curs_add_wch(3x) Library calls curs_add_wch(3x)
@@ -75,34 +76,44 @@
o If wch refers to a spacing character, then any previous character
at that location is removed. A new character specified by wch is
placed at that location with rendition specified by wch. 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.
- o If wch refers to a non-spacing character, all previous characters
- at that location are preserved. The non-spacing characters of wch
- are added to the spacing complex character, and the rendition
- specified by wch 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 wmove.
- o If the character part of wch is a tab, newline, backspace or other
+ o If wch 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 wch 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.
+
+ o If the character part of wch is a tab, newline, backspace or other
control character, the window is updated and the cursor moves as if
addch were called.
The echo_wchar function is functionally equivalent to a call to add_wch
- followed by a call to refresh(3x). Similarly, the wecho_wchar is
- functionally equivalent to a call to wadd_wch followed by a call to
- wrefresh. 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 *echo*
+ followed by a call to refresh(3x). Similarly, the wecho_wchar is
+ functionally equivalent to a call to wadd_wch followed by a call to
+ wrefresh. 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 *echo*
functions instead of their equivalents.
- Like addch(3x), addch_wch accepts symbols which make it simple to draw
- lines and other frequently used special characters. These symbols
+ Like addch(3x), addch_wch 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 addch(3x).
ACSUnicodeASCIIacscGlyph
+
NameDefaultDefaultcharName
------------------------------------------------------------------------
WACS_BLOCK 0x25ae # 0 solid square block
@@ -112,7 +123,6 @@
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
@@ -139,7 +149,7 @@
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 (acsc "J" to "V"):
ACSUnicodeASCIIacscGlyph
@@ -169,14 +179,15 @@
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:
o U+2500 BOX DRAWINGS LIGHT HORIZONTAL
@@ -189,7 +200,7 @@
All routines return the integer ERR upon failure and OK 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
o if the window pointer is null or
@@ -198,15 +209,15 @@
The latter may be due to different causes:
- o If scrollok(3x) is not enabled, writing a character at the lower
+ o If scrollok(3x) 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
- o 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
+ o 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
wmove, and return an error if the position is outside the window, or if
the window pointer is null.
@@ -216,81 +227,101 @@
- 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
+
+
+ X/Open Curses makes it clear that the WACS_ symbols should be defined
as a pointer to cchar_t data, e.g., in the discussion of border_set. A
few implementations are problematic:
o NetBSD curses defines the symbols as a wchar_t within a cchar_t.
o HPUX curses equates some of the ACS_ symbols to the analogous WACS_
- symbols as if the ACS_ symbols were wide characters. The
- misdefined symbols are the arrows and other symbols which are not
+ symbols as if the ACS_ 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 acsc 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 acsc 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 acsc 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 acsc mapping as discussed in ncurses(3x) for the
- environment variable NCURSES_NO_UTF8_ACS. In contrast, for the same
+ environment variable NCURSES_NO_UTF8_ACS. In contrast, for the same
cases, the line-drawing characters described in curs_addch(3x) 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:
- o The closest Unicode equivalents to the VT100 graphics S1, S3, S7
- and S9 frequently are not displayed at the regular intervals which
+ o The closest Unicode equivalents to the VT100 graphics S1, S3, S7
+ and S9 frequently are not displayed at the regular intervals which
the terminal used.
- o The lantern is a special case. It originated with the AT&T 4410
- terminal in the early 1980s. There is no accessible documentation
+ o The lantern 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 stormlantern 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 stormlanterns 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).
+
+ The complex character type cchar_t can store more than one wide
+ character (wchar_t). The X/Open Curses description does not mention
+ this possibility, describing only the cases where wch is a spacing
+ character or a non-spacing character.
+
+ This implementation assumes that wch is constructed using setcchar(3x),
+ and in turn that the result
+
+ o contains at most one spacing character in the beginning of its list
+ of wide characters, and zero or more non-spacing characters or
+
+ o may hold one non-spacing character.
+
+ In the latter case, ncurses adds the non-spacing character to the
+ active (base) spacing character.
+
+