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31 * @Id: curs_attr.3x,v 1.106 2024/05/11 20:39:53 tom Exp @
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43 <H1 class="no-header">curs_attr 3x 2024-05-11 ncurses 6.5 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 You can thus use <STRONG>A_CHARTEXT</STRONG> to extract the character from a <EM>chtype</EM>,
224 <STRONG>A_ATTRIBUTES</STRONG> to obtain its rendering attributes, and <STRONG>A_COLOR</STRONG> to find
225 the color pair it uses.
227 These video attributes are supported by <STRONG>attr_on</STRONG> and related functions
228 (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):
230 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
231 -----------------------------------------------------------------
232 <STRONG>WA_HORIZONTAL</STRONG> Horizontal highlight
233 <STRONG>WA_LEFT</STRONG> Left highlight
234 <STRONG>WA_LOW</STRONG> Low highlight
235 <STRONG>WA_RIGHT</STRONG> Right highlight
236 <STRONG>WA_TOP</STRONG> Top highlight
237 <STRONG>WA_VERTICAL</STRONG> Vertical highlight
239 The return values of many of these routines are not meaningful (they
240 are implemented as macro-expanded assignments and simply return their
241 argument). The SVr4 manual page claims (falsely) that these routines
242 always return <STRONG>1</STRONG>.
245 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
246 All routines return the integer <STRONG>OK</STRONG> on success, or <STRONG>ERR</STRONG> on failure.
248 X/Open Curses does not specify any error conditions.
252 <STRONG>o</STRONG> returns an error if the window pointer is null.
254 <STRONG>o</STRONG> returns an error if the color pair parameter for <STRONG>wcolor_set</STRONG> is
255 outside the range 0..COLOR_PAIRS-1.
257 <STRONG>o</STRONG> does not return an error if either of the parameters of <STRONG>wattr_get</STRONG>
258 used for retrieving attribute or color pair values is <STRONG>NULL</STRONG>.
260 Functions prefixed with "mv" first perform cursor movement and fail if
261 the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.
264 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
265 These functions may be macros:
267 <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>standend</STRONG>
268 and <STRONG>standout</STRONG>.
270 Color pair values can only be OR'd with attributes if the pair number
271 is less than 256. The alternate functions such as <STRONG>color_set</STRONG> can pass a
272 color pair value directly. However, <EM>ncurses</EM> ABI 4 and 5 simply OR this
273 value within the alternate functions. You must use <EM>ncurses</EM> ABI 6 to
274 support more than 256 color pairs.
277 </PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
278 This implementation provides the <STRONG>A_ITALIC</STRONG> attribute for terminals which
279 have the <STRONG>enter_italics_mode</STRONG> (<STRONG>sitm</STRONG>) and <STRONG>exit_italics_mode</STRONG> (<STRONG>ritm</STRONG>)
280 capabilities. Italics are not mentioned in X/Open Curses. Unlike the
281 other video attributes, <STRONG>A_ITALIC</STRONG> is unrelated to the <STRONG>set_attributes</STRONG>
282 capabilities. This implementation makes the assumption that
283 <STRONG>exit_attribute_mode</STRONG> may also reset italics.
285 Each of the functions added by XSI Curses has a parameter <EM>opts</EM>, which
286 X/Open Curses still (after more than twenty years) documents as
287 reserved for future use, saying that it should be <STRONG>NULL</STRONG>. This
288 implementation uses that parameter in ABI 6 for the functions which
289 have a color pair parameter to support <EM>extended</EM> <EM>color</EM> <EM>pairs</EM>:
291 <STRONG>o</STRONG> For functions which modify the color, e.g., <STRONG>wattr_set</STRONG> and <STRONG>wattr_on</STRONG>,
292 if <EM>opts</EM> is set it is treated as a pointer to <STRONG>int</STRONG>, and used to set
293 the color pair instead of the <STRONG>short</STRONG> <EM>pair</EM> parameter.
295 <STRONG>o</STRONG> For functions which retrieve the color, e.g., <STRONG>wattr_get</STRONG>, if <EM>opts</EM> is
296 set it is treated as a pointer to <STRONG>int</STRONG>, and used to retrieve the
297 color pair as an <STRONG>int</STRONG> value, in addition to retrieving it via the
298 standard pointer to <STRONG>short</STRONG> parameter.
300 <STRONG>o</STRONG> For functions which turn attributes off, e.g., <STRONG>wattr_off</STRONG>, the <EM>opts</EM>
301 parameter is ignored except except to check that it is <STRONG>NULL</STRONG>.
304 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
305 These functions are described in X/Open Curses, Issue 4. The standard
306 defined the dedicated type for highlights, <STRONG>attr_t</STRONG>, which was not
307 defined in SVr4 curses. The functions taking <STRONG>attr_t</STRONG> arguments were not
308 supported under SVr4.
310 Very old versions of this library did not force an update of the screen
311 when changing the attributes. Use <STRONG>touchwin</STRONG> to force the screen to
312 match the updated attributes.
314 X/Open Curses states that whether the traditional functions
315 <STRONG>attron</STRONG>/<STRONG>attroff</STRONG>/<STRONG>attrset</STRONG> can manipulate attributes other than <STRONG>A_BLINK</STRONG>,
316 <STRONG>A_BOLD</STRONG>, <STRONG>A_DIM</STRONG>, <STRONG>A_REVERSE</STRONG>, <STRONG>A_STANDOUT</STRONG>, or <STRONG>A_UNDERLINE</STRONG> is "unspecified".
317 Under this implementation as well as SVr4 curses, these functions
318 correctly manipulate all other highlights (specifically, <STRONG>A_ALTCHARSET</STRONG>,
319 <STRONG>A_PROTECT</STRONG>, and <STRONG>A_INVIS</STRONG>).
321 X/Open Curses added these entry points:
323 <STRONG>attr_get</STRONG>, <STRONG>attr_on</STRONG>, <STRONG>attr_off</STRONG>, <STRONG>attr_set</STRONG>, <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>,
324 <STRONG>wattr_get</STRONG>, <STRONG>wattr_set</STRONG>
326 The new functions are intended to work with a new series of highlight
327 macros prefixed with <STRONG>WA_</STRONG>. The older macros have direct counterparts in
328 the newer set of names:
330 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
331 -----------------------------------------------------------------
332 <STRONG>WA_NORMAL</STRONG> Normal display (no highlight)
333 <STRONG>WA_STANDOUT</STRONG> Best highlighting mode of the terminal
334 <STRONG>WA_UNDERLINE</STRONG> Underlining
335 <STRONG>WA_REVERSE</STRONG> Reverse video
336 <STRONG>WA_BLINK</STRONG> Blinking
337 <STRONG>WA_DIM</STRONG> Half bright
338 <STRONG>WA_BOLD</STRONG> Extra bright or bold
339 <STRONG>WA_ALTCHARSET</STRONG> Alternate character set
341 X/Open Curses does not assign values to these symbols, nor does it
342 state whether or not they are related to the similarly-named A_NORMAL,
345 <STRONG>o</STRONG> X/Open Curses specifies that each pair of corresponding <STRONG>A_</STRONG> and
346 <STRONG>WA_</STRONG>-using functions operates on the same current-highlight
349 <STRONG>o</STRONG> However, in some implementations, those symbols have unrelated
352 For example, the Solaris <EM>xpg4</EM> (X/Open) curses declares <STRONG>attr_t</STRONG> to be
353 an unsigned short integer (16-bits), while <STRONG>chtype</STRONG> is a unsigned
354 integer (32-bits). The <STRONG>WA_</STRONG> symbols in this case are different from
355 the <STRONG>A_</STRONG> symbols because they are used for a smaller datatype which
356 does not represent <STRONG>A_CHARTEXT</STRONG> or <STRONG>A_COLOR</STRONG>.
358 In this implementation (as in many others), the values happen to be
359 the same because it simplifies copying information between <STRONG>chtype</STRONG>
360 and <STRONG>cchar_t</STRONG> variables.
362 <STRONG>o</STRONG> Because <EM>ncurses</EM>'s <STRONG>attr_t</STRONG> can hold a color pair (in the <STRONG>A_COLOR</STRONG>
363 field), a call to <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>, or <STRONG>wattr_set</STRONG> may alter the
364 window's color. If the color pair information in the attribute
365 parameter is zero, no change is made to the window's color.
367 This is consistent with SVr4 curses; X/Open Curses does not specify
370 The X/Open Curses extended conformance level adds new highlights
371 <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
372 corresponding <STRONG>WA_</STRONG> macros for each). As of August 2013, no known
373 terminal provides these highlights (i.e., via the <STRONG>sgr1</STRONG> capability).
376 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
377 X/Open Curses is largely based on SVr4 curses, adding support for
378 "wide-characters" (not specific to Unicode). Some of the X/Open
379 differences from SVr4 curses address the way video attributes can be
380 applied to wide-characters. But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
381 are similar. SVr4 curses provided the basic features for manipulating
382 video attributes. However, earlier versions of curses provided a part
385 As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth
386 bit of a byte to represent the <EM>standout</EM> feature (often implemented as
387 bold and/or reverse video). The BSD curses library provided functions
388 <STRONG>standout</STRONG> and <STRONG>standend</STRONG> which were carried along into X/Open Curses due
389 to their pervasive use in legacy applications.
391 Some terminals in the 1980s could support a variety of video
392 attributes, although the BSD curses library could do nothing with
393 those. System V (1983) provided an improved curses library. It
394 defined the <STRONG>A_</STRONG> symbols for use by applications to manipulate the other
395 attributes. There are few useful references for the chronology.
397 Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991) describes SVr3 (1987),
398 commenting on several functions:
400 <STRONG>o</STRONG> the <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
401 found in SVr4 but not in BSD curses) were introduced by System V,
403 <STRONG>o</STRONG> the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added in
404 SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),
406 <STRONG>o</STRONG> <STRONG>start_color</STRONG> and related color-functions were introduced by System
409 <STRONG>o</STRONG> pads, soft-keys were added in SVr3, and
411 Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
412 Those are respectively SVr4 and X/Open features. He did mention the <STRONG>A_</STRONG>
413 constants, but did not indicate their values. Those were not the same
414 in different systems, even for those marked as System V.
416 Different Unix systems used different sizes for the bit-fields in
417 <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account the different
418 integer sizes (32-bit versus 64-bit).
420 This table showing the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
421 gleaned from the curses header files for various operating systems and
422 architectures. The inferred architecture and notes reflect the format
423 and size of the defined constants as well as clues such as the
424 alternate character set implementation. A 32-bit library can be used
425 on a 64-bit system, but not necessarily the reverse.
427 <STRONG>Bits</STRONG>
428 <STRONG>Year</STRONG> <STRONG>System</STRONG> <STRONG>Arch</STRONG> <STRONG>Color</STRONG> <STRONG>Char</STRONG> <STRONG>Notes</STRONG>
429 ------------------------------------------------------------------------
430 1992 Solaris 5.2 32 6 17 SVr4 <EM>curses</EM>
431 1992 HP-UX 9 32 no 8 SVr2 <EM>curses</EM>
432 1992 AIX 3.2 32 no 23 SVr2 <EM>curses</EM>
433 1994 OSF/1 r3 32 no 23 SVr2 <EM>curses</EM>
434 1995 HP-UX 10.00 32 6 16 SVr3 <EM>curses</EM><STRONG>_</STRONG><EM>colr</EM>
435 1995 HP-UX 10.00 32 6 8 SVr4, X/Open <EM>curses</EM>
436 1995 Solaris 5.4 32/64 7 16 X/Open <EM>curses</EM>
437 1996 AIX 4.2 32 7 16 X/Open <EM>curses</EM>
438 1996 OSF/1 r4 32 6 16 X/Open <EM>curses</EM>
439 1997 HP-UX 11.00 32 6 8 X/Open <EM>curses</EM>
440 2000 U/Win 32/64 7/31 16 uses <EM>chtype</EM>
446 <STRONG>o</STRONG> HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
449 <STRONG>o</STRONG> HP-UX 10.30 (1997) marked "curses_colr" obsolete. That version
450 of curses was dropped with HP-UX 11.30 in 2006.
452 Regarding OSF/1 (and Tru64),
454 <STRONG>o</STRONG> These used 64-bit hardware. Like <EM>ncurses</EM>, the OSF/1 curses
455 interface is not customized for 32-bit and 64-bit versions.
457 <STRONG>o</STRONG> Unlike other systems which evolved from AT&T code, OSF/1
458 provided a new implementation for X/Open curses.
462 <STRONG>o</STRONG> The initial release of Solaris was in 1992.
464 <STRONG>o</STRONG> The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
465 Sun's copyright began in 1996.
467 <STRONG>o</STRONG> Sun updated the X/Open curses interface after 64-bit support was
468 introduced in 1997, but did not modify the SVr4 curses
473 <STRONG>o</STRONG> Development of the curses library began in 1991, stopped in
476 <STRONG>o</STRONG> Color support was added in 1998.
478 <STRONG>o</STRONG> The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).
480 Once X/Open curses was adopted in the mid-1990s, the constraint of a
481 32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
482 a moot point. The <STRONG>cchar_t</STRONG> structure (whose size and members are not
483 specified in X/Open Curses) could be extended as needed.
485 Other interfaces are rarely used now:
487 <STRONG>o</STRONG> BSD curses was improved slightly in 1993/1994 using Keith Bostic's
488 modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>. He moved
489 <EM>standout</EM> attribute to a structure member.
491 The resulting 4.4BSD curses was replaced by <EM>ncurses</EM> over the next
494 <STRONG>o</STRONG> U/Win is rarely used now.
497 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
498 <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>,
499 <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
503 ncurses 6.5 2024-05-11 <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
507 <li><a href="#h2-NAME">NAME</a></li>
508 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
509 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
511 <li><a href="#h3-Window-Attributes">Window Attributes</a></li>
512 <li><a href="#h3-Legacy-Window-Attributes">Legacy Window Attributes</a></li>
513 <li><a href="#h3-Change-Character-Rendition">Change Character Rendition</a></li>
514 <li><a href="#h3-Change-Window-Color">Change Window Color</a></li>
515 <li><a href="#h3-Standout">Standout</a></li>
516 <li><a href="#h3-Video-Attributes">Video Attributes</a></li>
519 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
520 <li><a href="#h2-NOTES">NOTES</a></li>
521 <li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
522 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
523 <li><a href="#h2-HISTORY">HISTORY</a></li>
524 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
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