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
+ a curses complex character to a window, possibly advancing 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 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.
+
+ wadd_wch writes the complex character wch to the window win, then may
+ advance the cursor position, analogously to the standard C library's
+ putwchar(3). ncurses(3x) describes the variants of this function.
+
+ Much behavior depends on whether the wide characters in wch are spacing
+ or non-spacing; see subsection "Complex Characters" below.
+
+ o If wch contains a spacing character, then any character at the
+ cursor is first removed. The complex character wch, with its
+ attributes and color pair identifier, becomes the base of the
+ activecomplexcharacter.
+
+ o If wch contains only non-spacing characters, they are combined with
+ the active complex character. curses ignores its attributes and
+ color pair identifier, and does not advance the cursor.
+
+ Further non-spacing characters added with wadd_wch are not written at
+ the new cursor position but combine with the active complex character
+ until another spacing character is written to the window or the cursor
+ is moved.
+
+ If advancement occurs at the right margin,
+
+ o the cursor automatically wraps to the beginning of the next line,
+ then,
+
+ o if it was at the bottom of the scrolling region, and if
+ scrollok(3x) is enabled for win, the scrolling region scrolls up
+ one line.
+
+ If wch is a backspace, carriage return, line feed, or tab, the cursor
+ moves appropriately within the window.
+
+ o Backspace moves the cursor one character left; at the left margin
+ of a window, it does nothing.
+
+ o Carriage return moves the cursor to the left margin on the current
+ line of the window.
- 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.
+ o Line feed does a clrtoeol(3x), then advances as if from the right
+ margin.
+ o Tab advances the cursor to the next tab stop (possibly on the next
+ line); these are placed at every eighth column by default. Alter
+ the tab interval with the TABSIZE extension; see
+ curs_variables(3x).
-
- 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.
+ If wch is any other nonprintable character, it is drawn in printable
+ form using the same convention as wunctrl(3x).
+ Calling win_wch(3x) on the location of a nonprintable character does
+ not return the character itself, but its wunctrl(3x) representation.
-
- 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
+
+ echo_wchar and wecho_wchar are equivalent to calling (w)add_wch
+ followed by (w)refresh. curses interprets these functions as a hint
+ that only a single (complex) character is being output; for non-control
+ characters, a considerable performance gain may be enjoyed by employing
+ them.
- NameDefaultDefaultcharName
+
+
+ curses defines macros starting with WACS_ that can be used with
+ wadd_wch to write line-drawing and other special characters to the
+ screen. ncurses terms these forms-drawingcharacters. The ACS default
+ listed below is used if the acs_chars (acsc) terminfo capability does
+ not define a terminal-specific replacement for it, or if the terminal
+ and locale configuration requires Unicode to access these characters
+ but the library is unable to use Unicode. The "acsc char" column
+ corresponds to how the characters are specified in the acs_chars (acsc)
+ string capability, and the characters in it may appear on the screen if
+ the terminal type's database entry incorrectly advertises ACS support.
+ The name "ACS" originates in the Alternate Character Set feature of the
+ DEC VT100 terminal.
+
+ UnicodeACSacsc
+ SymbolDefaultDefaultcharGlyphName
------------------------------------------------------------------------
- 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
-
- The wide-character configuration of ncurses also defines symbols for
+ 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
+
+ The wide-character configuration of ncurses also defines symbols for
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
+ 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"):
- ACSUnicodeASCIIacscGlyph
- NameDefaultDefaultcharName
+ 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
+ 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
@@ -197,72 +227,73 @@
- All routines return the integer ERR upon failure and OK on success.
+ These functions return OK on success and ERR on failure. In ncurses,
+ wadd_wch returns ERR if
- X/Open does not define any error conditions. This implementation
- returns an error
+ owin is NULL,
- o if the window pointer is null or
+ o wrapping to a new line is impossible because scrollok(3x) has not
+ been called on win when writing to its bottom right location is
+ attempted, or
- o if it is not possible to add a complete character in the window.
+ o it is not possible to add a complete character at the cursor
+ position.
- The latter may be due to different causes:
+ Functions prefixed with "mv" first perform cursor movement and fail if
+ the position (y, x) is outside the window boundaries.
- 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.
+
+ add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be implemented as
+ macros.
- 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.
+
- 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.
+ These functions are described in X/Open Curses, Issue 4. It specifies
+ no error conditions for them.
+ SVr4 curses describes a successful return value only as "an integer
+ value other than ERR".
-
- 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:
+ The defaults specified for forms-drawing characters apply in the POSIX
+ locale. 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
+ 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 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,
+ 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, HPUX, Solaris) use only
+ 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
+ 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.
+ 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:
@@ -297,30 +328,34 @@
- 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.
+ The complex character type cchar_t can store more than one wide
+ character (wchar_t). X/Open Curses does not mention this possibility,
+ specifying behavior only where wch is a single character, either
+ spacing or non-spacing.
- This implementation assumes that wch is constructed using setcchar(3x),
- and in turn that the result
+ ncurses 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 contains at most one spacing character at the beginning of its list
+ of wide characters, and zero or more non-spacing characters, or
- o may hold one non-spacing character.
+ o holds one non-spacing character.
- In the latter case, ncurses adds the non-spacing character to the
- active (base) spacing character.
+ In the latter case, ncurses adds the non-spacing character to the
+ active complex character.