The bkgdset and wbkgdset routines manipulate the background of the named window. The window background is a chtype consisting of any combination of attributes (i.e., rendition) and a character. The attribute part of the background is combined (ORed) 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 bkgd and wbkgd functions set the background property of the current or specified window and then apply this setting to every character position in that window:
The rendition of every character on the screen is changed to the new background rendition.
Wherever the former background character appears, it is changed to the new background character.
The getbkgd function returns the given windows current background character/attribute pair.
The routines bkgd and wbkgd return the integer OK. The SVr4.0 manual says "or a non-negative integer if immedok is set", but this appears to be an error.
Note that bkgdset and bkgd may be macros.
These functions are described in the XSI Curses standard, Issue 4. The draft does not include const qualifiers on the arguments. The standard specifies that bkgd and wbkgd return ERR, on failure. but gives no failure conditions.
curses(3), curs_addch(3), curs_outopts(3)