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58 <H1 class="no-header">curs_attr 3x 2023-11-25 ncurses 6.4 Library calls</H1>
60 <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>
65 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
66 <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>,
67 <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>,
68 <STRONG>wchgat</STRONG>, <STRONG>mvchgat</STRONG>, <STRONG>mvwchgat</STRONG>, <STRONG>color_set</STRONG>, <STRONG>wcolor_set</STRONG>, <STRONG>standend</STRONG>, <STRONG>wstandend</STRONG>,
69 <STRONG>standout</STRONG>, <STRONG>wstandout</STRONG> - manipulate attributes of character cells in
70 <EM>curses</EM> windows
73 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
74 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
76 <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>
77 <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>
78 <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>
79 <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>
81 <STRONG>int</STRONG> <STRONG>attr_off(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
82 <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>
83 <STRONG>int</STRONG> <STRONG>attr_on(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
84 <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>
86 <STRONG>int</STRONG> <STRONG>attroff(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
87 <STRONG>int</STRONG> <STRONG>wattroff(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
88 <STRONG>int</STRONG> <STRONG>attron(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
89 <STRONG>int</STRONG> <STRONG>wattron(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
90 <STRONG>int</STRONG> <STRONG>attrset(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
91 <STRONG>int</STRONG> <STRONG>wattrset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
93 <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>
94 <STRONG>int</STRONG> <STRONG>wchgat(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG>
95 <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>
96 <STRONG>int</STRONG> <STRONG>mvchgat(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG>
97 <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>
98 <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>
99 <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>
101 <STRONG>int</STRONG> <STRONG>color_set(short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
102 <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>
104 <STRONG>int</STRONG> <STRONG>standend(void);</STRONG>
105 <STRONG>int</STRONG> <STRONG>wstandend(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
106 <STRONG>int</STRONG> <STRONG>standout(void);</STRONG>
107 <STRONG>int</STRONG> <STRONG>wstandout(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
110 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
111 These routines manipulate the current attributes of the named window,
112 which then apply to all characters that are written into the window
113 with <STRONG>waddch</STRONG>, <STRONG>waddstr</STRONG> and <STRONG>wprintw</STRONG>. Attributes are a property of the
114 character, and move with the character through any scrolling and
115 insert/delete line/character operations. To the extent possible, they
116 are displayed as appropriate modifications to the graphic rendition of
117 characters put on the screen.
119 These routines do not affect the attributes used when erasing portions
120 of the window. See <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG> for functions which modify the
121 attributes used for erasing and clearing.
123 Routines which do not have a <STRONG>WINDOW*</STRONG> parameter apply to <STRONG>stdscr</STRONG>. For
124 example, <STRONG>attr_set</STRONG> is the <STRONG>stdscr</STRONG> variant of <STRONG>wattr_set</STRONG>.
127 </PRE><H3><a name="h3-Window-attributes">Window attributes</a></H3><PRE>
128 There are two sets of functions:
130 <STRONG>o</STRONG> functions for manipulating the window attributes and color:
131 <STRONG>wattr_set</STRONG> and <STRONG>wattr_get</STRONG>.
133 <STRONG>o</STRONG> functions for manipulating only the window attributes (not color):
134 <STRONG>wattr_on</STRONG> and <STRONG>wattr_off</STRONG>.
136 The <STRONG>wattr_set</STRONG> function sets the current attributes of the given window
137 to <EM>attrs</EM>, with color specified by <EM>pair</EM>.
139 Use <STRONG>wattr_get</STRONG> to retrieve attributes for the given window.
141 Use <STRONG>attr_on</STRONG> and <STRONG>wattr_on</STRONG> to turn on window attributes, i.e., values
142 OR'd together in <EM>attr</EM>, without affecting other attributes. Use
143 <STRONG>attr_off</STRONG> and <STRONG>wattr_off</STRONG> to turn off window attributes, again values OR'd
144 together in <EM>attr</EM>, without affecting other attributes.
147 </PRE><H3><a name="h3-Legacy-window-attributes">Legacy window attributes</a></H3><PRE>
148 The X/Open window attribute routines which <EM>set</EM> or <EM>get</EM>, turn <EM>on</EM> or <EM>off</EM>
149 are extensions of older routines which assume that color pairs are OR'd
150 into the attribute parameter. These newer routines use similar names,
151 because X/Open simply added an underscore (<STRONG>_</STRONG>) for the newer names.
153 The <STRONG>int</STRONG> datatype used in the legacy routines is treated as if it is the
154 same size as <STRONG>chtype</STRONG> (used by <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>). It holds the common video
155 attributes (such as bold, reverse), as well as a few bits for color.
156 Those bits correspond to the <STRONG>A_COLOR</STRONG> symbol. The <STRONG>COLOR_PAIR</STRONG> macro
157 provides a value which can be OR'd into the attribute parameter. For
158 example, as long as that value fits into the <STRONG>A_COLOR</STRONG> mask, then these
159 calls produce similar results:
161 attrset(A_BOLD | COLOR_PAIR(<EM>pair</EM>));
162 attr_set(A_BOLD, <EM>pair</EM>, NULL);
164 However, if the value does not fit, then the <STRONG>COLOR_PAIR</STRONG> macro uses only
165 the bits that fit. For example, because in ncurses <STRONG>A_COLOR</STRONG> has eight
166 (8) bits, then <STRONG>COLOR_PAIR(</STRONG><EM>259</EM><STRONG>)</STRONG> is 4 (i.e., 259 is 4 more than the limit
169 The <STRONG>PAIR_NUMBER</STRONG> macro extracts a pair number from an <STRONG>int</STRONG> (or <STRONG>chtype</STRONG>).
170 For example, the <EM>input</EM> and <EM>output</EM> values in these statements would be
173 int value = A_BOLD | COLOR_PAIR(<EM>input</EM>);
174 int <EM>output</EM> = PAIR_NUMBER(value);
176 The <STRONG>attrset</STRONG> routine is a legacy feature predating SVr4 curses but kept
177 in X/Open Curses for the same reason that SVr4 curses kept it:
180 The remaining <STRONG>attr</STRONG>* functions operate exactly like the corresponding
181 <STRONG>attr_</STRONG>* functions, except that they take arguments of type <STRONG>int</STRONG> rather
182 than <STRONG>attr_t</STRONG>.
184 There is no corresponding <STRONG>attrget</STRONG> function as such in X/Open Curses,
185 although ncurses provides <STRONG>getattrs</STRONG> (see <STRONG><A HREF="curs_legacy.3x.html">curs_legacy(3x)</A></STRONG>).
188 </PRE><H3><a name="h3-Change-character-rendition">Change character rendition</a></H3><PRE>
189 The routine <STRONG>chgat</STRONG> changes the attributes of a given number of
190 characters starting at the current cursor location of <STRONG>stdscr</STRONG>. It does
191 not update the cursor and does not perform wrapping. A character count
192 of -1 or greater than the remaining window width means to change
193 attributes all the way to the end of the current line. The <STRONG>wchgat</STRONG>
194 function generalizes this to any window; the <STRONG>mvwchgat</STRONG> function does a
195 cursor move before acting.
197 In these functions, the color <EM>pair</EM> argument is a color-pair index (as
198 in the first argument of <STRONG>init_pair</STRONG>, see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>).
201 </PRE><H3><a name="h3-Change-window-color">Change window color</a></H3><PRE>
202 The routine <STRONG>color_set</STRONG> sets the current color of the given window to the
203 foreground/background combination described by the color <EM>pair</EM>
207 </PRE><H3><a name="h3-Standout">Standout</a></H3><PRE>
208 The routine <STRONG>standout</STRONG> is the same as <STRONG>attron(A_STANDOUT)</STRONG>. The routine
209 <STRONG>standend</STRONG> is the same as <STRONG>attrset(A_NORMAL)</STRONG> or <STRONG>attrset(0)</STRONG>, that is, it
210 turns off all attributes.
212 X/Open does not mark these "restricted", because
214 <STRONG>o</STRONG> they have well established legacy use, and
216 <STRONG>o</STRONG> there is no ambiguity about the way the attributes might be
217 combined with a color pair.
220 </PRE><H3><a name="h3-Video-Attributes">Video Attributes</a></H3><PRE>
221 The following video attributes, defined in <STRONG><curses.h></STRONG>, can be passed to
222 the routines <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, and <STRONG>attrset</STRONG>, or OR'd with the characters
223 passed to <STRONG>addch</STRONG> (see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>).
225 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
226 -----------------------------------------------------------------
227 <STRONG>A_NORMAL</STRONG> Normal display (no highlight)
228 <STRONG>A_STANDOUT</STRONG> Best highlighting mode of the terminal.
229 <STRONG>A_UNDERLINE</STRONG> Underlining
230 <STRONG>A_REVERSE</STRONG> Reverse video
231 <STRONG>A_BLINK</STRONG> Blinking
232 <STRONG>A_DIM</STRONG> Half bright
233 <STRONG>A_BOLD</STRONG> Extra bright or bold
234 <STRONG>A_PROTECT</STRONG> Protected mode
235 <STRONG>A_INVIS</STRONG> Invisible or blank mode
236 <STRONG>A_ALTCHARSET</STRONG> Alternate character set
237 <STRONG>A_ITALIC</STRONG> Italics (non-X/Open extension)
238 <STRONG>A_CHARTEXT</STRONG> Bit-mask to extract a character
239 <STRONG>A_COLOR</STRONG> Bit-mask to extract a color (legacy routines)
241 These video attributes are supported by <STRONG>attr_on</STRONG> and related functions
242 (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):
244 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
245 -----------------------------------------
246 <STRONG>WA_HORIZONTAL</STRONG> Horizontal highlight
247 <STRONG>WA_LEFT</STRONG> Left highlight
248 <STRONG>WA_LOW</STRONG> Low highlight
249 <STRONG>WA_RIGHT</STRONG> Right highlight
250 <STRONG>WA_TOP</STRONG> Top highlight
251 <STRONG>WA_VERTICAL</STRONG> Vertical highlight
253 The return values of many of these routines are not meaningful (they
254 are implemented as macro-expanded assignments and simply return their
255 argument). The SVr4 manual page claims (falsely) that these routines
256 always return <STRONG>1</STRONG>.
259 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
260 All routines return the integer <STRONG>OK</STRONG> on success, or <STRONG>ERR</STRONG> on failure.
262 X/Open does not define any error conditions.
266 <STRONG>o</STRONG> returns an error if the window pointer is null.
268 <STRONG>o</STRONG> returns an error if the color pair parameter for <STRONG>wcolor_set</STRONG> is
269 outside the range 0..COLOR_PAIRS-1.
271 <STRONG>o</STRONG> does not return an error if either of the parameters of <STRONG>wattr_get</STRONG>
272 used for retrieving attribute or color-pair values is <STRONG>NULL</STRONG>.
274 Functions with a "mv" prefix first perform a cursor movement using
275 <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
276 the window pointer is null.
279 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
280 These functions may be macros:
282 <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>standend</STRONG>
283 and <STRONG>standout</STRONG>.
285 Color pair values can only be OR'd with attributes if the pair number
286 is less than 256. The alternate functions such as <STRONG>color_set</STRONG> can pass a
287 color pair value directly. However, ncurses ABI 4 and 5 simply OR this
288 value within the alternate functions. You must use ncurses ABI 6 to
289 support more than 256 color pairs.
292 </PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
293 This implementation provides the <STRONG>A_ITALIC</STRONG> attribute for terminals which
294 have the <STRONG>enter_italics_mode</STRONG> (<STRONG>sitm</STRONG>) and <STRONG>exit_italics_mode</STRONG> (<STRONG>ritm</STRONG>)
295 capabilities. Italics are not mentioned in X/Open Curses. Unlike the
296 other video attributes, <STRONG>A_ITALIC</STRONG> is unrelated to the <STRONG>set_attributes</STRONG>
297 capabilities. This implementation makes the assumption that
298 <STRONG>exit_attribute_mode</STRONG> may also reset italics.
300 Each of the functions added by XSI Curses has a parameter <EM>opts</EM>, which
301 X/Open Curses still (after more than twenty years) documents as
302 reserved for future use, saying that it should be <STRONG>NULL</STRONG>. This
303 implementation uses that parameter in ABI 6 for the functions which
304 have a color-pair parameter to support <EM>extended</EM> <EM>color</EM> <EM>pairs</EM>:
306 <STRONG>o</STRONG> For functions which modify the color, e.g., <STRONG>wattr_set</STRONG> and <STRONG>wattr_on</STRONG>,
307 if <EM>opts</EM> is set it is treated as a pointer to <STRONG>int</STRONG>, and used to set
308 the color pair instead of the <STRONG>short</STRONG> <EM>pair</EM> parameter.
310 <STRONG>o</STRONG> For functions which retrieve the color, e.g., <STRONG>wattr_get</STRONG>, if <EM>opts</EM> is
311 set it is treated as a pointer to <STRONG>int</STRONG>, and used to retrieve the
312 color pair as an <STRONG>int</STRONG> value, in addition to retrieving it via the
313 standard pointer to <STRONG>short</STRONG> parameter.
315 <STRONG>o</STRONG> For functions which turn attributes off, e.g., <STRONG>wattr_off</STRONG>, the <EM>opts</EM>
316 parameter is ignored except except to check that it is <STRONG>NULL</STRONG>.
319 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
320 These functions are described in the XSI Curses standard, Issue 4. The
321 standard defined the dedicated type for highlights, <STRONG>attr_t</STRONG>, which was
322 not defined in SVr4 curses. The functions taking <STRONG>attr_t</STRONG> arguments were
323 not supported under SVr4.
325 Very old versions of this library did not force an update of the screen
326 when changing the attributes. Use <STRONG>touchwin</STRONG> to force the screen to
327 match the updated attributes.
329 The XSI Curses standard states that whether the traditional functions
330 <STRONG>attron</STRONG>/<STRONG>attroff</STRONG>/<STRONG>attrset</STRONG> can manipulate attributes other than <STRONG>A_BLINK</STRONG>,
331 <STRONG>A_BOLD</STRONG>, <STRONG>A_DIM</STRONG>, <STRONG>A_REVERSE</STRONG>, <STRONG>A_STANDOUT</STRONG>, or <STRONG>A_UNDERLINE</STRONG> is "unspecified".
332 Under this implementation as well as SVr4 curses, these functions
333 correctly manipulate all other highlights (specifically, <STRONG>A_ALTCHARSET</STRONG>,
334 <STRONG>A_PROTECT</STRONG>, and <STRONG>A_INVIS</STRONG>).
336 XSI Curses added these entry points:
338 <STRONG>attr_get</STRONG>, <STRONG>attr_on</STRONG>, <STRONG>attr_off</STRONG>, <STRONG>attr_set</STRONG>, <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>,
339 <STRONG>wattr_get</STRONG>, <STRONG>wattr_set</STRONG>
341 The new functions are intended to work with a new series of highlight
342 macros prefixed with <STRONG>WA_</STRONG>. The older macros have direct counterparts in
343 the newer set of names:
345 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
346 ------------------------------------------------------------
347 <STRONG>WA_NORMAL</STRONG> Normal display (no highlight)
348 <STRONG>WA_STANDOUT</STRONG> Best highlighting mode of the terminal.
349 <STRONG>WA_UNDERLINE</STRONG> Underlining
350 <STRONG>WA_REVERSE</STRONG> Reverse video
351 <STRONG>WA_BLINK</STRONG> Blinking
352 <STRONG>WA_DIM</STRONG> Half bright
353 <STRONG>WA_BOLD</STRONG> Extra bright or bold
354 <STRONG>WA_ALTCHARSET</STRONG> Alternate character set
356 XSI curses does not assign values to these symbols, nor does it state
357 whether or not they are related to the similarly-named A_NORMAL, etc.:
359 <STRONG>o</STRONG> The XSI curses standard specifies that each pair of corresponding
360 <STRONG>A_</STRONG> and <STRONG>WA_</STRONG>-using functions operates on the same current-highlight
363 <STRONG>o</STRONG> However, in some implementations, those symbols have unrelated
366 For example, the Solaris <EM>xpg4</EM> (X/Open) curses declares <STRONG>attr_t</STRONG> to be
367 an unsigned short integer (16-bits), while <STRONG>chtype</STRONG> is a unsigned
368 integer (32-bits). The <STRONG>WA_</STRONG> symbols in this case are different from
369 the <STRONG>A_</STRONG> symbols because they are used for a smaller datatype which
370 does not represent <STRONG>A_CHARTEXT</STRONG> or <STRONG>A_COLOR</STRONG>.
372 In this implementation (as in many others), the values happen to be
373 the same because it simplifies copying information between <STRONG>chtype</STRONG>
374 and <STRONG>cchar_t</STRONG> variables.
376 <STRONG>o</STRONG> Because ncurses's <STRONG>attr_t</STRONG> can hold a color pair (in the <STRONG>A_COLOR</STRONG>
377 field), a call to <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>, or <STRONG>wattr_set</STRONG> may alter the
378 window's color. If the color pair information in the attribute
379 parameter is zero, no change is made to the window's color.
381 This is consistent with SVr4 curses; X/Open Curses does not specify
384 The XSI standard extended conformance level adds new highlights
385 <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
386 corresponding <STRONG>WA_</STRONG> macros for each). As of August 2013, no known
387 terminal provides these highlights (i.e., via the <STRONG>sgr1</STRONG> capability).
390 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
391 X/Open Curses is largely based on SVr4 curses, adding support for
392 "wide-characters" (not specific to Unicode). Some of the X/Open
393 differences from SVr4 curses address the way video attributes can be
394 applied to wide-characters. But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
395 are similar. SVr4 curses provided the basic features for manipulating
396 video attributes. However, earlier versions of curses provided a part
399 As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth
400 bit of a byte to represent the <EM>standout</EM> feature (often implemented as
401 bold and/or reverse video). The BSD curses library provided functions
402 <STRONG>standout</STRONG> and <STRONG>standend</STRONG> which were carried along into X/Open Curses due
403 to their pervasive use in legacy applications.
405 Some terminals in the 1980s could support a variety of video
406 attributes, although the BSD curses library could do nothing with
407 those. System V (1983) provided an improved curses library. It
408 defined the <STRONG>A_</STRONG> symbols for use by applications to manipulate the other
409 attributes. There are few useful references for the chronology.
411 Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991) describes SVr3 (1987),
412 commenting on several functions:
414 <STRONG>o</STRONG> the <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
415 found in SVr4 but not in BSD curses) were introduced by System V,
417 <STRONG>o</STRONG> the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added in
418 SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),
420 <STRONG>o</STRONG> <STRONG>start_color</STRONG> and related color-functions were introduced by System
423 <STRONG>o</STRONG> pads, soft-keys were added in SVr3, and
425 Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
426 Those are respectively SVr4 and X/Open features. He did mention the <STRONG>A_</STRONG>
427 constants, but did not indicate their values. Those were not the same
428 in different systems, even for those marked as System V.
430 Different Unix systems used different sizes for the bit-fields in
431 <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account the different
432 integer sizes (32-bit versus 64-bit).
434 This table showing the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
435 gleaned from the curses header files for various operating systems and
436 architectures. The inferred architecture and notes reflect the format
437 and size of the defined constants as well as clues such as the
438 alternate character set implementation. A 32-bit library can be used
439 on a 64-bit system, but not necessarily the reverse.
441 <STRONG>Year</STRONG> <STRONG>System</STRONG> <STRONG>Arch</STRONG> <STRONG>Color</STRONG> <STRONG>Char</STRONG> <STRONG>Notes</STRONG>
442 ----------------------------------------------------------------
443 1992 Solaris 5.2 32 6 17 SVr4 curses
444 1992 HP-UX 9 32 no 8 SVr2 curses
445 1992 AIX 3.2 32 no 23 SVr2 curses
446 1994 OSF/1 r3 32 no 23 SVr2 curses
447 1995 HP-UX 10.00 32 6 16 SVr3 "curses_colr"
448 1995 HP-UX 10.00 32 6 8 SVr4, X/Open curses
449 1995 Solaris 5.4 32/64 7 16 X/Open curses
450 1996 AIX 4.2 32 7 16 X/Open curses
451 1996 OSF/1 r4 32 6 16 X/Open curses
452 1997 HP-UX 11.00 32 6 8 X/Open curses
453 2000 U/Win 32/64 7/31 16 uses <STRONG>chtype</STRONG>
459 <STRONG>o</STRONG> HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
462 <STRONG>o</STRONG> HP-UX 10.30 (1997) marked "curses_colr" obsolete. That version
463 of curses was dropped with HP-UX 11.30 in 2006.
465 Regarding OSF/1 (and Tru64),
467 <STRONG>o</STRONG> These used 64-bit hardware. Like ncurses, the OSF/1 curses
468 interface is not customized for 32-bit and 64-bit versions.
470 <STRONG>o</STRONG> Unlike other systems which evolved from AT&T code, OSF/1
471 provided a new implementation for X/Open curses.
475 <STRONG>o</STRONG> The initial release of Solaris was in 1992.
477 <STRONG>o</STRONG> The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
478 Sun's copyright began in 1996.
480 <STRONG>o</STRONG> Sun updated the X/Open curses interface after 64-bit support was
481 introduced in 1997, but did not modify the SVr4 curses
486 <STRONG>o</STRONG> Development of the curses library began in 1991, stopped in
489 <STRONG>o</STRONG> Color support was added in 1998.
491 <STRONG>o</STRONG> The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).
493 Once X/Open curses was adopted in the mid-1990s, the constraint of a
494 32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
495 a moot point. The <STRONG>cchar_t</STRONG> structure (whose size and members are not
496 specified in X/Open Curses) could be extended as needed.
498 Other interfaces are rarely used now:
500 <STRONG>o</STRONG> BSD curses was improved slightly in 1993/1994 using Keith Bostic's
501 modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>. He moved
502 <EM>standout</EM> attribute to a structure member.
504 The resulting 4.4BSD curses was replaced by ncurses over the next
507 <STRONG>o</STRONG> U/Win is rarely used now.
510 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
511 <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>,
512 <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
516 ncurses 6.4 2023-11-25 <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
520 <li><a href="#h2-NAME">NAME</a></li>
521 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
522 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
524 <li><a href="#h3-Window-attributes">Window attributes</a></li>
525 <li><a href="#h3-Legacy-window-attributes">Legacy window attributes</a></li>
526 <li><a href="#h3-Change-character-rendition">Change character rendition</a></li>
527 <li><a href="#h3-Change-window-color">Change window color</a></li>
528 <li><a href="#h3-Standout">Standout</a></li>
529 <li><a href="#h3-Video-Attributes">Video Attributes</a></li>
532 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
533 <li><a href="#h2-NOTES">NOTES</a></li>
534 <li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
535 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
536 <li><a href="#h2-HISTORY">HISTORY</a></li>
537 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>