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+ * Copyright 2018-2019,2020 Thomas E. Dickey *
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- * @Id: curs_addch.3x,v 1.46 2018/07/28 21:02:35 tom Exp @
+ * @Id: curs_addch.3x,v 1.52 2020/03/21 23:47:23 tom Exp @
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<STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
the window pointer is null.
+ If it is not possible to add a complete character, an error is
+ returned:
+
+ <STRONG>o</STRONG> If <STRONG>scrollok</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
+ resulting bytes in the window, an error is returned.
+
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
Note that <STRONG>addch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, and <STRONG>echochar</STRONG> may be macros.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- All these functions are described in the XSI Curses standard, Issue 4.
- The defaults specified for forms-drawing characters apply in the POSIX
+ All these functions are described in the XSI Curses standard, Issue 4.
+ The defaults specified for forms-drawing characters apply in the POSIX
locale.
</PRE><H3><a name="h3-ACS-Symbols">ACS Symbols</a></H3><PRE>
X/Open Curses states that the <EM>ACS</EM><STRONG>_</STRONG> definitions are <STRONG>char</STRONG> constants. For
- the wide-character implementation (see <STRONG>curs_add_wch</STRONG>), there are analo-
- gous <EM>WACS</EM><STRONG>_</STRONG> definitions which are <STRONG>cchar_t</STRONG> constants.
-
- Some ACS symbols (ACS_S3, ACS_S7, ACS_LEQUAL, ACS_GEQUAL, ACS_PI,
- ACS_NEQUAL, ACS_STERLING) were not documented in any publicly released
- System V. However, many publicly available terminfos include <STRONG>acsc</STRONG>
- strings in which their key characters (pryz{|}) are embedded, and a
- second-hand list of their character descriptions has come to light.
+ the wide-character implementation (see <STRONG>curs_add_wch</STRONG>), there are analo-
+ gous <EM>WACS</EM><STRONG>_</STRONG> definitions which are <STRONG>cchar_t</STRONG> constants. Some implementa-
+ tions are problematic:
+
+ <STRONG>o</STRONG> Some implementations define the ACS symbols to a constant (such as
+ Solaris), while others define those to entries in an array.
+
+ This implementation uses an array <STRONG>acs_map</STRONG>, as done in SVr4 curses.
+ NetBSD also uses an array, actually named <STRONG>_acs_char</STRONG>, with a <STRONG>#define</STRONG>
+ for compatibility.
+
+ <STRONG>o</STRONG> HPUX curses equates some of the <EM>ACS</EM><STRONG>_</STRONG> symbols to the analogous <EM>WACS</EM><STRONG>_</STRONG>
+ symbols as if the <EM>ACS</EM><STRONG>_</STRONG> symbols were wide characters. The misde-
+ fined symbols are the arrows and other symbols which are not used
+ for line-drawing.
+
+ <STRONG>o</STRONG> X/Open Curses (issues 2 through 7) has a typographical error for
+ the ACS_LANTERN symbol, equating its "VT100+ Character" to <STRONG>I</STRONG> (capi-
+ tal I), while the header files for SVr4 curses and the various
+ implementations use <STRONG>i</STRONG> (lowercase).
+
+ None of the terminal descriptions on Unix platforms use uppercase-
+ I, except for Solaris (i.e., <EM>screen</EM>'s terminal description, appar-
+ ently based on the X/Open documentation around 1995). On the other
+ hand, the terminal description <EM>gs6300</EM> (AT&T PC6300 with EMOTS Ter-
+ minal Emulator) uses lowercase-i.
+
+ Some ACS symbols (ACS_S3, ACS_S7, ACS_LEQUAL, ACS_GEQUAL, ACS_PI,
+ ACS_NEQUAL, ACS_STERLING) were not documented in any publicly released
+ System V. However, many publicly available terminfos include <STRONG>acsc</STRONG>
+ strings in which their key characters (pryz{|}) are embedded, and a
+ second-hand list of their character descriptions has come to light.
The ACS-prefixed names for them were invented for <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
The <EM>displayed</EM> values for the <EM>ACS</EM><STRONG>_</STRONG> and <EM>WACS</EM><STRONG>_</STRONG> constants depend on
<STRONG>o</STRONG> the library configuration, i.e., <STRONG>ncurses</STRONG> versus <STRONG>ncursesw</STRONG>, where the
- latter is capable of displaying Unicode while the former is not,
+ latter is capable of displaying Unicode while the former is not,
and
<STRONG>o</STRONG> whether the <EM>locale</EM> uses UTF-8 encoding.
- In certain cases, the terminal is unable to display line-drawing char-
+ In certain cases, the terminal is unable to display line-drawing char-
acters except by using UTF-8 (see the discussion of <STRONG>NCURSES_NO_UTF8_ACS</STRONG>
in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>).
</PRE><H3><a name="h3-Character-Set">Character Set</a></H3><PRE>
- X/Open Curses assumes that the parameter passed to <STRONG>waddch</STRONG> contains a
- single character. As discussed in <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, that character may
- have been more than eight bits in an SVr3 or SVr4 implementation, but
- in the X/Open Curses model, the details are not given. The important
+ X/Open Curses assumes that the parameter passed to <STRONG>waddch</STRONG> contains a
+ single character. As discussed in <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, that character may
+ have been more than eight bits in an SVr3 or SVr4 implementation, but
+ in the X/Open Curses model, the details are not given. The important
distinction between SVr4 curses and X/Open Curses is that the non-char-
acter information (attributes and color) was separated from the charac-
ter information which is packed in a <STRONG>chtype</STRONG> to pass to <STRONG>waddch</STRONG>.
- In this implementation, <STRONG>chtype</STRONG> holds eight bits. But ncurses allows
- multibyte characters to be passed in a succession of calls to <STRONG>waddch</STRONG>.
- The other implementations do not do this; a call to <STRONG>waddch</STRONG> passes
- exactly one character which may be rendered as one or more cells on the
- screen depending on whether it is printable.
+ In this implementation, <STRONG>chtype</STRONG> holds an eight-bit character. But
+ ncurses allows multibyte characters to be passed in a succession of
+ calls to <STRONG>waddch</STRONG>. The other implementations do not do this; a call to
+ <STRONG>waddch</STRONG> passes exactly one character which may be rendered as one or
+ more cells on the screen depending on whether it is printable.
- Depending on the locale settings, ncurses will inspect the byte passed
- in each call to <STRONG>waddch</STRONG>, and check if the latest call will continue a
+ Depending on the locale settings, ncurses will inspect the byte passed
+ in each call to <STRONG>waddch</STRONG>, and check if the latest call will continue a
multibyte sequence. When a character is <EM>complete</EM>, ncurses displays the
character and moves to the next position in the screen.
- If the calling application interrupts the succession of bytes in a
+ If the calling application interrupts the succession of bytes in a
multibyte character by moving the current location (e.g., using <STRONG>wmove</STRONG>),
ncurses discards the partially built character, starting over again.
- For portability to other implementations, do not rely upon this behav-
+ For portability to other implementations, do not rely upon this behav-
ior:
- <STRONG>o</STRONG> check if a character can be represented as a single byte in the
+ <STRONG>o</STRONG> check if a character can be represented as a single byte in the
current locale before attempting call <STRONG>waddch</STRONG>, and
<STRONG>o</STRONG> call <STRONG>wadd_wch</STRONG> for characters which cannot be handled by <STRONG>waddch</STRONG>.
</PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
- The <STRONG>TABSIZE</STRONG> variable is implemented in some versions of curses, but is
- not part of X/Open curses.
+ The <STRONG>TABSIZE</STRONG> variable is implemented in SVr4 and other versions of
+ curses, but is not part of X/Open curses (see <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG> for
+ more details).
If <EM>ch</EM> is a carriage return, the cursor is moved to the beginning of the
current row of the window. This is true of other implementations, but
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