.\"***************************************************************************
-.\" Copyright (c) 1998-2006,2007 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2007,2008 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 1.23 2007/02/24 15:59:07 tom Exp $
+.\" $Id: curs_util.3x,v 1.27 2008/10/25 23:45:41 tom Exp $
.TH curs_util 3X ""
.na
.hy 0
The corresponding \fBwunctrl\fR returns a printable representation of
a wide-character.
.PP
-The \fBkeyname\fR routine returns a character string corresponding to the key \fIc\fR.
+The \fBkeyname\fR routine returns a character string corresponding to the key \fIc\fR:
+.RS 3
+.TP 3
+-
+Printable characters are displayed as themselves, e.g., a one-character string containing the key.
+.TP 3
+-
Control characters are displayed in the \fB^\fR\fIX\fR notation.
-Values above 128 are either meta characters, shown in the \fBM-\fR\fIX\fR notation,
-or the names of function keys, or null.
+.TP 3
+-
+DEL (character 127) is displayed as \fB^?\fP.
+.TP 3
+-
+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),
+shown in the \fBM-\fR\fIX\fR notation,
+or are displayed as themselves.
+In the latter case, the values may not be printable;
+this follows the X/Open specification.
+.TP 3
+-
+Values above 256 may be the names of the names of function keys.
+.TP 3
+-
+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.
+.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;
.PP
X/Open does not define any error conditions.
In this implementation
-.RS
+.RS 3
.TP 5
\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
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
+.TP 5
+-
+the parameter is a 7-bit US-ASCII code.
+This is the case that X/Open Curses documented.
+.TP 5
+-
+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,
+\fBunctrl\fP returns the parameter, i.e., a one-character string with
+the parameter as the first character.
+Otherwise, it returns ``~@'', ``~A'', etc., analogous to ``^@'', ``^A'', C0 controls.
+.IP
+X/Open Curses does not document whether \fBunctrl\fP can be called before
+initializing curses.
+This implementation permits that,
+and returns the ``~@'', etc., values in that case.
+.TP 5
+-
+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
Other implementations have different conventions.
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-1280 codes as
+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
change the output of \fBunctrl\fP.
.PP
+Likewise, the \fBmeta\fP function allows the caller to change the
+output of \fBkeyname\fP, i.e.,
+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.
+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 \fBtic\fP.
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.
.PP
The \fBnofilter\fP routine is specific to ncurses.
It was not supported on Version 7, BSD or System V implementations.
\fBcurses\fR(3X),
\fBcurs_initscr\fR(3X),
\fBcurs_kernel\fR(3X),
-\fBcurs_scr_dump\fR(3X).
+\fBcurs_scr_dump\fR(3X),
+\fBlegacy_coding\fR(3X).
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