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curs_attr(3X)							 curs_attr(3X)

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

       #include	<curses.h>

       int attr_get(attr_t *attrs, short *pair,	void *opts);
       int wattr_get(WINDOW *win, attr_t *attrs, short *pair, 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 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 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 chgat(int n,	attr_t attr, short pair, const void *opts);
       int wchgat(WINDOW *win,
	     int n, attr_t attr, short pair, const void	*opts);
       int mvchgat(int y, int x,
	     int n, attr_t attr, short pair, const void	*opts);
       int mvwchgat(WINDOW *win, int y,	int x,
	     int n, attr_t attr, short pair, const void	*opts);

       int color_set(short pair, void* opts);
       int wcolor_set(WINDOW *win, short pair, void* opts);

       int standend(void);
       int wstandend(WINDOW *win);
       int standout(void);
       int wstandout(WINDOW *win);

       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  in-
       sert/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  at-
       tributes	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:

       o   functions for manipulating the window attributes  and  color:  wat-
	   tr_set and wattr_get.

       o   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  at-
       tr_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 at-
       tributes	 (such	as  bold,  reverse),  as well as a few bits for	color.
       Those bits correspond to	the A_COLOR symbol.  The COLOR_PAIR macro pro-
       vides  a	value which can	be OR'd	into the attribute parameter.  For ex-
       ample, 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

       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: compati-

       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 charac-
       ters 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  at-
       tributes	 all the way to	the end	of the current line.  The wchgat func-
       tion generalizes	this to	any window; the	mvwchgat function does a  cur-
       sor 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 parame-

       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

       o   they	have well established legacy use, and

       o   there is no ambiguity about the way the attributes  might  be  com-
	   bined with a	color pair.

       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_NORMAL	     Normal display (no	highlight)
	      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
	      A_COLOR	     Bit-mask to extract a color (legacy routines)

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

	      Name	      Description
	      WA_HORIZONTAL   Horizontal highlight
	      WA_LEFT	      Left highlight
	      WA_LOW	      Low highlight
	      WA_RIGHT	      Right highlight
	      WA_TOP	      Top highlight
	      WA_VERTICAL     Vertical highlight

       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.

       These functions may be macros:

	      attroff,	wattroff, attron, wattron, attrset, wattrset, standend
	      and standout.

       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.

       X/Open Curses is	largely	based  on  SVr4	 curses,  adding  support  for
       "wide-characters"  (not	specific to Unicode).  Some of the X/Open dif-
       ferences	from SVr4 curses address the way video attributes can  be  ap-
       plied  to  wide-characters.   But aside from that, attrset and attr_set
       are similar.  SVr4 curses provided the basic features for  manipulating
       video  attributes.  However, earlier versions of	curses provided	a part
       of these	features.

       As seen in 2.8BSD, curses assumed 7-bit characters,  using  the	eighth
       bit  of	a byte to represent the	standout feature (often	implemented as
       bold and/or reverse video).  The	BSD curses library provided  functions
       standout	 and  standend which were carried along	into X/Open Curses due
       to their	pervasive use in legacy	applications.

       Some terminals in the 1980s  could  support  a  variety	of  video  at-
       tributes,  although the BSD curses library could	do nothing with	those.
       System V	(1983) provided	an improved curses library.  It	defined	the A_
       symbols	for  use  by  applications to manipulate the other attributes.
       There are few useful references for the chronology.

       Goodheart's book	UNIX Curses Explained (1991)  describes	 SVr3  (1987),
       commenting on several functions:

       o   the	attron,	 attroff, attrset functions (and most of the functions
	   found in SVr4 but not in BSD	curses)	were introduced	by System V,

       o   the alternate character set feature with A_ALTCHARSET was added  in
	   SVr2	and improved in	SVr3 (by adding	acs_map[]),

       o   start_color	and  related color-functions were introduced by	System

       o   pads, soft-keys were	added in SVr3, and

       Goodheart did not mention the background	character or the cchar_t type.
       Those are respectively SVr4 and X/Open features.	 He did	mention	the A_
       constants, but did not indicate their values.  Those were not the  same
       in different systems, even for those marked as System V.

       Different  Unix	systems	 used  different  sizes	 for the bit-fields in
       chtype for characters and colors, and took into account	the  different
       integer sizes (32-bit versus 64-bit).

       This  table  showing  the number	of bits	for A_COLOR and	A_CHARTEXT was
       gleaned from the	curses header files for	various	operating systems  and
       architectures.	The inferred architecture and notes reflect the	format
       and size	of the defined constants as well as clues such as  the	alter-
       nate  character	set implementation.  A 32-bit library can be used on a
       64-bit system, but not necessarily the reverse.

	      Year   System	   Arch	   Color   Char	  Notes
	      1992   Solaris 5.2   32	   6	   17	  SVr4 curses
	      1992   HPUX 9	   32	   no	   8	  SVr2 curses
	      1992   AIX 3.2	   32	   no	   23	  SVr2 curses
	      1994   OSF/1 r3	   32	   no	   23	  SVr2 curses
	      1995   HP-UX 10.00   32	   6	   16	  SVr3 "curses_colr"
	      1995   HP-UX 10.00   32	   6	   8	  SVr4,	X/Open curses
	      1995   Solaris 5.4   32/64   7	   16	  X/Open curses
	      1996   AIX 4.2	   32	   7	   16	  X/Open curses
	      1996   OSF/1 r4	   32	   6	   16	  X/Open curses

	      1997   HP-UX 11.00   32	   6	   8	  X/Open curses
	      2000   U/Win	   32/64   7/31	   16	  uses chtype


	  Regarding HP-UX,

	  o   HP-UX 10.20 (1996) added support for 64-bit  PA-RISC  processors
	      in 1996.

	  o   HP-UX  10.30 (1997) marked "curses_colr" obsolete.  That version
	      of curses	was dropped with HP-UX 11.30 in	2006.

	  Regarding OSF/1 (and Tru64),

	  o   These used 64-bit	hardware.  Like	ncurses, the OSF/1 curses  in-
	      terface is not customized	for 32-bit and 64-bit versions.

	  o   Unlike other systems which evolved from AT&T code, OSF/1 provid-
	      ed a new implementation for X/Open curses.

	  Regarding Solaris,

	  o   The initial release of Solaris was in 1992.

	  o   The xpg4 (X/Open)	curses was developed by	MKS from 1990 to 1995.
	      Sun's copyright began in 1996.

	  o   Sun updated the X/Open curses interface after 64-bit support was
	      introduced in 1997, but did not modify the  SVr4	curses	inter-

	  Regarding U/Win,

	  o   Development  of  the  curses  library  began in 1991, stopped in

	  o   Color support was	added in 1998.

	  o   The library uses only chtype (no cchar_t).

       Once X/Open curses was adopted in the mid-1990s,	the  constraint	 of  a
       32-bit interface	with many colors and wide-characters for chtype	became
       a moot point.  The cchar_t structure (whose size	and  members  are  not
       specified in X/Open Curses) could be extended as	needed.

       Other interfaces	are rarely used	now:

       o   BSD	curses was improved slightly in	1993/1994 using	Keith Bostic's
	   modification	to make	the library 8-bit clean	 for  nvi.   He	 moved
	   standout attribute to a structure member.

	   The	resulting  4.4BSD curses was replaced by ncurses over the next
	   ten years.

       o   U/Win is rarely used	now.

       This implementation provides the	A_ITALIC attribute for terminals which
       have  the  enter_italics_mode (sitm) and	exit_italics_mode (ritm) capa-
       bilities.  Italics are not mentioned in X/Open Curses.  Unlike the oth-
       er  video attributes, A_ITALIC is unrelated to the set_attributes capa-
       bilities.  This implementation makes the	 assumption  that  exit_attri-
       bute_mode may also reset	italics.

       Each  of	 the functions added by	XSI Curses has a parameter opts, which
       X/Open Curses still (after more than twenty  years)  documents  as  re-
       served for future use, saying that it should be NULL.  This implementa-
       tion uses that parameter	in ABI 6 for the functions which have a	color-
       pair parameter to support extended color	pairs:

       o   For	functions  which modify	the color, e.g., wattr_set, if opts is
	   set it is treated as	a pointer to int, and used to  set  the	 color
	   pair	instead	of the short pair parameter.

       o   For functions which retrieve	the color, e.g., wattr_get, if opts is
	   set it is treated as	a pointer to int, and  used  to	 retrieve  the
	   color pair as an int	value, in addition retrieving it via the stan-
	   dard	pointer	to short parameter.

       The remaining functions which have opts,	but do not  manipulate	color,
       e.g., wattr_on and wattr_off are	not used by this implementation	except
       to check	that they are NULL.

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

       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 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  cor-
       rectly  manipulate  all	other  highlights (specifically, A_ALTCHARSET,
       A_PROTECT, and A_INVIS).

       XSI Curses added	these entry points:

	      attr_get,	attr_on, attr_off, attr_set, wattr_on, wattr_off, wat-
	      tr_get, wattr_set

       The  new	 functions 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_NORMAL	      Normal display (no highlight)
	      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

       XSI  curses  does not assign values to these symbols, nor does it state
       whether or not they are related to the similarly-named A_NORMAL,	etc.:

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

       o   However, in some implementations, those symbols have	unrelated val-

	   For example,	the Solaris xpg4 (X/Open) curses declares attr_t to be
	   an unsigned short integer (16-bits),	while chtype is	a unsigned in-
	   teger  (32-bits).   The WA_ symbols in this case are	different from
	   the A_ symbols because they are used	for a smaller  datatype	 which
	   does	not represent A_CHARTEXT or A_COLOR.

	   In this implementation (as in many others), the values happen to be
	   the same because it simplifies copying information  between	chtype
	   and cchar_t variables.

       The XSI standard	extended conformance level adds	new highlights A_HORI-
       ZONTAL, 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).

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

       X/Open does not define any error	conditions.

       This implementation

       o   returns an error if the window pointer is null.

       o   returns an error if the color pair parameter	for wcolor_set is out-
	   side	the range 0..COLOR_PAIRS-1.

       o   does	 not  return an	error if either	of the parameters of wattr_get
	   used	for retrieving attribute or color-pair values is NULL.

       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.

       curses(3X), curs_addch(3X), curs_addstr(3X), curs_bkgd(3X),
       curs_printw(3X),	curs_variables(3X)



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