1curs_add_wch(3X)                                              curs_add_wch(3X)
2
3
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
18       int echo_wchar( const cchar_t *wch );
19       int wecho_wchar( WINDOW *win, const cchar_t *wch );
20

DESCRIPTION

22   add_wch
23       The add_wch, wadd_wch, mvadd_wch, and mvwadd_wch functions put the com‐
24       plex character wch into the given window at its current position, which
25       is then advanced.  These functions perform wrapping and special-charac‐
26       ter processing as follows:
27
28       •   If wch refers to a spacing character, then any  previous  character
29           at  that  location is removed.  A new character specified by wch is
30           placed at that location with rendition specified by wch.  The  cur‐
31           sor then advances to the next spacing character on the screen.
32
33       •   If  wch  refers to a non-spacing character, all previous characters
34           at that location are preserved.  The non-spacing characters of  wch
35           are added to the spacing complex character, and the rendition spec‐
36           ified by wch is ignored.
37
38       •   If the character part of wch is a tab, newline, backspace or  other
39           control character, the window is updated and the cursor moves as if
40           addch were called.
41
42   echo_wchar
43       The echo_wchar function is functionally equivalent to a call to add_wch
44       followed by a call to refresh(3X).  Similarly, the wecho_wchar is func‐
45       tionally equivalent to a call to wadd_wch followed by a  call  to  wre‐
46       fresh.   The  knowledge that only a single character is being output is
47       taken into consideration and, for non-control characters,  a  consider‐
48       able  performance  gain might be seen by using the *echo* functions in‐
49       stead of their equivalents.
50
51   Line Graphics
52       Like addch(3X), addch_wch accepts symbols which make it simple to  draw
53       lines and other frequently used special characters.  These symbols cor‐
54       respond to the same VT100 line-drawing set as addch(3X).
55
56       ACS               Unicode    ASCII     acsc    Glyph
57       Name              Default    Default   char    Name
58       ────────────────────────────────────────────────────────────────────────
59       WACS_BLOCK        0x25ae     #         0       solid square block
60       WACS_BOARD        0x2592     #         h       board of squares
61       WACS_BTEE         0x2534     +         v       bottom tee
62       WACS_BULLET       0x00b7     o         ~       bullet
63       WACS_CKBOARD      0x2592     :         a       checker board (stipple)
64       WACS_DARROW       0x2193     v         .       arrow pointing down
65       WACS_DEGREE       0x00b0     '         f       degree symbol
66
67       WACS_DIAMOND      0x25c6     +         `       diamond
68       WACS_GEQUAL       0x2265     >         >       greater-than-or-equal-to
69       WACS_HLINE        0x2500     -         q       horizontal line
70       WACS_LANTERN      0x2603     #         i       lantern symbol
71       WACS_LARROW       0x2190     <         ,       arrow pointing left
72       WACS_LEQUAL       0x2264     <         y       less-than-or-equal-to
73       WACS_LLCORNER     0x2514     +         m       lower left-hand corner
74       WACS_LRCORNER     0x2518     +         j       lower right-hand corner
75       WACS_LTEE         0x2524     +         t       left tee
76       WACS_NEQUAL       0x2260     !         |       not-equal
77       WACS_PI           0x03c0     *         {       greek pi
78       WACS_PLMINUS      0x00b1     #         g       plus/minus
79       WACS_PLUS         0x253c     +         n       plus
80       WACS_RARROW       0x2192     >         +       arrow pointing right
81       WACS_RTEE         0x251c     +         u       right tee
82       WACS_S1           0x23ba     -         o       scan line 1
83       WACS_S3           0x23bb     -         p       scan line 3
84       WACS_S7           0x23bc     -         r       scan line 7
85       WACS_S9           0x23bd     _         s       scan line 9
86       WACS_STERLING     0x00a3     f         }       pound-sterling symbol
87       WACS_TTEE         0x252c     +         w       top tee
88       WACS_UARROW       0x2191     ^         -       arrow pointing up
89       WACS_ULCORNER     0x250c     +         l       upper left-hand corner
90       WACS_URCORNER     0x2510     +         k       upper right-hand corner
91       WACS_VLINE        0x2502     |         x       vertical line
92
93       The wide-character configuration of ncurses also  defines  symbols  for
94       thick lines (acsc “J” to “V”):
95
96       ACS               Unicode   ASCII     acsc    Glyph
97       Name              Default   Default   char    Name
98       ───────────────────────────────────────────────────────────────────────
99       WACS_T_BTEE       0x253b    +         V       thick tee pointing up
100       WACS_T_HLINE      0x2501    -         Q       thick horizontal line
101       WACS_T_LLCORNER   0x2517    +         M       thick lower left corner
102       WACS_T_LRCORNER   0x251b    +         J       thick lower right corner
103       WACS_T_LTEE       0x252b    +         T       thick tee pointing right
104       WACS_T_PLUS       0x254b    +         N       thick large plus
105       WACS_T_RTEE       0x2523    +         U       thick tee pointing left
106       WACS_T_TTEE       0x2533    +         W       thick tee pointing down
107       WACS_T_ULCORNER   0x250f    +         L       thick upper left corner
108       WACS_T_URCORNER   0x2513    +         K       thick upper right corner
109       WACS_T_VLINE      0x2503    |         X       thick vertical line
110
111       and for double-lines (acsc “A” to “I”):
112
113       ACS               Unicode   ASCII     acsc    Glyph
114       Name              Default   Default   char    Name
115       ────────────────────────────────────────────────────────────────────────
116       WACS_D_BTEE       0x2569    +         H       double tee pointing up
117       WACS_D_HLINE      0x2550    -         R       double horizontal line
118       WACS_D_LLCORNER   0x255a    +         D       double lower left corner
119       WACS_D_LRCORNER   0x255d    +         A       double lower right corner
120       WACS_D_LTEE       0x2560    +         F       double tee pointing right
121       WACS_D_PLUS       0x256c    +         E       double large plus
122       WACS_D_RTEE       0x2563    +         G       double tee pointing left
123       WACS_D_TTEE       0x2566    +         I       double tee pointing down
124       WACS_D_ULCORNER   0x2554    +         C       double upper left corner
125       WACS_D_URCORNER   0x2557    +         B       double upper right corner
126       WACS_D_VLINE      0x2551    |         Y       double vertical line
127
128       Unicode's  descriptions  for  these  characters  differs  slightly from
129       ncurses, by introducing the term “light” (along with less important de‐
130       tails).   Here  are  its descriptions for the normal, thick, and double
131       horizontal lines:
132
133       •   U+2500 BOX DRAWINGS LIGHT HORIZONTAL
134
135       •   U+2501 BOX DRAWINGS HEAVY HORIZONTAL
136
137       •   U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
138

RETURN VALUE

140       All routines return the integer ERR upon failure and OK on success.
141
142       X/Open does not define any error conditions.  This  implementation  re‐
143       turns an error
144
145       •   if the window pointer is null or
146
147       •   if it is not possible to add a complete character in the window.
148
149       The latter may be due to different causes:
150
151       •   If  scrollok is not enabled, writing a character at the lower right
152           margin succeeds.  However, an error is returned because it  is  not
153           possible to wrap to a new line
154
155       •   If  an error is detected when converting a multibyte character to a
156           sequence of bytes, or if it is not possible to add all of  the  re‐
157           sulting bytes in the window, an error is returned.
158
159       Functions  with  a  “mv”  prefix  first perform a cursor movement using
160       wmove, and return an error if the position is outside the window, or if
161       the window pointer is null.
162

NOTES

164       Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
165

PORTABILITY

167       All  of these functions are described in the XSI Curses standard, Issue
168       4.  The defaults specified for line-drawing  characters  apply  in  the
169       POSIX locale.
170
171       X/Open  Curses  makes it clear that the WACS_ symbols should be defined
172       as a pointer to cchar_t data, e.g., in the discussion of border_set.  A
173       few implementations are problematic:
174
175       •   NetBSD curses defines the symbols as a wchar_t within a cchar_t.
176
177       •   HPUX curses equates some of the ACS_ symbols to the analogous WACS_
178           symbols as if the ACS_ symbols were wide  characters.   The  misde‐
179           fined  symbols  are the arrows and other symbols which are not used
180           for line-drawing.
181
182       X/Open Curses does not define symbols for thick- or double-lines.  SVr4
183       curses  implementations  defined their line-drawing symbols in terms of
184       intermediate symbols.  This implementation extends those symbols,  pro‐
185       viding new definitions which are not in the SVr4 implementations.
186
187       Not  all  Unicode-capable terminals provide support for VT100-style al‐
188       ternate character sets (i.e., the acsc capability), with  their  corre‐
189       sponding  line-drawing  characters.   X/Open Curses did not address the
190       aspect of integrating Unicode with line-drawing  characters.   Existing
191       implementations  of  Unix curses (AIX, HPUX, Solaris) use only the acsc
192       character-mapping to provide this feature.  As a result,  those  imple‐
193       mentations  can  only use single-byte line-drawing characters.  Ncurses
194       5.3 (2002) provided a table of Unicode values to solve these  problems.
195       NetBSD curses incorporated that table in 2010.
196
197       In this implementation, the Unicode values are used instead of the ter‐
198       minal description's acsc mapping as discussed in  ncurses(3X)  for  the
199       environment  variable  NCURSES_NO_UTF8_ACS.   In contrast, for the same
200       cases, the line-drawing characters described in curs_addch(3X) will use
201       only the ASCII default values.
202
203       Having  Unicode available does not solve all of the problems with line-
204       drawing for curses:
205
206       •   The closest Unicode equivalents to the VT100 graphics  S1,  S3,  S7
207           and  S9 frequently are not displayed at the regular intervals which
208           the terminal used.
209
210       •   The lantern is a special case.  It originated with  the  AT&T  4410
211           terminal  in the early 1980s.  There is no accessible documentation
212           depicting the lantern symbol on the AT&T terminal.
213
214           Lacking documentation, most readers assume that a storm lantern was
215           intended.  But there are several possibilities, all with problems.
216
217           Unicode  6.0  (2010)  does provide two lantern symbols: U+1F383 and
218           U+1F3EE.  Those were not available  in  2002,  and  are  irrelevant
219           since  they  lie  outside the BMP and as a result are not generally
220           available in terminals.  They are not storm lanterns, in any case.
221
222           Most storm lanterns have a tapering glass chimney (to guard against
223           tipping); some have a wire grid protecting the chimney.
224
225           For  the  tapering  appearance, ☃ U+2603 was adequate.  In use on a
226           terminal, no one can tell what the image represents.  Unicode calls
227           it a snowman.
228
229           Others  have suggested these alternatives: § U+00A7 (section mark),
230           Θ U+0398 (theta), Φ U+03A6 (phi), δ U+03B4 (delta), ⌧ U+2327 (x  in
231           a  rectangle), ╬ U+256C (forms double vertical and horizontal), and
232           ☒ U+2612 (ballot box with x).
233

SEE ALSO

235       curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_out‐
236       opts(3X), curs_refresh(3X), putwc(3)
237
238
239
240                                                              curs_add_wch(3X)
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