- add_wch, wadd_wch, mvadd_wch, mvwadd_wch, echo_wchar,
- wecho_wchar - add a complex character and rendition to a
- curses window, then advance the cursor
+
- 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 fol-
- lows:
-
- - If wch refers to a spacing character, then any previ-
- ous 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.
-
- - If wch refers to a non-spacing character, all previ-
- ous characters at that location are preserved. The
- non-spacing characters of wch are added to the spac-
- ing complex character, and the rendition specified by
- wch is ignored.
-
- - 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. 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 consider-
- able performance gain might be seen by using the *echo*
+
+
+ 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
+ cursor then advances after this spacing character, to prepare for
+ writing the next character on the screen.
+
+ 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 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*
functions instead of their equivalents.
-
-
RETURN VALUES
- All routines return the integer ERR upon failure and OK on
- success.
+
+ 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).
+ UnicodeASCIIacsc
-
-
NOTES
- Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar
- may be macros.
+ ACSNameDefaultDefaultCharGlyphName
+ ------------------------------------------------------------------------
+ WACS_BLOCK 0x25ae # 0 solid square block
+ WACS_BOARD 0x2592 # h board of squares
+ WACS_BTEE 0x2534 + v bottom tee
+ WACS_BULLET 0x00b7 o ~ bullet
+ 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_LANTERN 0x2603 # i lantern symbol
+ WACS_LARROW 0x2190 < , arrow pointing left
+ WACS_LEQUAL 0x2264 < y less-than-or-equal-to
+ WACS_LLCORNER 0x2514 + m lower left-hand corner
+ WACS_LRCORNER 0x2518 + j lower right-hand corner
+ WACS_LTEE 0x2524 + t left tee
+ WACS_NEQUAL 0x2260 ! | not-equal
+ WACS_PI 0x03c0 * { greek pi
+ WACS_PLMINUS 0x00b1 # g plus/minus
+ WACS_PLUS 0x253c + n plus
+ WACS_RARROW 0x2192 > + arrow pointing right
+ WACS_RTEE 0x251c + u right tee
+ WACS_S1 0x23ba - o scan line 1
+ WACS_S3 0x23bb - p scan line 3
+ WACS_S7 0x23bc - r scan line 7
+ WACS_S9 0x23bd _ s scan line 9
+ WACS_STERLING 0x00a3 f } pound-sterling symbol
+ WACS_TTEE 0x252c + w top tee
+ WACS_UARROW 0x2191 ^ - arrow pointing up
+ WACS_ULCORNER 0x250c + l upper left-hand corner
+ WACS_URCORNER 0x2510 + k upper right-hand corner
+ WACS_VLINE 0x2502 | x vertical line
-
-
PORTABILITY
- All these functions are described in the XSI Curses stan-
- dard, Issue 4. The defaults specified for forms-drawing
- characters apply in the POSIX locale.
+ The wide-character configuration of ncurses also defines symbols for
+ thick lines (acsc "J" to "V"):
- XSI documents constants beginning with WACS_ which are
- used for line-drawing. Those are not currently imple-
- mented in ncurses.
+ UnicodeASCIIacsc
+ ACSNameDefaultDefaultCharGlyphName
+ ------------------------------------------------------------------------
+ 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"):
-
-
SEE ALSO
- curses(3x), curs_addch(3x), curs_attr(3x), curs_clear(3x),
- curs_outopts(3x), curs_refresh(3x), putwc(3)
+ UnicodeASCIIacsc
+ ACSNameDefaultDefaultCharGlyphName
+ ------------------------------------------------------------------------
+ WACS_D_BTEE 0x2569 + H double tee pointing up
+ WACS_D_HLINE 0x2550 - R double horizontal line
+ WACS_D_LLCORNER 0x255a + D double lower left corner
+ WACS_D_LRCORNER 0x255d + A double lower right corner
+ 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
+ horizontal lines:
+
+ 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 Curses does not specify 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(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
+ resulting bytes in the window, an error is returned.
+
+ Functions prefixed with "mv" first perform cursor movement and fail if
+ the position (y, x) is outside the window boundaries.
+
+
+
+ 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 HP-UX 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
+ used for line-drawing.
+
+ X/Open Curses does not specify symbols for thick- or double-lines.
+ SVr4 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, HP-UX, 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 addch(3x) will use only
+ the ASCII default values.
+
+ 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
+ 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
+ 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
+ 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
+ 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
+ (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.
+
+
+