ncurses 6.2 - patch 20200418

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

diff --git a/man/curs_addch.3x b/man/curs_addch.3x
index 729382d49fcce828c3014db21c49bcd9587cc6fd..ccf8da212e8e24c54d79b79fac84f4f1ac71b534 100644 (file)
--- a/man/curs_addch.3x
+++ b/man/curs_addch.3x
@@ -1,6 +1,7 @@
 '\" t
 .\"***************************************************************************
-.\" Copyright (c) 1998-2018,2019 Free Software Foundation, Inc.              *
+.\" Copyright 2018-2019,2020 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            *
@@ -27,7 +28,7 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: curs_addch.3x,v 1.47 2019/02/16 23:50:17 tom Exp $
+.\" $Id: curs_addch.3x,v 1.52 2020/03/21 23:47:23 tom Exp $
 .TH curs_addch 3X ""
 .ie \n(.g .ds `` \(lq
 .el       .ds `` ``
@@ -174,6 +175,19 @@ unless otherwise noted in the preceding routine descriptions.
 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.
+.PP
+If it is not possible to add a complete character,
+an error is returned:
+.bP
+If \fBscrollok\fR is not enabled,
+writing a character at the lower right margin succeeds.
+However, an error is returned because
+it is not possible to wrap to a new line
+.bP
+If an error is detected when converting a multibyte character to a sequence
+of bytes,
+or if it is not possible to add all of the resulting bytes in the window,
+an error is returned.
 .SH NOTES
 Note that \fBaddch\fR, \fBmvaddch\fR, \fBmvwaddch\fR, and
 \fBechochar\fR may be macros.
@@ -185,6 +199,31 @@ The defaults specified for forms-drawing characters apply in the POSIX locale.
 X/Open Curses states that the \fIACS_\fP definitions are \fBchar\fP constants.
 For the wide-character implementation (see \fBcurs_add_wch\fP),
 there are analogous \fIWACS_\fP definitions which are \fBcchar_t\fP constants.
+Some implementations are problematic:
+.bP
+Some implementations define the ACS symbols to a constant
+(such as Solaris), while others define those to entries in an array.
+.IP
+This implementation uses an array \fBacs_map\fP, as done in SVr4 curses.
+NetBSD also uses an array, actually named \fB_acs_char\fP, with a \fB#define\fP
+for compatibility.
+.bP
+HPUX curses equates some of the \fIACS_\fP symbols
+to the analogous \fIWACS_\fP symbols as if the \fIACS_\fP symbols were
+wide characters.
+The misdefined symbols are the arrows
+and other symbols which are not used for line-drawing.
+.bP
+X/Open Curses (issues 2 through 7) has a typographical error
+for the ACS_LANTERN symbol, equating its \*(``VT100+ Character\*(''
+to \fBI\fP (capital I), while the header files for SVr4 curses
+and the various implementations use \fBi\fP (lowercase).
+.IP
+None of the terminal descriptions on Unix platforms use uppercase-I,
+except for Solaris (i.e., \fIscreen\fP's terminal description,
+apparently based on the X/Open documentation around 1995).
+On the other hand, the terminal description \fIgs6300\fP
+(AT&T PC6300 with EMOTS Terminal Emulator) uses lowercase-i.
 .LP
 Some ACS symbols
 (ACS_S3,
@@ -224,7 +263,7 @@ that the non-character information (attributes and color) was
 separated from the character information which is packed in a \fBchtype\fP
 to pass to \fBwaddch\fP.
 .PP
-In this implementation, \fBchtype\fP holds eight bits.
+In this implementation, \fBchtype\fP holds an eight-bit character.
 But ncurses allows multibyte characters to be passed in a succession
 of calls to \fBwaddch\fP.
 The other implementations do not do this;