NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON

curs_add_wch(3X)                                            curs_add_wch(3X)

NAME         top

       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         top

       #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         top

   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:

       ·   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.

       ·   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.

       ·   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_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
       double-lines:

       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

       and for thick lines:

       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

RETURN VALUE         top

       All routines return the integer ERR upon failure and OK on success.

       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         top

       Note that add_wch, mvadd_wch, mvwadd_wch, and echo_wchar may be
       macros.

PORTABILITY         top

       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
           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 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.

       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: § U+00A7 (section
           mark), Θ U+0398 (theta), Φ U+03A6 (phi), δ 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         top

       curses(3X), curs_addch(3X), curs_attr(3X), curs_clear(3X),
       curs_outopts(3X), curs_refresh(3X), putwc(3)

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
       about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
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       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2017-09-15.  If you
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       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

                                                            curs_add_wch(3X)