1curs_add_wch(3X)                                              curs_add_wch(3X)
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4

NAME

6       add_wch, wadd_wch, mvadd_wch, mvwadd_wch, echo_wchar, wecho_wchar - add
7       a complex character and rendition to a curses window, then advance  the
8       cursor
9

SYNOPSIS

11       #include <curses.h>
12
13       int add_wch( const cchar_t *wch );
14       int wadd_wch( WINDOW *win, const cchar_t *wch );
15       int mvadd_wch( int y, int x, const cchar_t *wch );
16       int mvwadd_wch( WINDOW *win, int y, int x, const cchar_t *wch );
17       int echo_wchar( const cchar_t *wch );
18       int wecho_wchar( WINDOW *win, const cchar_t *wch );
19

DESCRIPTION

21   add_wch
22       The add_wch, wadd_wch, mvadd_wch, and mvwadd_wch functions put the com‐
23       plex character wch into the given window at its current position, which
24       is then advanced.  These functions perform wrapping and special-charac‐
25       ter processing as follows:
26
27       ·   If wch refers to a spacing character, then any  previous  character
28           at  that  location is removed.  A new character specified by wch is
29           placed at that location with rendition specified by wch.  The  cur‐
30           sor then advances to the next spacing character on the screen.
31
32       ·   If  wch  refers to a non-spacing character, all previous characters
33           at that location are preserved.  The non-spacing characters of  wch
34           are added to the spacing complex character, and the rendition spec‐
35           ified by wch is ignored.
36
37       ·   If the character part of wch is a tab, newline, backspace or  other
38           control character, the window is updated and the cursor moves as if
39           addch were called.
40
41   echo_wchar
42       The echo_wchar function is functionally equivalent to a call to add_wch
43       followed by a call to refresh(3X).  Similarly, the wecho_wchar is func‐
44       tionally equivalent to a call to wadd_wch followed by a  call  to  wre‐
45       fresh.   The  knowledge that only a single character is being output is
46       taken into consideration and, for non-control characters,  a  consider‐
47       able  performance  gain  might  be  seen  by using the *echo* functions
48       instead of their equivalents.
49
50   Line Graphics
51       Like addch(3X), addch_wch accepts symbols which make it simple to  draw
52       lines and other frequently used special characters.  These symbols cor‐
53       respond to the same VT100 line-drawing set as addch(3X).
54
55       ACS               Unicode    ASCII     acsc    Glyph
56       Name              Default    Default   char    Name
57       ────────────────────────────────────────────────────────────────────────
58       WACS_BLOCK        0x25ae     #         0       solid square block
59       WACS_BOARD        0x2592     #         h       board of squares
60       WACS_BTEE         0x2534     +         v       bottom tee
61       WACS_BULLET       0x00b7     o         ~       bullet
62       WACS_CKBOARD      0x2592     :         a       checker board (stipple)
63       WACS_DARROW       0x2193     v         .       arrow pointing down
64       WACS_DEGREE       0x00b0     '         f       degree symbol
65       WACS_DIAMOND      0x25c6     +         `       diamond
66
67       WACS_GEQUAL       0x2265     >         >       greater-than-or-equal-to
68       WACS_HLINE        0x2500     -         q       horizontal line
69       WACS_LANTERN      0x2603     #         i       lantern symbol
70       WACS_LARROW       0x2190     <         ,       arrow pointing left
71       WACS_LEQUAL       0x2264     <         y       less-than-or-equal-to
72       WACS_LLCORNER     0x2514     +         m       lower left-hand corner
73       WACS_LRCORNER     0x2518     +         j       lower right-hand corner
74       WACS_LTEE         0x2524     +         t       left tee
75       WACS_NEQUAL       0x2260     !         |       not-equal
76       WACS_PI           0x03c0     *         {       greek pi
77       WACS_PLMINUS      0x00b1     #         g       plus/minus
78       WACS_PLUS         0x253c     +         n       plus
79       WACS_RARROW       0x2192     >         +       arrow pointing right
80       WACS_RTEE         0x251c     +         u       right tee
81       WACS_S1           0x23ba     -         o       scan line 1
82       WACS_S3           0x23bb     -         p       scan line 3
83       WACS_S7           0x23bc     -         r       scan line 7
84       WACS_S9           0x23bd     _         s       scan line 9
85       WACS_STERLING     0x00a3     f         }       pound-sterling symbol
86       WACS_TTEE         0x252c     +         w       top tee
87       WACS_UARROW       0x2191     ^         -       arrow pointing up
88       WACS_ULCORNER     0x250c     +         l       upper left-hand corner
89       WACS_URCORNER     0x2510     +         k       upper right-hand corner
90       WACS_VLINE        0x2502     |         x       vertical line
91
92       The wide-character configuration of ncurses also  defines  symbols  for
93       double-lines:
94
95       ACS               Unicode   ASCII     acsc    Glyph
96       Name              Default   Default   char    Name
97       ────────────────────────────────────────────────────────────────────────
98       WACS_D_BTEE       0x2569    +         H       double tee pointing up
99       WACS_D_HLINE      0x2550    -         R       double horizontal line
100       WACS_D_LLCORNER   0x255a    +         D       double lower left corner
101       WACS_D_LRCORNER   0x255d    +         A       double lower right corner
102       WACS_D_LTEE       0x2560    +         F       double tee pointing right
103       WACS_D_PLUS       0x256c    +         E       double large plus
104       WACS_D_RTEE       0x2563    +         G       double tee pointing left
105       WACS_D_TTEE       0x2566    +         I       double tee pointing down
106       WACS_D_ULCORNER   0x2554    +         C       double upper left corner
107       WACS_D_URCORNER   0x2557    +         B       double upper right corner
108       WACS_D_VLINE      0x2551    |         Y       double vertical line
109
110       and for thick lines:
111
112       ACS               Unicode   ASCII     acsc    Glyph
113       Name              Default   Default   char    Name
114       ───────────────────────────────────────────────────────────────────────
115       WACS_T_BTEE       0x253b    +         V       thick tee pointing up
116       WACS_T_HLINE      0x2501    -         Q       thick horizontal line
117       WACS_T_LLCORNER   0x2517    +         M       thick lower left corner
118       WACS_T_LRCORNER   0x251b    +         J       thick lower right corner
119       WACS_T_LTEE       0x252b    +         T       thick tee pointing right
120       WACS_T_PLUS       0x254b    +         N       thick large plus
121       WACS_T_RTEE       0x2523    +         U       thick tee pointing left
122       WACS_T_TTEE       0x2533    +         W       thick tee pointing down
123       WACS_T_ULCORNER   0x250f    +         L       thick upper left corner
124       WACS_T_URCORNER   0x2513    +         K       thick upper right corner
125       WACS_T_VLINE      0x2503    |         X       thick vertical line
126

RETURN VALUE

128       All routines return the integer ERR upon failure and OK on success.
129
130       Functions  with  a  “mv”  prefix  first perform a cursor movement using
131       wmove, and return an error if the position is outside the window, or if
132       the window pointer is null.
133

NOTES

135       Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
136

PORTABILITY

138       All  of these functions are described in the XSI Curses standard, Issue
139       4.  The defaults specified for line-drawing  characters  apply  in  the
140       POSIX locale.
141
142       X/Open  Curses  makes it clear that the WACS_ symbols should be defined
143       as a pointer to cchar_t data, e.g., in the discussion of border_set.  A
144       few implementations are problematic:
145
146       ·   NetBSD curses defines the symbols as a wchar_t within a cchar_t.
147
148       ·   HPUX curses equates some of the ACS_ symbols to the analogous WACS_
149           symbols as if the ACS_ symbols were wide  characters.   The  misde‐
150           fined  symbols  are the arrows and other symbols which are not used
151           for line-drawing.
152
153       X/Open Curses does not define symbols for thick- or double-lines.  SVr4
154       curses  implementations  defined their line-drawing symbols in terms of
155       intermediate symbols.  This implementation extends those symbols,  pro‐
156       viding new definitions which are not in the SVr4 implementations.
157
158       Not  all  Unicode-capable  terminals  provide  support  for VT100-style
159       alternate character sets (i.e., the acsc capability), with their corre‐
160       sponding  line-drawing  characters.   X/Open Curses did not address the
161       aspect of integrating Unicode with line-drawing  characters.   Existing
162       implementations  of  Unix curses (AIX, HPUX, Solaris) use only the acsc
163       character-mapping to provide this feature.  As a result,  those  imple‐
164       mentations  can  only use single-byte line-drawing characters.  Ncurses
165       5.3 (2002) provided a table of Unicode values to solve these  problems.
166       NetBSD curses incorporated that table in 2010.
167
168       In this implementation, the Unicode values are used instead of the ter‐
169       minal description's acsc mapping as discussed in  ncurses(3X)  for  the
170       environment  variable  NCURSES_NO_UTF8_ACS.   In contrast, for the same
171       cases, the line-drawing characters described in curs_addch(3X) will use
172       only the ASCII default values.
173
174       Having  Unicode available does not solve all of the problems with line-
175       drawing for curses:
176
177       ·   The closest Unicode equivalents to the VT100 graphics  S1,  S3,  S7
178           and  S9 frequently are not displayed at the regular intervals which
179           the terminal used.
180
181       ·   The lantern is a special case.  It originated with  the  AT&T  4410
182           terminal  in the early 1980s.  There is no accessible documentation
183           depicting the lantern symbol on the AT&T terminal.
184
185           Lacking documentation, most readers assume that a storm lantern was
186           intended.  But there are several possibilities, all with problems.
187
188           Unicode  6.0  (2010)  does provide two lantern symbols: U+1F383 and
189           U+1F3EE.  Those were not available  in  2002,  and  are  irrelevant
190           since  they  lie  outside the BMP and as a result are not generally
191           available in terminals.  They are not storm lanterns, in any case.
192
193           Most storm lanterns have a tapering glass chimney (to guard against
194           tipping); some have a wire grid protecting the chimney.
195
196           For  the  tapering  appearance, ☃ U+2603 was adequate.  In use on a
197           terminal, no one can tell what the image represents.  Unicode calls
198           it a snowman.
199
200           Others  have suggested these alternatives: § U+00A7 (section mark),
201           Θ U+0398 (theta), Φ U+03A6 (phi), δ U+03B4 (delta), ⌧ U+2327 (x  in
202           a  rectangle), ╬ U+256C (forms double vertical and horizontal), and
203           ☒ U+2612 (ballot box with x).
204

SEE ALSO

206       curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_out‐
207       opts(3X), curs_refresh(3X), putwc(3)
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209
210
211                                                              curs_add_wch(3X)
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