'\" t
.\"***************************************************************************
-.\" Copyright 2018-2022,2023 Thomas E. Dickey *
+.\" 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_util.3x,v 1.86 2023/10/07 21:19:07 tom Exp $
-.TH curs_util 3X 2023-10-07 "ncurses 6.4" "Library calls"
+.\" $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
.nf
\fB#include <curses.h>
.PP
-\fBconst char *unctrl(chtype \fIc\fP);
-\fBwchar_t *wunctrl(cchar_t *\fIc\fP);
+\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 \fIw\fP);
+\fBconst char *key_name(wchar_t \fIwc\fP);
.PP
\fBvoid filter(void);
.PP
.SH DESCRIPTION
.SS unctrl
The \fBunctrl\fP routine returns a character string which is a printable
-representation of the character \fIc\fP:
+representation of the character \fIch\fP:
.bP
Printable characters are displayed as themselves,
e.g., a one-character string containing the key.
this follows the X/Open specification.
.PP
The corresponding \fBwunctrl\fP returns a printable representation of
-a complex character \fIc\fP.
+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
+.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.
\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
+.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:
should be called before \fBinitscr\fP or
\fBnewterm\fP are called
(because those compute the screen size).
-It modifies the way \fIncurses\fP treats environment variables
+It modifies the way \fI\%ncurses\fP treats environment variables
when determining the screen size.
.bP
-Normally \fIncurses\fP 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
it overrides the values from the terminal database.
.bP
Finally (unless \fBuse_env\fP was called with \fBFALSE\fP parameter),
-\fBncurses\fP examines the \fBLINES\fP or \fBCOLUMNS\fP 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
-\fBNcurses\fP also updates the screen size in response to \fBSIGWINCH\fP,
-unless overridden by the \fBLINES\fP or \fBCOLUMNS\fP environment variables,
+\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\fP is called with \fBTRUE\fP as an argument,
-\fBncurses\fP modifies the last step in its computation
+\fI\%ncurses\fP modifies the last step in its computation
of screen size as follows:
.bP
-checks if the \fBLINES\fP and \fBCOLUMNS\fP environment variables
+checks if the \fILINES\fP and \fI\%COLUMNS\fP environment variables
are set to a number greater than zero.
.bP
-for each, \fBncurses\fP 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
-\fBncurses\fP 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 \fB\%use_env\fP and \fB\%use_tioctl\fP routines combine as follows.
.IP
_
TRUE FALSE T{
This is the default behavior.
-\fIncurses\fP uses operating system calls
-unless overridden by \fBLINES\fP or \fB\%COLUMNS\fP environment
+\fI\%ncurses\fP uses operating system calls
+unless overridden by \fILINES\fP or \fI\%COLUMNS\fP environment
variables;
default.
T}
TRUE TRUE T{
-\fIncurses\fP updates \fBLINES\fP and \fB\%COLUMNS\fP based on operating
-system calls.
+\fI\%ncurses\fP updates \fILINES\fP and \fI\%COLUMNS\fP based on
+operating system calls.
T}
FALSE TRUE T{
-\fIncurses\fP ignores \fBLINES\fP and \fB\%COLUMNS\fP,
+\fI\%ncurses\fP ignores \fILINES\fP and \fI\%COLUMNS\fP,
using operating system calls to obtain size.
T}
.TE
-.SS putwin/getwin
+.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.
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 (\fBncursesw\fP) and
-non-wide (\fBncurses\fP) 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),
.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\fP 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
+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.
.PP
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
.SS filter
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
+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
merged from all terminal descriptions which have been loaded.
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
-The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to \fBncurses\fP.
+.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 \fBncurses\fP extensions
+It is recommended that any code depending on \fI\%ncurses\fP extensions
be conditioned using \fBNCURSES_VERSION\fP.
-.SS putwin/getwin file-format
+.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.
+Most implementations simply dump the binary \fI\%WINDOW\fP structure
+to the file.
These include SVr4 curses, NetBSD and PDCurses,
-as well as older \fBncurses\fP versions.
+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.
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 successful.
-.SS unctrl/wunctrl
-The XSI Curses standard, Issue 4 describes these functions.
+.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:
this implementation returns strings \*(``M\-^@\*('', \*(``M\-^A\*('', etc.
.PP
X/Open Curses documents \fBunctrl\fP as declared in \fB<unctrl.h>\fP,
-which \fBncurses\fP does.
-However, \fBncurses\fP' \fB<curses.h>\fP includes \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 \fBncurses\fP is configured to provide the sp-functions extension,
+.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)).
projects / ncurses.git / blobdiff