.\"***************************************************************************
-.\" Copyright (c) 2001-2010,2011 Free Software Foundation, Inc. *
+.\" Copyright 2019,2020 Thomas E. Dickey *
+.\" Copyright 2001-2015,2017 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_add_wch.3x,v 1.14 2011/01/15 15:27:43 tom Exp $
+.\" $Id: curs_add_wch.3x,v 1.27 2020/03/22 00:25:15 tom Exp $
.TH curs_add_wch 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
..
.SH NAME
\fBadd_wch\fP,
.B "int wecho_wchar( WINDOW *\fIwin\fP, const cchar_t *\fIwch\fB );"
.br
.SH DESCRIPTION
+.SS add_wch
.PP
The
\fBadd_wch\fP,
If the character part of \fIwch\fP is
a tab, newline, backspace or other control character,
the window is updated and the cursor moves as if \fBaddch\fR were called.
+.SS echo_wchar
.PP
The \fBecho_wchar\fP
function is functionally equivalent to a call to
\fBadd_wch\fP
followed by a call to
-\fBrefresh\fP.
+\fBrefresh\fP(3X).
Similarly, the
\fBwecho_wchar\fP
is functionally equivalent to a call to
\fBaddch\fP(3X).
.PP
.TS
-l l l l
-_ _ _ _
-lw(1.5i) lw7 lw7 lw20.
-\fIName\fR \fIUnicode\fP \fIDefault\fR \fIDescription\fR
-WACS_BLOCK 0x25ae # solid square block
-WACS_BOARD 0x2592 # board of squares
-WACS_BTEE 0x2534 + bottom tee
-WACS_BULLET 0x00b7 o bullet
-WACS_CKBOARD 0x2592 : checker board (stipple)
-WACS_DARROW 0x2193 v arrow pointing down
-WACS_DEGREE 0x00b0 ' degree symbol
-WACS_DIAMOND 0x25c6 + diamond
-WACS_GEQUAL 0x2265 > greater-than-or-equal-to
-WACS_HLINE 0x2500 \- horizontal line
-WACS_LANTERN 0x2603 # lantern symbol
-WACS_LARROW 0x2190 < arrow pointing left
-WACS_LEQUAL 0x2264 < less-than-or-equal-to
-WACS_LLCORNER 0x2514 + lower left-hand corner
-WACS_LRCORNER 0x2518 + lower right-hand corner
-WACS_LTEE 0x2524 + left tee
-WACS_NEQUAL 0x2260 ! not-equal
-WACS_PI 0x03c0 * greek pi
-WACS_PLMINUS 0x00b1 # plus/minus
-WACS_PLUS 0x253c + plus
-WACS_RARROW 0x2192 > arrow pointing right
-WACS_RTEE 0x251c + right tee
-WACS_S1 0x23ba \- scan line 1
-WACS_S3 0x23bb \- scan line 3
-WACS_S7 0x23bc \- scan line 7
-WACS_S9 0x23bd \&_ scan line 9
-WACS_STERLING 0x00a3 f pound-sterling symbol
-WACS_TTEE 0x252c + top tee
-WACS_UARROW 0x2191 ^ arrow pointing up
-WACS_ULCORNER 0x250c + upper left-hand corner
-WACS_URCORNER 0x2510 + upper right-hand corner
-WACS_VLINE 0x2502 | vertical line
+l l l l l
+l l l l l
+_ _ _ _ _
+lw(1.5i) lw5 lw5 lw5 lw20.
+\fBACS\fR \fBUnicode\fP \fBASCII\fR \fBacsc\fP \fBGlyph\fR
+\fBName\fR \fBDefault\fP \fBDefault\fR \fBchar\fP \fBName\fR
+WACS_BLOCK 0x25ae # 0 solid square block
+WACS_BOARD 0x2592 # h board of squares
+WACS_BTEE 0x2534 + v bottom tee
+WACS_BULLET 0x00b7 o ~ bullet
+WACS_CKBOARD 0x2592 : a checker board (stipple)
+WACS_DARROW 0x2193 v . arrow pointing down
+WACS_DEGREE 0x00b0 ' f degree symbol
+WACS_DIAMOND 0x25c6 + ` diamond
+WACS_GEQUAL 0x2265 > > greater-than-or-equal-to
+WACS_HLINE 0x2500 \- q horizontal line
+WACS_LANTERN 0x2603 # i lantern symbol
+WACS_LARROW 0x2190 < , arrow pointing left
+WACS_LEQUAL 0x2264 < y less-than-or-equal-to
+WACS_LLCORNER 0x2514 + m lower left-hand corner
+WACS_LRCORNER 0x2518 + j lower right-hand corner
+WACS_LTEE 0x2524 + t left tee
+WACS_NEQUAL 0x2260 ! | not-equal
+WACS_PI 0x03c0 * { greek pi
+WACS_PLMINUS 0x00b1 # g plus/minus
+WACS_PLUS 0x253c + n plus
+WACS_RARROW 0x2192 > + arrow pointing right
+WACS_RTEE 0x251c + u right tee
+WACS_S1 0x23ba \- o scan line 1
+WACS_S3 0x23bb \- p scan line 3
+WACS_S7 0x23bc \- r scan line 7
+WACS_S9 0x23bd \&_ s scan line 9
+WACS_STERLING 0x00a3 f } pound-sterling symbol
+WACS_TTEE 0x252c + w top tee
+WACS_UARROW 0x2191 ^ \- arrow pointing up
+WACS_ULCORNER 0x250c + l upper left-hand corner
+WACS_URCORNER 0x2510 + k upper right-hand corner
+WACS_VLINE 0x2502 | x vertical line
.TE
.PP
The wide-character configuration of ncurses also defines symbols
-for thick- and double-lines:
+for thick lines (\fBacsc\fP \*(``J\*('' to \*(``V\*(''):
+.TS
+l l l l l
+l l l l l
+_ _ _ _ _
+lw(1.5i) lw5 lw5 lw5 lw20.
+\fBACS\fR \fBUnicode\fP \fBASCII\fR \fBacsc\fP \fBGlyph\fR
+\fBName\fR \fBDefault\fP \fBDefault\fR \fBchar\fP \fBName\fR
+WACS_T_BTEE 0x253b + V thick tee pointing up
+WACS_T_HLINE 0x2501 - Q thick horizontal line
+WACS_T_LLCORNER 0x2517 + M thick lower left corner
+WACS_T_LRCORNER 0x251b + J thick lower right corner
+WACS_T_LTEE 0x252b + T thick tee pointing right
+WACS_T_PLUS 0x254b + N thick large plus
+WACS_T_RTEE 0x2523 + U thick tee pointing left
+WACS_T_TTEE 0x2533 + W thick tee pointing down
+WACS_T_ULCORNER 0x250f + L thick upper left corner
+WACS_T_URCORNER 0x2513 + K thick upper right corner
+WACS_T_VLINE 0x2503 | X thick vertical line
+.TE
+.PP
+and for double-lines (\fBacsc\fP \*(``A\*('' to \*(``I\*(''):
.PP
.TS
-l l l l
-_ _ _ _
-lw(1.5i) lw7 lw7 lw20.
-\fIName\fR \fIUnicode\fP \fIDefault\fR \fIDescription\fR
-WACS_T_ULCORNER 0x250f + thick upper left corner
-WACS_T_LLCORNER 0x2517 + thick lower left corner
-WACS_T_URCORNER 0x2513 + thick upper right corner
-WACS_T_LRCORNER 0x251b + thick lower right corner
-WACS_T_LTEE 0x252b + thick tee pointing right
-WACS_T_RTEE 0x2523 + thick tee pointing left
-WACS_T_BTEE 0x253b + thick tee pointing up
-WACS_T_TTEE 0x2533 + thick tee pointing down
-WACS_T_HLINE 0x2501 - thick horizontal line
-WACS_T_VLINE 0x2503 | thick vertical line
-WACS_T_PLUS 0x254b + thick large plus or crossover
-WACS_D_ULCORNER 0x2554 + double upper left corner
-WACS_D_LLCORNER 0x255a + double lower left corner
-WACS_D_URCORNER 0x2557 + double upper right corner
-WACS_D_LRCORNER 0x255d + double lower right corner
-WACS_D_RTEE 0x2563 + double tee pointing left
-WACS_D_LTEE 0x2560 + double tee pointing right
-WACS_D_BTEE 0x2569 + double tee pointing up
-WACS_D_TTEE 0x2566 + double tee pointing down
-WACS_D_HLINE 0x2550 - double horizontal line
-WACS_D_VLINE 0x2551 | double vertical line
-WACS_D_PLUS 0x256c + double large plus or crossover
+l l l l l
+l l l l l
+_ _ _ _ _
+lw(1.5i) lw5 lw5 lw5 lw20.
+\fBACS\fR \fBUnicode\fP \fBASCII\fR \fBacsc\fP \fBGlyph\fR
+\fBName\fR \fBDefault\fP \fBDefault\fR \fBchar\fP \fBName\fR
+WACS_D_BTEE 0x2569 + H double tee pointing up
+WACS_D_HLINE 0x2550 - R double horizontal line
+WACS_D_LLCORNER 0x255a + D double lower left corner
+WACS_D_LRCORNER 0x255d + A double lower right corner
+WACS_D_LTEE 0x2560 + F double tee pointing right
+WACS_D_PLUS 0x256c + E double large plus
+WACS_D_RTEE 0x2563 + G double tee pointing left
+WACS_D_TTEE 0x2566 + I double tee pointing down
+WACS_D_ULCORNER 0x2554 + C double upper left corner
+WACS_D_URCORNER 0x2557 + B double upper right corner
+WACS_D_VLINE 0x2551 | Y double vertical line
.TE
-.SH RETURN VALUES
+.PP
+Unicode's descriptions for these characters differs slightly from ncurses,
+by introducing the term \*(``light\*('' (along with less important details).
+Here are its descriptions for the normal, thick, and double horizontal lines:
+.bP
+U+2500 BOX DRAWINGS LIGHT HORIZONTAL
+.bP
+U+2501 BOX DRAWINGS HEAVY HORIZONTAL
+.bP
+U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
+.SH RETURN VALUE
.PP
All routines return the integer \fBERR\fR upon failure and \fBOK\fR on success.
.PP
-Functions with a "mv" prefix first perform a cursor movement using
+X/Open does not define any error conditions.
+This implementation returns an error
+.bP
+if the window pointer is null or
+.bP
+if it is not possible to add a complete character in the window.
+.PP
+The latter may be due to different causes:
+.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.
+.PP
+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.
.SH NOTES
terms of intermediate symbols.
This implementation extends those symbols, providing new definitions
which are not in the SVr4 implementations.
+.PP
+Not all Unicode-capable terminals provide support for VT100-style
+alternate character sets (i.e., the \fBacsc\fP capability),
+with their corresponding line-drawing characters.
+X/Open Curses did not address the aspect of integrating Unicode with
+line-drawing characters.
+Existing implementations of Unix curses (AIX, HPUX, Solaris)
+use only the \fBacsc\fP character-mapping to provide this feature.
+As a result, those implementations can only use single-byte line-drawing
+characters.
+Ncurses 5.3 (2002) provided a table of Unicode values to solve these problems.
+NetBSD curses incorporated that table in 2010.
+.PP
+In this implementation, the Unicode values are used instead of the
+terminal description's \fBacsc\fP mapping as discussed in ncurses(3X)
+for the environment variable \fBNCURSES_NO_UTF8_ACS\fP.
+In contrast, for the same cases, the line-drawing characters
+described in \fBcurs_addch\fP(3X) will use only the ASCII default values.
+.PP
+Having Unicode available does not solve all of the problems with
+line-drawing for curses:
+.bP
+The closest Unicode equivalents to the
+VT100 graphics \fIS1\fP, \fIS3\fP, \fIS7\fP and \fIS9\fP
+frequently are not displayed at
+the regular intervals which the terminal used.
+.bP
+The \fIlantern\fP is a special case.
+It originated with the AT&T 4410 terminal in the early 1980s.
+There is no accessible documentation depicting the lantern symbol
+on the AT&T terminal.
+.IP
+Lacking documentation, most readers assume that a \fIstorm lantern\fP
+was intended.
+But there are several possibilities, all with problems.
+.IP
+Unicode 6.0 (2010) does provide two lantern symbols: U+1F383 and U+1F3EE.
+Those were not available in 2002, and are irrelevant since
+they lie outside the BMP and as a result are not generally available
+in terminals.
+They are not storm lanterns, in any case.
+.IP
+Most \fIstorm lanterns\fP have a tapering glass chimney
+(to guard against tipping);
+some have a wire grid protecting the chimney.
+.IP
+For the tapering appearance, \[u2603] U+2603 was adequate.
+In use on a terminal, no one can tell what the image represents.
+Unicode calls it a snowman.
+.IP
+Others have suggested these alternatives:
+\[sc] U+00A7 (section mark),
+\[u0398] U+0398 (theta),
+\[u03A6] U+03A6 (phi),
+\[u03B4] U+03B4 (delta),
+\[u2327] U+2327 (x in a rectangle),
+\[u256C] U+256C (forms double vertical and horizontal), and
+\[u2612] U+2612 (ballot box with x).
.SH SEE ALSO
+.na
.PP
\fBcurses\fR(3X),
\fBcurs_addch\fR(3X),