+ <STRONG>o</STRONG> functions for manipulating only the window attributes (not color):
+ <STRONG>wattr_on</STRONG> and <STRONG>wattr_off</STRONG>.
+
+ The <STRONG>wattr_set</STRONG> function sets the current attributes of the given window
+ to <EM>attrs</EM>, with color specified by <EM>pair</EM>.
+
+ Use <STRONG>wattr_get</STRONG> to retrieve attributes for the given window.
+
+ Use <STRONG>attr_on</STRONG> and <STRONG>wattr_on</STRONG> to turn on window attributes, i.e., values
+ OR'd together in <EM>attr</EM>, without affecting other attributes. Use <STRONG>at-</STRONG>
+ <STRONG>tr_off</STRONG> and <STRONG>wattr_off</STRONG> to turn off window attributes, again values OR'd
+ together in <EM>attr</EM>, without affecting other attributes.
+
+
+</PRE><H3><a name="h3-Legacy-window-attributes">Legacy window attributes</a></H3><PRE>
+ The X/Open window attribute routines which <EM>set</EM> or <EM>get</EM>, turn <EM>on</EM> or <EM>off</EM>
+ are extensions of older routines which assume that color pairs are OR'd
+ into the attribute parameter. These newer routines use similar names,
+ because X/Open simply added an underscore (<STRONG>_</STRONG>) for the newer names.
+
+ The <STRONG>int</STRONG> datatype used in the legacy routines is treated as if it is the
+ same size as <STRONG>chtype</STRONG> (used by <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>). It holds the common video at-
+ tributes (such as bold, reverse), as well as a few bits for color.
+ Those bits correspond to the <STRONG>A_COLOR</STRONG> symbol. The <STRONG>COLOR_PAIR</STRONG> macro pro-
+ vides a value which can be OR'd into the attribute parameter. For ex-
+ ample, as long as that value fits into the <STRONG>A_COLOR</STRONG> mask, then these
+ calls produce similar results:
+
+ attrset(A_BOLD | COLOR_PAIR(<EM>pair</EM>));
+ attr_set(A_BOLD, <EM>pair</EM>, NULL);
+
+ However, if the value does not fit, then the <STRONG>COLOR_PAIR</STRONG> macro uses only
+ the bits that fit. For example, because in ncurses <STRONG>A_COLOR</STRONG> has eight
+ (8) bits, then <STRONG>COLOR_PAIR(</STRONG><EM>259</EM><STRONG>)</STRONG> is 4 (i.e., 259 is 4 more than the limit
+ 255).
+
+ The <STRONG>PAIR_NUMBER</STRONG> macro extracts a pair number from an <STRONG>int</STRONG> (or <STRONG>chtype</STRONG>).
+ For example, the <EM>input</EM> and <EM>output</EM> values in these statements would be
+ the same:
+
+ int value = A_BOLD | COLOR_PAIR(<EM>input</EM>);
+ int <EM>output</EM> = PAIR_NUMBER(value);
+
+ The <STRONG>attrset</STRONG> routine is a legacy feature predating SVr4 curses but kept
+ in X/Open Curses for the same reason that SVr4 curses kept it: compati-
+ bility.
+
+ The remaining <STRONG>attr</STRONG>* functions operate exactly like the corresponding
+ <STRONG>attr_</STRONG>* functions, except that they take arguments of type <STRONG>int</STRONG> rather
+ than <STRONG>attr_t</STRONG>.
+
+ There is no corresponding <STRONG>attrget</STRONG> function as such in X/Open Curses,
+ although ncurses provides <STRONG>getattrs</STRONG> (see <STRONG><A HREF="curs_legacy.3x.html">curs_legacy(3x)</A></STRONG>).
+
+
+</PRE><H3><a name="h3-Change-character-rendition">Change character rendition</a></H3><PRE>
+ The routine <STRONG>chgat</STRONG> changes the attributes of a given number of charac-
+ ters starting at the current cursor location of <STRONG>stdscr</STRONG>. It does not
+ update the cursor and does not perform wrapping. A character count of
+ -1 or greater than the remaining window width means to change at-
+ tributes all the way to the end of the current line. The <STRONG>wchgat</STRONG> func-
+ tion generalizes this to any window; the <STRONG>mvwchgat</STRONG> function does a cur-
+ sor move before acting.
+
+ In these functions, the color <EM>pair</EM> argument is a color-pair index (as
+ in the first argument of <STRONG>init_pair</STRONG>, see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>).
+
+
+</PRE><H3><a name="h3-Change-window-color">Change window color</a></H3><PRE>
+ The routine <STRONG>color_set</STRONG> sets the current color of the given window to the
+ foreground/background combination described by the color <EM>pair</EM> parame-
+ ter.
+
+
+</PRE><H3><a name="h3-Standout">Standout</a></H3><PRE>
+ The routine <STRONG>standout</STRONG> is the same as <STRONG>attron(A_STANDOUT)</STRONG>. The routine
+ <STRONG>standend</STRONG> is the same as <STRONG>attrset(A_NORMAL)</STRONG> or <STRONG>attrset(0)</STRONG>, that is, it
+ turns off all attributes.
+
+ X/Open does not mark these "restricted", because
+
+ <STRONG>o</STRONG> they have well established legacy use, and
+
+ <STRONG>o</STRONG> there is no ambiguity about the way the attributes might be com-
+ bined with a color pair.
+
+
+</PRE><H2><a name="h2-VIDEO-ATTRIBUTES">VIDEO ATTRIBUTES</a></H2><PRE>
+ The following video attributes, defined in <STRONG><curses.h></STRONG>, can be passed to
+ the routines <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, and <STRONG>attrset</STRONG>, or OR'd with the characters
+ passed to <STRONG>addch</STRONG> (see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>).
+
+ <EM>Name</EM> <EM>Description</EM>
+ -----------------------------------------------------------------
+ <STRONG>A_NORMAL</STRONG> Normal display (no highlight)
+ <STRONG>A_STANDOUT</STRONG> Best highlighting mode of the terminal.
+ <STRONG>A_UNDERLINE</STRONG> Underlining
+ <STRONG>A_REVERSE</STRONG> Reverse video
+ <STRONG>A_BLINK</STRONG> Blinking
+ <STRONG>A_DIM</STRONG> Half bright
+ <STRONG>A_BOLD</STRONG> Extra bright or bold
+ <STRONG>A_PROTECT</STRONG> Protected mode
+ <STRONG>A_INVIS</STRONG> Invisible or blank mode
+ <STRONG>A_ALTCHARSET</STRONG> Alternate character set
+ <STRONG>A_ITALIC</STRONG> Italics (non-X/Open extension)
+ <STRONG>A_CHARTEXT</STRONG> Bit-mask to extract a character
+ <STRONG>A_COLOR</STRONG> Bit-mask to extract a color (legacy routines)
+
+ These video attributes are supported by <STRONG>attr_on</STRONG> and related functions
+ (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):
+
+ <EM>Name</EM> <EM>Description</EM>
+ -----------------------------------------
+ <STRONG>WA_HORIZONTAL</STRONG> Horizontal highlight
+ <STRONG>WA_LEFT</STRONG> Left highlight
+ <STRONG>WA_LOW</STRONG> Low highlight
+ <STRONG>WA_RIGHT</STRONG> Right highlight
+ <STRONG>WA_TOP</STRONG> Top highlight
+ <STRONG>WA_VERTICAL</STRONG> Vertical highlight
+
+ The return values of many of these routines are not meaningful (they
+ are implemented as macro-expanded assignments and simply return their
+ argument). The SVr4 manual page claims (falsely) that these routines
+ always return <STRONG>1</STRONG>.
+
+
+</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
+ These functions may be macros:
+
+ <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>standend</STRONG>
+ and <STRONG>standout</STRONG>.
+
+ Color pair values can only be OR'd with attributes if the pair number
+ is less than 256. The alternate functions such as <STRONG>color_set</STRONG> can pass a
+ color pair value directly. However, ncurses ABI 4 and 5 simply OR this
+ value within the alternate functions. You must use ncurses ABI 6 to
+ support more than 256 color pairs.
+
+
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ X/Open Curses is largely based on SVr4 curses, adding support for
+ "wide-characters" (not specific to Unicode). Some of the X/Open dif-
+ ferences from SVr4 curses address the way video attributes can be ap-
+ plied to wide-characters. But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
+ are similar. SVr4 curses provided the basic features for manipulating
+ video attributes. However, earlier versions of curses provided a part
+ of these features.
+
+ As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth
+ bit of a byte to represent the <EM>standout</EM> feature (often implemented as
+ bold and/or reverse video). The BSD curses library provided functions
+ <STRONG>standout</STRONG> and <STRONG>standend</STRONG> which were carried along into X/Open Curses due
+ to their pervasive use in legacy applications.
+
+ Some terminals in the 1980s could support a variety of video at-
+ tributes, although the BSD curses library could do nothing with those.
+ System V (1983) provided an improved curses library. It defined the <STRONG>A_</STRONG>
+ symbols for use by applications to manipulate the other attributes.
+ There are few useful references for the chronology.
+
+ Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991) describes SVr3 (1987),
+ commenting on several functions:
+
+ <STRONG>o</STRONG> the <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
+ found in SVr4 but not in BSD curses) were introduced by System V,
+
+ <STRONG>o</STRONG> the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added in
+ SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),
+
+ <STRONG>o</STRONG> <STRONG>start_color</STRONG> and related color-functions were introduced by System
+ V.3.2,
+
+ <STRONG>o</STRONG> pads, soft-keys were added in SVr3, and
+
+ Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
+ Those are respectively SVr4 and X/Open features. He did mention the <STRONG>A_</STRONG>
+ constants, but did not indicate their values. Those were not the same
+ in different systems, even for those marked as System V.
+
+ Different Unix systems used different sizes for the bit-fields in
+ <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account the different
+ integer sizes (32-bit versus 64-bit).
+
+ This table showing the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
+ gleaned from the curses header files for various operating systems and
+ architectures. The inferred architecture and notes reflect the format
+ and size of the defined constants as well as clues such as the alter-
+ nate character set implementation. A 32-bit library can be used on a
+ 64-bit system, but not necessarily the reverse.
+
+ <EM>Year</EM> <EM>System</EM> <EM>Arch</EM> <EM>Color</EM> <EM>Char</EM> <EM>Notes</EM>
+ ----------------------------------------------------------------
+ 1992 Solaris 5.2 32 6 17 SVr4 curses
+ 1992 HPUX 9 32 no 8 SVr2 curses
+ 1992 AIX 3.2 32 no 23 SVr2 curses
+ 1994 OSF/1 r3 32 no 23 SVr2 curses
+ 1995 HP-UX 10.00 32 6 16 SVr3 "curses_colr"
+ 1995 HP-UX 10.00 32 6 8 SVr4, X/Open curses
+ 1995 Solaris 5.4 32/64 7 16 X/Open curses
+ 1996 AIX 4.2 32 7 16 X/Open curses
+ 1996 OSF/1 r4 32 6 16 X/Open curses
+
+ 1997 HP-UX 11.00 32 6 8 X/Open curses
+ 2000 U/Win 32/64 7/31 16 uses <STRONG>chtype</STRONG>
+
+ Notes:
+
+ Regarding HP-UX,
+
+ <STRONG>o</STRONG> HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
+ in 1996.
+
+ <STRONG>o</STRONG> HP-UX 10.30 (1997) marked "curses_colr" obsolete. That version
+ of curses was dropped with HP-UX 11.30 in 2006.
+
+ Regarding OSF/1 (and Tru64),
+
+ <STRONG>o</STRONG> These used 64-bit hardware. Like ncurses, the OSF/1 curses in-
+ terface is not customized for 32-bit and 64-bit versions.
+
+ <STRONG>o</STRONG> Unlike other systems which evolved from AT&T code, OSF/1 provid-
+ ed a new implementation for X/Open curses.