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43 <H1 class="no-header">curs_add_wch 3x 2023-08-05 ncurses 6.4 Library calls</H1>
45 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>add_wch</STRONG>, <STRONG>wadd_wch</STRONG>, <STRONG>mvadd_wch</STRONG>, <STRONG>mvwadd_wch</STRONG>, <STRONG>echo_wchar</STRONG>, <STRONG>wecho_wchar</STRONG> - add
52 a complex character and rendition to a <STRONG>curses</STRONG> window, then advance the
56 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
57 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
59 <STRONG>int</STRONG> <STRONG>add_wch(</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
60 <STRONG>int</STRONG> <STRONG>wadd_wch(</STRONG> <STRONG>WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
61 <STRONG>int</STRONG> <STRONG>mvadd_wch(</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
62 <STRONG>int</STRONG> <STRONG>mvwadd_wch(</STRONG> <STRONG>WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
64 <STRONG>int</STRONG> <STRONG>echo_wchar(</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
65 <STRONG>int</STRONG> <STRONG>wecho_wchar(</STRONG> <STRONG>WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM> <STRONG>);</STRONG>
68 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
70 </PRE><H3><a name="h3-add_wch">add_wch</a></H3><PRE>
71 The <STRONG>add_wch</STRONG>, <STRONG>wadd_wch</STRONG>, <STRONG>mvadd_wch</STRONG>, and <STRONG>mvwadd_wch</STRONG> functions put the
72 complex character <EM>wch</EM> into the given window at its current position,
73 which is then advanced. These functions perform wrapping and special-
74 character processing as follows:
76 <STRONG>o</STRONG> If <EM>wch</EM> refers to a spacing character, then any previous character
77 at that location is removed. A new character specified by <EM>wch</EM> is
78 placed at that location with rendition specified by <EM>wch</EM>. The
79 cursor then advances after this spacing character, to prepare for
80 writing the next character on the screen.
82 The newly added spacing character is the base of the active complex
83 character. Subsequent non-spacing characters can be combined with
84 this base until another spacing character is written to the screen,
85 or the cursor is moved, e.g., using <STRONG>wmove</STRONG>.
87 <STRONG>o</STRONG> If <EM>wch</EM> refers to a non-spacing character, it is appended to the
88 active complex character, retaining the previous characters at that
89 location. The rendition specified by <EM>wch</EM> is ignored.
91 The cursor is not advanced after adding a non-spacing character.
92 Subsequent calls to add non-spacing characters will update the same
95 <STRONG>o</STRONG> If the character part of <EM>wch</EM> is a tab, newline, backspace or other
96 control character, the window is updated and the cursor moves as if
97 <STRONG>addch</STRONG> were called.
100 </PRE><H3><a name="h3-echo_wchar">echo_wchar</a></H3><PRE>
101 The <STRONG>echo_wchar</STRONG> function is functionally equivalent to a call to <STRONG>add_wch</STRONG>
102 followed by a call to <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>. Similarly, the <STRONG>wecho_wchar</STRONG> is
103 functionally equivalent to a call to <STRONG>wadd_wch</STRONG> followed by a call to
104 <STRONG>wrefresh</STRONG>. The knowledge that only a single character is being output
105 is taken into consideration and, for non-control characters, a
106 considerable performance gain might be seen by using the *<STRONG>echo</STRONG>*
107 functions instead of their equivalents.
110 </PRE><H3><a name="h3-Line-Graphics">Line Graphics</a></H3><PRE>
111 Like <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>, <STRONG>addch_wch</STRONG> accepts symbols which make it simple to draw
112 lines and other frequently used special characters. These symbols
113 correspond to the same VT100 line-drawing set as <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>.
115 <STRONG>ACS</STRONG> <STRONG>Unicode</STRONG> <STRONG>ASCII</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
117 <STRONG>Name</STRONG> <STRONG>Default</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Name</STRONG>
118 ------------------------------------------------------------------------
119 WACS_BLOCK 0x25ae # 0 solid square block
120 WACS_BOARD 0x2592 # h board of squares
121 WACS_BTEE 0x2534 + v bottom tee
122 WACS_BULLET 0x00b7 o ~ bullet
123 WACS_CKBOARD 0x2592 : a checker board (stipple)
124 WACS_DARROW 0x2193 v . arrow pointing down
125 WACS_DEGREE 0x00b0 ' f degree symbol
126 WACS_DIAMOND 0x25c6 + ` diamond
127 WACS_GEQUAL 0x2265 > > greater-than-or-equal-to
128 WACS_HLINE 0x2500 - q horizontal line
129 WACS_LANTERN 0x2603 # i lantern symbol
130 WACS_LARROW 0x2190 < , arrow pointing left
131 WACS_LEQUAL 0x2264 < y less-than-or-equal-to
132 WACS_LLCORNER 0x2514 + m lower left-hand corner
133 WACS_LRCORNER 0x2518 + j lower right-hand corner
134 WACS_LTEE 0x2524 + t left tee
135 WACS_NEQUAL 0x2260 ! | not-equal
136 WACS_PI 0x03c0 * { greek pi
137 WACS_PLMINUS 0x00b1 # g plus/minus
138 WACS_PLUS 0x253c + n plus
139 WACS_RARROW 0x2192 > + arrow pointing right
140 WACS_RTEE 0x251c + u right tee
141 WACS_S1 0x23ba - o scan line 1
142 WACS_S3 0x23bb - p scan line 3
143 WACS_S7 0x23bc - r scan line 7
144 WACS_S9 0x23bd _ s scan line 9
145 WACS_STERLING 0x00a3 f } pound-sterling symbol
146 WACS_TTEE 0x252c + w top tee
147 WACS_UARROW 0x2191 ^ - arrow pointing up
148 WACS_ULCORNER 0x250c + l upper left-hand corner
149 WACS_URCORNER 0x2510 + k upper right-hand corner
150 WACS_VLINE 0x2502 | x vertical line
152 The wide-character configuration of ncurses also defines symbols for
153 thick lines (<STRONG>acsc</STRONG> "J" to "V"):
155 <STRONG>ACS</STRONG> <STRONG>Unicode</STRONG> <STRONG>ASCII</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
156 <STRONG>Name</STRONG> <STRONG>Default</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Name</STRONG>
157 -----------------------------------------------------------------------
158 WACS_T_BTEE 0x253b + V thick tee pointing up
159 WACS_T_HLINE 0x2501 - Q thick horizontal line
160 WACS_T_LLCORNER 0x2517 + M thick lower left corner
161 WACS_T_LRCORNER 0x251b + J thick lower right corner
162 WACS_T_LTEE 0x252b + T thick tee pointing right
163 WACS_T_PLUS 0x254b + N thick large plus
164 WACS_T_RTEE 0x2523 + U thick tee pointing left
165 WACS_T_TTEE 0x2533 + W thick tee pointing down
166 WACS_T_ULCORNER 0x250f + L thick upper left corner
167 WACS_T_URCORNER 0x2513 + K thick upper right corner
168 WACS_T_VLINE 0x2503 | X thick vertical line
170 and for double-lines (<STRONG>acsc</STRONG> "A" to "I"):
172 <STRONG>ACS</STRONG> <STRONG>Unicode</STRONG> <STRONG>ASCII</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
173 <STRONG>Name</STRONG> <STRONG>Default</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Name</STRONG>
174 ------------------------------------------------------------------------
175 WACS_D_BTEE 0x2569 + H double tee pointing up
176 WACS_D_HLINE 0x2550 - R double horizontal line
177 WACS_D_LLCORNER 0x255a + D double lower left corner
178 WACS_D_LRCORNER 0x255d + A double lower right corner
179 WACS_D_LTEE 0x2560 + F double tee pointing right
180 WACS_D_PLUS 0x256c + E double large plus
181 WACS_D_RTEE 0x2563 + G double tee pointing left
183 WACS_D_TTEE 0x2566 + I double tee pointing down
184 WACS_D_ULCORNER 0x2554 + C double upper left corner
185 WACS_D_URCORNER 0x2557 + B double upper right corner
186 WACS_D_VLINE 0x2551 | Y double vertical line
188 Unicode's descriptions for these characters differs slightly from
189 ncurses, by introducing the term "light" (along with less important
190 details). Here are its descriptions for the normal, thick, and double
193 <STRONG>o</STRONG> U+2500 BOX DRAWINGS LIGHT HORIZONTAL
195 <STRONG>o</STRONG> U+2501 BOX DRAWINGS HEAVY HORIZONTAL
197 <STRONG>o</STRONG> U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
200 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
201 All routines return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> on success.
203 X/Open does not define any error conditions. This implementation
206 <STRONG>o</STRONG> if the window pointer is null or
208 <STRONG>o</STRONG> if it is not possible to add a complete character in the window.
210 The latter may be due to different causes:
212 <STRONG>o</STRONG> If <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not enabled, writing a character at the lower
213 right margin succeeds. However, an error is returned because it is
214 not possible to wrap to a new line
216 <STRONG>o</STRONG> If an error is detected when converting a multibyte character to a
217 sequence of bytes, or if it is not possible to add all of the
218 resulting bytes in the window, an error is returned.
220 Functions with a "mv" prefix first perform a cursor movement using
221 <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
222 the window pointer is null.
225 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
226 Note that <STRONG>add_wch</STRONG>, <STRONG>mvadd_wch</STRONG>, <STRONG>mvwadd_wch</STRONG>, and <STRONG>echo_wchar</STRONG> may be macros.
229 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
230 All of these functions are described in the XSI Curses standard, Issue
231 4. The defaults specified for line-drawing characters apply in the
235 </PRE><H3><a name="h3-WACS-Symbols">WACS Symbols</a></H3><PRE>
236 X/Open Curses makes it clear that the WACS_ symbols should be defined
237 as a pointer to <STRONG>cchar_t</STRONG> data, e.g., in the discussion of <STRONG>border_set</STRONG>. A
238 few implementations are problematic:
240 <STRONG>o</STRONG> NetBSD curses defines the symbols as a <STRONG>wchar_t</STRONG> within a <STRONG>cchar_t</STRONG>.
242 <STRONG>o</STRONG> HPUX curses equates some of the <STRONG>ACS_</STRONG> symbols to the analogous <STRONG>WACS_</STRONG>
243 symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters. The
244 misdefined symbols are the arrows and other symbols which are not
245 used for line-drawing.
247 X/Open Curses does not define symbols for thick- or double-lines. SVr4
248 curses implementations defined their line-drawing symbols in terms of
249 intermediate symbols. This implementation extends those symbols,
250 providing new definitions which are not in the SVr4 implementations.
252 Not all Unicode-capable terminals provide support for VT100-style
253 alternate character sets (i.e., the <STRONG>acsc</STRONG> capability), with their
254 corresponding line-drawing characters. X/Open Curses did not address
255 the aspect of integrating Unicode with line-drawing characters.
256 Existing implementations of Unix curses (AIX, HPUX, Solaris) use only
257 the <STRONG>acsc</STRONG> character-mapping to provide this feature. As a result, those
258 implementations can only use single-byte line-drawing characters.
259 Ncurses 5.3 (2002) provided a table of Unicode values to solve these
260 problems. NetBSD curses incorporated that table in 2010.
262 In this implementation, the Unicode values are used instead of the
263 terminal description's <STRONG>acsc</STRONG> mapping as discussed in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG> for the
264 environment variable <STRONG>NCURSES_NO_UTF8_ACS</STRONG>. In contrast, for the same
265 cases, the line-drawing characters described in <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG> will use
266 only the ASCII default values.
268 Having Unicode available does not solve all of the problems with line-
271 <STRONG>o</STRONG> The closest Unicode equivalents to the VT100 graphics <EM>S1</EM>, <EM>S3</EM>, <EM>S7</EM>
272 and <EM>S9</EM> frequently are not displayed at the regular intervals which
275 <STRONG>o</STRONG> The <EM>lantern</EM> is a special case. It originated with the AT&T 4410
276 terminal in the early 1980s. There is no accessible documentation
277 depicting the lantern symbol on the AT&T terminal.
279 Lacking documentation, most readers assume that a <EM>storm</EM> <EM>lantern</EM> was
280 intended. But there are several possibilities, all with problems.
282 Unicode 6.0 (2010) does provide two lantern symbols: U+1F383 and
283 U+1F3EE. Those were not available in 2002, and are irrelevant
284 since they lie outside the BMP and as a result are not generally
285 available in terminals. They are not storm lanterns, in any case.
287 Most <EM>storm</EM> <EM>lanterns</EM> have a tapering glass chimney (to guard against
288 tipping); some have a wire grid protecting the chimney.
290 For the tapering appearance, U+2603 was adequate. In use on a
291 terminal, no one can tell what the image represents. Unicode calls
294 Others have suggested these alternatives: <section> U+00A7 (section
295 mark), <Theta> U+0398 (theta), <Phi> U+03A6 (phi), <delta> U+03B4
296 (delta), U+2327 (x in a rectangle), U+256C (forms double vertical
297 and horizontal), and U+2612 (ballot box with x).
300 </PRE><H3><a name="h3-Complex-Characters">Complex Characters</a></H3><PRE>
301 The complex character type <STRONG>cchar_t</STRONG> can store more than one wide
302 character (<STRONG>wchar_t</STRONG>). The X/Open Curses description does not mention
303 this possibility, describing only the cases where <EM>wch</EM> is a spacing
304 character or a non-spacing character.
306 This implementation assumes that <EM>wch</EM> is constructed using <STRONG><A HREF="curs_getcchar.3x.html">setcchar(3x)</A></STRONG>,
307 and in turn that the result
309 <STRONG>o</STRONG> contains at most one spacing character in the beginning of its list
310 of wide characters, and zero or more non-spacing characters or
312 <STRONG>o</STRONG> may hold one non-spacing character.
314 In the latter case, ncurses adds the non-spacing character to the
315 active (base) spacing character.
318 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
319 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>,
320 <STRONG><A HREF="curs_getcchar.3x.html">curs_getcchar(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG>putwc(3)</STRONG>
324 ncurses 6.4 2023-08-05 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>
328 <li><a href="#h2-NAME">NAME</a></li>
329 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
330 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
332 <li><a href="#h3-add_wch">add_wch</a></li>
333 <li><a href="#h3-echo_wchar">echo_wchar</a></li>
334 <li><a href="#h3-Line-Graphics">Line Graphics</a></li>
337 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
338 <li><a href="#h2-NOTES">NOTES</a></li>
339 <li><a href="#h2-PORTABILITY">PORTABILITY</a>
341 <li><a href="#h3-WACS-Symbols">WACS Symbols</a></li>
342 <li><a href="#h3-Complex-Characters">Complex Characters</a></li>
345 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>