseconds (where delay is positive).
- The curses library does ``line-breakout optimization'' by
+
+
+ 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
@@ -195,15 +240,24 @@
All routines that return an integer return ERR upon fail-
ure 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 im-
+ plementation, functions with a window parameter will re-
+ turn an error if it is null. Any function will also re-
+ turn an error if the terminal was not initialized. Also,
+
+ halfdelay
+ returns an error if its parameter is outside
+ the range 1..255.
+
These functions are described in the XSI Curses standard,
Issue 4.
@@ -212,69 +266,91 @@
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 portabil-
- ity, set echo or noecho explicitly just after initializa-
+ call turned it off as a side-effect. For best portabili-
+ ty, set echo or noecho explicitly just after initializa-
tion, even if your program remains in cooked mode.
+ When keypad is first enabled, ncurses loads the key-defi-
+ nitions for the current terminal description. If the ter-
+ minal description includes extended string capabilities,
+ e.g., from using the -x option of tic, then ncurses also
+ defines keys for the capabilities whose names begin with
+ "k". The corresponding keycodes are generated and (de-
+ pending on previous loads of terminal descriptions) may
+ differ from one execution of a program to the next. The
+ generated keycodes are recognized by the keyname function
+ (which will then return a name beginning with "k" denoting
+ the terminfo capability name rather than "K", used for
+ curses key-names). On the other hand, an application can
+ use define_key to establish a specific keycode for a given
+ string. This makes it possible for an application to
+ check for an extended capability's presence with tigetstr,
+ and reassign the keycode to match its own needs.
+
+ Low-level applications can use tigetstr to obtain the def-
+ inition of any particular string capability. Higher-level
+ applications which use the curses wgetch and similar func-
+ tions to return keycodes rely upon the order in which the
+ strings are loaded. If more than one key definition has
+ the same string value, then wgetch can return only one
+ keycode. Most curses implementations (including ncurses)
+ load key definitions in the order defined by the array of
+ string capability names. The last key to be loaded deter-
+ mines the keycode which will be returned. In ncurses, you
+ may also have extended capabilities interpreted as key
+ definitions. These are loaded after the predefined keys,
+ and if a capability's value is the same as a previously-
+ loaded key definition, the later definition is the one
+ used.
+
-
NOTES
- Note that echo, noecho, halfdelay, intrflush, meta, node-
- lay, notimeout, noqiflush, qiflush, timeout, and wtimeout
+
+ Note that echo, noecho, halfdelay, intrflush, meta, node-
+ lay, 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
+ 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.