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   attr_get.3x    ( 3 )

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Описание (Description)

These routines manipulate the current attributes of the named window, which then apply to all characters that are written into the window with waddch, waddstr and wprintw. Attributes are a property of the character, and move with the character through any scrolling and insert/delete line/character operations. To the extent possible, they are displayed as appropriate modifications to the graphic rendition of characters put on the screen.

These routines do not affect the attributes used when erasing portions of the window. See curs_bkgd(3X) for functions which modify the attributes used for erasing and clearing.

Routines which do not have a WINDOW* parameter apply to stdscr. For example, attr_set is the stdscr variant of wattr_set.

Window attributes There are two sets of functions:

• functions for manipulating the window attributes and color: wattr_set and wattr_get.

• functions for manipulating only the window attributes (not color): wattr_on and wattr_off.

The wattr_set function sets the current attributes of the given window to attrs, with color specified by pair.

Use wattr_get to retrieve attributes for the given window.

Use attr_on and wattr_on to turn on window attributes, i.e., values OR'd together in attr, without affecting other attributes. Use attr_off and wattr_off to turn off window attributes, again values OR'd together in attr, without affecting other attributes.

Legacy window attributes The X/Open window attribute routines which set or get, turn on or off are extensions of older routines which assume that color pairs are OR'd into the attribute parameter. These newer routines use similar names, because X/Open simply added an underscore (_) for the newer names.

The int datatype used in the legacy routines is treated as if it is the same size as chtype (used by addch(3X)). It holds the common video attributes (such as bold, reverse), as well as a few bits for color. Those bits correspond to the A_COLOR symbol. The COLOR_PAIR macro provides a value which can be OR'd into the attribute parameter. For example, as long as that value fits into the A_COLOR mask, then these calls produce similar results:

attrset(A_BOLD | COLOR_PAIR(pair)); attr_set(A_BOLD, pair, NULL);

However, if the value does not fit, then the COLOR_PAIR macro uses only the bits that fit. For example, because in ncurses A_COLOR has eight (8) bits, then COLOR_PAIR(259) is 4 (i.e., 259 is 4 more than the limit 255).

The PAIR_NUMBER macro extracts a pair number from an int (or chtype). For example, the input and output values in these statements would be the same:

int value = A_BOLD | COLOR_PAIR(input); int output = PAIR_NUMBER(value);

The attrset routine is a legacy feature predating SVr4 curses but kept in X/Open Curses for the same reason that SVr4 curses kept it: compatibility.

The remaining attr* functions operate exactly like the corresponding attr_* functions, except that they take arguments of type int rather than attr_t.

There is no corresponding attrget function as such in X/Open Curses, although ncurses provides getattrs (see curs_legacy(3X)).

Change character rendition The routine chgat changes the attributes of a given number of characters starting at the current cursor location of stdscr. It does not update the cursor and does not perform wrapping. A character count of -1 or greater than the remaining window width means to change attributes all the way to the end of the current line. The wchgat function generalizes this to any window; the mvwchgat function does a cursor move before acting.

In these functions, the color pair argument is a color-pair index (as in the first argument of init_pair, see curs_color(3X)).

Change window color The routine color_set sets the current color of the given window to the foreground/background combination described by the color pair parameter.

Standout The routine standout is the same as attron(A_STANDOUT). The routine standend is the same as attrset(A_NORMAL) or attrset(0), that is, it turns off all attributes.

X/Open does not mark these 'restricted', because

• they have well established legacy use, and

• there is no ambiguity about the way the attributes might be combined with a color pair.