curs_bkgrnd.3x man page
bkgrnd, wbkgrnd, bkgrndset, wbkgrndset, getbkgrnd, wgetbkgrnd — curses window complex background manipulation routines
int bkgrnd( const cchar_t *wch);
int wbkgrnd( WINDOW *win, const cchar_t *wch);
void bkgrndset(const cchar_t *wch );
void wbkgrndset(WINDOW *win, const cchar_t *wch);
int getbkgrnd(cchar_t *wch);
int wgetbkgrnd(WINDOW *win, cchar_t *wch);
The bkgrndset and wbkgrndset routines manipulate the background of the named window. The window background is a cchar_t consisting of any combination of attributes (i.e., rendition) and a complex character. The attribute part of the background is combined (OR'ed) with all non-blank characters that are written into the window with waddch. Both the character and attribute parts of the background are combined with the blank characters. The background becomes a property of the character and moves with the character through any scrolling and insert/delete line/character operations.
To the extent possible on a particular terminal, the attribute part of the background is displayed as the graphic rendition of the character put on the screen.
The bkgrnd and wbkgrnd functions set the background property of the current or specified window and then apply this setting to every character position in that window:
.IP · 4 The rendition of every character on the screen is changed to the new background rendition.
.IP · 4 Wherever the former background character appears, it is changed to the new background character.
The getbkgrnd function returns the given window's current background character/attribute pair via the wch pointer. If the given window pointer is null, the character is not updated (but no error returned).
Note that bkgrnd, bkgrndset, and getbkgrnd may be macros.
The bkgrndset and wbkgrndset routines do not return a value.
Upon successful completion, the other functions return OK. Otherwise, they return ERR:
.IP · 4 A null window pointer is treated as an error.
.IP · 4 A null character pointer is treated as an error.