# curs_add_wch

## 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
           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 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:
    
           •   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
           returns 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**(3X) 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 resulting 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 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).
    


* * *