ncurses 6.2 - patch 20201107

[ncurses.git] / man / curs_getch.3x

diff --git a/man/curs_getch.3x b/man/curs_getch.3x
index ce62ed17d8cb5237f986813f2ddf5a40bce548db..1cf9d18ba7bd86066d98b24217d6d7caed5c0cd8 100644 (file)
--- a/man/curs_getch.3x
+++ b/man/curs_getch.3x
@@ -1,6 +1,7 @@
 '\" t
 .\"***************************************************************************
 '\" t
 .\"***************************************************************************

-.\" Copyright (c) 1998-2003,2005 Free Software Foundation, Inc.              *
+.\" Copyright 2018-2019,2020 Thomas E. Dickey                                *
+.\" Copyright 1998-2016,2017 Free Software Foundation, Inc.                  *

 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *


@@ -27,10 +28,18 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"

-.\" $Id: curs_getch.3x,v 1.29 2005/06/25 22:03:09 tom Exp $
+.\" $Id: curs_getch.3x,v 1.56 2020/10/17 23:18:32 tom Exp $

 .TH curs_getch 3X ""
 .na
 .hy 0
 .TH curs_getch 3X ""
 .na
 .hy 0

+.ie \n(.g .ds `` \(lq
+.el       .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el       .ds '' ''
+.de bP
+.ie n  .IP \(bu 4
+.el    .IP \(bu 2
+..

 .SH NAME
 \fBgetch\fR,
 \fBwgetch\fR,
 .SH NAME
 \fBgetch\fR,
 \fBwgetch\fR,


@@ -45,17 +54,20 @@
 .PP
 \fBint getch(void);\fR
 .br
 .PP
 \fBint getch(void);\fR
 .br

-\fBint wgetch(WINDOW *win);\fR
-.br
-\fBint mvgetch(int y, int x);\fR
-.br
-\fBint mvwgetch(WINDOW *win, int y, int x);\fR
+\fBint wgetch(WINDOW *\fP\fIwin);\fR
+.sp
+\fBint mvgetch(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR

 .br
 .br

-\fBint ungetch(int ch);\fR
+\fBint mvwgetch(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR
+.sp
+\fBint ungetch(int \fP\fIch\fP\fB);\fR
+.sp
+/* extension */

 .br
 .br

-\fBint has_key(int ch);\fR
+\fBint has_key(int \fP\fIch\fP\fB);\fR

 .br
 .SH DESCRIPTION
 .br
 .SH DESCRIPTION

+.SS Reading characters

 The \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR and \fBmvwgetch\fR, routines read
 a character from the window.
 In no-delay mode, if no input is waiting, the value \fBERR\fR is returned.
 The \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR and \fBmvwgetch\fR, routines read
 a character from the window.
 In no-delay mode, if no input is waiting, the value \fBERR\fR is returned.


@@ -68,25 +80,42 @@ In half-delay mode,
 the program waits until a character is typed or the
 specified timeout has been reached.
 .PP
 the program waits until a character is typed or the
 specified timeout has been reached.
 .PP

-Unless \fBnoecho\fR has been set,
+If \fBecho\fR is enabled, and the window is not a pad,

 then the character will also be echoed into the
 designated window according to the following rules:
 then the character will also be echoed into the
 designated window according to the following rules:

+.bP

 If the character is the current erase character, left arrow, or backspace,
 the cursor is moved one space to the left and that screen position is erased
 as if \fBdelch\fR had been called.
 If the character is the current erase character, left arrow, or backspace,
 the cursor is moved one space to the left and that screen position is erased
 as if \fBdelch\fR had been called.

+.bP

 If the character value is any other \fBKEY_\fR define, the user is alerted
 with a \fBbeep\fR call.
 If the character value is any other \fBKEY_\fR define, the user is alerted
 with a \fBbeep\fR call.

+.bP
+If the character is a carriage-return,
+and if \fBnl\fP is enabled,
+it is translated to a line-feed after echoing.
+.bP

 Otherwise the character is simply output to the screen.
 .PP
 If the window is not a pad, and it has been moved or modified since the last
 call to \fBwrefresh\fR, \fBwrefresh\fR will be called before another character
 is read.
 Otherwise the character is simply output to the screen.
 .PP
 If the window is not a pad, and it has been moved or modified since the last
 call to \fBwrefresh\fR, \fBwrefresh\fR will be called before another character
 is read.

+.SS Keypad mode

 .PP
 If \fBkeypad\fR is \fBTRUE\fR, and a function key is pressed, the token for
 .PP
 If \fBkeypad\fR is \fBTRUE\fR, and a function key is pressed, the token for

-that function key is returned instead of the raw characters.
-Possible function
-keys are defined in \fB<curses.h>\fR as macros with values outside the range
-of 8-bit characters whose names begin with \fBKEY_\fR. Thus, a variable
+that function key is returned instead of the raw characters:
+.bP
+The predefined function
+keys are listed in \fB<curses.h>\fR as macros with values outside the range
+of 8-bit characters.
+Their names begin with \fBKEY_\fR.
+.bP
+Other (user-defined) function keys which may be defined
+using \fBdefine_key\fP(3X)
+have no names, but also are expected to have values outside the range of
+8-bit characters.
+.PP
+Thus, a variable

 intended to hold the return value of a function key must be of short size or
 larger.
 .PP
 intended to hold the return value of a function key must be of short size or
 larger.
 .PP


@@ -99,21 +128,37 @@ otherwise, the function key value is returned.
 For this reason, many terminals experience a delay between the time
 a user presses the escape key and the escape is returned to the program.
 .PP
 For this reason, many terminals experience a delay between the time
 a user presses the escape key and the escape is returned to the program.
 .PP

+In \fBncurses\fP, the timer normally expires after
+the value in \fBESCDELAY\fP (see \fBcurs_variables\fP(3X)).
+If \fBnotimeout\fP is \fBTRUE\fP, the timer does not expire;
+it is an infinite (or very large) value.
+Because function keys usually begin with an escape character,
+the terminal may appear to hang in notimeout mode after pressing the escape key
+until another key is pressed.
+.SS Ungetting characters
+.PP

 The \fBungetch\fR routine places \fIch\fR back onto the input queue to be
 returned by the next call to \fBwgetch\fR.
 There is just one input queue for all windows.
 .PP
 The \fBungetch\fR routine places \fIch\fR back onto the input queue to be
 returned by the next call to \fBwgetch\fR.
 There is just one input queue for all windows.
 .PP

-.SS Function Keys
-The following function keys, defined in \fB<curses.h>\fR, might be returned by
-\fBgetch\fR if \fBkeypad\fR has been enabled.
-Note that not all of these are
-necessarily supported on any particular terminal.
-.sp
+.SS Predefined key-codes
+The following special keys are defined in \fB<curses.h>\fR.
+.bP
+Except for the special case \fBKEY_RESIZE\fP,
+it is necessary to enable \fBkeypad\fR for \fBgetch\fP to return these codes.
+.bP
+Not all of these are necessarily supported on any particular terminal.
+.bP
+The naming convention may seem obscure, with some apparent
+misspellings (such as \*(``RSUME\*('' for \*(``resume\*('').
+The names correspond to the long terminfo capability names for the keys,
+and were defined long ago, in the 1980s.
+.PP

 .TS
 center tab(/) ;
 .TS
 center tab(/) ;

-l l

 l l .
 \fIName\fR/\fIKey\fR \fIname\fR
 l l .
 \fIName\fR/\fIKey\fR \fIname\fR

+_

 KEY_BREAK/Break key
 KEY_DOWN/The four arrow keys ...
 KEY_UP
 KEY_BREAK/Break key
 KEY_DOWN/The four arrow keys ...
 KEY_UP


@@ -213,7 +258,7 @@ KEY_UNDO/Undo key
 .TE
 .PP
 Keypad is arranged like this:
 .TE
 .PP
 Keypad is arranged like this:

-.sp
+.br

 .TS
 center allbox tab(/) ;
 c c c .
 .TS
 center allbox tab(/) ;
 c c c .


@@ -222,36 +267,66 @@ c c c .
 \fBC1\fR/\fBdown\fR/\fBC3\fR
 .TE
 .sp
 \fBC1\fR/\fBdown\fR/\fBC3\fR
 .TE
 .sp

-The \fBhas_key\fR routine takes a key value from the above list, and
-returns TRUE or FALSE according to whether
+A few of these predefined values do \fInot\fP correspond to a real key:
+.bP
+.B KEY_RESIZE
+is returned when the \fBSIGWINCH\fP signal has been detected
+(see \fBinitscr\fP(3X) and \fBresizeterm\fR(3X)).
+This code is returned whether or not \fBkeypad\fP has been enabled.
+.bP
+.B KEY_MOUSE
+is returned for mouse-events (see \fBcurs_mouse\fR(3X)).
+This code relies upon whether or not \fBkeypad\fP(3X) has been enabled,
+because (e.g., with \fIxterm\fP mouse prototocol) ncurses must
+read escape sequences,
+just like a function key.
+.SS Testing key-codes
+.PP
+The \fBhas_key\fR routine takes a key-code value from the above list, and
+returns \fBTRUE\fP or \fBFALSE\fP according to whether

 the current terminal type recognizes a key with that value.
 the current terminal type recognizes a key with that value.

-Note that a few values do not correspond to a real key,
-e.g., \fBKEY_RESIZE\fP and \fBKEY_MOUSE\fP.
-See \fBresizeterm\fR(3X) for more details about \fBKEY_RESIZE\fP, and
-\fBcurs_mouse\fR(3X) for a discussion of \fBKEY_MOUSE\fP.
+.PP
+The library also supports these extensions:
+.RS 3
+.TP 5
+.B define_key
+defines a key-code for a given string (see \fBdefine_key\fP(3X)).
+.TP 5
+.B key_defined
+checks if there is a key-code defined for a given
+string (see \fBkey_defined\fP(3X)).
+.RE

 .PP
 .SH RETURN VALUE
 All routines return the integer \fBERR\fR upon failure and an integer value
 .PP
 .SH RETURN VALUE
 All routines return the integer \fBERR\fR upon failure and an integer value

-other than \fBERR\fR (\fBOK\fR in the case of ungetch()) upon successful
+other than \fBERR\fR (\fBOK\fR in the case of \fBungetch\fP) upon successful

 completion.
 completion.

-.RS
+.RS 3

 .TP 5
 \fBungetch\fP
 .TP 5
 \fBungetch\fP

-returns an error
+returns \fBERR\fP

 if there is no more room in the FIFO.
 if there is no more room in the FIFO.

-.TP 5
+.TP

 \fBwgetch\fP
 \fBwgetch\fP

-returns an error
+returns \fBERR\fP

 if the window pointer is null, or
 if the window pointer is null, or

-if its timeout expires without having any data.
+if its timeout expires without having any data, or
+if the execution was interrupted by a signal (\fBerrno\fR will be set to
+\fBEINTR\fR).

 .RE
 .RE

+.PP
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
+\fBwmove\fP, and return an error if the position is outside the window,
+or if the window pointer is null.

 .SH NOTES
 Use of the escape key by a programmer for a single character function is
 discouraged, as it will cause a delay of up to one second while the
 keypad code looks for a following function-key sequence.
 .PP
 .SH NOTES
 Use of the escape key by a programmer for a single character function is
 discouraged, as it will cause a delay of up to one second while the
 keypad code looks for a following function-key sequence.
 .PP

-Note that some keys may be the same as commonly used control
-keys, e.g., \fBKEY_ENTER\fP versus control/M, \fBKEY_BACKSPACE\fP versus control/H.
+Some keys may be the same as commonly used control
+keys, e.g.,
+\fBKEY_ENTER\fP versus control/M,
+\fBKEY_BACKSPACE\fP versus control/H.

 Some curses implementations may differ according to whether they
 treat these control keys specially (and ignore the terminfo), or
 use the terminfo definitions.
 Some curses implementations may differ according to whether they
 treat these control keys specially (and ignore the terminfo), or
 use the terminfo definitions.


@@ -260,6 +335,20 @@ If it says that \fBKEY_ENTER\fP is control/M,
 \fBgetch\fR will return \fBKEY_ENTER\fP
 when you press control/M.
 .PP
 \fBgetch\fR will return \fBKEY_ENTER\fP
 when you press control/M.
 .PP

+Generally, \fBKEY_ENTER\fP denotes the character(s) sent by the \fIEnter\fP
+key on the numeric keypad:
+.bP
+the terminal description lists the most useful keys,
+.bP
+the \fIEnter\fP key on the regular keyboard is already handled by
+the standard ASCII characters for carriage-return and line-feed,
+.bP
+depending on whether \fBnl\fP or \fBnonl\fP was called,
+pressing \*(``Enter\*('' on the regular keyboard
+may return either a carriage-return or line-feed, and finally
+.bP
+\*(``Enter or send\*('' is the standard description for this key.
+.PP

 When using \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, or
 \fBmvwgetch\fR, nocbreak mode (\fBnocbreak\fR) and echo mode
 (\fBecho\fR) should not be used at the same time.
 When using \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, or
 \fBmvwgetch\fR, nocbreak mode (\fBnocbreak\fR) and echo mode
 (\fBecho\fR) should not be used at the same time.


@@ -299,12 +388,17 @@ implementation of handled signal receipt interrupts a \fBread\fR(2) call in
 progress or not, and also (in some implementations) depending on whether an
 input timeout or non-blocking mode has been set.
 .PP
 progress or not, and also (in some implementations) depending on whether an
 input timeout or non-blocking mode has been set.
 .PP

+\fBKEY_MOUSE\fP is mentioned in XSI Curses, along with a few related
+terminfo capabilities, but no higher-level functions use the feature.
+The implementation in ncurses is an extension.
+.PP
+\fBKEY_RESIZE\fP is an extension first implemented for ncurses.
+NetBSD curses later added this extension.
+.PP

 Programmers concerned about portability should be prepared for either of two
 cases: (a) signal receipt does not interrupt \fBgetch\fR; (b) signal receipt
 Programmers concerned about portability should be prepared for either of two
 cases: (a) signal receipt does not interrupt \fBgetch\fR; (b) signal receipt

-interrupts \fBgetch\fR and causes it to return ERR with \fBerrno\fR set to
+interrupts \fBgetch\fR and causes it to return \fBERR\fP with \fBerrno\fR set to

 \fBEINTR\fR.
 \fBEINTR\fR.

-Under the \fBncurses\fR implementation, handled signals never
-interrupt \fBgetch\fR.

 .PP
 The \fBhas_key\fR function is unique to \fBncurses\fR.
 We recommend that
 .PP
 The \fBhas_key\fR function is unique to \fBncurses\fR.
 We recommend that


@@ -312,13 +406,13 @@ any code using it be conditionalized on the \fBNCURSES_VERSION\fR feature macro.
 .SH SEE ALSO
 \fBcurses\fR(3X),
 \fBcurs_inopts\fR(3X),
 .SH SEE ALSO
 \fBcurses\fR(3X),
 \fBcurs_inopts\fR(3X),

+\fBcurs_outopts\fR(3X),

 \fBcurs_mouse\fR(3X),
 \fBcurs_move\fR(3X),
 \fBcurs_refresh\fR(3X),
 \fBcurs_mouse\fR(3X),
 \fBcurs_move\fR(3X),
 \fBcurs_refresh\fR(3X),

+\fBcurs_variables\fR(3X),

 \fBresizeterm\fR(3X).
 \fBresizeterm\fR(3X).

-.\"#
-.\"# The following sets edit modes for GNU EMACS
-.\"# Local Variables:
-.\"# mode:nroff
-.\"# fill-column:79
-.\"# End:
+.PP
+Comparable functions in the wide-character (ncursesw) library are
+described in
+\fBcurs_get_wch\fR(3X).