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 );
19 int wecho_wchar( WINDOW *win, const cchar_t *wch );
20
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 • 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 • 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 • 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 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 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 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 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 The wide-character configuration of ncurses also defines symbols for
94 thick lines (acsc “J” to “V”):
95 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 and for double-lines (acsc “A” to “I”):
112 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 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 • U+2500 BOX DRAWINGS LIGHT HORIZONTAL
134 • U+2501 BOX DRAWINGS HEAVY HORIZONTAL
136 • U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
138
140 All routines return the integer ERR upon failure and OK on success.
141 X/Open does not define any error conditions. This implementation re‐
143 turns an error
144 • if the window pointer is null or
146 • if it is not possible to add a complete character in the window.
148 The latter may be due to different causes:
150 • 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 • 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 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
164 Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
165
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 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 • NetBSD curses defines the symbols as a wchar_t within a cchar_t.
176 • 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 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 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 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 Having Unicode available does not solve all of the problems with line-
204 drawing for curses:
205 • 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 • 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 Lacking documentation, most readers assume that a storm lantern was
215 intended. But there are several possibilities, all with problems.
216 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 Most storm lanterns have a tapering glass chimney (to guard against
223 tipping); some have a wire grid protecting the chimney.
224 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 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
235 curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_out‐
236 opts(3X), curs_refresh(3X), putwc(3)
237 curs_add_wch(3X)