'\" t
.\"***************************************************************************
-.\" Copyright 2018-2021,2022 Thomas E. Dickey *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
.\" Copyright 1998-2016,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_attr.3x,v 1.74 2023/06/17 17:50:37 tom Exp $
-.TH curs_attr 3X 2023-06-17 "ncurses 6.4" "Library calls"
-.ie \n(.g .ds `` \(lq
-.el .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el .ds '' ''
-.de NS
-.ie n .sp
-.el .sp .5
-.ie n .in +4
-.el .in +2
-.nf
-.ft CR \" Courier
-..
-.de NE
-.fi
-.ft R
-.ie n .in -4
-.el .in -2
-..
+.\" $Id: curs_attr.3x,v 1.96 2024/01/13 22:05:39 tom Exp $
+.TH curs_attr 3X 2024-01-13 "ncurses 6.4" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
.de bP
.ie n .IP \(bu 4
.el .IP \(bu 2
..
-.na
-.hy 0
.\" ---------------------------------------------------------------------------
.SH NAME
-.\" attr_get
-\fBattr_get\fP,
-\fBwattr_get\fP,
-\fBattr_set\fP,
-\fBwattr_set\fP,
-.\" .br
-\fBattr_off\fP,
-\fBwattr_off\fP,
-\fBattr_on\fP,
-\fBwattr_on\fP,
-.\" .br
-\fBattroff\fP,
-\fBwattroff\fP,
-\fBattron\fP,
-\fBwattron\fP,
-\fBattrset\fP,
-\fBwattrset\fP,
-.\" .br
-\fBchgat\fP,
-\fBwchgat\fP,
-\fBmvchgat\fP,
-\fBmvwchgat\fP,
-.\" .br
-\fBcolor_set\fP,
-\fBwcolor_set\fP,
-.\" .br
-\fBstandend\fP,
-\fBwstandend\fP,
-\fBstandout\fP,
-\fBwstandout\fP \- \fBcurses\fP character and window attribute control routines
-.ad
-.hy
+\fB\%attr_get\fP,
+\fB\%wattr_get\fP,
+\fB\%attr_set\fP,
+\fB\%wattr_set\fP,
+\fB\%attr_off\fP,
+\fB\%wattr_off\fP,
+\fB\%attr_on\fP,
+\fB\%wattr_on\fP,
+\fB\%attroff\fP,
+\fB\%wattroff\fP,
+\fB\%attron\fP,
+\fB\%wattron\fP,
+\fB\%attrset\fP,
+\fB\%wattrset\fP,
+\fB\%chgat\fP,
+\fB\%wchgat\fP,
+\fB\%mvchgat\fP,
+\fB\%mvwchgat\fP,
+\fB\%color_set\fP,
+\fB\%wcolor_set\fP,
+\fB\%standend\fP,
+\fB\%wstandend\fP,
+\fB\%standout\fP,
+\fB\%wstandout\fP \-
+manipulate attributes of character cells in \fIcurses\fR windows
.\" ---------------------------------------------------------------------------
.SH SYNOPSIS
-\fB#include <curses.h>\fP
-.sp
-\fBint attr_get(attr_t *\fIattrs\fB, short *\fIpair\fB, void *\fIopts\fB);\fR
-.br
-\fBint wattr_get(WINDOW *\fIwin\fB, attr_t *\fIattrs\fB, short *\fIpair\fB,\fR \fBvoid *\fIopts\fB);\fR
-.br
-\fBint attr_set(attr_t \fIattrs\fB, short \fIpair\fB, void *\fIopts\fB);\fR
-.br
-\fBint wattr_set(WINDOW *\fIwin\fB, attr_t \fIattrs\fB, short \fIpair\fB, void *\fIopts\fB);\fR
-.sp
-\fBint attr_off(attr_t \fIattrs\fB, void *\fIopts\fB);\fR
-.br
-\fBint wattr_off(WINDOW *\fIwin\fB, attr_t \fIattrs\fB, void *\fIopts\fB);\fR
-.br
-\fBint attr_on(attr_t \fIattrs\fB, void *\fIopts\fB);\fR
-.br
-\fBint wattr_on(WINDOW *\fIwin\fB, attr_t \fIattrs\fB, void *\fIopts\fB);\fR
-.sp
-\fBint attroff(int \fIattrs);\fR
-.br
-\fBint wattroff(WINDOW *\fIwin\fB, int \fIattrs\fB);\fR
-.br
-\fBint attron(int \fIattrs\fB);\fR
-.br
-\fBint wattron(WINDOW *\fIwin\fB, int \fIattrs\fB);\fR
-.br
-\fBint attrset(int \fIattrs\fB);\fR
-.br
-\fBint wattrset(WINDOW *\fIwin\fB, int \fIattrs\fB);\fR
-.sp
-\fBint chgat(int \fIn\fB, attr_t \fIattr\fB, short \fIpair\fB,\fR \fBconst void *\fIopts\fB);\fR
-.br
-\fBint wchgat(WINDOW *\fIwin\fB,\fR
+.nf
+\fB#include <curses.h>
+.PP
+\fBint attr_get(attr_t *\fIattrs\fP, short *\fIpair\fP, void *\fIopts\fP);
+\fBint wattr_get(WINDOW *\fIwin\fP, attr_t *\fIattrs\fP, short *\fIpair\fP,\fR \fPvoid *\fIopts\fP);
+\fBint attr_set(attr_t \fIattrs\fP, short \fIpair\fP, void *\fIopts\fP);
+\fBint wattr_set(WINDOW *\fIwin\fP, attr_t \fIattrs\fP, short \fIpair\fP, void *\fIopts\fP);
+.PP
+\fBint attr_off(attr_t \fIattrs\fP, void *\fIopts\fP);
+\fBint wattr_off(WINDOW *\fIwin\fP, attr_t \fIattrs\fP, void *\fIopts\fP);
+\fBint attr_on(attr_t \fIattrs\fP, void *\fIopts\fP);
+\fBint wattr_on(WINDOW *\fIwin\fP, attr_t \fIattrs\fP, void *\fIopts\fP);
+.PP
+\fBint attroff(int \fIattrs\fP);
+\fBint wattroff(WINDOW *\fIwin\fP, int \fIattrs\fP);
+\fBint attron(int \fIattrs\fP);
+\fBint wattron(WINDOW *\fIwin\fP, int \fIattrs\fP);
+\fBint attrset(int \fIattrs\fP);
+\fBint wattrset(WINDOW *\fIwin\fP, int \fIattrs\fP);
+.PP
+\fBint chgat(int \fIn\fP, attr_t \fIattr\fP, short \fIpair\fP,\fR \fPconst void *\fIopts\fP);
+\fBint wchgat(WINDOW *\fIwin\fP,
\fBint \fIn\fB, attr_t \fIattr\fB,\fR \fBshort \fIpair\fB, const void *\fIopts\fB);\fR
-.br
\fBint mvchgat(int \fIy\fB, int \fIx\fB,\fR
- \fBint \fIn\fB, attr_t \fIattr\fB,\fR \fBshort \fIpair\fB, const void *\fIopts\fB);\fR
-.br
-\fBint mvwchgat(WINDOW *\fIwin, int \fIy, int \fIx\fB,\fR
- \fBint \fIn,\fR \fBattr_t \fIattr\fB, short \fIpair\fB, const void *\fIopts\fB);\fR
-.sp
+ \fBint \fIn\fB, attr_t \fIattr\fB, short \fIpair\fB, const void *\fIopts\fB);\fR
+\fBint mvwchgat(WINDOW *\fIwin\fB, int \fIy\fB, int \fIx\fB,\fR
+ \fBint \fIn\fB, attr_t \fIattr\fB, short \fIpair\fB, const void *\fIopts\fB);\fR
+.PP
\fBint color_set(short \fIpair\fB, void* \fIopts\fB);\fR
-.br
-\fBint wcolor_set(WINDOW *\fIwin\fB, short \fIpair\fB,\fR \fBvoid* \fIopts);\fR
-.sp
+\fBint wcolor_set(WINDOW *\fIwin\fB, short \fIpair\fB,\fR \fBvoid* \fIopts\fP);\fR
+.PP
\fBint standend(void);\fP
-.br
\fBint wstandend(WINDOW *\fIwin\fB);\fR
-.br
\fBint standout(void);\fP
-.br
\fBint wstandout(WINDOW *\fIwin\fB);\fR
+.fi
.\" ---------------------------------------------------------------------------
.SH DESCRIPTION
-.PP
These routines manipulate the current attributes of the named window,
which then apply to all characters that are written into
the window with \fBwaddch\fP, \fBwaddstr\fP and \fBwprintw\fP.
when erasing portions of the window.
See \fBcurs_bkgd\fP(3X) for functions which modify the attributes used for
erasing and clearing.
-.PP
-Routines which do not have a \fBWINDOW*\fP parameter apply to \fBstdscr\fP.
-For example,
-\fBattr_set\fP is the \fBstdscr\fP variant of \fBwattr_set\fP.
.\" ---------------------------------------------------------------------------
-.SS Window attributes
-.PP
+.SS "Window Attributes"
There are two sets of functions:
.bP
functions for manipulating the window attributes and color:
again values OR'd together in \fIattr\fP,
without affecting other attributes.
.\" ---------------------------------------------------------------------------
-.SS Legacy window attributes
+.SS "Legacy Window Attributes"
The X/Open window attribute routines which \fIset\fP or \fIget\fP,
turn \fIon\fP or \fIoff\fP
are extensions of older routines
For example,
as long as that value fits into the \fBA_COLOR\fP mask,
then these calls produce similar results:
-.NS
+.PP
+.RS 4
+.EX
attrset(A_BOLD | COLOR_PAIR(\fIpair\fP));
attr_set(A_BOLD, \fIpair\fP, NULL);
-.NE
+.EE
+.RE
.PP
However, if the value does not fit, then the \fBCOLOR_PAIR\fP macro
uses only the bits that fit.
-For example, because in ncurses \fBA_COLOR\fP has eight (8) bits,
+For example,
+because in \fI\%ncurses\fP \fBA_COLOR\fP has eight (8) bits,
then \fBCOLOR_PAIR(\fI259\fB)\fR is 4
(i.e., 259 is 4 more than the limit 255).
.PP
(or \fBchtype\fP).
For example, the \fIinput\fP and \fIoutput\fP values in these statements
would be the same:
-.NS
+.PP
+.RS 4
+.EX
int value = A_BOLD | COLOR_PAIR(\fIinput\fP);
int \fIoutput\fP = PAIR_NUMBER(value);
-.NE
+.EE
+.RE
.PP
The \fBattrset\fP routine is a legacy feature predating SVr4 curses
but kept in X/Open Curses for the same reason that SVr4 curses kept it:
\fBattr_\fP* functions, except that they take arguments of type \fBint\fP
rather than \fBattr_t\fP.
.PP
-There is no corresponding \fBattrget\fP function as such in X/Open Curses,
-although ncurses provides \fBgetattrs\fP (see curs_legacy(3X)).
+There is no corresponding \fB\%attrget\fP function as such
+in X/Open Curses,
+although \fI\%ncurses\fP provides \fB\%getattrs\fP
+(see \fB\%curs_legacy\fP(3X)).
.\" ---------------------------------------------------------------------------
-.SS Change character rendition
-.PP
+.SS "Change Character Rendition"
The routine \fBchgat\fP changes the attributes of a given number of characters
starting at the current cursor location of \fBstdscr\fP.
It does not update
the \fBmvwchgat\fP function does a cursor move before acting.
.PP
In these functions,
-the color \fIpair\fP argument is a color-pair index
+the color \fIpair\fP argument is a color pair index
(as in the first argument of \fBinit_pair\fP, see \fBcurs_color\fP(3X)).
.\" ---------------------------------------------------------------------------
-.SS Change window color
+.SS "Change Window Color"
The routine \fBcolor_set\fP sets the current color of the given window to the
foreground/background combination described by the color \fIpair\fP parameter.
.\" ---------------------------------------------------------------------------
.SS Standout
-.PP
The routine \fBstandout\fP is
the same as \fBattron(A_STANDOUT)\fP.
The routine \fBstandend\fP is the same
there is no ambiguity about the way the attributes
might be combined with a color pair.
.\" ---------------------------------------------------------------------------
-.SH VIDEO ATTRIBUTES
+.SS "Video Attributes"
The following video attributes, defined in \fB<curses.h>\fP, can be passed to
the routines \fBattron\fP, \fBattroff\fP, and \fBattrset\fP, or OR'd with the
characters passed to \fBaddch\fP (see \fBcurs_addch\fP(3X)).
.PP
+.ne 15
.RS
.TS
-l l
-_ _ _
-l l .
-\fBName\fP \fBDescription\fP
-\fBA_NORMAL\fP Normal display (no highlight)
-\fBA_STANDOUT\fP Best highlighting mode of the terminal.
-\fBA_UNDERLINE\fP Underlining
-\fBA_REVERSE\fP Reverse video
-\fBA_BLINK\fP Blinking
-\fBA_DIM\fP Half bright
-\fBA_BOLD\fP Extra bright or bold
-\fBA_PROTECT\fP Protected mode
-\fBA_INVIS\fP Invisible or blank mode
-\fBA_ALTCHARSET\fP Alternate character set
-\fBA_ITALIC\fP Italics (non-X/Open extension)
-\fBA_CHARTEXT\fP Bit-mask to extract a character
-\fBA_COLOR\fP Bit-mask to extract a color (legacy routines)
+Lb Lb
+Lb Lx.
+Name Description
+_
+A_NORMAL Normal display (no highlight)
+A_STANDOUT T{
+Best highlighting mode of the terminal
+T}
+A_UNDERLINE Underlining
+A_REVERSE Reverse video
+A_BLINK Blinking
+A_DIM Half bright
+A_BOLD Extra bright or bold
+A_PROTECT Protected mode
+A_INVIS Invisible or blank mode
+A_ALTCHARSET Alternate character set
+A_ITALIC Italics (non-X/Open extension)
+A_CHARTEXT Bit-mask to extract a character
+A_COLOR T{
+Bit-mask to extract a color (legacy routines)
+T}
.TE
.RE
.PP
These video attributes are supported by \fBattr_on\fP and related functions
(which also support the attributes recognized by \fBattron\fP, etc.):
+.PP
.RS
.TS
-l l
-_ _ _
-l l .
-\fBName\fP \fBDescription\fP
-\fBWA_HORIZONTAL\fP Horizontal highlight
-\fBWA_LEFT\fP Left highlight
-\fBWA_LOW\fP Low highlight
-\fBWA_RIGHT\fP Right highlight
-\fBWA_TOP\fP Top highlight
-\fBWA_VERTICAL\fP Vertical highlight
+Lb Lb
+Lb Lx.
+Name Description
+_
+WA_HORIZONTAL Horizontal highlight
+WA_LEFT Left highlight
+WA_LOW Low highlight
+WA_RIGHT Right highlight
+WA_TOP Top highlight
+WA_VERTICAL Vertical highlight
.TE
.RE
.PP
implemented as macro-expanded assignments and simply return their argument).
The SVr4 manual page claims (falsely) that these routines always return \fB1\fP.
.\" ---------------------------------------------------------------------------
+.SH RETURN VALUE
+All routines return the integer \fBOK\fP on success, or \fBERR\fP on failure.
+.PP
+X/Open does not define any error conditions.
+.PP
+This implementation
+.bP
+returns an error if the window pointer is null.
+.bP
+returns an error if the color pair parameter
+for \fBwcolor_set\fP is outside the range 0..COLOR_PAIRS\-1.
+.bP
+does not return an error if either of the parameters of \fBwattr_get\fP
+used for retrieving attribute or color pair values is \fBNULL\fP.
+.PP
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
+\fBwmove\fP, and return an error if the position is outside the window,
+or if the window pointer is null.
+.\" ---------------------------------------------------------------------------
.SH NOTES
These functions may be macros:
.sp
number is less than 256.
The alternate functions such as \fBcolor_set\fP can pass a color pair
value directly.
-However, ncurses ABI 4 and 5 simply OR this value
+However, \fI\%ncurses\fP 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.
-.\" ---------------------------------------------------------------------------
-.SH HISTORY
-X/Open Curses is largely based on SVr4 curses,
-adding support for \*(``wide-characters\*('' (not specific to Unicode).
-Some of the X/Open differences from SVr4 curses address the way
-video attributes can be applied to wide-characters.
-But aside from that, \fBattrset\fP and \fBattr_set\fP are similar.
-SVr4 curses provided the basic features for manipulating video attributes.
-However, earlier versions of curses provided a part of these features.
-.PP
-As seen in 2.8BSD, curses assumed 7-bit characters,
-using the eighth bit of a byte to represent the \fIstandout\fP
-feature (often implemented as bold and/or reverse video).
-The BSD curses library provided functions \fBstandout\fP and \fBstandend\fP
-which were carried along into X/Open Curses due to their pervasive use
-in legacy applications.
-.PP
-Some terminals in the 1980s could support a variety of video attributes,
-although the BSD curses library could do nothing with those.
-System V (1983) provided an improved curses library.
-It defined the \fBA_\fP symbols for use by applications to manipulate the
-other attributes.
-There are few useful references for the chronology.
-.PP
-Goodheart's book
-\fIUNIX Curses Explained\fP (1991) describes SVr3 (1987),
-commenting on several functions:
-.bP
-the \fBattron\fP, \fBattroff\fP, \fBattrset\fP functions
-(and most of the functions found in SVr4 but not in BSD curses) were
-introduced by System V,
-.bP
-the alternate character set feature with \fBA_ALTCHARSET\fP was
-added in SVr2 and improved in SVr3 (by adding \fBacs_map[]\fP),
-.bP
-\fBstart_color\fP and related color-functions were introduced by System V.3.2,
-.bP
-pads, soft-keys were added in SVr3, and
-.PP
-Goodheart did not mention the background character or the \fBcchar_t\fP type.
-Those are respectively SVr4 and X/Open features.
-He did mention the \fBA_\fP constants, but did not indicate their values.
-Those were not the same in different systems,
-even for those marked as System V.
-.PP
-Different Unix systems used different sizes for the bit-fields in \fBchtype\fP
-for \fIcharacters\fP and \fIcolors\fP, and took into account the different
-integer sizes (32-bit versus 64-bit).
-.PP
-This table showing the number of bits for \fBA_COLOR\fP
-and \fBA_CHARTEXT\fP
-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 alternate character set implementation.
-A 32-bit library can be used on a 64-bit system,
-but not necessarily the reverse.
-.RS
-.TS
-l l l l l l
-_ _ _ _ _ _
-l l l l l l .
-\fBYear\fP \fBSystem\fP \fBArch\fP \fBColor\fP \fBChar\fP \fBNotes\fP
-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 \fBchtype\fP
-.TE
-.RE
-.PP
-Notes:
-.RS 3
-.PP
-Regarding HP-UX,
-.bP
-HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors in 1996.
-.bP
-HP-UX 10.30 (1997) marked \*(``curses_colr\*('' obsolete.
-That version of curses was dropped with HP-UX 11.30 in 2006.
-.PP
-Regarding OSF/1 (and Tru64),
-.bP
-These used 64-bit hardware.
-Like ncurses, the OSF/1 curses interface is not customized for 32-bit
-and 64-bit versions.
-.bP
-Unlike other systems which evolved from AT&T code,
-OSF/1 provided a new implementation for X/Open curses.
-.PP
-Regarding Solaris,
-.bP
-The initial release of Solaris was in 1992.
-.bP
-The \fIxpg4\fP (X/Open) curses was developed by MKS from 1990 to 1995.
-Sun's copyright began in 1996.
-.bP
-Sun updated the X/Open curses interface
-after 64-bit support was introduced in 1997,
-but did not modify the SVr4 curses interface.
-.PP
-Regarding U/Win,
-.bP
-Development of the curses library began in 1991, stopped in 2000.
-.bP
-Color support was added in 1998.
-.bP
-The library uses only \fBchtype\fP (no \fBcchar_t\fP).
-.RE
-.PP
-Once X/Open curses was adopted in the mid-1990s, the constraint of
-a 32-bit interface with many colors and wide-characters for \fBchtype\fP
-became a moot point.
-The \fBcchar_t\fP structure (whose size and
-members are not specified in X/Open Curses) could be extended as needed.
-.PP
-Other interfaces are rarely used now:
-.bP
-BSD curses was improved slightly in 1993/1994 using Keith Bostic's
-modification to make the library 8-bit clean for \fBnvi\fP(1).
-He moved \fIstandout\fP attribute to a structure member.
-.IP
-The resulting 4.4BSD curses was replaced by ncurses over the next ten years.
-.bP
-U/Win is rarely used now.
+You must use \fI\%ncurses\fP ABI 6 to support more than 256 color pairs.
.\" ---------------------------------------------------------------------------
.SH EXTENSIONS
-.PP
This implementation provides the \fBA_ITALIC\fP attribute for terminals
which have the \fBenter_italics_mode\fP (\fBsitm\fP)
and \fBexit_italics_mode\fP (\fBritm\fP) capabilities.
which X/Open Curses still (after more than twenty years) documents
as reserved for future use, saying that it should be \fBNULL\fP.
This implementation uses that parameter in ABI 6 for the functions which
-have a color-pair parameter to support \fIextended color pairs\fP:
+have a color pair parameter to support \fIextended color pairs\fP:
.bP
For functions which modify the color, e.g.,
\fBwattr_set\fP and \fBwattr_on\fP,
except to check that it is \fBNULL\fP.
.\" ---------------------------------------------------------------------------
.SH PORTABILITY
-These functions are supported in the XSI Curses standard, Issue 4.
+These functions are described in the XSI Curses standard, Issue 4.
The standard defined the dedicated type for highlights,
\fBattr_t\fP, which was not defined in SVr4 curses.
The functions taking \fBattr_t\fP arguments were not supported under SVr4.
.RS
.ne 9
.TS
-l l
-_ _ _
-l l .
-\fBName\fP \fBDescription\fP
-\fBWA_NORMAL\fP Normal display (no highlight)
-\fBWA_STANDOUT\fP Best highlighting mode of the terminal.
-\fBWA_UNDERLINE\fP Underlining
-\fBWA_REVERSE\fP Reverse video
-\fBWA_BLINK\fP Blinking
-\fBWA_DIM\fP Half bright
-\fBWA_BOLD\fP Extra bright or bold
-\fBWA_ALTCHARSET\fP Alternate character set
+Lb Lb
+Lb Lx.
+Name Description
+_
+WA_NORMAL Normal display (no highlight)
+WA_STANDOUT T{
+Best highlighting mode of the terminal
+T}
+WA_UNDERLINE Underlining
+WA_REVERSE Reverse video
+WA_BLINK Blinking
+WA_DIM Half bright
+WA_BOLD Extra bright or bold
+WA_ALTCHARSET Alternate character set
.TE
.RE
.PP
the same because it simplifies copying information between
\fBchtype\fP and \fBcchar_t\fP variables.
.bP
-Because ncurses's \fBattr_t\fP can hold a color pair
+Because \fI\%ncurses\fP's \fBattr_t\fP can hold a color pair
(in the \fBA_COLOR\fP field),
a call to
\fBwattr_on\fP,
no known terminal provides these highlights
(i.e., via the \fBsgr1\fP capability).
.\" ---------------------------------------------------------------------------
-.SH RETURN VALUE
-All routines return the integer \fBOK\fP on success, or \fBERR\fP on failure.
+.SH HISTORY
+X/Open Curses is largely based on SVr4 curses,
+adding support for \*(``wide-characters\*('' (not specific to Unicode).
+Some of the X/Open differences from SVr4 curses address the way
+video attributes can be applied to wide-characters.
+But aside from that, \fBattrset\fP and \fBattr_set\fP are similar.
+SVr4 curses provided the basic features for manipulating video attributes.
+However, earlier versions of curses provided a part of these features.
.PP
-X/Open does not define any error conditions.
+As seen in 2.8BSD, curses assumed 7-bit characters,
+using the eighth bit of a byte to represent the \fIstandout\fP
+feature (often implemented as bold and/or reverse video).
+The BSD curses library provided functions \fBstandout\fP and \fBstandend\fP
+which were carried along into X/Open Curses due to their pervasive use
+in legacy applications.
.PP
-This implementation
+Some terminals in the 1980s could support a variety of video attributes,
+although the BSD curses library could do nothing with those.
+System V (1983) provided an improved curses library.
+It defined the \fBA_\fP symbols for use by applications to manipulate the
+other attributes.
+There are few useful references for the chronology.
+.PP
+Goodheart's book
+\fIUNIX Curses Explained\fP (1991) describes SVr3 (1987),
+commenting on several functions:
.bP
-returns an error if the window pointer is null.
+the \fBattron\fP, \fBattroff\fP, \fBattrset\fP functions
+(and most of the functions found in SVr4 but not in BSD curses) were
+introduced by System V,
.bP
-returns an error if the color pair parameter
-for \fBwcolor_set\fP is outside the range 0..COLOR_PAIRS\-1.
+the alternate character set feature with \fBA_ALTCHARSET\fP was
+added in SVr2 and improved in SVr3 (by adding \fBacs_map[]\fP),
.bP
-does not return an error if either of the parameters of \fBwattr_get\fP
-used for retrieving attribute or color-pair values is \fBNULL\fP.
+\fBstart_color\fP and related color-functions were introduced by System V.3.2,
+.bP
+pads, soft-keys were added in SVr3, and
.PP
-Functions with a \*(``mv\*('' prefix first perform a cursor movement using
-\fBwmove\fP, and return an error if the position is outside the window,
-or if the window pointer is null.
+Goodheart did not mention the background character or the \fBcchar_t\fP type.
+Those are respectively SVr4 and X/Open features.
+He did mention the \fBA_\fP constants, but did not indicate their values.
+Those were not the same in different systems,
+even for those marked as System V.
+.PP
+Different Unix systems used different sizes for the bit-fields in \fBchtype\fP
+for \fIcharacters\fP and \fIcolors\fP, and took into account the different
+integer sizes (32-bit versus 64-bit).
+.PP
+This table showing the number of bits for \fBA_COLOR\fP
+and \fBA_CHARTEXT\fP
+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 alternate character set implementation.
+A 32-bit library can be used on a 64-bit system,
+but not necessarily the reverse.
+.PP
+.TS
+Lb Lb Lb Cb S Lb
+Lb2 Lb Lb2 Lbz Lb2 Lb
+L L L L L Lx.
+\& \& \& Bits \&
+Year System Arch Color Char Notes
+_
+1992 Solaris 5.2 32 6 17 SVr4 \fIcurses\fP
+1992 HP-UX 9 32 no 8 SVr2 \fIcurses\fP
+1992 AIX 3.2 32 no 23 SVr2 \fIcurses\fP
+1994 OSF/1 r3 32 no 23 SVr2 \fIcurses\fP
+1995 HP-UX 10.00 32 6 16 SVr3 \fIcurses_colr\fP
+1995 HP-UX 10.00 32 6 8 SVr4, X/Open \fIcurses\fP
+1995 Solaris 5.4 32/64 7 16 X/Open \fIcurses\fP
+1996 AIX 4.2 32 7 16 X/Open \fIcurses\fP
+1996 OSF/1 r4 32 6 16 X/Open \fIcurses\fP
+1997 HP-UX 11.00 32 6 8 X/Open \fIcurses\fP
+2000 U/Win 32/64 7/31 16 uses \fIchtype\fP
+.TE
+.PP
+Notes:
+.RS 3
+.PP
+Regarding HP-UX,
+.bP
+HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors in 1996.
+.bP
+HP-UX 10.30 (1997) marked \*(``curses_colr\*('' obsolete.
+That version of curses was dropped with HP-UX 11.30 in 2006.
+.PP
+Regarding OSF/1 (and Tru64),
+.bP
+These used 64-bit hardware.
+Like \fI\%ncurses\fP,
+the OSF/1 curses interface is not customized for 32-bit and 64-bit
+versions.
+.bP
+Unlike other systems which evolved from AT&T code,
+OSF/1 provided a new implementation for X/Open curses.
+.PP
+Regarding Solaris,
+.bP
+The initial release of Solaris was in 1992.
+.bP
+The \fIxpg4\fP (X/Open) curses was developed by MKS from 1990 to 1995.
+Sun's copyright began in 1996.
+.bP
+Sun updated the X/Open curses interface
+after 64-bit support was introduced in 1997,
+but did not modify the SVr4 curses interface.
+.PP
+Regarding U/Win,
+.bP
+Development of the curses library began in 1991, stopped in 2000.
+.bP
+Color support was added in 1998.
+.bP
+The library uses only \fBchtype\fP (no \fBcchar_t\fP).
+.RE
+.PP
+Once X/Open curses was adopted in the mid-1990s, the constraint of
+a 32-bit interface with many colors and wide-characters for \fBchtype\fP
+became a moot point.
+The \fBcchar_t\fP structure (whose size and
+members are not specified in X/Open Curses) could be extended as needed.
+.PP
+Other interfaces are rarely used now:
+.bP
+BSD curses was improved slightly in 1993/1994 using Keith Bostic's
+modification to make the library 8-bit clean for \fBnvi\fP(1).
+He moved \fIstandout\fP attribute to a structure member.
+.IP
+The resulting 4.4BSD curses was replaced by \fI\%ncurses\fP over the
+next ten years.
+.bP
+U/Win is rarely used now.
.\" ---------------------------------------------------------------------------
.SH SEE ALSO
-.na
-\fBcurses\fP(3X),
-\fBcurs_addch\fP(3X),
-\fBcurs_addstr\fP(3X),
-\fBcurs_bkgd\fP(3X),
-\fBcurs_printw\fP(3X),
-\fBcurs_variables\fP(3X)
+\fB\%curses\fP(3X),
+\fB\%curs_addch\fP(3X),
+\fB\%curs_addstr\fP(3X),
+\fB\%curs_bkgd\fP(3X),
+\fB\%curs_printw\fP(3X),
+\fB\%curs_variables\fP(3X)