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  53 <TITLE>curs_attr 3x 2023-12-16 ncurses 6.4 Library calls</TITLE>
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  58 <H1 class="no-header">curs_attr 3x 2023-12-16 ncurses 6.4 Library calls</H1>
  59 <PRE>
  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>
  61
  62
  63
  64
  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
  71
  72
  73 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
  74        <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
  75
  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>
  80
  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>
  85
  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>
  92
  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>
 100
 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>
 103
 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>
 108
 109
 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.
 118
 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.
 122
 123
 124 </PRE><H3><a name="h3-Window-attributes">Window attributes</a></H3><PRE>
 125        There are two sets of functions:
 126
 127        <STRONG>o</STRONG>   functions   for  manipulating  the  window  attributes  and  color:
 128            <STRONG>wattr_set</STRONG> and <STRONG>wattr_get</STRONG>.
 129
 130        <STRONG>o</STRONG>   functions for manipulating only the window attributes (not  color):
 131            <STRONG>wattr_on</STRONG> and <STRONG>wattr_off</STRONG>.
 132
 133        The  <STRONG>wattr_set</STRONG> function sets the current attributes of the given window
 134        to <EM>attrs</EM>, with color specified by <EM>pair</EM>.
 135
 136        Use <STRONG>wattr_get</STRONG> to retrieve attributes for the given window.
 137
 138        Use <STRONG>attr_on</STRONG> and <STRONG>wattr_on</STRONG> to turn on  window  attributes,  i.e.,  values
 139        OR'd  together  in  <EM>attr</EM>,  without  affecting  other  attributes.   Use
 140        <STRONG>attr_off</STRONG> and <STRONG>wattr_off</STRONG> to turn off window attributes, again values OR'd
 141        together in <EM>attr</EM>, without affecting other attributes.
 142
 143
 144 </PRE><H3><a name="h3-Legacy-window-attributes">Legacy window attributes</a></H3><PRE>
 145        The  X/Open  window attribute routines which <EM>set</EM> or <EM>get</EM>, turn <EM>on</EM> or <EM>off</EM>
 146        are extensions of older routines which assume that color pairs are OR'd
 147        into  the attribute parameter.  These newer routines use similar names,
 148        because X/Open simply added an underscore (<STRONG>_</STRONG>) for the newer names.
 149
 150        The <STRONG>int</STRONG> datatype used in the legacy routines is treated as if it is the
 151        same  size  as  <STRONG>chtype</STRONG>  (used by <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>).  It holds the common video
 152        attributes (such as bold, reverse), as well as a few  bits  for  color.
 153        Those  bits  correspond  to  the  <STRONG>A_COLOR</STRONG> symbol.  The <STRONG>COLOR_PAIR</STRONG> macro
 154        provides a value which can be OR'd into the attribute  parameter.   For
 155        example,  as  long as that value fits into the <STRONG>A_COLOR</STRONG> mask, then these
 156        calls produce similar results:
 157
 158            attrset(A_BOLD | COLOR_PAIR(<EM>pair</EM>));
 159            attr_set(A_BOLD, <EM>pair</EM>, NULL);
 160
 161        However, if the value does not fit, then the <STRONG>COLOR_PAIR</STRONG> macro uses only
 162        the  bits  that fit.  For example, because in <EM>ncurses</EM> <STRONG>A_COLOR</STRONG> has eight
 163        (8) bits, then <STRONG>COLOR_PAIR(</STRONG><EM>259</EM><STRONG>)</STRONG> is 4 (i.e., 259 is 4 more than the limit
 164        255).
 165
 166        The  <STRONG>PAIR_NUMBER</STRONG>  macro extracts a pair number from an <STRONG>int</STRONG> (or <STRONG>chtype</STRONG>).
 167        For example, the <EM>input</EM> and <EM>output</EM> values in these statements  would  be
 168        the same:
 169
 170            int value = A_BOLD | COLOR_PAIR(<EM>input</EM>);
 171            int <EM>output</EM> = PAIR_NUMBER(value);
 172
 173        The  <STRONG>attrset</STRONG> routine is a legacy feature predating SVr4 curses but kept
 174        in X/Open Curses  for  the  same  reason  that  SVr4  curses  kept  it:
 175        compatibility.
 176
 177        The  remaining  <STRONG>attr</STRONG>*  functions operate exactly like the corresponding
 178        <STRONG>attr_</STRONG>* functions, except that they take arguments of  type  <STRONG>int</STRONG>  rather
 179        than <STRONG>attr_t</STRONG>.
 180
 181        There  is  no  corresponding <STRONG>attrget</STRONG> function as such in X/Open Curses,
 182        although <EM>ncurses</EM> provides <STRONG>getattrs</STRONG> (see <STRONG><A HREF="curs_legacy.3x.html">curs_legacy(3x)</A></STRONG>).
 183
 184
 185 </PRE><H3><a name="h3-Change-character-rendition">Change character rendition</a></H3><PRE>
 186        The  routine  <STRONG>chgat</STRONG>  changes  the  attributes  of  a  given  number  of
 187        characters  starting at the current cursor location of <STRONG>stdscr</STRONG>.  It does
 188        not update the cursor and does not perform wrapping.  A character count
 189        of  -1  or  greater  than  the  remaining  window width means to change
 190        attributes all the way to the end of  the  current  line.   The  <STRONG>wchgat</STRONG>
 191        function  generalizes  this to any window; the <STRONG>mvwchgat</STRONG> function does a
 192        cursor move before acting.
 193
 194        In these functions, the color <EM>pair</EM> argument is a color pair  index  (as
 195        in the first argument of <STRONG>init_pair</STRONG>, see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>).
 196
 197
 198 </PRE><H3><a name="h3-Change-window-color">Change window color</a></H3><PRE>
 199        The routine <STRONG>color_set</STRONG> sets the current color of the given window to the
 200        foreground/background  combination  described   by   the   color   <EM>pair</EM>
 201        parameter.
 202
 203
 204 </PRE><H3><a name="h3-Standout">Standout</a></H3><PRE>
 205        The  routine  <STRONG>standout</STRONG>  is the same as <STRONG>attron(A_STANDOUT)</STRONG>.  The routine
 206        <STRONG>standend</STRONG> is the same as <STRONG>attrset(A_NORMAL)</STRONG> or <STRONG>attrset(0)</STRONG>,  that  is,  it
 207        turns off all attributes.
 208
 209        X/Open does not mark these "restricted", because
 210
 211        <STRONG>o</STRONG>   they have well established legacy use, and
 212
 213        <STRONG>o</STRONG>   there  is  no  ambiguity  about  the  way  the  attributes might be
 214            combined with a color pair.
 215
 216
 217 </PRE><H3><a name="h3-Video-Attributes">Video Attributes</a></H3><PRE>
 218        The following video attributes, defined in <STRONG>&lt;curses.h&gt;</STRONG>, can be passed to
 219        the  routines <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, and <STRONG>attrset</STRONG>, or OR'd with the characters
 220        passed to <STRONG>addch</STRONG> (see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>).
 221
 222               <STRONG>Name</STRONG>           <STRONG>Description</STRONG>
 223               -----------------------------------------------------------------
 224               <STRONG>A_NORMAL</STRONG>       Normal display (no highlight)
 225               <STRONG>A_STANDOUT</STRONG>     Best highlighting mode of the terminal.
 226               <STRONG>A_UNDERLINE</STRONG>    Underlining
 227               <STRONG>A_REVERSE</STRONG>      Reverse video
 228               <STRONG>A_BLINK</STRONG>        Blinking
 229               <STRONG>A_DIM</STRONG>          Half bright
 230               <STRONG>A_BOLD</STRONG>         Extra bright or bold
 231               <STRONG>A_PROTECT</STRONG>      Protected mode
 232               <STRONG>A_INVIS</STRONG>        Invisible or blank mode
 233               <STRONG>A_ALTCHARSET</STRONG>   Alternate character set
 234               <STRONG>A_ITALIC</STRONG>       Italics (non-X/Open extension)
 235               <STRONG>A_CHARTEXT</STRONG>     Bit-mask to extract a character
 236               <STRONG>A_COLOR</STRONG>        Bit-mask to extract a color (legacy routines)
 237
 238        These video attributes are supported by <STRONG>attr_on</STRONG> and  related  functions
 239        (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):
 240
 241               <STRONG>Name</STRONG>            <STRONG>Description</STRONG>
 242               -----------------------------------------
 243               <STRONG>WA_HORIZONTAL</STRONG>   Horizontal highlight
 244               <STRONG>WA_LEFT</STRONG>         Left highlight
 245               <STRONG>WA_LOW</STRONG>          Low highlight
 246               <STRONG>WA_RIGHT</STRONG>        Right highlight
 247               <STRONG>WA_TOP</STRONG>          Top highlight
 248               <STRONG>WA_VERTICAL</STRONG>     Vertical highlight
 249
 250        The  return  values  of many of these routines are not meaningful (they
 251        are implemented as macro-expanded assignments and simply  return  their
 252        argument).   The  SVr4 manual page claims (falsely) that these routines
 253        always return <STRONG>1</STRONG>.
 254
 255
 256 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
 257        All routines return the integer <STRONG>OK</STRONG> on success, or <STRONG>ERR</STRONG> on failure.
 258
 259        X/Open does not define any error conditions.
 260
 261        This implementation
 262
 263        <STRONG>o</STRONG>   returns an error if the window pointer is null.
 264
 265        <STRONG>o</STRONG>   returns an error if the color  pair  parameter  for  <STRONG>wcolor_set</STRONG>  is
 266            outside the range 0..COLOR_PAIRS-1.
 267
 268        <STRONG>o</STRONG>   does  not  return an error if either of the parameters of <STRONG>wattr_get</STRONG>
 269            used for retrieving attribute or color pair values is <STRONG>NULL</STRONG>.
 270
 271        Functions with a "mv" prefix first  perform  a  cursor  movement  using
 272        <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
 273        the window pointer is null.
 274
 275
 276 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
 277        These functions may be macros:
 278
 279               <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>,  <STRONG>standend</STRONG>
 280               and <STRONG>standout</STRONG>.
 281
 282        Color  pair  values can only be OR'd with attributes if the pair number
 283        is less than 256.  The alternate functions such as <STRONG>color_set</STRONG> can pass a
 284        color pair value directly.  However, <EM>ncurses</EM> ABI 4 and 5 simply OR this
 285        value within the alternate functions.  You must use <EM>ncurses</EM>  ABI  6  to
 286        support more than 256 color pairs.
 287
 288
 289 </PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
 290        This implementation provides the <STRONG>A_ITALIC</STRONG> attribute for terminals which
 291        have  the  <STRONG>enter_italics_mode</STRONG>  (<STRONG>sitm</STRONG>)  and   <STRONG>exit_italics_mode</STRONG>   (<STRONG>ritm</STRONG>)
 292        capabilities.   Italics are not mentioned in X/Open Curses.  Unlike the
 293        other video attributes, <STRONG>A_ITALIC</STRONG> is  unrelated  to  the  <STRONG>set_attributes</STRONG>
 294        capabilities.    This   implementation   makes   the   assumption  that
 295        <STRONG>exit_attribute_mode</STRONG> may also reset italics.
 296
 297        Each of the functions added by XSI Curses has a parameter  <EM>opts</EM>,  which
 298        X/Open  Curses  still  (after  more  than  twenty  years)  documents as
 299        reserved  for  future  use,  saying  that  it  should  be  <STRONG>NULL</STRONG>.   This
 300        implementation  uses  that  parameter  in ABI 6 for the functions which
 301        have a color pair parameter to support <EM>extended</EM> <EM>color</EM> <EM>pairs</EM>:
 302
 303        <STRONG>o</STRONG>   For functions which modify the color, e.g., <STRONG>wattr_set</STRONG> and <STRONG>wattr_on</STRONG>,
 304            if  <EM>opts</EM>  is set it is treated as a pointer to <STRONG>int</STRONG>, and used to set
 305            the color pair instead of the <STRONG>short</STRONG> <EM>pair</EM> parameter.
 306
 307        <STRONG>o</STRONG>   For functions which retrieve the color, e.g., <STRONG>wattr_get</STRONG>, if <EM>opts</EM> is
 308            set  it  is  treated  as a pointer to <STRONG>int</STRONG>, and used to retrieve the
 309            color pair as an <STRONG>int</STRONG> value, in addition to retrieving  it  via  the
 310            standard pointer to <STRONG>short</STRONG> parameter.
 311
 312        <STRONG>o</STRONG>   For  functions which turn attributes off, e.g., <STRONG>wattr_off</STRONG>, the <EM>opts</EM>
 313            parameter is ignored except except to check that it is <STRONG>NULL</STRONG>.
 314
 315
 316 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
 317        These functions are described in the XSI Curses standard, Issue 4.  The
 318        standard  defined  the dedicated type for highlights, <STRONG>attr_t</STRONG>, which was
 319        not defined in SVr4 curses.  The functions taking <STRONG>attr_t</STRONG> arguments were
 320        not supported under SVr4.
 321
 322        Very old versions of this library did not force an update of the screen
 323        when changing the attributes.  Use <STRONG>touchwin</STRONG>  to  force  the  screen  to
 324        match the updated attributes.
 325
 326        The  XSI  Curses standard states that whether the traditional functions
 327        <STRONG>attron</STRONG>/<STRONG>attroff</STRONG>/<STRONG>attrset</STRONG> can manipulate attributes  other  than  <STRONG>A_BLINK</STRONG>,
 328        <STRONG>A_BOLD</STRONG>,  <STRONG>A_DIM</STRONG>, <STRONG>A_REVERSE</STRONG>, <STRONG>A_STANDOUT</STRONG>, or <STRONG>A_UNDERLINE</STRONG> is "unspecified".
 329        Under this implementation as  well  as  SVr4  curses,  these  functions
 330        correctly  manipulate all other highlights (specifically, <STRONG>A_ALTCHARSET</STRONG>,
 331        <STRONG>A_PROTECT</STRONG>, and <STRONG>A_INVIS</STRONG>).
 332
 333        XSI Curses added these entry points:
 334
 335               <STRONG>attr_get</STRONG>,  <STRONG>attr_on</STRONG>,  <STRONG>attr_off</STRONG>,  <STRONG>attr_set</STRONG>,  <STRONG>wattr_on</STRONG>,  <STRONG>wattr_off</STRONG>,
 336               <STRONG>wattr_get</STRONG>, <STRONG>wattr_set</STRONG>
 337
 338        The  new  functions are intended to work with a new series of highlight
 339        macros prefixed with <STRONG>WA_</STRONG>.  The older macros have direct counterparts in
 340        the newer set of names:
 341
 342               <STRONG>Name</STRONG>            <STRONG>Description</STRONG>
 343               ------------------------------------------------------------
 344               <STRONG>WA_NORMAL</STRONG>       Normal display (no highlight)
 345               <STRONG>WA_STANDOUT</STRONG>     Best highlighting mode of the terminal.
 346               <STRONG>WA_UNDERLINE</STRONG>    Underlining
 347               <STRONG>WA_REVERSE</STRONG>      Reverse video
 348               <STRONG>WA_BLINK</STRONG>        Blinking
 349               <STRONG>WA_DIM</STRONG>          Half bright
 350               <STRONG>WA_BOLD</STRONG>         Extra bright or bold
 351
 352               <STRONG>WA_ALTCHARSET</STRONG>   Alternate character set
 353
 354        XSI  curses  does not assign values to these symbols, nor does it state
 355        whether or not they are related to the similarly-named A_NORMAL, etc.:
 356
 357        <STRONG>o</STRONG>   The XSI curses standard specifies that each pair  of  corresponding
 358            <STRONG>A_</STRONG>  and  <STRONG>WA_</STRONG>-using functions operates on the same current-highlight
 359            information.
 360
 361        <STRONG>o</STRONG>   However, in some  implementations,  those  symbols  have  unrelated
 362            values.
 363
 364            For example, the Solaris <EM>xpg4</EM> (X/Open) curses declares <STRONG>attr_t</STRONG> to be
 365            an unsigned short integer (16-bits), while  <STRONG>chtype</STRONG>  is  a  unsigned
 366            integer (32-bits).  The <STRONG>WA_</STRONG> symbols in this case are different from
 367            the <STRONG>A_</STRONG> symbols because they are used for a smaller  datatype  which
 368            does not represent <STRONG>A_CHARTEXT</STRONG> or <STRONG>A_COLOR</STRONG>.
 369
 370            In this implementation (as in many others), the values happen to be
 371            the same because it simplifies copying information  between  <STRONG>chtype</STRONG>
 372            and <STRONG>cchar_t</STRONG> variables.
 373
 374        <STRONG>o</STRONG>   Because  <EM>ncurses</EM>'s  <STRONG>attr_t</STRONG>  can  hold  a color pair (in the <STRONG>A_COLOR</STRONG>
 375            field), a call to <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>, or <STRONG>wattr_set</STRONG> may  alter  the
 376            window's  color.   If  the  color pair information in the attribute
 377            parameter is zero, no change is made to the window's color.
 378
 379            This is consistent with SVr4 curses; X/Open Curses does not specify
 380            this.
 381
 382        The  XSI  standard  extended  conformance  level  adds  new  highlights
 383        <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
 384        corresponding  <STRONG>WA_</STRONG>  macros  for  each).   As  of  August 2013, no known
 385        terminal provides these highlights (i.e., via the <STRONG>sgr1</STRONG> capability).
 386
 387
 388 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
 389        X/Open Curses is largely based  on  SVr4  curses,  adding  support  for
 390        "wide-characters"  (not  specific  to  Unicode).   Some  of  the X/Open
 391        differences from SVr4 curses address the way video  attributes  can  be
 392        applied  to wide-characters.  But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
 393        are similar.  SVr4 curses provided the basic features for  manipulating
 394        video  attributes.  However, earlier versions of curses provided a part
 395        of these features.
 396
 397        As seen in 2.8BSD, curses assumed 7-bit characters,  using  the  eighth
 398        bit  of  a byte to represent the <EM>standout</EM> feature (often implemented as
 399        bold and/or reverse video).  The BSD curses library provided  functions
 400        <STRONG>standout</STRONG>  and  <STRONG>standend</STRONG> which were carried along into X/Open Curses due
 401        to their pervasive use in legacy applications.
 402
 403        Some  terminals  in  the  1980s  could  support  a  variety  of   video
 404        attributes,  although  the  BSD  curses  library  could do nothing with
 405        those.  System V  (1983)  provided  an  improved  curses  library.   It
 406        defined  the <STRONG>A_</STRONG> symbols for use by applications to manipulate the other
 407        attributes.  There are few useful references for the chronology.
 408
 409        Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991)  describes  SVr3  (1987),
 410        commenting on several functions:
 411
 412        <STRONG>o</STRONG>   the  <STRONG>attron</STRONG>,  <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
 413            found in SVr4 but not in BSD curses) were introduced by System V,
 414
 415        <STRONG>o</STRONG>   the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added  in
 416            SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),
 417
 418        <STRONG>o</STRONG>   <STRONG>start_color</STRONG>  and  related color-functions were introduced by System
 419            V.3.2,
 420
 421        <STRONG>o</STRONG>   pads, soft-keys were added in SVr3, and
 422
 423        Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
 424        Those are respectively SVr4 and X/Open features.  He did mention the <STRONG>A_</STRONG>
 425        constants, but did not indicate their values.  Those were not the  same
 426        in different systems, even for those marked as System V.
 427
 428        Different  Unix  systems  used  different  sizes  for the bit-fields in
 429        <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account  the  different
 430        integer sizes (32-bit versus 64-bit).
 431
 432        This  table  showing  the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
 433        gleaned from the curses header files for various operating systems  and
 434        architectures.   The inferred architecture and notes reflect the format
 435        and size of the  defined  constants  as  well  as  clues  such  as  the
 436        alternate  character  set implementation.  A 32-bit library can be used
 437        on a 64-bit system, but not necessarily the reverse.
 438
 439               <STRONG>Year</STRONG>   <STRONG>System</STRONG>        <STRONG>Arch</STRONG>    <STRONG>Color</STRONG>   <STRONG>Char</STRONG>   <STRONG>Notes</STRONG>
 440               ----------------------------------------------------------------
 441               1992   Solaris 5.2   32      6       17     SVr4 curses
 442               1992   HP-UX 9       32      no      8      SVr2 curses
 443               1992   AIX 3.2       32      no      23     SVr2 curses
 444               1994   OSF/1 r3      32      no      23     SVr2 curses
 445               1995   HP-UX 10.00   32      6       16     SVr3 "curses_colr"
 446               1995   HP-UX 10.00   32      6       8      SVr4, X/Open curses
 447               1995   Solaris 5.4   32/64   7       16     X/Open curses
 448               1996   AIX 4.2       32      7       16     X/Open curses
 449               1996   OSF/1 r4      32      6       16     X/Open curses
 450               1997   HP-UX 11.00   32      6       8      X/Open curses
 451               2000   U/Win         32/64   7/31    16     uses <STRONG>chtype</STRONG>
 452
 453        Notes:
 454
 455           Regarding HP-UX,
 456
 457           <STRONG>o</STRONG>   HP-UX 10.20 (1996) added support for 64-bit  PA-RISC  processors
 458               in 1996.
 459
 460           <STRONG>o</STRONG>   HP-UX  10.30 (1997) marked "curses_colr" obsolete.  That version
 461               of curses was dropped with HP-UX 11.30 in 2006.
 462
 463           Regarding OSF/1 (and Tru64),
 464
 465           <STRONG>o</STRONG>   These used 64-bit hardware.   Like  <EM>ncurses</EM>,  the  OSF/1  curses
 466               interface is not customized for 32-bit and 64-bit versions.
 467
 468           <STRONG>o</STRONG>   Unlike  other  systems  which  evolved  from  AT&amp;T  code,  OSF/1
 469               provided a new implementation for X/Open curses.
 470
 471           Regarding Solaris,
 472
 473           <STRONG>o</STRONG>   The initial release of Solaris was in 1992.
 474
 475           <STRONG>o</STRONG>   The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
 476               Sun's copyright began in 1996.
 477
 478           <STRONG>o</STRONG>   Sun updated the X/Open curses interface after 64-bit support was
 479               introduced  in  1997,  but  did  not  modify  the  SVr4   curses
 480               interface.
 481
 482           Regarding U/Win,
 483
 484           <STRONG>o</STRONG>   Development  of  the  curses  library  began in 1991, stopped in
 485               2000.
 486
 487           <STRONG>o</STRONG>   Color support was added in 1998.
 488
 489           <STRONG>o</STRONG>   The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).
 490
 491        Once X/Open curses was adopted in the mid-1990s, the  constraint  of  a
 492        32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
 493        a moot point.  The <STRONG>cchar_t</STRONG> structure (whose size and  members  are  not
 494        specified in X/Open Curses) could be extended as needed.
 495
 496        Other interfaces are rarely used now:
 497
 498        <STRONG>o</STRONG>   BSD  curses was improved slightly in 1993/1994 using Keith Bostic's
 499            modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>.  He  moved
 500            <EM>standout</EM> attribute to a structure member.
 501
 502            The  resulting  4.4BSD curses was replaced by <EM>ncurses</EM> over the next
 503            ten years.
 504
 505        <STRONG>o</STRONG>   U/Win is rarely used now.
 506
 507
 508 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
 509        <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>,
 510        <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
 511
 512
 513
 514 ncurses 6.4                       2023-12-16                     <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
 515 </PRE>
 516 <div class="nav">
 517 <ul>
 518 <li><a href="#h2-NAME">NAME</a></li>
 519 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
 520 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
 521 <ul>
 522 <li><a href="#h3-Window-attributes">Window attributes</a></li>
 523 <li><a href="#h3-Legacy-window-attributes">Legacy window attributes</a></li>
 524 <li><a href="#h3-Change-character-rendition">Change character rendition</a></li>
 525 <li><a href="#h3-Change-window-color">Change window color</a></li>
 526 <li><a href="#h3-Standout">Standout</a></li>
 527 <li><a href="#h3-Video-Attributes">Video Attributes</a></li>
 528 </ul>
 529 </li>
 530 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
 531 <li><a href="#h2-NOTES">NOTES</a></li>
 532 <li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
 533 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
 534 <li><a href="#h2-HISTORY">HISTORY</a></li>
 535 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
 536 </ul>
 537 </div>
 538 </BODY>
 539 </HTML>