'\" t
.\"***************************************************************************
-.\" Copyright (c) 1998-2013,2015 Free Software Foundation, Inc. *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
+.\" Copyright 1998-2015,2017 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_util.3x,v 1.41 2015/04/11 10:22:50 tom Exp $
-.TH curs_util 3X ""
-.ie \n(.g .ds `` \(lq
-.el .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el .ds '' ''
+.\" $Id: curs_util.3x,v 1.101 2024/04/20 21:20:07 tom Exp $
+.TH curs_util 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
-.na
-.hy 0
.SH NAME
-\fBdelay_output\fR,
-\fBfilter\fR,
-\fBflushinp\fR,
-\fBgetwin\fR,
-\fBkey_name\fR,
-\fBkeyname\fR,
-\fBnofilter\fR,
-\fBputwin\fR,
-\fBunctrl\fR,
-\fBuse_env\fR,
-\fBuse_tioctl\fR,
-\fBwunctrl\fR \- miscellaneous \fBcurses\fR utility routines
-.ad
-.hy
+\fB\%delay_output\fP,
+\fB\%filter\fP,
+\fB\%flushinp\fP,
+\fB\%getwin\fP,
+\fB\%key_name\fP,
+\fB\%keyname\fP,
+\fB\%nofilter\fP,
+\fB\%putwin\fP,
+\fB\%unctrl\fP,
+\fB\%use_env\fP,
+\fB\%use_tioctl\fP,
+\fB\%wunctrl\fP \-
+miscellaneous \fIcurses\fR utility routines
.SH SYNOPSIS
-\fB#include <curses.h>\fR
-.sp
-\fBchar *unctrl(chtype c);\fR
-.br
-\fBwchar_t *wunctrl(cchar_t *c);\fR
-.br
-\fBchar *keyname(int c);\fR
-.br
-\fBchar *key_name(wchar_t w);\fR
-.br
-\fBvoid filter(void);\fR
-.br
-\fBvoid nofilter(void);\fR
-.br
-\fBvoid use_env(bool f);\fR
-.br
-\fBvoid use_tioctl(bool f);\fR
-.br
-\fBint putwin(WINDOW *win, FILE *filep);\fR
-.br
-\fBWINDOW *getwin(FILE *filep);\fR
-.br
-\fBint delay_output(int ms);\fR
-.br
-\fBint flushinp(void);\fR
-.br
-.SH DESCRIPTION
-The \fBunctrl\fR routine returns a character string which is a printable
-representation of the character \fIc\fR, ignoring attributes.
-Control characters are displayed in the \fB^\fR\fIX\fR notation.
-Printing characters are displayed as is.
-The corresponding \fBwunctrl\fR returns a printable representation of
-a wide character.
+.nf
+\fB#include <curses.h>
+.PP
+\fBconst char *unctrl(chtype \fIch\fP);
+\fBwchar_t *wunctrl(cchar_t *\fIwch\fP);
+.PP
+\fBconst char *keyname(int \fIc\fP);
+\fBconst char *key_name(wchar_t \fIwc\fP);
+.PP
+\fBvoid filter(void);
.PP
-The \fBkeyname\fR routine returns a character string
-corresponding to the key \fIc\fR:
+\fBvoid use_env(bool \fIf\fP);
+.PP
+\fBint putwin(WINDOW *\fIwin\fP, FILE *\fIfilep\fP);
+\fBWINDOW *getwin(FILE *\fIfilep\fP);
+.PP
+\fBint delay_output(int \fIms\fP);
+\fBint flushinp(void);
+.PP
+\fI/* extensions */
+\fBvoid nofilter(void);
+\fBvoid use_tioctl(bool \fIf\fP);
+.fi
+.SH DESCRIPTION
+.SS unctrl
+The \fBunctrl\fP routine returns a character string which is a printable
+representation of the character \fIch\fP:
.bP
Printable characters are displayed as themselves,
e.g., a one-character string containing the key.
.bP
-Control characters are displayed in the \fB^\fR\fIX\fR notation.
+Control characters are displayed in the \fB^\fIX\fR notation.
+.bP
+Printing characters are displayed as is.
.bP
DEL (character 127) is displayed as \fB^?\fP.
.bP
Values above 128 are either meta characters
(if the screen has not been initialized,
-or if \fBmeta\fP has been called with a \fBTRUE\fP parameter),
-shown in the \fBM\-\fR\fIX\fR notation,
+or if \fBmeta\fP(3X) has been called with a \fBTRUE\fP parameter),
+shown in the \fBM\-\fIX\fR notation,
or are displayed as themselves.
In the latter case, the values may not be printable;
this follows the X/Open specification.
+.PP
+The corresponding \fBwunctrl\fP returns a printable representation of
+a complex character \fIwch\fP.
+.PP
+In both \fBunctrl\fP and \fBwunctrl\fP the attributes and color associated
+with the character parameter are ignored.
+.SS "keyname, key_name"
+The \fBkeyname\fP routine returns a character string
+corresponding to the key \fIc\fP.
+Key codes are different from character codes.
.bP
-Values above 256 may be the names of the names of function keys.
+Key codes below 256 are characters.
+They are displayed using \fBunctrl\fP.
.bP
-Otherwise (if there is no corresponding name) the function returns null,
-to denote an error.
-X/Open also lists an "UNKNOWN KEY" return value, which some implementations
-return rather than null.
+Values above 256 may be the codes for function keys.
+The function key name is displayed.
+.bP
+Otherwise (if there is no corresponding name and the key is not a character)
+the function returns null, to denote an error.
+X/Open also lists an \*(``UNKNOWN KEY\*('' return value,
+which some implementations return rather than null.
.LP
-The corresponding \fBkey_name\fR returns a character string corresponding
-to the wide-character value \fIw\fR.
-The two functions do not return the same set of strings;
-the latter returns null where the former would display a meta character.
-.PP
-The \fBfilter\fR routine, if used, must be called before \fBinitscr\fR or
-\fBnewterm\fR are called.
-The effect is that, during those calls, \fBLINES\fR
-is set to 1; the capabilities \fBclear\fR, \fBcup\fR, \fBcud\fR, \fBcud1\fR,
-\fBcuu1\fR, \fBcuu\fR, \fBvpa\fR are disabled; and the \fBhome\fR string is
-set to the value of \fBcr\fR.
+The corresponding \fBkey_name\fP returns
+a multibyte character string corresponding
+to the wide-character value \fIw\fP.
+The two functions (\fBkeyname\fP and \fBkey_name\fP)
+do not return the same set of strings:
+.bP
+\fBkeyname\fP returns null where \fBkey_name\fP would display a meta character.
+.bP
+\fBkey_name\fP does not return the name of a function key.
+.SS "filter, nofilter"
+The \fBfilter\fP routine, if used, must be called before \fBinitscr\fP or
+\fBnewterm\fP are called.
+Calling \fBfilter\fP causes these changes in initialization:
+.bP
+\fBLINES\fP is set to 1;
+.bP
+the capabilities
+\fBclear\fP,
+\fBcud1\fP,
+\fBcud\fP,
+\fBcup\fP,
+\fBcuu1\fP,
+\fBcuu\fP,
+\fBvpa\fP
+are disabled;
+.bP
+the capability \fBed\fP is disabled if \fBbce\fP is set;
+.bP
+and the \fBhome\fP string is set to the value of \fBcr\fP.
.PP
The \fBnofilter\fP routine cancels the effect of a preceding \fBfilter\fP
call.
using a different value of \fB$TERM\fP.
The limitation arises because the \fBfilter\fP routine modifies the
in-memory copy of the terminal information.
-.PP
-The \fBuse_env\fR routine, if used,
-should be called before \fBinitscr\fR or
-\fBnewterm\fR are called
+.SS use_env
+The \fBuse_env\fP routine, if used,
+should be called before \fBinitscr\fP or
+\fBnewterm\fP are called
(because those compute the screen size).
-It modifies the way \fBncurses\fP treats environment variables
+It modifies the way \fI\%ncurses\fP treats environment variables
when determining the screen size.
.bP
-Normally ncurses looks first at the terminal database for the screen size.
+Normally \fI\%ncurses\fP looks first at the terminal database for the
+screen size.
.IP
If \fBuse_env\fP was called with \fBFALSE\fP for parameter,
it stops here unless
-If \fBuse_tioctl\fP was also called with \fBTRUE\fP for parameter.
+\fBuse_tioctl\fP was also called with \fBTRUE\fP for parameter.
.bP
Then it asks for the screen size via operating system calls.
If successful,
it overrides the values from the terminal database.
.bP
Finally (unless \fBuse_env\fP was called with \fBFALSE\fP parameter),
-ncurses examines the \fBLINES\fR or \fBCOLUMNS\fR environment variables,
+\fI\%ncurses\fP examines the \fILINES\fP or \fI\%COLUMNS\fP environment
+variables,
using a value in those to override the results
from the operating system or terminal database.
.IP
-Ncurses also updates the screen size in response to SIGWINCH,
-unless overridden by the \fBLINES\fR or \fBCOLUMNS\fR environment variables,
-.PP
-The \fBuse_tioctl\fR routine, if used,
-should be called before \fBinitscr\fR or \fBnewterm\fR are called
+\fI\%curses\fP also updates the screen size in response to
+\fBSIGWINCH\fP,
+unless overridden by the \fILINES\fP or \fI\%COLUMNS\fP environment
+variables,
+.SS use_tioctl
+The \fBuse_tioctl\fP routine, if used,
+should be called before \fBinitscr\fP or \fBnewterm\fP are called
(because those compute the screen size).
-After \fBuse_tioctl\fR is called with \fBTRUE\fR as an argument,
-ncurses modifies the last step in its computation of screen size as follows:
+After \fBuse_tioctl\fP is called with \fBTRUE\fP as an argument,
+\fI\%ncurses\fP modifies the last step in its computation
+of screen size as follows:
.bP
-checks if the \fBLINES\fR and \fBCOLUMNS\fR environment variables
+checks if the \fILINES\fP and \fI\%COLUMNS\fP environment variables
are set to a number greater than zero.
.bP
-for each, ncurses updates the corresponding environment variable
+for each, \fI\%ncurses\fP updates the corresponding environment variable
with the value that it has obtained via operating system call
or from the terminal database.
.bP
-ncurses re-fetches the value of the environment variables so that
-it is still the environment variables which set the screen size.
+\fI\%ncurses\fP re-fetches the value of the environment variables so
+that it is still the environment variables which set the screen size.
.PP
-The \fBuse_env\fP and \fBuse_tioctl\fP routines combine as
-summarized here:
+The \fB\%use_env\fP and \fB\%use_tioctl\fP routines combine as follows.
+.IP
.TS
-center tab(/);
-l l l
-_ _ _
-lw7 lw7 lw40.
-\fIuse_env\fR/\fIuse_tioctl\fR/\fISummary\fR
-TRUE/FALSE/T{
+lB lB lB
+lB lB lx.
+use_env use_tioctl Summary
+_
+TRUE FALSE T{
This is the default behavior.
-ncurses uses operating system calls
-unless overridden by $LINES or $COLUMNS environment variables.
-T}
-TRUE/TRUE/T{
-ncurses updates $LINES and $COLUMNS based on operating system calls.
+\fI\%ncurses\fP uses operating system calls
+unless overridden by \fILINES\fP or \fI\%COLUMNS\fP environment
+variables;
+default.
T}
-FALSE/TRUE/T{
-ncurses ignores $LINES and $COLUMNS, uses operating system calls to obtain size.
+TRUE TRUE T{
+\fI\%ncurses\fP updates \fILINES\fP and \fI\%COLUMNS\fP based on
+operating system calls.
T}
-FALSE/FALSE/T{
-ncurses relies on the terminal database to determine size.
+FALSE TRUE T{
+\fI\%ncurses\fP ignores \fILINES\fP and \fI\%COLUMNS\fP,
+using operating system calls to obtain size.
T}
.TE
-.PP
-The \fBputwin\fR routine writes all data associated
-with window (or pad) \fIwin\fR into
-the file to which \fIfilep\fR points.
+.SS "putwin, getwin"
+The \fBputwin\fP routine writes all data associated
+with window (or pad) \fIwin\fP into
+the file to which \fIfilep\fP points.
This information can be later retrieved
-using the \fBgetwin\fR function.
+using the \fBgetwin\fP function.
.PP
-The \fBgetwin\fR routine reads window related data stored in the file by
-\fBputwin\fR.
+The \fBgetwin\fP routine reads window related data stored in the file by
+\fBputwin\fP.
The routine then creates and initializes a new window using that
data.
It returns a pointer to the new window.
There are a few caveats:
.bP
-the data written is a copy of the \fBWINDOW\fP structure,
+the data written is a copy of the \fI\%WINDOW\fP structure,
and its associated character cells.
-The format differs between the wide-character (ncursesw) and
-non-wide (ncurses) libraries.
+The format differs between the wide-character (\fI\%ncursesw\fP) and
+non-wide (\fI\%ncurses\fP) libraries.
You can transfer data between the two, however.
.bP
the retrieved window is always created as a top-level window (or pad),
If cells in the retrieved window use color pairs which have not been
created in the application using \fBinit_pair\fP,
they will not be colored when the window is refreshed.
-.PP
-The \fBdelay_output\fR routine inserts an \fIms\fR millisecond pause
+.SS delay_output
+The \fBdelay_output\fP routine inserts an \fIms\fP millisecond pause
in output.
-This routine should not be used extensively because
-padding characters are used rather than a CPU pause.
-If no padding character is specified,
-this uses \fBnapms\fR to perform the delay.
+Employ this function judiciously when terminal output uses padding,
+because \fI\%ncurses\fP transmits null characters
+(consuming CPU and I/O resources)
+instead of sleeping and requesting resumption from the operating system.
+Padding is used unless:
+.bP
+the terminal description has \fBnpc\fP (\fBno_pad_char\fP) capability, or
+.bP
+the environment variable \fB\%NCURSES_NO_PADDING\fP is set.
.PP
-The \fBflushinp\fR routine throws away any typeahead that has been typed by the
+If padding is not in use,
+\fI\%ncurses\fP uses \fBnapms\fP to perform the delay.
+If the value of \fIms\fP exceeds 30,000
+(thirty seconds),
+it is capped at that value.
+.SS flushinp
+The \fBflushinp\fP routine throws away any typeahead that has been typed by the
user and has not yet been read by the program.
.SH RETURN VALUE
-Except for \fBflushinp\fR, routines that return an integer return \fBERR\fR
-upon failure and \fBOK\fR (SVr4 specifies only "an integer value other than
-\fBERR\fR") upon successful completion.
+Except for \fBflushinp\fP, routines that return an integer return \fBERR\fP
+upon failure and \fBOK\fP (SVr4 specifies only "an integer value other than
+\fBERR\fP") upon successful completion.
.PP
-Routines that return pointers return \fBNULL\fR on error.
+Routines that return pointers return \fBNULL\fP on error.
.PP
-X/Open does not define any error conditions.
+X/Open Curses does not specify any error conditions.
In this implementation
.RS 3
.TP 5
-\fBflushinp\fR
-returns an error if the terminal was not initialized.
-.TP 5
-\fBmeta\fR
+\fBflushinp\fP
returns an error if the terminal was not initialized.
.TP 5
\fBputwin\fP
.RE
.SH PORTABILITY
.SS filter
-.PP
-The SVr4 documentation describes the action of \fBfilter\fR only in the vaguest
+The SVr4 documentation describes the action of \fBfilter\fP only in the vaguest
terms.
-The description here is adapted from the XSI Curses standard (which
-erroneously fails to describe the disabling of \fBcuu\fR).
-.SS keyname
+The description here is adapted from X/Open Curses (which
+erroneously fails to describe the disabling of \fBcuu\fP).
+.SS "delay_output padding"
+The limitation to 30 seconds
+and the use of \fBnapms\fP
+differ from other implementations.
+.bP
+SVr4 curses does not delay if no padding character is available.
+.bP
+NetBSD curses uses \fBnapms\fP when no padding character is available,
+but does not take timing into account when using the padding character.
.PP
+Neither limits the delay.
+.SS keyname
The \fBkeyname\fP function may return the names of user-defined
string capabilities which are defined in the terminfo entry via the \fB\-x\fP
option of \fB@TIC@\fP.
This implementation automatically assigns at run-time keycodes to
-user-defined strings which begin with "k".
+user-defined strings which begin with \*(``k\*(''.
The keycodes start at KEY_MAX, but are not guaranteed to be
the same value for different runs because user-defined codes are
merged from all terminal descriptions which have been loaded.
-The \fBuse_extended_names\fP function controls whether this data is
+The \fBuse_extended_names\fP(3X) function controls whether this data is
loaded when the terminal description is read by the library.
-.SS nofilter/use_tioctl
-.PP
-The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to ncurses.
+.SS "nofilter, use_tioctl"
+The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to
+\fI\%ncurses\fP.
They were not supported on Version 7, BSD or System V implementations.
-It is recommended that any code depending on ncurses extensions
-be conditioned using NCURSES_VERSION.
-.SS putwin/getwin
-.PP
+It is recommended that any code depending on \fI\%ncurses\fP extensions
+be conditioned using \fBNCURSES_VERSION\fP.
+.SS "putwin/getwin file-format"
The \fBputwin\fP and \fBgetwin\fP functions have several issues with
portability:
.bP
and were later (in 1988) incorporated into SVr4.
Oddly, there are no such functions in the 4.3BSD curses sources.
.bP
-Most implementations simply dump the binary \fBWINDOW\fP structure to the file.
-These include SVr4 curses, NetBSD and PDCurses, as well as older ncurses versions.
-This implementation (as well as the X/Open variant of Solaris curses, dated 1995)
+Most implementations simply dump the binary \fI\%WINDOW\fP structure
+to the file.
+These include SVr4 curses, NetBSD and PDCurses,
+as well as older \fI\%ncurses\fP versions.
+This implementation
+(as well as the X/Open variant of Solaris curses, dated 1995)
uses textual dumps.
.IP
The implementations which use binary dumps use block-I/O
these functions.
Doing that can run into problems mixing block- and buffered-I/O.
This implementation reduces the problem on writes by flushing the output.
-However, reading from a file written using mixed schemes may not be succesful.
-.SS unctrl/wunctrl
-.PP
-The XSI Curses standard, Issue 4 describes these functions.
-It states that \fBunctrl\fR and \fBwunctrl\fR will return a null pointer if
+However, reading from a file written using mixed schemes may not be successful.
+.SS "unctrl, wunctrl"
+X/Open Curses, Issue 4 describes these functions.
+It states that \fBunctrl\fP and \fBwunctrl\fP will return a null pointer if
unsuccessful, but does not define any error conditions.
This implementation checks for three cases:
.bP
This is the case that X/Open Curses documented.
.bP
the parameter is in the range 128\-159, i.e., a C1 control code.
-If \fBuse_legacy_coding\fP has been called with a \fB2\fP parameter,
+If \fBuse_legacy_coding\fP(3X) has been called with a \fB2\fP parameter,
\fBunctrl\fP returns the parameter, i.e., a one-character string with
the parameter as the first character.
Otherwise, it returns \*(``~@\*('', \*(``~A\*('', etc.,
parameter values outside the 0 to 255 range.
\fBunctrl\fP returns a null pointer.
.PP
-The strings returned by \fBunctrl\fR in this implementation are determined
+The strings returned by \fBunctrl\fP in this implementation are determined
at compile time,
-showing C1 controls from the upper-128 codes with a `~' prefix rather than `^'.
+showing C1 controls from the upper-128 codes
+with a \*(``~\*('' prefix rather than \*(``^\*(''.
Other implementations have different conventions.
-For example, they may show both sets of control characters with `^',
+For example, they may show both sets of control characters with \*(``^\*('',
and strip the parameter to 7 bits.
Or they may ignore C1 controls and treat all of the upper-128 codes as
printable.
This implementation uses 8 bits but does not modify the string to reflect
locale.
-The \fBuse_legacy_coding\fP function allows the caller to
+The \fBuse_legacy_coding\fP(3X) function allows the caller to
change the output of \fBunctrl\fP.
.PP
-Likewise, the \fBmeta\fP function allows the caller to change the
+Likewise, the \fBmeta\fP(3X) function allows the caller to change the
output of \fBkeyname\fP, i.e.,
-it determines whether to use the `M\-' prefix
+it determines whether to use the \*(``M\-\*('' prefix
for \*(``meta\*('' keys (codes in the range 128 to 255).
-Both \fBuse_legacy_coding\fP and \fBmeta\fP succeed only after
+Both \fBuse_legacy_coding\fP(3X) and \fBmeta\fP(3X) succeed only after
curses is initialized.
X/Open Curses does not document the treatment of codes 128 to 159.
When treating them as \*(``meta\*('' keys
(or if \fBkeyname\fP is called before initializing curses),
this implementation returns strings \*(``M\-^@\*('', \*(``M\-^A\*('', etc.
+.PP
+X/Open Curses documents \fBunctrl\fP as declared in \fB<unctrl.h>\fP,
+which \fI\%ncurses\fP does.
+However, \fI\%ncurses\fP' \fB<curses.h>\fP includes \fB<unctrl.h>\fP,
+matching the behavior of SVr4 curses.
+Other implementations may not do that.
+.SS "use_env, use_tioctl"
+If \fI\%ncurses\fP is configured to provide the sp-functions extension,
+the state of \fBuse_env\fP and \fBuse_tioctl\fP may be updated before
+creating each \fIscreen\fP rather than once only
+(\fBcurs_sp_funcs\fP(3X)).
+This feature of \fBuse_env\fP
+is not provided by other implementations of curses.
.SH SEE ALSO
-\fBlegacy_coding\fR(3X),
-\fBcurses\fR(3X),
-\fBcurs_initscr\fR(3X),
-\fBcurs_kernel\fR(3X),
-\fBcurs_scr_dump\fR(3X),
-\fBcurs_variables\fR(3X),
-\fBlegacy_coding\fR(3X).
+\fB\%curses\fP(3X),
+\fB\%curs_initscr\fP(3X),
+\fB\%curs_inopts\fP(3X),
+\fB\%curs_kernel\fP(3X),
+\fB\%curs_scr_dump\fP(3X),
+\fB\%curs_sp_funcs\fP(3X),
+\fB\%curs_variables\fP(3X),
+\fB\%legacy_coding\fP(3X)
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