'\" t
.\"***************************************************************************
-.\" Copyright (c) 1998-2012,2013 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2017,2018 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 1.37 2013/07/20 19:43:45 tom Exp $
+.\" $Id: curs_util.3x,v 1.54 2018/07/28 22:08:59 tom Exp $
.TH curs_util 3X ""
.ie \n(.g .ds `` \(lq
.el .ds `` ``
.ie \n(.g .ds '' \(rq
.el .ds '' ''
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.na
.hy 0
\fBint flushinp(void);\fR
.br
.SH DESCRIPTION
+.SS unctrl
+.PP
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.
+.SS keyname/key_name
.PP
The \fBkeyname\fR routine returns a character string
corresponding to the key \fIc\fR:
-.RS 3
.bP
Printable characters are displayed as themselves,
e.g., a one-character string containing the key.
.bP
Values above 128 are either meta characters
(if the screen has not been initialized,
-or if \fBmeta\fP has been called with a TRUE parameter),
+or if \fBmeta\fP(3X) has been called with a \fBTRUE\fP parameter),
shown in the \fBM\-\fR\fIX\fR notation,
or are displayed as themselves.
In the latter case, the values may not be printable;
to denote an error.
X/Open also lists an "UNKNOWN KEY" return value, which some implementations
return rather than null.
-.RE
.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.
+.SS filter/nofilter
.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.
+\fBnewterm\fR are called.
+Calling \fBfilter\fP causes these changes in initialization:
+.bP
+\fBLINES\fR is set to 1;
+.bP
+the capabilities
+\fBclear\fR,
+\fBcud1\fR,
+\fBcud\fR,
+\fBcup\fR,
+\fBcuu1\fR,
+\fBcuu\fR,
+\fBvpa\fR
+are disabled;
+.bP
+the capability \fBed\fP is disabled if \fBbce\fP is set;
+.bP
+and the \fBhome\fR string is set to the value of \fBcr\fR.
.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.
+.SS use_env
.PP
The \fBuse_env\fR routine, if used,
should be called before \fBinitscr\fR or
It modifies the way \fBncurses\fP treats environment variables
when determining the screen size.
.bP
-Normally ncurses looks first at the terminal database for the screen size.
+Normally \fBncurses\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,
+\fBncurses\fP examines the \fBLINES\fR or \fBCOLUMNS\fR 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,
+\fBNcurses\fP also updates the screen size in response to \fBSIGWINCH\fP,
unless overridden by the \fBLINES\fR or \fBCOLUMNS\fR environment variables,
+.SS use_tioctl
.PP
The \fBuse_tioctl\fR routine, if used,
should be called before \fBinitscr\fR or \fBnewterm\fR 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:
+\fBncurses\fP modifies the last step in its computation
+of screen size as follows:
.bP
checks if the \fBLINES\fR and \fBCOLUMNS\fR environment variables
are set to a number greater than zero.
.bP
-for each, ncurses updates the corresponding environment variable
+for each, \fBncurses\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
+\fBncurses\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
\fIuse_env\fR/\fIuse_tioctl\fR/\fISummary\fR
TRUE/FALSE/T{
This is the default behavior.
-ncurses uses operating system calls
+\fBncurses\fP 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.
+\fBncurses\fP updates $LINES and $COLUMNS based on operating system calls.
T}
FALSE/TRUE/T{
-ncurses ignores $LINES and $COLUMNS, uses operating system calls to obtain size.
+\fBncurses\fP ignores $LINES and $COLUMNS,
+uses operating system calls to obtain size.
T}
FALSE/FALSE/T{
-ncurses relies on the terminal database to determine size.
+\fBncurses\fP relies on the terminal database to determine size.
T}
.TE
+.SS putwin/getwin
.PP
-The \fBputwin\fR routine writes all data associated with window \fIwin\fR into
-the file to which \fIfilep\fR points. This information can be later retrieved
+The \fBputwin\fR routine writes all data associated
+with window (or pad) \fIwin\fR into
+the file to which \fIfilep\fR points.
+This information can be later retrieved
using the \fBgetwin\fR function.
.PP
The \fBgetwin\fR routine reads window related data stored in the file by
-\fBputwin\fR. The routine then creates and initializes a new window using that
-data. It returns a pointer to the new window.
+\fBputwin\fR.
+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,
+and its associated character cells.
+The format differs between the wide-character (\fBncursesw\fP) and
+non-wide (\fBncurses\fP) libraries.
+You can transfer data between the two, however.
+.bP
+the retrieved window is always created as a top-level window (or pad),
+rather than a subwindow.
+.bP
+the window's character cells contain the color pair \fIvalue\fP,
+but not the actual color \fInumbers\fP.
+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.
+.SS delay_output
.PP
The \fBdelay_output\fR routine inserts an \fIms\fR millisecond pause
-in output. This routine should not be used extensively because
+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.
+.SS flushinp
.PP
The \fBflushinp\fR routine throws away any typeahead that has been typed by the
user and has not yet been read by the program.
\fBflushinp\fR
returns an error if the terminal was not initialized.
.TP 5
-\fBmeta\fR
-returns an error if the terminal was not initialized.
-.TP 5
\fBputwin\fP
returns an error if the associated \fBfwrite\fP calls return an error.
.RE
.SH PORTABILITY
+.SS filter
+.PP
+The SVr4 documentation describes the action of \fBfilter\fR 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
+.PP
+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".
+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(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 \fBncurses\fP.
+They were not supported on Version 7, BSD or System V implementations.
+It is recommended that any code depending on \fBncurses\fP extensions
+be conditioned using NCURSES_VERSION.
+.SS putwin/getwin
+.PP
+The \fBputwin\fP and \fBgetwin\fP functions have several issues with
+portability:
+.bP
+The files written and read by these functions
+use an implementation-specific format.
+Although the format is an obvious target for standardization,
+it has been overlooked.
+.IP
+Interestingly enough, according to the copyright dates in Solaris source,
+the functions (along with \fBscr_init\fP, etc.) originated with
+the University of California, Berkeley (in 1982)
+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 \fBncurses\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
+(the \fBfwrite\fP and \fBfread\fP functions).
+Those that use textual dumps use buffered-I/O.
+A few applications may happen to write extra data in the file using
+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 successful.
+.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
unsuccessful, but does not define any error conditions.
This implementation checks for three cases:
-.RS 3
.bP
the parameter is a 7-bit US\-ASCII code.
This is the case that X/Open Curses documented.
.bP
parameter values outside the 0 to 255 range.
\fBunctrl\fP returns a null pointer.
-.RE
-.PP
-The SVr4 documentation describes the action of \fBfilter\fR 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).
.PP
The strings returned by \fBunctrl\fR 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.
The \fBuse_legacy_coding\fP 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
-curses is initialized.
+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
-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".
-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
-loaded when the terminal description is read by the library.
+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,
+matching the behavior of SVr4 curses.
+Other implementations may not do that.
+.SS use_env/use_tioctl
.PP
-The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to ncurses.
-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.
+If \fBncurses\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\fR(3X)).
+This feature of \fBuse_env\fP
+is not provided by other implementation of curses.
.SH SEE ALSO
\fBlegacy_coding\fR(3X),
\fBcurses\fR(3X),
\fBcurs_initscr\fR(3X),
+\fBcurs_inopts\fR(3X),
\fBcurs_kernel\fR(3X),
\fBcurs_scr_dump\fR(3X),
+\fBcurs_sp_funcs\fR(3X),
\fBcurs_variables\fR(3X),
\fBlegacy_coding\fR(3X).
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