1curs_add_wch(3X)                                              curs_add_wch(3X)
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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       thick lines (acsc “J” to “V”):
94
95       ACS               Unicode   ASCII     acsc    Glyph
96       Name              Default   Default   char    Name
97       ───────────────────────────────────────────────────────────────────────
98       WACS_T_BTEE       0x253b    +         V       thick tee pointing up
99       WACS_T_HLINE      0x2501    -         Q       thick horizontal line
100       WACS_T_LLCORNER   0x2517    +         M       thick lower left corner
101       WACS_T_LRCORNER   0x251b    +         J       thick lower right corner
102       WACS_T_LTEE       0x252b    +         T       thick tee pointing right
103       WACS_T_PLUS       0x254b    +         N       thick large plus
104       WACS_T_RTEE       0x2523    +         U       thick tee pointing left
105       WACS_T_TTEE       0x2533    +         W       thick tee pointing down
106       WACS_T_ULCORNER   0x250f    +         L       thick upper left corner
107       WACS_T_URCORNER   0x2513    +         K       thick upper right corner
108       WACS_T_VLINE      0x2503    |         X       thick vertical line
109
110       and for double-lines (acsc “A” to “I”):
111
112       ACS               Unicode   ASCII     acsc    Glyph
113       Name              Default   Default   char    Name
114       ────────────────────────────────────────────────────────────────────────
115       WACS_D_BTEE       0x2569    +         H       double tee pointing up
116       WACS_D_HLINE      0x2550    -         R       double horizontal line
117       WACS_D_LLCORNER   0x255a    +         D       double lower left corner
118       WACS_D_LRCORNER   0x255d    +         A       double lower right corner
119       WACS_D_LTEE       0x2560    +         F       double tee pointing right
120       WACS_D_PLUS       0x256c    +         E       double large plus
121       WACS_D_RTEE       0x2563    +         G       double tee pointing left
122       WACS_D_TTEE       0x2566    +         I       double tee pointing down
123       WACS_D_ULCORNER   0x2554    +         C       double upper left corner
124       WACS_D_URCORNER   0x2557    +         B       double upper right corner
125       WACS_D_VLINE      0x2551    |         Y       double vertical line
126
127       Unicode's  descriptions  for  these  characters  differs  slightly from
128       ncurses, by introducing the term “light”  (along  with  less  important
129       details).   Here are its descriptions for the normal, thick, and double
130       horizontal lines:
131
132       ·   U+2500 BOX DRAWINGS LIGHT HORIZONTAL
133
134       ·   U+2501 BOX DRAWINGS HEAVY HORIZONTAL
135
136       ·   U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
137

RETURN VALUE

139       All routines return the integer ERR upon failure and OK on success.
140
141       Functions with a “mv” prefix first  perform  a  cursor  movement  using
142       wmove, and return an error if the position is outside the window, or if
143       the window pointer is null.
144

NOTES

146       Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
147

PORTABILITY

149       All of these functions are described in the XSI Curses standard,  Issue
150       4.   The  defaults  specified  for line-drawing characters apply in the
151       POSIX locale.
152
153       X/Open Curses makes it clear that the WACS_ symbols should  be  defined
154       as a pointer to cchar_t data, e.g., in the discussion of border_set.  A
155       few implementations are problematic:
156
157       ·   NetBSD curses defines the symbols as a wchar_t within a cchar_t.
158
159       ·   HPUX curses equates some of the ACS_ symbols to the analogous WACS_
160           symbols  as  if  the ACS_ symbols were wide characters.  The misde‐
161           fined symbols are the arrows and other symbols which are  not  used
162           for line-drawing.
163
164       X/Open Curses does not define symbols for thick- or double-lines.  SVr4
165       curses implementations defined their line-drawing symbols in  terms  of
166       intermediate  symbols.  This implementation extends those symbols, pro‐
167       viding new definitions which are not in the SVr4 implementations.
168
169       Not all  Unicode-capable  terminals  provide  support  for  VT100-style
170       alternate character sets (i.e., the acsc capability), with their corre‐
171       sponding line-drawing characters.  X/Open Curses did  not  address  the
172       aspect  of  integrating Unicode with line-drawing characters.  Existing
173       implementations of Unix curses (AIX, HPUX, Solaris) use only  the  acsc
174       character-mapping  to  provide this feature.  As a result, those imple‐
175       mentations can only use single-byte line-drawing  characters.   Ncurses
176       5.3  (2002) provided a table of Unicode values to solve these problems.
177       NetBSD curses incorporated that table in 2010.
178
179       In this implementation, the Unicode values are used instead of the ter‐
180       minal  description's  acsc  mapping as discussed in ncurses(3X) for the
181       environment variable NCURSES_NO_UTF8_ACS.  In contrast,  for  the  same
182       cases, the line-drawing characters described in curs_addch(3X) will use
183       only the ASCII default values.
184
185       Having Unicode available does not solve all of the problems with  line-
186       drawing for curses:
187
188       ·   The  closest  Unicode  equivalents to the VT100 graphics S1, S3, S7
189           and S9 frequently are not displayed at the regular intervals  which
190           the terminal used.
191
192       ·   The  lantern  is  a special case.  It originated with the AT&T 4410
193           terminal in the early 1980s.  There is no accessible  documentation
194           depicting the lantern symbol on the AT&T terminal.
195
196           Lacking documentation, most readers assume that a storm lantern was
197           intended.  But there are several possibilities, all with problems.
198
199           Unicode 6.0 (2010) does provide two lantern  symbols:  U+1F383  and
200           U+1F3EE.   Those  were  not  available  in 2002, and are irrelevant
201           since they lie outside the BMP and as a result  are  not  generally
202           available in terminals.  They are not storm lanterns, in any case.
203
204           Most storm lanterns have a tapering glass chimney (to guard against
205           tipping); some have a wire grid protecting the chimney.
206
207           For the tapering appearance, ☃ U+2603 was adequate.  In  use  on  a
208           terminal, no one can tell what the image represents.  Unicode calls
209           it a snowman.
210
211           Others have suggested these alternatives: § U+00A7 (section  mark),
212           Θ  U+0398 (theta), Φ U+03A6 (phi), δ U+03B4 (delta), ⌧ U+2327 (x in
213           a rectangle), ╬ U+256C (forms double vertical and horizontal),  and
214           ☒ U+2612 (ballot box with x).
215

SEE ALSO

217       curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_out‐
218       opts(3X), curs_refresh(3X), putwc(3)
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220
221
222                                                              curs_add_wch(3X)
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