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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 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: • 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. • 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. • 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 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 in- stead 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 cor- respond 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_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"): 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 ncurses, by introducing the term "light" (along with less important de- tails). Here are its descriptions for the normal, thick, and double horizontal lines: • U+2500 BOX DRAWINGS LIGHT HORIZONTAL • U+2501 BOX DRAWINGS HEAVY HORIZONTAL • 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 re- turns an error • if the window pointer is null or • if it is not possible to add a complete character in the window. The latter may be due to different causes: • 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 • 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 re- sulting 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: • NetBSD curses defines the symbols as a wchar_t within a cchar_t. • 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. 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. Not all Unicode-capable terminals provide support for VT100-style al- ternate 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 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- drawing for curses: • 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. • 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_out- opts(3X), curs_refresh(3X), putwc(3) curs_add_wch(3X)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO
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