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 cursor

#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 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.

The echo_wchar function is functionally equivalent to a call to add_wch followed by a call to refresh. 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.

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).

Name Unicode Default Description
WACS_BLOCK 0x25ae # solid square block
WACS_BOARD 0x2592 # board of squares
WACS_BTEE 0x2534 + bottom tee
WACS_BULLET 0x00b7 o bullet
WACS_CKBOARD 0x2592 : checker board (stipple)
WACS_DARROW 0x2193 v arrow pointing down
WACS_DEGREE 0x00b0 ' degree symbol
WACS_DIAMOND 0x25c6 + diamond
WACS_GEQUAL 0x2265 > greater-than-or-equal-to
WACS_HLINE 0x2500 - horizontal line
WACS_LANTERN 0x2603 # lantern symbol
WACS_LARROW 0x2190 < arrow pointing left
WACS_LEQUAL 0x2264 < less-than-or-equal-to
WACS_LLCORNER 0x2514 + lower left-hand corner
WACS_LRCORNER 0x2518 + lower right-hand corner
WACS_LTEE 0x2524 + left tee
WACS_NEQUAL 0x2260 ! not-equal
WACS_PI 0x03c0 * greek pi
WACS_PLMINUS 0x00b1 # plus/minus
WACS_PLUS 0x253c + plus
WACS_RARROW 0x2192 > arrow pointing right
WACS_RTEE 0x251c + right tee
WACS_S1 0x23ba - scan line 1
WACS_S3 0x23bb - scan line 3
WACS_S7 0x23bc - scan line 7
WACS_S9 0x23bd _ scan line 9
WACS_STERLING 0x00a3 f pound-sterling symbol
WACS_TTEE 0x252c + top tee
WACS_UARROW 0x2191 ^ arrow pointing up
WACS_ULCORNER 0x250c + upper left-hand corner
WACS_URCORNER 0x2510 + upper right-hand corner
WACS_VLINE 0x2502 | vertical line

The wide-character configuration of ncurses also defines symbols for thick- and double-lines:

Name Unicode Default Description
WACS_T_ULCORNER 0x250f + thick upper left corner
WACS_T_LLCORNER 0x2517 + thick lower left corner
WACS_T_URCORNER 0x2513 + thick upper right corner
WACS_T_LRCORNER 0x251b + thick lower right corner
WACS_T_LTEE 0x252b + thick tee pointing right
WACS_T_RTEE 0x2523 + thick tee pointing left
WACS_T_BTEE 0x253b + thick tee pointing up
WACS_T_TTEE 0x2533 + thick tee pointing down
WACS_T_HLINE 0x2501 - thick horizontal line
WACS_T_VLINE 0x2503 | thick vertical line
WACS_T_PLUS 0x254b + thick large plus or crossover
WACS_D_ULCORNER 0x2554 + double upper left corner
WACS_D_LLCORNER 0x255a + double lower left corner
WACS_D_URCORNER 0x2557 + double upper right corner
WACS_D_LRCORNER 0x255d + double lower right corner
WACS_D_RTEE 0x2563 + double tee pointing left
WACS_D_LTEE 0x2560 + double tee pointing right
WACS_D_BTEE 0x2569 + double tee pointing up
WACS_D_TTEE 0x2566 + double tee pointing down
WACS_D_HLINE 0x2550 - double horizontal line
WACS_D_VLINE 0x2551 | double vertical line
WACS_D_PLUS 0x256c + double large plus or crossover

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:

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.

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