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- * @Id: curs_add_wch.3x,v 1.36 2023/07/01 14:23:04 tom Exp @
+ * @Id: curs_add_wch.3x,v 1.37 2023/07/15 16:45:14 tom Exp @
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-<H1 class="no-header">curs_add_wch 3x 2023-07-01 ncurses 6.4 Library calls</H1>
+<H1 class="no-header">curs_add_wch 3x 2023-07-15 ncurses 6.4 Library calls</H1>
<PRE>
<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>
<STRONG>o</STRONG> If <EM>wch</EM> refers to a spacing character, then any previous character
at that location is removed. A new character specified by <EM>wch</EM> is
placed at that location with rendition specified by <EM>wch</EM>. The
- cursor then advances to the next spacing character on the screen.
+ cursor then advances after this spacing character, to prepare for
+ writing the next character on the screen.
- <STRONG>o</STRONG> If <EM>wch</EM> refers to a non-spacing character, all previous characters
- at that location are preserved. The non-spacing characters of <EM>wch</EM>
- are added to the spacing complex character, and the rendition
- specified by <EM>wch</EM> is ignored.
+ The newly added spacing character is the base of the active complex
+ character. Subsequent non-spacing characters can be combined with
+ this base until another spacing character is written to the screen,
+ or the cursor is moved, e.g., using <STRONG>wmove</STRONG>.
- <STRONG>o</STRONG> If the character part of <EM>wch</EM> is a tab, newline, backspace or other
+ <STRONG>o</STRONG> If <EM>wch</EM> refers to a non-spacing character, it is appended to the
+ active complex character, retaining the previous characters at that
+ location. The rendition specified by <EM>wch</EM> is ignored.
+
+ The cursor is not advanced after adding a non-spacing character.
+ Subsequent calls to add non-spacing characters will update the same
+ position.
+
+ <STRONG>o</STRONG> If the character part of <EM>wch</EM> is a tab, newline, backspace or other
control character, the window is updated and the cursor moves as if
<STRONG>addch</STRONG> were called.
</PRE><H3><a name="h3-echo_wchar">echo_wchar</a></H3><PRE>
The <STRONG>echo_wchar</STRONG> function is functionally equivalent to a call to <STRONG>add_wch</STRONG>
- followed by a call to <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>. Similarly, the <STRONG>wecho_wchar</STRONG> is
- functionally equivalent to a call to <STRONG>wadd_wch</STRONG> followed by a call to
- <STRONG>wrefresh</STRONG>. The knowledge that only a single character is being output
- is taken into consideration and, for non-control characters, a
- considerable performance gain might be seen by using the *<STRONG>echo</STRONG>*
+ followed by a call to <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>. Similarly, the <STRONG>wecho_wchar</STRONG> is
+ functionally equivalent to a call to <STRONG>wadd_wch</STRONG> followed by a call to
+ <STRONG>wrefresh</STRONG>. The knowledge that only a single character is being output
+ is taken into consideration and, for non-control characters, a
+ considerable performance gain might be seen by using the *<STRONG>echo</STRONG>*
functions instead of their equivalents.
</PRE><H3><a name="h3-Line-Graphics">Line Graphics</a></H3><PRE>
- Like <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>, <STRONG>addch_wch</STRONG> accepts symbols which make it simple to draw
- lines and other frequently used special characters. These symbols
+ Like <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>, <STRONG>addch_wch</STRONG> accepts symbols which make it simple to draw
+ lines and other frequently used special characters. These symbols
correspond to the same VT100 line-drawing set as <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>.
<STRONG>ACS</STRONG> <STRONG>Unicode</STRONG> <STRONG>ASCII</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
+
<STRONG>Name</STRONG> <STRONG>Default</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Name</STRONG>
------------------------------------------------------------------------
WACS_BLOCK 0x25ae # 0 solid square block
WACS_CKBOARD 0x2592 : a checker board (stipple)
WACS_DARROW 0x2193 v . arrow pointing down
WACS_DEGREE 0x00b0 ' f degree symbol
-
WACS_DIAMOND 0x25c6 + ` diamond
WACS_GEQUAL 0x2265 > > greater-than-or-equal-to
WACS_HLINE 0x2500 - q horizontal line
WACS_URCORNER 0x2510 + k upper right-hand corner
WACS_VLINE 0x2502 | x vertical line
- The wide-character configuration of ncurses also defines symbols for
+ The wide-character configuration of ncurses also defines symbols for
thick lines (<STRONG>acsc</STRONG> "J" to "V"):
<STRONG>ACS</STRONG> <STRONG>Unicode</STRONG> <STRONG>ASCII</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
WACS_D_LTEE 0x2560 + F double tee pointing right
WACS_D_PLUS 0x256c + E double large plus
WACS_D_RTEE 0x2563 + G double tee pointing left
+
WACS_D_TTEE 0x2566 + I double tee pointing down
WACS_D_ULCORNER 0x2554 + C double upper left corner
WACS_D_URCORNER 0x2557 + B double upper right corner
WACS_D_VLINE 0x2551 | Y double vertical line
- Unicode's descriptions for these characters differs slightly from
- ncurses, by introducing the term "light" (along with less important
- details). Here are its descriptions for the normal, thick, and double
+ Unicode's descriptions for these characters differs slightly from
+ ncurses, by introducing the term "light" (along with less important
+ details). Here are its descriptions for the normal, thick, and double
horizontal lines:
<STRONG>o</STRONG> U+2500 BOX DRAWINGS LIGHT HORIZONTAL
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
All routines return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> on success.
- X/Open does not define any error conditions. This implementation
+ X/Open does not define any error conditions. This implementation
returns an error
<STRONG>o</STRONG> if the window pointer is null or
The latter may be due to different causes:
- <STRONG>o</STRONG> If <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not enabled, writing a character at the lower
+ <STRONG>o</STRONG> If <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not enabled, writing a character at the lower
right margin succeeds. However, an error is returned because it is
not possible to wrap to a new line
- <STRONG>o</STRONG> If an error is detected when converting a multibyte character to a
- sequence of bytes, or if it is not possible to add all of the
+ <STRONG>o</STRONG> If an error is detected when converting a multibyte character to a
+ sequence of bytes, or if it is not possible to add all of the
resulting bytes in the window, an error is returned.
- Functions with a "mv" prefix first perform a cursor movement using
+ Functions with a "mv" prefix first perform a cursor movement using
<STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
the window pointer is null.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- All of these functions are described in the XSI Curses standard, Issue
- 4. The defaults specified for line-drawing characters apply in the
+ All of these functions are described in the XSI Curses standard, Issue
+ 4. The defaults specified for line-drawing characters apply in the
POSIX locale.
- X/Open Curses makes it clear that the WACS_ symbols should be defined
+
+</PRE><H3><a name="h3-WACS-Symbols">WACS Symbols</a></H3><PRE>
+ X/Open Curses makes it clear that the WACS_ symbols should be defined
as a pointer to <STRONG>cchar_t</STRONG> data, e.g., in the discussion of <STRONG>border_set</STRONG>. A
few implementations are problematic:
<STRONG>o</STRONG> NetBSD curses defines the symbols as a <STRONG>wchar_t</STRONG> within a <STRONG>cchar_t</STRONG>.
<STRONG>o</STRONG> HPUX curses equates some of the <STRONG>ACS_</STRONG> symbols to the analogous <STRONG>WACS_</STRONG>
- symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters. The
- misdefined symbols are the arrows and other symbols which are not
+ symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters. The
+ misdefined symbols are the arrows and other symbols which are not
used for line-drawing.
X/Open Curses does not define symbols for thick- or double-lines. SVr4
- curses implementations defined their line-drawing symbols in terms of
+ curses implementations defined their line-drawing symbols in terms of
intermediate symbols. This implementation extends those symbols,
providing new definitions which are not in the SVr4 implementations.
- Not all Unicode-capable terminals provide support for VT100-style
- alternate character sets (i.e., the <STRONG>acsc</STRONG> capability), with their
- corresponding line-drawing characters. X/Open Curses did not address
- the aspect of integrating Unicode with line-drawing characters.
- Existing implementations of Unix curses (AIX, HPUX, Solaris) use only
+ Not all Unicode-capable terminals provide support for VT100-style
+ alternate character sets (i.e., the <STRONG>acsc</STRONG> capability), with their
+ corresponding line-drawing characters. X/Open Curses did not address
+ the aspect of integrating Unicode with line-drawing characters.
+ Existing implementations of Unix curses (AIX, HPUX, Solaris) use only
the <STRONG>acsc</STRONG> character-mapping to provide this feature. As a result, those
implementations can only use single-byte line-drawing characters.
- Ncurses 5.3 (2002) provided a table of Unicode values to solve these
+ Ncurses 5.3 (2002) provided a table of Unicode values to solve these
problems. NetBSD curses incorporated that table in 2010.
- In this implementation, the Unicode values are used instead of the
+ In this implementation, the Unicode values are used instead of the
terminal description's <STRONG>acsc</STRONG> mapping as discussed in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG> for the
- environment variable <STRONG>NCURSES_NO_UTF8_ACS</STRONG>. In contrast, for the same
+ environment variable <STRONG>NCURSES_NO_UTF8_ACS</STRONG>. In contrast, for the same
cases, the line-drawing characters described in <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG> will use
only the ASCII default values.
- Having Unicode available does not solve all of the problems with line-
+ Having Unicode available does not solve all of the problems with line-
drawing for curses:
- <STRONG>o</STRONG> The closest Unicode equivalents to the VT100 graphics <EM>S1</EM>, <EM>S3</EM>, <EM>S7</EM>
- and <EM>S9</EM> frequently are not displayed at the regular intervals which
+ <STRONG>o</STRONG> The closest Unicode equivalents to the VT100 graphics <EM>S1</EM>, <EM>S3</EM>, <EM>S7</EM>
+ and <EM>S9</EM> frequently are not displayed at the regular intervals which
the terminal used.
- <STRONG>o</STRONG> The <EM>lantern</EM> is a special case. It originated with the AT&T 4410
- terminal in the early 1980s. There is no accessible documentation
+ <STRONG>o</STRONG> The <EM>lantern</EM> is a special case. It originated with the AT&T 4410
+ terminal in the early 1980s. There is no accessible documentation
depicting the lantern symbol on the AT&T terminal.
Lacking documentation, most readers assume that a <EM>storm</EM> <EM>lantern</EM> was
intended. But there are several possibilities, all with problems.
- Unicode 6.0 (2010) does provide two lantern symbols: U+1F383 and
- U+1F3EE. Those were not available in 2002, and are irrelevant
- since they lie outside the BMP and as a result are not generally
+ Unicode 6.0 (2010) does provide two lantern symbols: U+1F383 and
+ U+1F3EE. Those were not available in 2002, and are irrelevant
+ since they lie outside the BMP and as a result are not generally
available in terminals. They are not storm lanterns, in any case.
Most <EM>storm</EM> <EM>lanterns</EM> have a tapering glass chimney (to guard against
tipping); some have a wire grid protecting the chimney.
- For the tapering appearance, U+2603 was adequate. In use on a
+ For the tapering appearance, U+2603 was adequate. In use on a
terminal, no one can tell what the image represents. Unicode calls
it a snowman.
Others have suggested these alternatives: <section> U+00A7 (section
- mark), <Theta> U+0398 (theta), <Phi> U+03A6 (phi), <delta> U+03B4
+ mark), <Theta> U+0398 (theta), <Phi> U+03A6 (phi), <delta> U+03B4
(delta), U+2327 (x in a rectangle), U+256C (forms double vertical
and horizontal), and U+2612 (ballot box with x).
+</PRE><H3><a name="h3-Complex-Characters">Complex Characters</a></H3><PRE>
+ The complex character type <STRONG>cchar_t</STRONG> can store more than one wide
+ character (<STRONG>wchar_t</STRONG>). The X/Open Curses description does not mention
+ this possibility, describing only the cases where <EM>wch</EM> is a spacing
+ character or a non-spacing character.
+
+ This implementation assumes that <EM>wch</EM> is constructed using <STRONG><A HREF="curs_getcchar.3x.html">setcchar(3x)</A></STRONG>,
+ and in turn that the result
+
+ <STRONG>o</STRONG> contains at most one spacing character in the beginning of its list
+ of wide characters, and zero or more non-spacing characters or
+
+ <STRONG>o</STRONG> may hold one non-spacing character.
+
+ In the latter case, ncurses adds the non-spacing character to the
+ active (base) spacing character.
+
+
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<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>,
- <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>
+ <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>
-ncurses 6.4 2023-07-
01 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>
+ncurses 6.4 2023-07-
15 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
-<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
+<li><a href="#h2-PORTABILITY">PORTABILITY</a>
+<ul>
+<li><a href="#h3-WACS-Symbols">WACS Symbols</a></li>
+<li><a href="#h3-Complex-Characters">Complex Characters</a></li>
+</ul>
+</li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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