1curs_attr(3X)                                                    curs_attr(3X)
2
3
4

NAME

6       attr_get, wattr_get, attr_set, wattr_set, attr_off, wattr_off, attr_on,
7       wattr_on, attroff, wattroff, attron, wattron, attrset, wattrset, chgat,
8       wchgat, mvchgat, mvwchgat, color_set, wcolor_set, standend, wstandend,
9       standout, wstandout - curses character and window attribute control
10       routines
11

SYNOPSIS

13       #include <curses.h>
14
15       int attr_get(attr_t *attrs, short *pair, void *opts);
16       int wattr_get(WINDOW *win, attr_t *attrs, short *pair, void *opts);
17       int attr_set(attr_t attrs, short pair, void *opts);
18       int wattr_set(WINDOW *win, attr_t attrs, short pair, void *opts);
19
20       int attr_off(attr_t attrs, void *opts);
21       int wattr_off(WINDOW *win, attr_t attrs, void *opts);
22       int attr_on(attr_t attrs, void *opts);
23       int wattr_on(WINDOW *win, attr_t attrs, void *opts);
24
25       int attroff(int attrs);
26       int wattroff(WINDOW *win, int attrs);
27       int attron(int attrs);
28       int wattron(WINDOW *win, int attrs);
29       int attrset(int attrs);
30       int wattrset(WINDOW *win, int attrs);
31
32       int chgat(int n, attr_t attr, short pair, const void *opts);
33       int wchgat(WINDOW *win,
34             int n, attr_t attr, short pair, const void *opts);
35       int mvchgat(int y, int x,
36             int n, attr_t attr, short pair, const void *opts);
37       int mvwchgat(WINDOW *win, int y, int x,
38             int n, attr_t attr, short pair, const void *opts);
39
40       int color_set(short pair, void* opts);
41       int wcolor_set(WINDOW *win, short pair, void* opts);
42
43       int standend(void);
44       int wstandend(WINDOW *win);
45       int standout(void);
46       int wstandout(WINDOW *win);
47

DESCRIPTION

49       These  routines  manipulate the current attributes of the named window,
50       which then apply to all characters that are  written  into  the  window
51       with  waddch,  waddstr  and  wprintw.  Attributes are a property of the
52       character, and move with the character through any  scrolling  and  in‐
53       sert/delete  line/character  operations.   To the extent possible, they
54       are displayed as appropriate modifications to the graphic rendition  of
55       characters put on the screen.
56
57       These  routines do not affect the attributes used when erasing portions
58       of the window.  See curs_bkgd(3X) for functions which  modify  the  at‐
59       tributes used for erasing and clearing.
60
61       Routines  which  do  not have a WINDOW* parameter apply to stdscr.  For
62       example, attr_set is the stdscr variant of wattr_set.
63
64   Window attributes
65       There are two sets of functions:
66
67       ·   functions for manipulating the window attributes  and  color:  wat‐
68           tr_set and wattr_get.
69
70       ·   functions  for manipulating only the window attributes (not color):
71           wattr_on and wattr_off.
72
73       The wattr_set function sets the current attributes of the given  window
74       to attrs, with color specified by pair.
75
76       Use wattr_get to retrieve attributes for the given window.
77
78       Use  attr_on  and  wattr_on  to turn on window attributes, i.e., values
79       OR'd together in attr, without affecting  other  attributes.   Use  at‐
80       tr_off  and  wattr_off to turn off window attributes, again values OR'd
81       together in attr, without affecting other attributes.
82
83   Legacy window attributes
84       The X/Open window attribute routines which set or get, turn on  or  off
85       are extensions of older routines which assume that color pairs are OR'd
86       into the attribute parameter.  These newer routines use similar  names,
87       because X/Open simply added an underscore (_) for the newer names.
88
89       The int datatype used in the legacy routines is treated as if it is the
90       same size as chtype (used by addch(3X)).  It holds the common video at‐
91       tributes  (such  as  bold,  reverse),  as well as a few bits for color.
92       Those bits correspond to the A_COLOR symbol.  The COLOR_PAIR macro pro‐
93       vides  a value which can be OR'd into the attribute parameter.  For ex‐
94       ample, as long as that value fits into the  A_COLOR  mask,  then  these
95       calls produce similar results:
96
97           attrset(A_BOLD | COLOR_PAIR(pair));
98           attr_set(A_BOLD, pair, NULL);
99
100       However, if the value does not fit, then the COLOR_PAIR macro uses only
101       the bits that fit.  For example, because in ncurses A_COLOR  has  eight
102       (8) bits, then COLOR_PAIR(259) is 4 (259-255).
103
104       The  PAIR_NUMBER  macro extracts a pair number from an int (or chtype).
105       For example, the input and output values in these statements  would  be
106       the same:
107
108           int value = A_BOLD | COLOR_PAIR(input);
109           int output = PAIR_NUMBER(value);
110
111       The  attrset routine is a legacy feature predating SVr4 curses but kept
112       in X/Open Curses for the same reason that SVr4 curses kept it: compati‐
113       bility.
114
115       The  remaining  attr*  functions operate exactly like the corresponding
116       attr_* functions, except that they take arguments of  type  int  rather
117       than attr_t.
118
119       There  is  no  corresponding attrget function as such in X/Open Curses,
120       although ncurses provides getattrs (see curs_legacy(3X)).
121
122   Change character rendition
123       The routine chgat changes the attributes of a given number  of  charac‐
124       ters  starting  at  the current cursor location of stdscr.  It does not
125       update the cursor and does not perform wrapping.  A character count  of
126       -1  or  greater  than  the  remaining  window width means to change at‐
127       tributes all the way to the end of the current line.  The wchgat  func‐
128       tion  generalizes this to any window; the mvwchgat function does a cur‐
129       sor move before acting.
130
131       In these functions, the color pair argument is a color-pair  index  (as
132       in the first argument of init_pair, see curs_color(3X)).
133
134   Change window color
135       The routine color_set sets the current color of the given window to the
136       foreground/background combination described by the color  pair  parame‐
137       ter.
138
139   Standout
140       The  routine  standout  is the same as attron(A_STANDOUT).  The routine
141       standend is the same as attrset(A_NORMAL) or attrset(0),  that  is,  it
142       turns off all attributes.
143
144       X/Open does not mark these "restricted", because
145
146       ·   they have well established legacy use, and
147
148       ·   there  is  no  ambiguity about the way the attributes might be com‐
149           bined with a color pair.
150

VIDEO ATTRIBUTES

152       The following video attributes, defined in <curses.h>, can be passed to
153       the  routines attron, attroff, and attrset, or OR'd with the characters
154       passed to addch (see curs_addch(3X)).
155
156              Name           Description
157              ─────────────────────────────────────────────────────────────────
158              A_NORMAL       Normal display (no highlight)
159              A_STANDOUT     Best highlighting mode of the terminal.
160              A_UNDERLINE    Underlining
161              A_REVERSE      Reverse video
162              A_BLINK        Blinking
163              A_DIM          Half bright
164              A_BOLD         Extra bright or bold
165              A_PROTECT      Protected mode
166              A_INVIS        Invisible or blank mode
167              A_ALTCHARSET   Alternate character set
168              A_ITALIC       Italics (non-X/Open extension)
169              A_CHARTEXT     Bit-mask to extract a character
170              A_COLOR        Bit-mask to extract a color (legacy routines)
171
172       These video attributes are supported by attr_on and  related  functions
173       (which also support the attributes recognized by attron, etc.):
174
175              Name            Description
176              ─────────────────────────────────────────
177              WA_HORIZONTAL   Horizontal highlight
178              WA_LEFT         Left highlight
179              WA_LOW          Low highlight
180              WA_RIGHT        Right highlight
181              WA_TOP          Top highlight
182              WA_VERTICAL     Vertical highlight
183
184       The  return  values  of many of these routines are not meaningful (they
185       are implemented as macro-expanded assignments and simply  return  their
186       argument).   The  SVr4 manual page claims (falsely) that these routines
187       always return 1.
188

NOTES

190       These functions may be macros:
191
192              attroff, wattroff, attron, wattron, attrset, wattrset,  standend
193              and standout.
194
195       Color  pair  values can only be OR'd with attributes if the pair number
196       is less than 256.  The alternate functions such as color_set can pass a
197       color pair value directly.  However, ncurses ABI 4 and 5 simply OR this
198       value within the alternate functions.  You must use ncurses  ABI  6  to
199       support more than 256 color pairs.
200

HISTORY

202       X/Open  Curses  is  largely  based  on  SVr4 curses, adding support for
203       “wide-characters” (not specific to Unicode).  Some of the  X/Open  dif‐
204       ferences  from  SVr4 curses address the way video attributes can be ap‐
205       plied to wide-characters.  But aside from that,  attrset  and  attr_set
206       are  similar.  SVr4 curses provided the basic features for manipulating
207       video attributes.  However, earlier versions of curses provided a  part
208       of these features.
209
210       As  seen  in  2.8BSD, curses assumed 7-bit characters, using the eighth
211       bit of a byte to represent the standout feature (often  implemented  as
212       bold  and/or reverse video).  The BSD curses library provided functions
213       standout and standend which were carried along into X/Open  Curses  due
214       to their pervasive use in legacy applications.
215
216       Some  terminals  in  the  1980s  could  support  a variety of video at‐
217       tributes, although the BSD curses library could do nothing with  those.
218       System V (1983) provided an improved curses library.  It defined the A_
219       symbols for use by applications to  manipulate  the  other  attributes.
220       There are few useful references for the chronology.
221
222       Goodheart's  book  UNIX  Curses Explained (1991) describes SVr3 (1987),
223       commenting on several functions:
224
225       ·   the attron, attroff, attrset functions (and most of  the  functions
226           found in SVr4 but not in BSD curses) were introduced by System V,
227
228       ·   the  alternate character set feature with A_ALTCHARSET was added in
229           SVr2 and improved in SVr3 (by adding acs_map[]),
230
231       ·   start_color and related color-functions were introduced  by  System
232           V.3.2,
233
234       ·   pads, soft-keys were added in SVr3, and
235
236       Goodheart did not mention the background character or the cchar_t type.
237       Those are respectively SVr4 and X/Open features.  He did mention the A_
238       constants,  but did not indicate their values.  Those were not the same
239       in different systems, even for those marked as System V.
240
241       Different Unix systems used  different  sizes  for  the  bit-fields  in
242       chtype  for  characters and colors, and took into account the different
243       integer sizes (32-bit versus 64-bit).
244
245       This table showing the number of bits for A_COLOR  and  A_CHARTEXT  was
246       gleaned  from the curses header files for various operating systems and
247       architectures.  The inferred architecture and notes reflect the  format
248       and  size  of the defined constants as well as clues such as the alter‐
249       nate character set implementation.  A 32-bit library can be used  on  a
250       64-bit system, but not necessarily the reverse.
251
252              Year   System        Arch    Color   Char   Notes
253              ────────────────────────────────────────────────────────────────
254              1992   Solaris 5.2   32      6       17     SVr4 curses
255              1992   HPUX 9        32      no      8      SVr2 curses
256              1992   AIX 3.2       32      no      23     SVr2 curses
257              1994   OSF/1 r3      32      no      23     SVr2 curses
258              1995   HP-UX 10.00   32      6       16     SVr3 “curses_colr”
259              1995   HP-UX 10.00   32      6       8      SVr4, X/Open curses
260              1995   Solaris 5.4   32/64   7       16     X/Open curses
261              1996   AIX 4.2       32      7       16     X/Open curses
262              1996   OSF/1 r4      32      6       16     X/Open curses
263              1997   HP-UX 11.00   32      6       8      X/Open curses
264
265              2000   U/Win         32/64   7/31    16     uses chtype
266
267       Notes:
268
269          Regarding HP-UX,
270
271          ·   HP-UX  10.20  (1996) added support for 64-bit PA-RISC processors
272              in 1996.
273
274          ·   HP-UX 10.30 (1997) marked “curses_colr” obsolete.  That  version
275              of curses was dropped with HP-UX 11.30 in 2006.
276
277          Regarding OSF/1 (and Tru64),
278
279          ·   These  used 64-bit hardware.  Like ncurses, the OSF/1 curses in‐
280              terface is not customized for 32-bit and 64-bit versions.
281
282          ·   Unlike other systems which evolved from AT&T code, OSF/1 provid‐
283              ed a new implementation for X/Open curses.
284
285          Regarding Solaris,
286
287          ·   The initial release of Solaris was in 1992.
288
289          ·   The xpg4 (X/Open) curses was developed by MKS from 1990 to 1995.
290              Sun's copyright began in 1996.
291
292          ·   Sun updated the X/Open curses interface after 64-bit support was
293              introduced  in  1997,  but did not modify the SVr4 curses inter‐
294              face.
295
296          Regarding U/Win,
297
298          ·   Development of the curses library  began  in  1991,  stopped  in
299              2000.
300
301          ·   Color support was added in 1998.
302
303          ·   The library uses only chtype (no cchar_t).
304
305       Once  X/Open  curses  was adopted in the mid-1990s, the constraint of a
306       32-bit interface with many colors and wide-characters for chtype became
307       a  moot  point.   The cchar_t structure (whose size and members are not
308       specified in X/Open Curses) could be extended as needed.
309
310       Other interfaces are rarely used now:
311
312       ·   BSD curses was improved slightly in 1993/1994 using Keith  Bostic's
313           modification  to  make  the  library 8-bit clean for nvi.  He moved
314           standout attribute to a structure member.
315
316           The resulting 4.4BSD curses was replaced by ncurses over  the  next
317           ten years.
318
319       ·   U/Win is rarely used now.
320

EXTENSIONS

322       This implementation provides the A_ITALIC attribute for terminals which
323       have the enter_italics_mode (sitm) and exit_italics_mode  (ritm)  capa‐
324       bilities.  Italics are not mentioned in X/Open Curses.  Unlike the oth‐
325       er video attributes, A_ITALIC is unrelated to the set_attributes  capa‐
326       bilities.   This  implementation  makes  the  assumption  that exit_at‐
327       tribute_mode may also reset italics.
328
329       Each of the functions added by XSI Curses has a parameter  opts,  which
330       X/Open  Curses  still  (after  more than twenty years) documents as re‐
331       served for future use, saying that it should be NULL.  This implementa‐
332       tion uses that parameter in ABI 6 for the functions which have a color-
333       pair parameter to support extended color pairs:
334
335       ·   For functions which modify the color, e.g., wattr_set, if  opts  is
336           set  it  is  treated as a pointer to int, and used to set the color
337           pair instead of the short pair parameter.
338
339       ·   For functions which retrieve the color, e.g., wattr_get, if opts is
340           set  it  is  treated  as a pointer to int, and used to retrieve the
341           color pair as an int value, in addition retrieving it via the stan‐
342           dard pointer to short parameter.
343
344       The  remaining  functions which have opts, but do not manipulate color,
345       e.g., wattr_on and wattr_off are not used by this implementation except
346       to check that they are NULL.
347

PORTABILITY

349       These functions are supported in the XSI Curses standard, Issue 4.  The
350       standard defined the dedicated type for highlights, attr_t,  which  was
351       not defined in SVr4 curses.  The functions taking attr_t arguments were
352       not supported under SVr4.
353
354       Very old versions of this library did not force an update of the screen
355       when  changing  the  attributes.   Use  touchwin to force the screen to
356       match the updated attributes.
357
358       The XSI Curses standard states that whether the  traditional  functions
359       attron/attroff/attrset  can  manipulate  attributes other than A_BLINK,
360       A_BOLD, A_DIM, A_REVERSE, A_STANDOUT, or A_UNDERLINE is  "unspecified".
361       Under  this implementation as well as SVr4 curses, these functions cor‐
362       rectly manipulate all  other  highlights  (specifically,  A_ALTCHARSET,
363       A_PROTECT, and A_INVIS).
364
365       XSI Curses added these entry points:
366
367              attr_get, attr_on, attr_off, attr_set, wattr_on, wattr_off, wat‐
368              tr_get, wattr_set
369
370       The new functions are intended to work with a new series  of  highlight
371       macros prefixed with WA_.  The older macros have direct counterparts in
372       the newer set of names:
373
374              Name            Description
375              ────────────────────────────────────────────────────────────
376              WA_NORMAL       Normal display (no highlight)
377              WA_STANDOUT     Best highlighting mode of the terminal.
378              WA_UNDERLINE    Underlining
379              WA_REVERSE      Reverse video
380              WA_BLINK        Blinking
381              WA_DIM          Half bright
382              WA_BOLD         Extra bright or bold
383              WA_ALTCHARSET   Alternate character set
384
385       XSI curses does not assign values to these symbols, nor does  it  state
386       whether or not they are related to the similarly-named A_NORMAL, etc.:
387
388       ·   The  XSI  curses standard specifies that each pair of corresponding
389           A_ and WA_-using functions operates on the  same  current-highlight
390           information.
391
392       ·   However, in some implementations, those symbols have unrelated val‐
393           ues.
394
395           For example, the Solaris xpg4 (X/Open) curses declares attr_t to be
396           an unsigned short integer (16-bits), while chtype is a unsigned in‐
397           teger (32-bits).  The WA_ symbols in this case are  different  from
398           the  A_  symbols because they are used for a smaller datatype which
399           does not represent A_CHARTEXT or A_COLOR.
400
401           In this implementation (as in many others), the values happen to be
402           the  same  because it simplifies copying information between chtype
403           and cchar_t variables.
404
405       The XSI standard extended conformance level adds new highlights A_HORI‐
406       ZONTAL,  A_LEFT,  A_LOW,  A_RIGHT, A_TOP, A_VERTICAL (and corresponding
407       WA_ macros for each).  As of August 2013, no  known  terminal  provides
408       these highlights (i.e., via the sgr1 capability).
409

RETURN VALUE

411       All routines return the integer OK on success, or ERR on failure.
412
413       X/Open does not define any error conditions.
414
415       This implementation
416
417       ·   returns an error if the window pointer is null.
418
419       ·   returns an error if the color pair parameter for wcolor_set is out‐
420           side the range 0..COLOR_PAIRS-1.
421
422       ·   does not return an error if either of the parameters  of  wattr_get
423           used for retrieving attribute or color-pair values is NULL.
424
425       Functions  with  a  "mv"  prefix  first perform a cursor movement using
426       wmove, and return an error if the position is outside the window, or if
427       the window pointer is null.
428

SEE ALSO

430       curses(3X), curs_addch(3X), curs_addstr(3X), curs_bkgd(3X),
431       curs_printw(3X), curs_variables(3X)
432
433
434
435                                                                 curs_attr(3X)
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