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download PDF document: curs_add_wch.3x.pdf

curs_add_wch(3X) curs_add_wch(3X)
NAME 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
SYNOPSIS #include <curses.h>
int add_wch( const cchar_t *wch ); int wadd_wch( WINDOW *win, const cchar_t *wch ); int mvadd_wch( int y, int x, const cchar_t *wch ); int mvwadd_wch( WINDOW *win, int y, int x, const cchar_t *wch );
int echo_wchar( const cchar_t *wch ); int wecho_wchar( WINDOW *win, const cchar_t *wch );
DESCRIPTION add_wch 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 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 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 addch were called.
echo_wchar 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.
Line Graphics 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).
ACS Unicode ASCII acsc Glyph Name Default Default char Name ------------------------------------------------------------------------ WACS_BLOCK 0x25ae # 0 solid square block WACS_BOARD 0x2592 # h board of squares WACS_BTEE 0x2534 + v bottom tee 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"):
ACS Unicode ASCII acsc Glyph Name Default Default char Name ----------------------------------------------------------------------- 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"):
ACS Unicode ASCII acsc Glyph Name Default Default char Name ------------------------------------------------------------------------ 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
o U+2550 BOX DRAWINGS DOUBLE HORIZONTAL
RETURN VALUE 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.
NOTES Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be macros.
PORTABILITY 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 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 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, 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 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
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 storm lantern 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 storm lanterns 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).
SEE ALSO curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X), curs_outopts(3X), curs_refresh(3X), putwc(3)
curs_add_wch(3X)