curs_add_wch 3x

curs_add_wch(3x)                                              curs_add_wch(3x)


       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


       #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 );



       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:

       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  cur-
           sor 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 spec-
           ified 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.


       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
       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 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

       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


       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.


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


       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  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
       alternate 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:

       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 availble in 2002, and are irrelevant since
           they  lie  outside the BMP and as a result are not generally avail-
           able 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: S U+00A7 (section mark),
           O U+0398 (theta), O U+03A6 (phi), d U+03B4 (delta),  U+2327 (x in a
           rectangle),   U+256C  (forms  double  vertical and horizontal), and
           U+2612 (ballot box with x).


       curses(3x), curs_addch(3x), curs_attr(3x), curs_clear(3x), curs_out-
       opts(3x), curs_refresh(3x), putwc(3)