'\" t .\"*************************************************************************** .\" Copyright 2019-2023,2024 Thomas E. Dickey * .\" Copyright 2001-2015,2017 Free Software Foundation, Inc. * .\" * .\" Permission is hereby granted, free of charge, to any person obtaining a * .\" copy of this software and associated documentation files (the * .\" "Software"), to deal in the Software without restriction, including * .\" without limitation the rights to use, copy, modify, merge, publish, * .\" distribute, distribute with modifications, sublicense, and/or sell * .\" copies of the Software, and to permit persons to whom the Software is * .\" furnished to do so, subject to the following conditions: * .\" * .\" The above copyright notice and this permission notice shall be included * .\" in all copies or substantial portions of the Software. * .\" * .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * .\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * .\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * .\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * .\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. * .\" * .\" Except as contained in this notice, the name(s) of the above copyright * .\" holders shall not be used in advertising or otherwise to promote the * .\" sale, use or other dealings in this Software without prior written * .\" authorization. * .\"*************************************************************************** .\" .\" $Id: curs_add_wch.3x,v 1.63 2024/05/11 21:31:45 tom Exp $ .TH curs_add_wch 3X 2024-05-11 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls" .ie \n(.g \{\ .ds `` \(lq .ds '' \(rq .\} .el \{\ .ie t .ds `` `` .el .ds `` "" .ie t .ds '' '' .el .ds '' "" .\} . .de bP .ie n .IP \(bu 4 .el .IP \(bu 2 .. .SH NAME \fB\%add_wch\fP, \fB\%wadd_wch\fP, \fB\%mvadd_wch\fP, \fB\%mvwadd_wch\fP, \fB\%echo_wchar\fP, \fB\%wecho_wchar\fP \- add a \fIcurses\fR complex character to a window, possibly advancing the cursor .SH SYNOPSIS .nf \fB#include .PP \fBint add_wch(const cchar_t *\fIwch\fP); \fBint wadd_wch(WINDOW *\fIwin\fP, const cchar_t *\fIwch\fP); \fBint mvadd_wch(int \fIy\fP, int \fIx\fP, const cchar_t *\fIwch\fP); \fBint mvwadd_wch(WINDOW *\fIwin\fP, int \fIy\fP, int \fIx\fP, const cchar_t *\fIwch\fP); .PP \fBint echo_wchar(const cchar_t *\fIwch\fP); \fBint wecho_wchar(WINDOW *\fIwin\fP, const cchar_t *\fIwch\fP); .fi .SH DESCRIPTION .SS wadd_wch .B \%wadd_wch writes the complex character .I wch to the window .IR win "," then may advance the cursor position, analogously to the standard C library's \fI\%putwchar\fP(3). \fB\%ncurses\fP(3X) describes the variants of this function. .PP Much behavior depends on whether the wide characters in .I wch are spacing or non-spacing; see subsection \*(``Complex Characters\*('' below. .bP If .I wch contains a spacing character, then any character at the cursor is first removed. The complex character .IR wch "," with its attributes and color pair identifier, becomes the .I base of the .IR "active complex character" "." .bP If .I wch contains only non-spacing characters, .\" XXX: see wadd_wch_literal (the beginning of the array may be nonspacing) they are combined with the active complex character. .I curses ignores its attributes and color pair identifier, and does not advance the cursor. .PP Further non-spacing characters added with .B \%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. .PP If advancement occurs at the right margin, .bP the cursor automatically wraps to the beginning of the next line, then, .bP if it was at the bottom of the scrolling region, and if \fB\%scrollok\fP(3X) is enabled for .IR win , the scrolling region scrolls up one line. .PP If .I wch is a backspace, carriage return, line feed, or tab, the cursor moves appropriately within the window. .bP Backspace moves the cursor one character left; at the left margin of a window, it does nothing. .bP Carriage return moves the cursor to the left margin on the current line of the window. .bP Line feed does a \fB\%clrtoeol\fP(3X), then advances as if from the right margin. .bP 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 .B \%TABSIZE extension; see \fB\%curs_variables\fP(3X). .PP If .I wch is any other nonprintable character, it is drawn in printable form using the same convention as \fB\%wunctrl\fP(3X). .PP Calling \fB\%win_wch\fP(3X) on the location of a nonprintable character does not return the character itself, but its \fB\%wunctrl\fP(3X) representation. .SS wecho_wchar .B \%echo_wchar and .B \%wecho_wchar are equivalent to calling .RB \%( w ) add_wch followed by .RB \%( w ) refresh . .I 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. .\" TODO: Combine the following with the "Line Drawing" subsection of .\" terminfo(5) and replace this with a cross reference there. .SS "Forms-Drawing Characters" .I curses defines macros starting with .B \%WACS_ that can be used with .B \%wadd_wch to write line-drawing and other special characters to the screen. .I \%ncurses terms these .I "forms-drawing characters." The ACS default listed below is used if the .B \%acs_chars .RB ( \%acsc ) .I \%term\%info 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 .B \%acs_chars .RB ( \%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. .PP .TS Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb L L L Lx. \& Unicode ACS acsc \& Symbol Default Default char Glyph Name _ WACS_BLOCK 0x25ae # 0 T{ solid square block T} WACS_BOARD 0x2592 # h board of squares WACS_BTEE 0x2534 + v bottom tee WACS_BULLET 0x00b7 o ~ bullet WACS_CKBOARD 0x2592 : a T{ checker board (stipple) T} WACS_DARROW 0x2193 v . T{ arrow pointing down T} WACS_DEGREE 0x00b0 ' f degree symbol WACS_DIAMOND 0x25c6 + \(ga diamond WACS_GEQUAL 0x2265 > > T{ greater-than-or-equal-to T} WACS_HLINE 0x2500 \- q horizontal line WACS_LANTERN 0x2603 # i lantern symbol WACS_LARROW 0x2190 < , T{ arrow pointing left T} WACS_LEQUAL 0x2264 < y T{ less-than-or-equal-to T} WACS_LLCORNER 0x2514 + m T{ lower left-hand corner T} WACS_LRCORNER 0x2518 + j T{ lower right-hand corner T} 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 > + T{ arrow pointing right T} 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 } T{ pound-sterling symbol T} WACS_TTEE 0x252c + w top tee WACS_UARROW 0x2191 ^ \- T{ arrow pointing up T} WACS_ULCORNER 0x250c + l T{ upper left-hand corner T} WACS_URCORNER 0x2510 + k T{ upper right-hand corner T} WACS_VLINE 0x2502 | x vertical line .TE .PP The wide-character configuration of \fI\%ncurses\fP also defines symbols for thick lines (\fBacsc\fP \*(``J\*('' to \*(``V\*(''): .PP .TS Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb L L L Lx. \& Unicode ASCII acsc \& ACS Name Default Default Char Glyph Name _ WACS_T_BTEE 0x253b + V T{ thick tee pointing up T} WACS_T_HLINE 0x2501 - Q T{ thick horizontal line T} WACS_T_LLCORNER 0x2517 + M T{ thick lower left corner T} WACS_T_LRCORNER 0x251b + J T{ thick lower right corner T} WACS_T_LTEE 0x252b + T T{ thick tee pointing right T} WACS_T_PLUS 0x254b + N T{ thick large plus T} WACS_T_RTEE 0x2523 + U T{ thick tee pointing left T} WACS_T_TTEE 0x2533 + W T{ thick tee pointing down T} WACS_T_ULCORNER 0x250f + L T{ thick upper left corner T} WACS_T_URCORNER 0x2513 + K T{ thick upper right corner T} WACS_T_VLINE 0x2503 | X T{ thick vertical line T} .TE .PP and for double-lines (\fBacsc\fP \*(``A\*('' to \*(``I\*(''): .PP .TS Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb Lb L L L Lx. \& Unicode ASCII acsc \& ACS Name Default Default Char Glyph Name _ WACS_D_BTEE 0x2569 + H T{ double tee pointing up T} WACS_D_HLINE 0x2550 - R T{ double horizontal line T} WACS_D_LLCORNER 0x255a + D T{ double lower left corner T} WACS_D_LRCORNER 0x255d + A T{ double lower right corner T} WACS_D_LTEE 0x2560 + F T{ double tee pointing right T} WACS_D_PLUS 0x256c + E T{ double large plus T} WACS_D_RTEE 0x2563 + G T{ double tee pointing left T} WACS_D_TTEE 0x2566 + I T{ double tee pointing down T} WACS_D_ULCORNER 0x2554 + C T{ double upper left corner T} WACS_D_URCORNER 0x2557 + B T{ double upper right corner T} WACS_D_VLINE 0x2551 | Y T{ double vertical line T} .TE .PP Unicode's descriptions for these characters differs slightly from \fI\%ncurses\fP, by introducing the term \*(``light\*('' (along with less important details). Here are its descriptions for the normal, thick, and double horizontal lines: .bP U+2500 BOX DRAWINGS LIGHT HORIZONTAL .bP U+2501 BOX DRAWINGS HEAVY HORIZONTAL .bP U+2550 BOX DRAWINGS DOUBLE HORIZONTAL .SH RETURN VALUE These functions return .B OK on success and .B ERR on failure. In .IR \%ncurses , .B \%wadd_wch returns .B ERR if .bP .I win is .BR NULL "," .bP wrapping to a new line is impossible because \fB\%scrollok\fP(3X) has not been called on .I win when writing to its bottom right location is attempted, or .bP it is not possible to add a complete character at the cursor position. .PP Functions prefixed with \*(``mv\*('' first perform cursor movement and fail if the position .RI ( y , .IR x ) is outside the window boundaries. .SH NOTES .BR add_wch "," .BR mvadd_wch "," .BR mvwadd_wch "," and .B echo_wchar may be implemented as macros. .SH EXTENSIONS .SS TABSIZE The .B TABSIZE variable is implemented in SVr4 and other versions of .IR curses , but is not specified by X/Open Curses (see \fBcurs_variables\fP(3X)). .SH PORTABILITY These functions are described in X/Open Curses, Issue 4. It specifies no error conditions for them. .PP SVr4 .I curses describes a successful return value only as \*(``an integer value other than .BR ERR \*(''. .PP 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 \fBcchar_t\fP data, e.g., in the discussion of \fBborder_set\fP. A few implementations are problematic: .bP NetBSD curses defines the symbols as a \fBwchar_t\fP within a \fBcchar_t\fP. .bP HP-UX curses equates some of the \fBACS_\fP symbols to the analogous \fBWACS_\fP symbols as if the \fBACS_\fP symbols were wide characters. The misdefined symbols are the arrows and other symbols which are not used for line-drawing. .PP 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. .PP Not all Unicode-capable terminals provide support for VT100-style alternate character sets (i.e., the \fBacsc\fP 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 \fBacsc\fP character-mapping to provide this feature. As a result, those implementations can only use single-byte line-drawing characters. \fI\%ncurses\fP 5.3 (2002) provided a table of Unicode values to solve these problems. NetBSD curses incorporated that table in 2010. .PP In this implementation, the Unicode values are used instead of the terminal description's \fBacsc\fP mapping as discussed in \fB\%ncurses\fP(3X) for the environment variable \fINCURSES_NO_UTF8_ACS\fP. In contrast, for the same cases, the line-drawing characters described in \fB\%addch\fP(3X) will use only the ASCII default values. .PP Having Unicode available does not solve all of the problems with line-drawing for curses: .bP The closest Unicode equivalents to the VT100 graphics \fIS1\fP, \fIS3\fP, \fIS7\fP and \fIS9\fP frequently are not displayed at the regular intervals which the terminal used. .bP The \fIlantern\fP 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. .IP Lacking documentation, most readers assume that a \fIstorm lantern\fP was intended. But there are several possibilities, all with problems. .IP 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. .IP Most \fIstorm lanterns\fP have a tapering glass chimney (to guard against tipping); some have a wire grid protecting the chimney. .IP For the tapering appearance, \[u2603] U+2603 was adequate. In use on a terminal, no one can tell what the image represents. Unicode calls it a snowman. .IP Others have suggested these alternatives: \[sc] U+00A7 (section mark), \[u0398] U+0398 (theta), \[u03A6] U+03A6 (phi), \[u03B4] U+03B4 (delta), \[u2327] U+2327 (x in a rectangle), \[u256C] U+256C (forms double vertical and horizontal), and \[u2612] U+2612 (ballot box with x). .SS "Complex Characters" The complex character type .I \%cchar_t can store more than one wide character .RI ( \%wchar_t ). X/Open Curses does not mention this possibility, specifying behavior only where .I wch is a single character, either spacing or non-spacing. .PP .I \%ncurses assumes that .I wch is constructed using \fB\%setcchar\fP(3X), and in turn that the result .bP contains at most one spacing character at the beginning of its list of wide characters, and zero or more non-spacing characters, or .bP holds one non-spacing character. .PP In the latter case, .I \%ncurses adds the non-spacing character to the active complex character. .SH SEE ALSO \fB\%curs_addch\fP(3X) describes comparable functions of the .I \%ncurses library in its non-wide-character configuration. .PP \fB\%curses\fP(3X), \fB\%curs_addwstr\fP(3X), \fB\%curs_add_wchstr\fP(3X), \fB\%curs_attr\fP(3X), \fB\%curs_clear\fP(3X), \fB\%curs_getcchar\fP(3X), \fB\%curs_outopts\fP(3X), \fB\%curs_refresh\fP(3X), \fB\%curs_variables\fP(3X), \fB\%putwc\fP(3)