Provided by: ncurses-doc_6.1-1ubuntu1_all bug

NAME

       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 routines

SYNOPSIS

       #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);

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
       bkgd(3NCURSES) 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
       (259-255).

       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 color(3NCURSES)).

   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.

VIDEO 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
       addch(3NCURSES)).

              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.

NOTES

       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.

HISTORY

       X/Open  Curses  is largely based on SVr4 curses, adding support for “wide-characters” (not
       specific to Unicode).  Some of the X/Open differences from SVr4  curses  address  the  way
       video  attributes  can  be  applied  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 attributes, 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:

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

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

       ·   start_color and related color-functions were introduced by System V.3.2,

       ·   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 alternate 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

       Notes:

          Regarding HP-UX,

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

          ·   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),

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

          ·   Unlike  other  systems  which  evolved  from  AT&T  code,  OSF/1  provided  a   new
              implementation for X/Open curses.

          Regarding Solaris,

          ·   The initial release of Solaris was in 1992.

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

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

          Regarding U/Win,

          ·   Development of the curses library began in 1991, stopped in 2000.

          ·   Color support was added in 1998.

          ·   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:

       ·   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.

       ·   U/Win is rarely used now.

EXTENSIONS

       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, A_ITALIC is unrelated to
       the  set_attributes  capabilities.   This  implementation  makes   the   assumption   that
       exit_attribute_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 reserved for future use, saying that it should
       be  NULL.  This implementation uses that parameter in ABI 6 for the functions which have a
       color-pair parameter to support extended color pairs:

       ·   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.

       ·   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 standard 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.

PORTABILITY

       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 correctly 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, wattr_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.:

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

       ·   However, in some implementations, those symbols have unrelated values.

           For example, the Solaris xpg4 (X/Open) curses declares attr_t to be an unsigned  short
           integer  (16-bits),  while chtype is a unsigned integer (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_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.

       ·   returns an error if the color pair parameter  for  wcolor_set  is  outside  the  range
           0..COLOR_PAIRS-1.

       ·   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.

SEE ALSO

       ncurses(3NCURSES), addch(3NCURSES), addstr(3NCURSES), bkgd(3NCURSES), printw(3NCURSES),
       curses_variables(3NCURSES)

                                                                                   attr(3NCURSES)