# curs_add_wch 3x

    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:

           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.

### 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
           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
           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
           details).   Here are its descriptions for the normal, thick, and double
           horizontal lines:

           o   U+2500 BOX DRAWINGS LIGHT HORIZONTAL

           o   U+2501 BOX DRAWINGS HEAVY HORIZONTAL

           o   U+2550 BOX DRAWINGS DOUBLE HORIZONTAL

## RETURN VALUE

           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

           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 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  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: 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).

## 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)