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31 * @Id: curs_attr.3x,v 1.99 2024/03/16 15:38:33 tom Exp @
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43 <H1 class="no-header">curs_attr 3x 2024-03-16 ncurses 6.4 Library calls</H1>
45 <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>attr_get</STRONG>, <STRONG>wattr_get</STRONG>, <STRONG>attr_set</STRONG>, <STRONG>wattr_set</STRONG>, <STRONG>attr_off</STRONG>, <STRONG>wattr_off</STRONG>, <STRONG>attr_on</STRONG>,
52 <STRONG>wattr_on</STRONG>, <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>chgat</STRONG>,
53 <STRONG>wchgat</STRONG>, <STRONG>mvchgat</STRONG>, <STRONG>mvwchgat</STRONG>, <STRONG>color_set</STRONG>, <STRONG>wcolor_set</STRONG>, <STRONG>standend</STRONG>, <STRONG>wstandend</STRONG>,
54 <STRONG>standout</STRONG>, <STRONG>wstandout</STRONG> - manipulate attributes of character cells in
55 <EM>curses</EM> windows
58 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
59 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
61 <STRONG>int</STRONG> <STRONG>attr_get(attr_t</STRONG> <STRONG>*</STRONG><EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
62 <STRONG>int</STRONG> <STRONG>wattr_get(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <STRONG>*</STRONG><EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
63 <STRONG>int</STRONG> <STRONG>attr_set(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
64 <STRONG>int</STRONG> <STRONG>wattr_set(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
66 <STRONG>int</STRONG> <STRONG>attr_off(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
67 <STRONG>int</STRONG> <STRONG>wattr_off(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
68 <STRONG>int</STRONG> <STRONG>attr_on(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
69 <STRONG>int</STRONG> <STRONG>wattr_on(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
71 <STRONG>int</STRONG> <STRONG>attroff(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
72 <STRONG>int</STRONG> <STRONG>wattroff(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
73 <STRONG>int</STRONG> <STRONG>attron(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
74 <STRONG>int</STRONG> <STRONG>wattron(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
75 <STRONG>int</STRONG> <STRONG>attrset(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
76 <STRONG>int</STRONG> <STRONG>wattrset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
78 <STRONG>int</STRONG> <STRONG>chgat(int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
79 <STRONG>int</STRONG> <STRONG>wchgat(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG>
80 <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
81 <STRONG>int</STRONG> <STRONG>mvchgat(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG>
82 <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
83 <STRONG>int</STRONG> <STRONG>mvwchgat(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG>
84 <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
86 <STRONG>int</STRONG> <STRONG>color_set(short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
87 <STRONG>int</STRONG> <STRONG>wcolor_set(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
89 <STRONG>int</STRONG> <STRONG>standend(void);</STRONG>
90 <STRONG>int</STRONG> <STRONG>wstandend(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
91 <STRONG>int</STRONG> <STRONG>standout(void);</STRONG>
92 <STRONG>int</STRONG> <STRONG>wstandout(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
95 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
96 These routines manipulate the current attributes of the named window,
97 which then apply to all characters that are written into the window
98 with <STRONG>waddch</STRONG>, <STRONG>waddstr</STRONG> and <STRONG>wprintw</STRONG>. Attributes are a property of the
99 character, and move with the character through any scrolling and
100 insert/delete line/character operations. To the extent possible, they
101 are displayed as appropriate modifications to the graphic rendition of
102 characters put on the screen.
104 These routines do not affect the attributes used when erasing portions
105 of the window. See <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG> for functions which modify the
106 attributes used for erasing and clearing.
109 </PRE><H3><a name="h3-Window-Attributes">Window Attributes</a></H3><PRE>
110 There are two sets of functions:
112 <STRONG>o</STRONG> functions for manipulating the window attributes and color:
113 <STRONG>wattr_set</STRONG> and <STRONG>wattr_get</STRONG>.
115 <STRONG>o</STRONG> functions for manipulating only the window attributes (not color):
116 <STRONG>wattr_on</STRONG> and <STRONG>wattr_off</STRONG>.
118 The <STRONG>wattr_set</STRONG> function sets the current attributes of the given window
119 to <EM>attrs</EM>, with color specified by <EM>pair</EM>.
121 Use <STRONG>wattr_get</STRONG> to retrieve attributes for the given window.
123 Use <STRONG>attr_on</STRONG> and <STRONG>wattr_on</STRONG> to turn on window attributes, i.e., values
124 OR'd together in <EM>attr</EM>, without affecting other attributes. Use
125 <STRONG>attr_off</STRONG> and <STRONG>wattr_off</STRONG> to turn off window attributes, again values OR'd
126 together in <EM>attr</EM>, without affecting other attributes.
129 </PRE><H3><a name="h3-Legacy-Window-Attributes">Legacy Window Attributes</a></H3><PRE>
130 The X/Open window attribute routines which <EM>set</EM> or <EM>get</EM>, turn <EM>on</EM> or <EM>off</EM>
131 are extensions of older routines which assume that color pairs are OR'd
132 into the attribute parameter. These newer routines use similar names,
133 because X/Open simply added an underscore (<STRONG>_</STRONG>) for the newer names.
135 The <STRONG>int</STRONG> datatype used in the legacy routines is treated as if it is the
136 same size as <STRONG>chtype</STRONG> (used by <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>). It holds the common video
137 attributes (such as bold, reverse), as well as a few bits for color.
138 Those bits correspond to the <STRONG>A_COLOR</STRONG> symbol. The <STRONG>COLOR_PAIR</STRONG> macro
139 provides a value which can be OR'd into the attribute parameter. For
140 example, as long as that value fits into the <STRONG>A_COLOR</STRONG> mask, then these
141 calls produce similar results:
143 attrset(A_BOLD | COLOR_PAIR(<EM>pair</EM>));
144 attr_set(A_BOLD, <EM>pair</EM>, NULL);
146 However, if the value does not fit, then the <STRONG>COLOR_PAIR</STRONG> macro uses only
147 the bits that fit. For example, because in <EM>ncurses</EM> <STRONG>A_COLOR</STRONG> has eight
148 (8) bits, then <STRONG>COLOR_PAIR(</STRONG><EM>259</EM><STRONG>)</STRONG> is 4 (i.e., 259 is 4 more than the limit
151 The <STRONG>PAIR_NUMBER</STRONG> macro extracts a pair number from an <STRONG>int</STRONG> (or <STRONG>chtype</STRONG>).
152 For example, the <EM>input</EM> and <EM>output</EM> values in these statements would be
155 int value = A_BOLD | COLOR_PAIR(<EM>input</EM>);
156 int <EM>output</EM> = PAIR_NUMBER(value);
158 The <STRONG>attrset</STRONG> routine is a legacy feature predating SVr4 curses but kept
159 in X/Open Curses for the same reason that SVr4 curses kept it:
162 The remaining <STRONG>attr</STRONG>* functions operate exactly like the corresponding
163 <STRONG>attr_</STRONG>* functions, except that they take arguments of type <STRONG>int</STRONG> rather
164 than <STRONG>attr_t</STRONG>.
166 There is no corresponding <STRONG>attrget</STRONG> function as such in X/Open Curses,
167 although <EM>ncurses</EM> provides <STRONG>getattrs</STRONG> (see <STRONG><A HREF="curs_legacy.3x.html">curs_legacy(3x)</A></STRONG>).
170 </PRE><H3><a name="h3-Change-Character-Rendition">Change Character Rendition</a></H3><PRE>
171 The routine <STRONG>chgat</STRONG> changes the attributes of a given number of
172 characters starting at the current cursor location of <STRONG>stdscr</STRONG>. It does
173 not update the cursor and does not perform wrapping. A character count
174 of -1 or greater than the remaining window width means to change
175 attributes all the way to the end of the current line. The <STRONG>wchgat</STRONG>
176 function generalizes this to any window; the <STRONG>mvwchgat</STRONG> function does a
177 cursor move before acting.
179 In these functions, the color <EM>pair</EM> argument is a color pair index (as
180 in the first argument of <STRONG>init_pair</STRONG>, see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>).
183 </PRE><H3><a name="h3-Change-Window-Color">Change Window Color</a></H3><PRE>
184 The routine <STRONG>color_set</STRONG> sets the current color of the given window to the
185 foreground/background combination described by the color <EM>pair</EM>
189 </PRE><H3><a name="h3-Standout">Standout</a></H3><PRE>
190 The routine <STRONG>standout</STRONG> is the same as <STRONG>attron(A_STANDOUT)</STRONG>. The routine
191 <STRONG>standend</STRONG> is the same as <STRONG>attrset(A_NORMAL)</STRONG> or <STRONG>attrset(0)</STRONG>, that is, it
192 turns off all attributes.
194 X/Open Curses does not mark these "restricted", because
196 <STRONG>o</STRONG> they have well established legacy use, and
198 <STRONG>o</STRONG> there is no ambiguity about the way the attributes might be
199 combined with a color pair.
202 </PRE><H3><a name="h3-Video-Attributes">Video Attributes</a></H3><PRE>
203 The following video attributes, defined in <STRONG><curses.h></STRONG>, can be passed to
204 the routines <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, and <STRONG>attrset</STRONG>, or OR'd with the characters
205 passed to <STRONG>addch</STRONG> (see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>).
207 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
208 -----------------------------------------------------------------
209 <STRONG>A_NORMAL</STRONG> Normal display (no highlight)
210 <STRONG>A_STANDOUT</STRONG> Best highlighting mode of the terminal
211 <STRONG>A_UNDERLINE</STRONG> Underlining
212 <STRONG>A_REVERSE</STRONG> Reverse video
213 <STRONG>A_BLINK</STRONG> Blinking
214 <STRONG>A_DIM</STRONG> Half bright
215 <STRONG>A_BOLD</STRONG> Extra bright or bold
216 <STRONG>A_PROTECT</STRONG> Protected mode
217 <STRONG>A_INVIS</STRONG> Invisible or blank mode
218 <STRONG>A_ALTCHARSET</STRONG> Alternate character set
219 <STRONG>A_ITALIC</STRONG> Italics (non-X/Open extension)
220 <STRONG>A_CHARTEXT</STRONG> Bit-mask to extract a character
221 <STRONG>A_COLOR</STRONG> Bit-mask to extract a color (legacy routines)
223 These video attributes are supported by <STRONG>attr_on</STRONG> and related functions
224 (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):
226 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
227 -----------------------------------------------------------------
228 <STRONG>WA_HORIZONTAL</STRONG> Horizontal highlight
229 <STRONG>WA_LEFT</STRONG> Left highlight
230 <STRONG>WA_LOW</STRONG> Low highlight
231 <STRONG>WA_RIGHT</STRONG> Right highlight
232 <STRONG>WA_TOP</STRONG> Top highlight
233 <STRONG>WA_VERTICAL</STRONG> Vertical highlight
235 The return values of many of these routines are not meaningful (they
236 are implemented as macro-expanded assignments and simply return their
237 argument). The SVr4 manual page claims (falsely) that these routines
238 always return <STRONG>1</STRONG>.
241 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
242 All routines return the integer <STRONG>OK</STRONG> on success, or <STRONG>ERR</STRONG> on failure.
244 X/Open Curses does not specify any error conditions.
248 <STRONG>o</STRONG> returns an error if the window pointer is null.
250 <STRONG>o</STRONG> returns an error if the color pair parameter for <STRONG>wcolor_set</STRONG> is
251 outside the range 0..COLOR_PAIRS-1.
253 <STRONG>o</STRONG> does not return an error if either of the parameters of <STRONG>wattr_get</STRONG>
254 used for retrieving attribute or color pair values is <STRONG>NULL</STRONG>.
256 Functions with a "mv" prefix first perform a cursor movement using
257 <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
258 the window pointer is null.
261 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
262 These functions may be macros:
264 <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>standend</STRONG>
265 and <STRONG>standout</STRONG>.
267 Color pair values can only be OR'd with attributes if the pair number
268 is less than 256. The alternate functions such as <STRONG>color_set</STRONG> can pass a
269 color pair value directly. However, <EM>ncurses</EM> ABI 4 and 5 simply OR this
270 value within the alternate functions. You must use <EM>ncurses</EM> ABI 6 to
271 support more than 256 color pairs.
274 </PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
275 This implementation provides the <STRONG>A_ITALIC</STRONG> attribute for terminals which
276 have the <STRONG>enter_italics_mode</STRONG> (<STRONG>sitm</STRONG>) and <STRONG>exit_italics_mode</STRONG> (<STRONG>ritm</STRONG>)
277 capabilities. Italics are not mentioned in X/Open Curses. Unlike the
278 other video attributes, <STRONG>A_ITALIC</STRONG> is unrelated to the <STRONG>set_attributes</STRONG>
279 capabilities. This implementation makes the assumption that
280 <STRONG>exit_attribute_mode</STRONG> may also reset italics.
282 Each of the functions added by XSI Curses has a parameter <EM>opts</EM>, which
283 X/Open Curses still (after more than twenty years) documents as
284 reserved for future use, saying that it should be <STRONG>NULL</STRONG>. This
285 implementation uses that parameter in ABI 6 for the functions which
286 have a color pair parameter to support <EM>extended</EM> <EM>color</EM> <EM>pairs</EM>:
288 <STRONG>o</STRONG> For functions which modify the color, e.g., <STRONG>wattr_set</STRONG> and <STRONG>wattr_on</STRONG>,
289 if <EM>opts</EM> is set it is treated as a pointer to <STRONG>int</STRONG>, and used to set
290 the color pair instead of the <STRONG>short</STRONG> <EM>pair</EM> parameter.
292 <STRONG>o</STRONG> For functions which retrieve the color, e.g., <STRONG>wattr_get</STRONG>, if <EM>opts</EM> is
293 set it is treated as a pointer to <STRONG>int</STRONG>, and used to retrieve the
294 color pair as an <STRONG>int</STRONG> value, in addition to retrieving it via the
295 standard pointer to <STRONG>short</STRONG> parameter.
297 <STRONG>o</STRONG> For functions which turn attributes off, e.g., <STRONG>wattr_off</STRONG>, the <EM>opts</EM>
298 parameter is ignored except except to check that it is <STRONG>NULL</STRONG>.
301 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
302 These functions are described in the XSI Curses standard, Issue 4. The
303 standard defined the dedicated type for highlights, <STRONG>attr_t</STRONG>, which was
304 not defined in SVr4 curses. The functions taking <STRONG>attr_t</STRONG> arguments were
305 not supported under SVr4.
307 Very old versions of this library did not force an update of the screen
308 when changing the attributes. Use <STRONG>touchwin</STRONG> to force the screen to
309 match the updated attributes.
311 The XSI Curses standard states that whether the traditional functions
312 <STRONG>attron</STRONG>/<STRONG>attroff</STRONG>/<STRONG>attrset</STRONG> can manipulate attributes other than <STRONG>A_BLINK</STRONG>,
313 <STRONG>A_BOLD</STRONG>, <STRONG>A_DIM</STRONG>, <STRONG>A_REVERSE</STRONG>, <STRONG>A_STANDOUT</STRONG>, or <STRONG>A_UNDERLINE</STRONG> is "unspecified".
314 Under this implementation as well as SVr4 curses, these functions
315 correctly manipulate all other highlights (specifically, <STRONG>A_ALTCHARSET</STRONG>,
316 <STRONG>A_PROTECT</STRONG>, and <STRONG>A_INVIS</STRONG>).
318 XSI Curses added these entry points:
320 <STRONG>attr_get</STRONG>, <STRONG>attr_on</STRONG>, <STRONG>attr_off</STRONG>, <STRONG>attr_set</STRONG>, <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>,
321 <STRONG>wattr_get</STRONG>, <STRONG>wattr_set</STRONG>
323 The new functions are intended to work with a new series of highlight
324 macros prefixed with <STRONG>WA_</STRONG>. The older macros have direct counterparts in
325 the newer set of names:
327 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
328 -----------------------------------------------------------------
329 <STRONG>WA_NORMAL</STRONG> Normal display (no highlight)
330 <STRONG>WA_STANDOUT</STRONG> Best highlighting mode of the terminal
331 <STRONG>WA_UNDERLINE</STRONG> Underlining
332 <STRONG>WA_REVERSE</STRONG> Reverse video
333 <STRONG>WA_BLINK</STRONG> Blinking
334 <STRONG>WA_DIM</STRONG> Half bright
335 <STRONG>WA_BOLD</STRONG> Extra bright or bold
337 <STRONG>WA_ALTCHARSET</STRONG> Alternate character set
339 XSI curses does not assign values to these symbols, nor does it state
340 whether or not they are related to the similarly-named A_NORMAL, etc.:
342 <STRONG>o</STRONG> The XSI curses standard specifies that each pair of corresponding
343 <STRONG>A_</STRONG> and <STRONG>WA_</STRONG>-using functions operates on the same current-highlight
346 <STRONG>o</STRONG> However, in some implementations, those symbols have unrelated
349 For example, the Solaris <EM>xpg4</EM> (X/Open) curses declares <STRONG>attr_t</STRONG> to be
350 an unsigned short integer (16-bits), while <STRONG>chtype</STRONG> is a unsigned
351 integer (32-bits). The <STRONG>WA_</STRONG> symbols in this case are different from
352 the <STRONG>A_</STRONG> symbols because they are used for a smaller datatype which
353 does not represent <STRONG>A_CHARTEXT</STRONG> or <STRONG>A_COLOR</STRONG>.
355 In this implementation (as in many others), the values happen to be
356 the same because it simplifies copying information between <STRONG>chtype</STRONG>
357 and <STRONG>cchar_t</STRONG> variables.
359 <STRONG>o</STRONG> Because <EM>ncurses</EM>'s <STRONG>attr_t</STRONG> can hold a color pair (in the <STRONG>A_COLOR</STRONG>
360 field), a call to <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>, or <STRONG>wattr_set</STRONG> may alter the
361 window's color. If the color pair information in the attribute
362 parameter is zero, no change is made to the window's color.
364 This is consistent with SVr4 curses; X/Open Curses does not specify
367 The XSI standard extended conformance level adds new highlights
368 <STRONG>A_HORIZONTAL</STRONG>, <STRONG>A_LEFT</STRONG>, <STRONG>A_LOW</STRONG>, <STRONG>A_RIGHT</STRONG>, <STRONG>A_TOP</STRONG>, <STRONG>A_VERTICAL</STRONG> (and
369 corresponding <STRONG>WA_</STRONG> macros for each). As of August 2013, no known
370 terminal provides these highlights (i.e., via the <STRONG>sgr1</STRONG> capability).
373 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
374 X/Open Curses is largely based on SVr4 curses, adding support for
375 "wide-characters" (not specific to Unicode). Some of the X/Open
376 differences from SVr4 curses address the way video attributes can be
377 applied to wide-characters. But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
378 are similar. SVr4 curses provided the basic features for manipulating
379 video attributes. However, earlier versions of curses provided a part
382 As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth
383 bit of a byte to represent the <EM>standout</EM> feature (often implemented as
384 bold and/or reverse video). The BSD curses library provided functions
385 <STRONG>standout</STRONG> and <STRONG>standend</STRONG> which were carried along into X/Open Curses due
386 to their pervasive use in legacy applications.
388 Some terminals in the 1980s could support a variety of video
389 attributes, although the BSD curses library could do nothing with
390 those. System V (1983) provided an improved curses library. It
391 defined the <STRONG>A_</STRONG> symbols for use by applications to manipulate the other
392 attributes. There are few useful references for the chronology.
394 Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991) describes SVr3 (1987),
395 commenting on several functions:
397 <STRONG>o</STRONG> the <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
398 found in SVr4 but not in BSD curses) were introduced by System V,
400 <STRONG>o</STRONG> the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added in
401 SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),
403 <STRONG>o</STRONG> <STRONG>start_color</STRONG> and related color-functions were introduced by System
406 <STRONG>o</STRONG> pads, soft-keys were added in SVr3, and
408 Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
409 Those are respectively SVr4 and X/Open features. He did mention the <STRONG>A_</STRONG>
410 constants, but did not indicate their values. Those were not the same
411 in different systems, even for those marked as System V.
413 Different Unix systems used different sizes for the bit-fields in
414 <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account the different
415 integer sizes (32-bit versus 64-bit).
417 This table showing the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
418 gleaned from the curses header files for various operating systems and
419 architectures. The inferred architecture and notes reflect the format
420 and size of the defined constants as well as clues such as the
421 alternate character set implementation. A 32-bit library can be used
422 on a 64-bit system, but not necessarily the reverse.
424 <STRONG>Bits</STRONG>
425 <STRONG>Year</STRONG> <STRONG>System</STRONG> <STRONG>Arch</STRONG> <STRONG>Color</STRONG> <STRONG>Char</STRONG> <STRONG>Notes</STRONG>
426 ------------------------------------------------------------------------
427 1992 Solaris 5.2 32 6 17 SVr4 <EM>curses</EM>
428 1992 HP-UX 9 32 no 8 SVr2 <EM>curses</EM>
429 1992 AIX 3.2 32 no 23 SVr2 <EM>curses</EM>
430 1994 OSF/1 r3 32 no 23 SVr2 <EM>curses</EM>
431 1995 HP-UX 10.00 32 6 16 SVr3 <EM>curses</EM><STRONG>_</STRONG><EM>colr</EM>
432 1995 HP-UX 10.00 32 6 8 SVr4, X/Open <EM>curses</EM>
433 1995 Solaris 5.4 32/64 7 16 X/Open <EM>curses</EM>
434 1996 AIX 4.2 32 7 16 X/Open <EM>curses</EM>
435 1996 OSF/1 r4 32 6 16 X/Open <EM>curses</EM>
436 1997 HP-UX 11.00 32 6 8 X/Open <EM>curses</EM>
437 2000 U/Win 32/64 7/31 16 uses <EM>chtype</EM>
443 <STRONG>o</STRONG> HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
446 <STRONG>o</STRONG> HP-UX 10.30 (1997) marked "curses_colr" obsolete. That version
447 of curses was dropped with HP-UX 11.30 in 2006.
449 Regarding OSF/1 (and Tru64),
451 <STRONG>o</STRONG> These used 64-bit hardware. Like <EM>ncurses</EM>, the OSF/1 curses
452 interface is not customized for 32-bit and 64-bit versions.
454 <STRONG>o</STRONG> Unlike other systems which evolved from AT&T code, OSF/1
455 provided a new implementation for X/Open curses.
459 <STRONG>o</STRONG> The initial release of Solaris was in 1992.
461 <STRONG>o</STRONG> The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
462 Sun's copyright began in 1996.
464 <STRONG>o</STRONG> Sun updated the X/Open curses interface after 64-bit support was
465 introduced in 1997, but did not modify the SVr4 curses
470 <STRONG>o</STRONG> Development of the curses library began in 1991, stopped in
473 <STRONG>o</STRONG> Color support was added in 1998.
475 <STRONG>o</STRONG> The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).
477 Once X/Open curses was adopted in the mid-1990s, the constraint of a
478 32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
479 a moot point. The <STRONG>cchar_t</STRONG> structure (whose size and members are not
480 specified in X/Open Curses) could be extended as needed.
482 Other interfaces are rarely used now:
484 <STRONG>o</STRONG> BSD curses was improved slightly in 1993/1994 using Keith Bostic's
485 modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>. He moved
486 <EM>standout</EM> attribute to a structure member.
488 The resulting 4.4BSD curses was replaced by <EM>ncurses</EM> over the next
491 <STRONG>o</STRONG> U/Win is rarely used now.
494 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
495 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>, <STRONG><A HREF="curs_addstr.3x.html">curs_addstr(3x)</A></STRONG>, <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>,
496 <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
500 ncurses 6.4 2024-03-16 <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
504 <li><a href="#h2-NAME">NAME</a></li>
505 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
506 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
508 <li><a href="#h3-Window-Attributes">Window Attributes</a></li>
509 <li><a href="#h3-Legacy-Window-Attributes">Legacy Window Attributes</a></li>
510 <li><a href="#h3-Change-Character-Rendition">Change Character Rendition</a></li>
511 <li><a href="#h3-Change-Window-Color">Change Window Color</a></li>
512 <li><a href="#h3-Standout">Standout</a></li>
513 <li><a href="#h3-Video-Attributes">Video Attributes</a></li>
516 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
517 <li><a href="#h2-NOTES">NOTES</a></li>
518 <li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
519 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
520 <li><a href="#h2-HISTORY">HISTORY</a></li>
521 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>