- The add_wch, wadd_wch, mvadd_wch, and mvwadd_wch functions put the com-
- plex character wch into the given window at its current position, which
- is then advanced. These functions perform wrapping and special-charac-
- ter processing as follows:
+ The add_wch, wadd_wch, mvadd_wch, and mvwadd_wch functions put the
+ complex character wch into the given window at its current position,
+ which is then advanced. These functions perform wrapping and special-
+ character processing as follows:
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 cur-
- sor then advances to the next spacing character on the screen.
+ placed at that location with rendition specified by wch. The
+ cursor then advances to the next spacing 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 spec-
- ified by wch is ignored.
+ are added to the spacing complex character, and the rendition
+ specified by wch is ignored.
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
@@ -87,18 +89,18 @@
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 func-
- tionally equivalent to a call to wadd_wch followed by a call to wre-
- fresh. The knowledge that only a single character is being output is
- taken into consideration and, for non-control characters, a consider-
- able performance gain might be seen by using the *echo* functions
- instead of their equivalents.
+ 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 cor-
- respond to the same VT100 line-drawing set as addch(3x).
+ lines and other frequently used special characters. These symbols
+ correspond to the same VT100 line-drawing set as addch(3x).
ACSUnicodeASCIIacscGlyphNameDefaultDefaultcharName
@@ -110,8 +112,8 @@
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_DIAMOND 0x25c6 + ` diamond
WACS_GEQUAL 0x2265 > > greater-than-or-equal-to
WACS_HLINE 0x2500 - q horizontal line
WACS_LANTERN 0x2603 # i lantern symbol
@@ -138,7 +140,24 @@
WACS_VLINE 0x2502 | x vertical line
The wide-character configuration of ncurses also defines symbols for
- double-lines:
+ thick lines (acsc "J" to "V"):
+
+ ACSUnicodeASCIIacscGlyph
+ NameDefaultDefaultcharName
+ -----------------------------------------------------------------------
+ WACS_T_BTEE 0x253b + V thick tee pointing up
+ WACS_T_HLINE 0x2501 - Q thick horizontal line
+ WACS_T_LLCORNER 0x2517 + M thick lower left corner
+ WACS_T_LRCORNER 0x251b + J thick lower right corner
+ WACS_T_LTEE 0x252b + T thick tee pointing right
+ WACS_T_PLUS 0x254b + N thick large plus
+ WACS_T_RTEE 0x2523 + U thick tee pointing left
+ WACS_T_TTEE 0x2533 + W thick tee pointing down
+ WACS_T_ULCORNER 0x250f + L thick upper left corner
+ WACS_T_URCORNER 0x2513 + K thick upper right corner
+ WACS_T_VLINE 0x2503 | X thick vertical line
+
+ and for double-lines (acsc "A" to "I"):
ACSUnicodeASCIIacscGlyphNameDefaultDefaultcharName
@@ -155,27 +174,38 @@
WACS_D_URCORNER 0x2557 + B double upper right corner
WACS_D_VLINE 0x2551 | Y double vertical line
- and for thick lines:
+ 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:
- ACSUnicodeASCIIacscGlyph
- NameDefaultDefaultcharName
- -----------------------------------------------------------------------
- WACS_T_BTEE 0x253b + V thick tee pointing up
- WACS_T_HLINE 0x2501 - Q thick horizontal line
- WACS_T_LLCORNER 0x2517 + M thick lower left corner
- WACS_T_LRCORNER 0x251b + J thick lower right corner
- WACS_T_LTEE 0x252b + T thick tee pointing right
- WACS_T_PLUS 0x254b + N thick large plus
- WACS_T_RTEE 0x2523 + U thick tee pointing left
- WACS_T_TTEE 0x2533 + W thick tee pointing down
- WACS_T_ULCORNER 0x250f + L thick upper left corner
- WACS_T_URCORNER 0x2513 + K thick upper right corner
- WACS_T_VLINE 0x2503 | X thick vertical line
+ o U+2500 BOX DRAWINGS LIGHT HORIZONTAL
+
+ o U+2501 BOX DRAWINGS HEAVY HORIZONTAL
+
+ o U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
All routines return the integer ERR upon failure and OK on success.
+ X/Open does not define any error conditions. This implementation
+ returns an error
+
+ o if the window pointer is null or
+
+ o if it is not possible to add a complete character in the window.
+
+ The latter may be due to different causes:
+
+ o If scrollok 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
+ resulting bytes in the window, an error is returned.
+
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.
@@ -197,27 +227,27 @@
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 misde-
- fined symbols are the arrows and other symbols which are not used
- for line-drawing.
+ 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
- intermediate symbols. This implementation extends those symbols, pro-
- viding new definitions which are not in the SVr4 implementations.
+ 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 corre-
- sponding 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 imple-
- mentations can only use single-byte line-drawing characters. 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 ter-
- minal description's acsc mapping as discussed in ncurses(3x) for the
+ 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
+ problems. NetBSD curses incorporated that table in 2010.
+
+ 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
cases, the line-drawing characters described in curs_addch(3x) will use
only the ASCII default values.
@@ -248,15 +278,15 @@
terminal, no one can tell what the image represents. Unicode calls
it a snowman.
- Others have suggested these alternatives: S U+00A7 (section mark),
- O U+0398 (theta), O U+03A6 (phi), d U+03B4 (delta), U+2327 (x in a
- rectangle), U+256C (forms double vertical and horizontal), and
- U+2612 (ballot box with x).
+ Others have suggested these alternatives: <section> U+00A7 (section
+ 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).