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curs_attr

Section: Miscellaneous Library Functions (3X)
Updated:
Index Return to Main Contents

NAME

attroff, wattroff, attron, wattron, attrset, wattrset, color_set, wcolor_set, standend, wstandend, standout, wstandout, attr_get, wattr_get, attr_off, wattr_off, attr_on, wattr_on, attr_set, wattr_set, chgat, wchgat, mvchgat, mvwchgat, PAIR_NUMBER - curses character and window attribute control routines

SYNOPSIS

#include <curses.h>
int attroff(int attrs);
int wattroff(WINDOW *win, int attrs);
int attron(int attrs);
int wattron(WINDOW *win, int attrs);
int attrset(int attrs);
int wattrset(WINDOW *win, int attrs);
int color_set(short color_pair_number, void* opts);
int wcolor_set(WINDOW *win, short color_pair_number,
      void* opts);
int standend(void);
int wstandend(WINDOW *win);
int standout(void);
int wstandout(WINDOW *win);
int attr_get(attr_t *attrs, short *pair, void *opts);
int wattr_get(WINDOW *win, attr_t *attrs, short *pair,
       void *opts);
int attr_off(attr_t attrs, void *opts);
int wattr_off(WINDOW *win, attr_t attrs, void *opts);
int attr_on(attr_t attrs, void *opts);
int wattr_on(WINDOW *win, attr_t attrs, void *opts);
int attr_set(attr_t attrs, short pair, void *opts);
int wattr_set(WINDOW *win, attr_t attrs, short pair, void *opts);
int chgat(int n, attr_t attr, short color,
      const void *opts);
int wchgat(WINDOW *win, int n, attr_t attr,
      short color, const void *opts);
int mvchgat(int y, int x, int n, attr_t attr,
      short color, const void *opts);
int mvwchgat(WINDOW *win, int y, int x, int n,
      attr_t attr, short color, const void *opts);

DESCRIPTION

These routines manipulate the current attributes of the named window. The current attributes of a window 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.

attrset

The routine attrset sets the current attributes of the given window to attrs. The routine attroff turns off the named attributes without turning any other attributes on or off. The routine attron turns on the named attributes without affecting any others. 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.

The attrset and related 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.

attr_set

The attrset routine is actually a legacy feature predating SVr4 curses but kept in X/Open Curses for the same reason that SVr4 curses kept it: compatbility. The routine attr_set provides for passing a color-pair parameter.

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

color_set

The routine color_set sets the current color of the given window to the foreground/background combination described by the color_pair_number. The parameter opts is reserved for future use, applications must supply a null pointer.

attr_get

The routine wattr_get returns the current attribute and color pair for the given window; attr_get returns the current attribute and color pair for stdscr.

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

chgat

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 argument is a color-pair index (as in the first argument of init_pair, see curs_color(3X)). The opts argument is not presently used, but is reserved for the future (leave it NULL).

Attributes

The following video attributes, defined in <curses.h>, can be passed to the routines attron, attroff, and attrset, or OR'd with the characters passed to addch (see curs_addch(3x)).

Name	Description

A_STANDOUT	Best highlighting mode of the terminal.
A_UNDERLINE	Underlining
A_REVERSE	Reverse video
A_BLINK	Blinking
A_DIM	Half bright
A_BOLD	Extra bright or bold
A_PROTECT	Protected mode
A_INVIS	Invisible or blank mode
A_ALTCHARSET	Alternate character set
A_ITALIC	Italics (non-X/Open extension)
A_CHARTEXT	Bit-mask to extract a character
COLOR_PAIR(n)	Color-pair number n

These video attributes are supported by attr_on and related functions (which also support the attributes recognized by attron, etc.):

Name	Description

WA_LEFT	Left highlight
WA_LOW	Low highlight
WA_RIGHT	Right highlight
WA_TOP	Top highlight
WA_VERTICAL	Vertical highlight

For consistency

The following macro is the reverse of COLOR_PAIR(n):

PAIR_NUMBER(attrs) Returns the pair number associated
with the COLOR_PAIR(n) attribute.

The return values of many of these routines are not meaningful (they are implemented as macro-expanded assignments and simply return their argument). The SVr4 manual page claims (falsely) that these routines always return 1.

NOTES

Note that attroff, wattroff, attron, wattron, attrset, wattrset, standend and standout may be macros.

COLOR_PAIR values can only be OR'd with attributes if the pair number is less than 256. The alternate functions such as color_set can pass a color pair value directly. However, ncurses ABI 4 and 5 simply OR this value within the alternate functions. You must use ncurses ABI 6 to support more than 256 color pairs.

PORTABILITY

These functions are supported in the XSI Curses standard, Issue 4. The standard defined the dedicated type for highlights, attr_t, which is not defined in SVr4 curses. The functions taking attr_t arguments are not supported under SVr4.

The XSI Curses standard states that whether the traditional functions attron/attroff/attrset can manipulate attributes other than A_BLINK, A_BOLD, A_DIM, A_REVERSE, A_STANDOUT, or A_UNDERLINE is "unspecified". Under this implementation as well as SVr4 curses, these functions correctly manipulate all other highlights (specifically, A_ALTCHARSET, A_PROTECT, and A_INVIS).

This implementation provides the A_ITALIC attribute for terminals which have the enter_italics_mode (sitm) and exit_italics_mode (ritm) capabilities. Italics are not mentioned in X/Open Curses. Unlike the other video attributes, I_ITALIC is unrelated to the set_attributes capabilities. This implementation makes the assumption that exit_attribute_mode may also reset italics.

XSI Curses added the new entry points, attr_get, attr_on, attr_off, attr_set, wattr_on, wattr_off, wattr_get, wattr_set. These are intended to work with a new series of highlight macros prefixed with WA_. The older macros have direct counterparts in the newer set of names:

Name	Description

WA_STANDOUT	Best highlighting mode of the terminal.
WA_UNDERLINE	Underlining
WA_REVERSE	Reverse video
WA_BLINK	Blinking
WA_DIM	Half bright
WA_BOLD	Extra bright or bold
WA_ALTCHARSET	Alternate character set

Very old versions of this library did not force an update of the screen when changing the attributes. Use touchwin to force the screen to match the updated attributes.

The XSI curses standard specifies that each pair of corresponding A_ and WA_-using functions operates on the same current-highlight information.

The XSI standard extended conformance level adds new highlights A_HORIZONTAL, A_LEFT, A_LOW, A_RIGHT, A_TOP, A_VERTICAL (and corresponding WA_ macros for each). As of August 2013, no known terminal provides these highlights (i.e., via the sgr1 capability).

RETURN VALUE

All routines return the integer OK on success, or ERR on failure.

X/Open does not define any error conditions.

This implementation returns an error if the window pointer is null. The wcolor_set function returns an error if the color pair parameter is outside the range 0..COLOR_PAIRS-1. This implementation also provides getattrs for compatibility with older versions of curses.

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.