1curs_add_wch(3X) curs_add_wch(3X)
2
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
11 #include <curses.h>
12 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
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 · 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 · 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 · 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 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 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 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 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 The wide-character configuration of ncurses also defines symbols for
93 thick lines (acsc “J” to “V”):
94 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 and for double-lines (acsc “A” to “I”):
111 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 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 · U+2500 BOX DRAWINGS LIGHT HORIZONTAL
133 · U+2501 BOX DRAWINGS HEAVY HORIZONTAL
135 · U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
137
139 All routines return the integer ERR upon failure and OK on success.
140 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
146 Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
147
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 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 · NetBSD curses defines the symbols as a wchar_t within a cchar_t.
158 · 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 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 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 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 Having Unicode available does not solve all of the problems with line-
186 drawing for curses:
187 · 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 · 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 Lacking documentation, most readers assume that a storm lantern was
197 intended. But there are several possibilities, all with problems.
198 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 Most storm lanterns have a tapering glass chimney (to guard against
205 tipping); some have a wire grid protecting the chimney.
206 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 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
217 curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_out‐
218 opts(3X), curs_refresh(3X), putwc(3)
219 curs_add_wch(3X)