.\"***************************************************************************
-.\" Copyright (c) 1998-2010,2015 Free Software Foundation, Inc. *
+.\" 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 *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_color.3x,v 1.39 2015/06/06 23:29:02 tom Exp $
-.TH curs_color 3X ""
-.ie \n(.g .ds `` \(lq
-.el .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el .ds '' ''
+.\" $Id: curs_color.3x,v 1.100 2024/04/20 21:24:19 tom Exp $
+.TH curs_color 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
-.ds n 5
-.na
-.hy 0
+.
.SH NAME
-\fBstart_color\fR,
-\fBinit_pair\fR,
-\fBinit_color\fR,
-\fBhas_colors\fR,
-\fBcan_change_color\fR,
-\fBcolor_content\fR,
-\fBpair_content\fR,
-\fBCOLOR_PAIR\fR \- \fBcurses\fR color manipulation routines
-.ad
-.hy
+\fB\%start_color\fP,
+\fB\%has_colors\fP,
+\fB\%can_change_color\fP,
+\fB\%init_pair\fP,
+\fB\%init_color\fP,
+\fB\%init_extended_pair\fP,
+\fB\%init_extended_color\fP,
+\fB\%color_content\fP,
+\fB\%pair_content\fP,
+\fB\%extended_color_content\fP,
+\fB\%extended_pair_content\fP,
+\fB\%reset_color_pairs\fP,
+\fB\%COLOR_PAIR\fP,
+\fB\%PAIR_NUMBER\fP,
+\fB\%COLORS\fP,
+\fB\%COLOR_PAIRS\fP,
+\fB\%COLOR_BLACK\fP,
+\fB\%COLOR_RED\fP,
+\fB\%COLOR_GREEN\fP,
+\fB\%COLOR_YELLOW\fP,
+\fB\%COLOR_BLUE\fP,
+\fB\%COLOR_MAGENTA\fP,
+\fB\%COLOR_CYAN\fP,
+\fB\%COLOR_WHITE\fP \-
+manipulate terminal colors with \fIcurses\fR
.SH SYNOPSIS
-\fB# include <curses.h>\fR
-.sp
-\fBint start_color(void);\fR
-.br
-\fBint init_pair(short pair, short f, short b);\fR
-.br
-\fBint init_color(short color, short r, short g, short b);\fR
-.br
-\fBbool has_colors(void);\fR
-.br
-\fBbool can_change_color(void);\fR
-.br
-\fBint color_content(short color, short *r, short *g, short *b);\fR
-.br
-\fBint pair_content(short pair, short *f, short *b);\fR
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fI/* variables */
+\fBint COLOR_PAIRS;
+\fBint COLORS;
+.PP
+\fBint start_color(void);
+.PP
+\fBbool has_colors(void);
+\fBbool can_change_color(void);
+.PP
+\fBint init_pair(short \fIpair\fP, short \fIf\fP, short \fIb\fP);
+\fBint init_color(short \fIcolor\fP, short \fIr\fP, short \fIg\fP, short \fIb\fP);
+\fI/* extensions */
+\fBint init_extended_pair(int \fIpair\fP, int \fIf\fP, int \fIb\fP);
+\fBint init_extended_color(int \fIcolor\fP, int \fIr\fP, int \fIg\fP, int \fIb\fP);
+.PP
+\fBint color_content(short \fIcolor\fP, short *\fIr\fP, short *\fIg\fP, short *\fIb\fP);
+\fBint pair_content(short \fIpair\fP, short *\fIf\fP, short *\fIb\fP);
+\fI/* extensions */
+\fBint extended_color_content(int \fIcolor\fP, int *\fIr\fP, int *\fIg\fP, int *\fIb\fP);
+\fBint extended_pair_content(int \fIpair\fP, int *\fIf\fP, int *\fIb\fP);
+.PP
+\fI/* extension */
+\fBvoid reset_color_pairs(void);
+.PP
+\fBint COLOR_PAIR(int \fIn\fP);
+\fBPAIR_NUMBER(int \fIattr\fP);
+.fi
.SH DESCRIPTION
.SS Overview
-\fBcurses\fR supports color attributes on terminals with that capability.
-To use these routines \fBstart_color\fR must be called, usually right after
-\fBinitscr\fR.
-Colors are always used in pairs (referred to as color-pairs).
-A color-pair consists of a foreground color (for characters) and a background
-color (for the blank field on which the characters are displayed).
-A programmer initializes a color-pair with the routine \fBinit_pair\fR.
-After it has been initialized, \fBCOLOR_PAIR\fR(\fIn\fR), a macro defined in
-\fB<curses.h>\fR, can be used as a new video attribute.
-.PP
-If a terminal is capable of redefining colors, the programmer can use the
-routine \fBinit_color\fR to change the definition of a color.
-The routines \fBhas_colors\fR and \fBcan_change_color\fR
-return \fBTRUE\fR or \fBFALSE\fR,
-depending on whether the terminal has color capabilities and whether the
+\fIcurses\fP supports color attributes on terminals with that
+capability.
+Call \fB\%start_color\fP
+(typically right after \fB\%initscr\fP(3X))
+to enable this feature.
+Colors are always used in pairs.
+A
+.I "color pair"
+couples a foreground color for characters with a background color for
+the blank field on which characters are rendered.
+\fB\%init_pair\fP initializes a color pair.
+The macro \fB\%COLOR_PAIR\fP(\fIn\fP) can then convert the pair to a
+video attribute.
+.PP
+If a terminal has the relevant capability,
+\fB\%init_color\fP permits (re)definition of a color.
+\fB\%has_colors\fP and \fB\%can_change_color\fP
+return \fBTRUE\fP or \fBFALSE\fP,
+depending on whether the terminal has color capability and whether the
programmer can change the colors.
-The routine \fBcolor_content\fR allows a
-programmer to extract the amounts of red, green, and blue components in an
-initialized color.
-The routine \fBpair_content\fR allows a programmer to find
-out how a given color-pair is currently defined.
-.SS Color Rendering
-The \fBcurses\fP library combines these inputs to produce the
-actual foreground and background colors shown on the screen:
+\fB\%color_content\fP permits extraction of the
+red,
+green,
+and blue components of an initialized color.
+\fB\%pair_content\fP permits discovery of a color pair's current
+definition.
+.SS Rendering
+.I curses
+combines the following data to render a character cell.
+Any of them can include color information.
.bP
-per-character video attributes (e.g., via \fBwaddch\fP),
+.I curses
+character attributes,
+as from \fB\%waddch\fP(3X) or \fB\%wadd_wch\fP(3X)
.bP
-the window attribute (e.g., by \fBwattrset\fP), and
+window attributes,
+as from \fB\%wattrset\fP(3X) or \fB\%wattr_set\fP(3X)
.bP
-the background character (e.g., \fBwbkgdset\fP).
+window background character attributes,
+as from \fB\%wbkgdset\fP(3X) or \fB\%wbkgrndset\fP(3X)
.PP
-Per-character and window attributes are usually set by a parameter containing
-video attributes including a \fBCOLOR_PAIR\fP value.
-Some functions such as \fBwattr_set\fP use a separate parameter which
-is the color pair number.
+Per-character and window attributes are usually set through a function
+parameter containing attributes including a color pair value.
+Some functions,
+such as \fB\%wattr_set\fP,
+use a separate color pair number parameter.
.PP
-The background character is a special case: it includes a character value,
-just as if it were passed to \fBwaddch\fP.
+The background character is a special case:
+it includes a character code,
+just as if it were passed to \fB\%waddch\fP.
.PP
-The \fBcurses\fP library does the actual work of combining these color
-pairs in an internal function called from \fBwaddch\fP:
+The \fIcurses\fP library does the actual work of combining these color
+pairs in an internal function called from \fB\%waddch\fP:
.bP
-If the parameter passed to \fBwaddch\fP is \fIblank\fP,
+If the parameter passed to \fB\%waddch\fP is \fIblank\fP,
and it uses the special color pair 0,
.RS
.bP
-\fBcurses\fP next checks the window attribute.
+\fIcurses\fP next checks the window attribute.
.bP
If the window attribute does not use color pair 0,
-\fBcurses\fP uses the color pair from the window attribute.
+\fIcurses\fP uses the color pair from the window attribute.
.bP
-Otherwise, \fBcurses\fP uses the background character.
+Otherwise, \fIcurses\fP uses the background character.
.RE
.bP
-If the parameter passed to \fBwaddch\fP is \fInot blank\fP,
+If the parameter passed to \fB\%waddch\fP is \fInot blank\fP,
or it does not use the special color pair 0,
-\fBcurses\fP prefers the color pair from the parameter,
+\fIcurses\fP prefers the color pair from the parameter,
if it is nonzero.
Otherwise, it tries the window attribute next, and finally the
background character.
.PP
-Some \fBcurses\fP functions such as \fBwprintw\fP call \fBwaddch\fP.
+Some \fIcurses\fP functions such as \fB\%wprintw\fP call \fB\%waddch\fP.
Those do not combine its parameter with a color pair.
Consequently those calls use only the window attribute or
the background character.
-.SS Routine Descriptions
-The \fBstart_color\fR routine requires no arguments.
+.SH CONSTANTS
+In \fB\%<curses.h>\fP the following macros are defined.
+These are the standard colors (ISO-6429).
+\fIcurses\fP also assumes that \fB\%COLOR_BLACK\fP is the default
+background color for all terminals.
+.PP
+.nf
+ \fBCOLOR_BLACK\fP
+ \fBCOLOR_RED\fP
+ \fBCOLOR_GREEN\fP
+ \fBCOLOR_YELLOW\fP
+ \fBCOLOR_BLUE\fP
+ \fBCOLOR_MAGENTA\fP
+ \fBCOLOR_CYAN\fP
+ \fBCOLOR_WHITE\fP
+.fi
+.PP
+Some terminals support more than the eight (8) \*(``ANSI\*('' colors.
+There are no standard names for those additional colors.
+.SH VARIABLES
+.SS COLORS
+is initialized by \fB\%start_color\fP to the maximum number of colors
+the terminal can support.
+.SS COLOR_PAIRS
+is initialized by \fB\%start_color\fP to the maximum number of color
+pairs the terminal can support.
+Often,
+its value is the product \fB\%COLORS\fP \(mu \fB\%COLORS\fP,
+but this is not always true.
+.bP
+A few terminals use the HLS color space
+(see \fB\%start_color\fP below),
+ignoring this rule;
+and
+.bP
+terminals supporting a large number of colors are limited to the number
+of color pairs that a
+.I "signed short"
+value can represent.
+.SH FUNCTIONS
+.SS start_color
+The \fB\%start_color\fP routine requires no arguments.
It must be called if the programmer wants to use colors, and before any other
color manipulation routine is called.
-It is good practice to call this routine right after \fBinitscr\fR.
-\fBstart_color\fR does this:
+It is good practice to call this routine right after \fB\%initscr\fP.
+\fB\%start_color\fP does this:
.bP
-It initializes two global variables, \fBCOLORS\fR and
-\fBCOLOR_PAIRS\fR (respectively defining the maximum number of colors
-and color-pairs the terminal can support).
+It initializes two global variables, \fB\%COLORS\fP and
+\fB\%COLOR_PAIRS\fP (respectively defining the maximum number of colors
+and color pairs the terminal can support).
.bP
-It initializes the special color pair \fB0\fP to the default foreground
+It initializes the special color pair \fB\%0\fP to the default foreground
and background colors.
No other color pairs are initialized.
.bP
It restores the colors on the terminal to the values
they had when the terminal was just turned on.
.bP
-If the terminal supports the \fBinitc\fP (\fBinitialize_color\fP) capability,
-\fBstart_color\fP
+If the terminal supports the \fBinitc\fP \%(\fBinitialize_color\fP) capability,
+\fB\%start_color\fP
initializes its internal table representing the
-red, green and blue components of the color palette.
+red, green, and blue components of the color palette.
.IP
The components depend on whether the terminal uses
-CGA (aka "ANSI") or
-HLS (i.e., the \fBhls\fP (\fBhue_lightness_saturation\fP) capability is set).
+CGA (aka \*(``ANSI\*('') or
+HLS (i.e., the \fBhls\fP \%(\fBhue_lightness_saturation\fP) capability is set).
The table is initialized first for eight basic colors
(black, red, green, yellow, blue, magenta, cyan, and white),
-and after that (if the terminal supports more than eight colors)
-the components are initialized to \fB1000\fP.
+using weights that depend upon the CGA/HLS choice.
+For \*(``ANSI\*('' colors the weights are \fB680\fP or \fB0\fP
+depending on whether the corresponding
+red, green, or blue component is used or not.
+That permits using \fB1000\fP to represent bold/bright colors.
+After the initial eight colors
+(if the terminal supports more than eight colors)
+the components are initialized using the same pattern,
+but with weights of \fB1000\fP.
+SVr4 uses a similar scheme, but uses \fB1000\fP
+for the components of the initial eight colors.
.IP
-\fBstart_color\fP does not attempt to set the terminal's color palette
+\fB\%start_color\fP does not attempt to set the terminal's color palette
to match its built-in table.
-An application may use \fBinit_color\fP to alter the internal table
+An application may use \fB\%init_color\fP to alter the internal table
along with the terminal's color.
.PP
These limits apply to color values and color pairs.
-Values outside these limits are not legal, and may result in a runtime error:
+Values outside these limits are not valid, and may result in a runtime error:
.bP
-\fBCOLORS\fP corresponds to the terminal database's \fBmax_colors\fP capability,
-which is typically a signed 16-bit integer (see \fBterminfo\fR(\*n)).
+\fBCOLORS\fP corresponds to the terminal database's \fB\%max_colors\fP capability,
+(see \fB\%terminfo\fP(5)).
.bP
-color values are expected to be in the range \fB0\fP to \fBCOLORS\-1\fP,
-inclusive (including \fB0\fP and \fBCOLORS\-1\fP).
+color values are expected to be in the range \fB0\fP to \fB\%COLORS\-1\fP,
+inclusive (including \fB0\fP and \fB\%COLORS\-1\fP).
.bP
a special color value \fB\-1\fP is used in certain extended functions
-to denote the \fIdefault color\fP (see \fBuse_default_colors\fP).
+to denote the \fIdefault color\fP (see \fB\%use_default_colors\fP(3X)).
.bP
-\fBCOLOR_PAIRS\fP corresponds to the terminal database's \fBmax_pairs\fP capability,
-which is typically a signed 16-bit integer (see \fBterminfo\fR(\*n)).
+\fB\%COLOR_PAIRS\fP corresponds to
+the terminal database's \fB\%max_pairs\fP capability,
+(see \fB\%terminfo\fP(5)).
.bP
-legal color pair values are in the range \fB1\fP to \fBCOLOR_PAIRS\-1\fP,
+valid color pair values are in the range \fB1\fP to \fB\%COLOR_PAIRS\-1\fP,
inclusive.
.bP
color pair \fB0\fP is special; it denotes \*(``no color\*(''.
Color pair \fB0\fP is assumed to be white on black,
but is actually whatever the terminal implements before color is initialized.
It cannot be modified by the application.
-.PP
-The \fBinit_pair\fR routine changes the definition of a color-pair.
-It takes three arguments: the number of the color-pair to be changed, the foreground
+.SS has_colors
+The \fB\%has_colors\fP routine requires no arguments.
+It returns \fBTRUE\fP if
+the terminal can manipulate colors; otherwise, it returns \fBFALSE\fP.
+This routine facilitates writing terminal-independent programs.
+For example, a programmer can use it to decide
+whether to use color or some other video attribute.
+.SS can_change_color
+The \fB\%can_change_color\fP routine requires no arguments.
+It returns \fBTRUE\fP if the terminal supports colors
+and can change their definitions;
+other, it returns \fBFALSE\fP.
+This routine facilitates writing terminal-independent programs.
+.SS init_pair
+The \fB\%init_pair\fP routine changes the definition of a color pair.
+It takes three arguments:
+the number of the color pair to be changed, the foreground
color number, and the background color number.
For portable applications:
.bP
-The first argument must be a legal color pair value.
-If default colors are used (see \fBuse_default_colors\fP)
+The first argument must be a valid color pair value.
+If default colors are used (see \fB\%use_default_colors\fP(3X))
the upper limit is adjusted to allow for extra pairs which use
a default color in foreground and/or background.
.bP
-The second and third arguments must be legal color values.
+The second and third arguments must be valid color values.
.PP
-If the color-pair was previously initialized,
-the screen is refreshed and all occurrences of that color-pair
+If the color pair was previously initialized,
+the screen is refreshed and all occurrences of that color pair
are changed to the new definition.
.PP
-As an extension, ncurses allows you to set color pair \fB0\fP via
-the \fBassume_default_colors\fR routine, or to specify the use of
-default colors (color number \fB\-1\fR) if you first invoke the
-\fBuse_default_colors\fR routine.
-.PP
-The \fBinit_color\fR routine changes the definition of a color.
-It takes four arguments: the number of the color to be changed followed by three RGB values
+As an extension,
+\fI\%ncurses\fP allows you to set color pair \fB0\fP via the
+\fB\%assume_default_colors\fP(3X) routine, or to specify the use of
+default colors (color number \fB\-1\fP) if you first invoke the
+\fB\%use_default_colors\fP(3X) routine.
+.SS init_extended_pair
+Because \fB\%init_pair\fP uses signed \fBshort\fPs for its parameters,
+that limits color pairs and color-values
+to 32767 on modern hardware.
+The extension \fB\%init_extended_pair\fP uses \fBint\fPs
+for the color pair and color-value,
+allowing a larger number of colors to be supported.
+.SS init_color
+The \fB\%init_color\fP routine changes the definition of a color.
+It takes four arguments:
+the number of the color to be changed followed by three RGB values
(for the amounts of red, green, and blue components).
-The first argument must be a legal color value;
+.bP
+The first argument must be a valid color value;
default colors are not allowed here.
-(See the section \fBColors\fR for the default color index.)
+(See the section \fB\%Colors\fP for the default color index.)
+.bP
Each of the last three arguments
must be a value in the range \fB0\fP through \fB1000\fP.
-When \fBinit_color\fR is used, all
+.PP
+When \fB\%init_color\fP is used, all
occurrences of that color on the screen immediately change to the new
definition.
-.PP
-The \fBhas_colors\fR routine requires no arguments.
-It returns \fBTRUE\fR if
-the terminal can manipulate colors; otherwise, it returns \fBFALSE\fR.
-This routine facilitates writing terminal-independent programs.
-For example, a programmer can use it to decide
-whether to use color or some other video attribute.
-.PP
-The \fBcan_change_color\fR routine requires no arguments.
-It returns \fBTRUE\fR if the terminal supports colors
-and can change their definitions;
-other, it returns \fBFALSE\fR.
-This routine facilitates writing terminal-independent programs.
-.PP
-The \fBcolor_content\fR routine gives programmers a way to find the intensity
+.SS init_extended_color
+Because \fB\%init_color\fP uses signed \fBshort\fPs for its parameters,
+that limits color-values and their red, green, and blue components
+to 32767 on modern hardware.
+The extension \fB\%init_extended_color\fP uses \fBint\fPs
+for the color value and
+for setting the red, green, and blue components,
+allowing a larger number of colors to be supported.
+.SS color_content
+The \fB\%color_content\fP routine gives programmers a way to find the intensity
of the red, green, and blue (RGB) components in a color.
It requires four arguments: the color number, and three addresses
of \fBshort\fRs for storing
the information about the amounts of red, green, and blue components in the
given color.
-The first argument must be a legal color value, i.e.,
-\fB0\fP through \fBCOLORS\-1\fP, inclusive.
+.bP
+The first argument must be a valid color value, i.e.,
+\fB0\fP through \fB\%COLORS\-1\fP, inclusive.
+.bP
The values that are stored at the addresses pointed to by the
last three arguments are in the range
-\fB0\fP (no component) through \fB1000\fP (maximum amount of component), inclusive.
-.PP
-The \fBpair_content\fR routine allows programmers to find out what colors a
-given color-pair consists of.
-It requires three arguments: the color-pair
+\fB0\fP (no component) through \fB1000\fP
+(maximum amount of component), inclusive.
+.SS extended_color_content
+Because \fB\%color_content\fP uses signed \fBshort\fPs for its parameters,
+that limits color-values and their red, green, and blue components
+to 32767 on modern hardware.
+The extension \fB\%extended_color_content\fP uses \fBint\fPs
+for the color value and
+for returning the red, green, and blue components,
+allowing a larger number of colors to be supported.
+.SS pair_content
+The \fB\%pair_content\fP routine allows programmers to find out what colors a
+given color pair consists of.
+It requires three arguments: the color pair
number, and two addresses of \fBshort\fRs for storing the foreground and the
background color numbers.
-The first argument must be a legal color value,
-i.e., in the range \fB1\fP through \fBCOLOR_PAIRS\-1\fR, inclusive.
+.bP
+The first argument must be a valid color value,
+i.e., in the range \fB1\fP through \fB\%COLOR_PAIRS\-1\fP, inclusive.
+.bP
The values that are stored at the addresses pointed
to by the second and third arguments are in the
-range \fB0\fP through \fBCOLORS\fR, inclusive.
-.SS Colors
-In \fB<curses.h>\fR the following macros are defined.
-These are the standard colors (ISO-6429).
-\fBcurses\fR also assumes that \fBCOLOR_BLACK\fR is the default
-background color for all terminals.
-.PP
-.nf
- \fBCOLOR_BLACK\fR
- \fBCOLOR_RED\fR
- \fBCOLOR_GREEN\fR
- \fBCOLOR_YELLOW\fR
- \fBCOLOR_BLUE\fR
- \fBCOLOR_MAGENTA\fR
- \fBCOLOR_CYAN\fR
- \fBCOLOR_WHITE\fR
-.fi
+range \fB0\fP through \fB\%COLORS\fP, inclusive.
+.SS extended_pair_content
+Because \fB\%pair_content\fP uses signed \fBshort\fPs for its parameters,
+that limits color pair and color-values to 32767 on modern hardware.
+The extension \fB\%extended_pair_content\fP uses \fBint\fPs
+for the color pair and
+for returning the foreground and background colors,
+allowing a larger number of colors to be supported.
+.SS reset_color_pairs
+The extension \fB\%reset_color_pairs\fP tells \fI\%ncurses\fP to discard
+all of the color pair information which was set with \fB\%init_pair\fP.
+It also touches the current- and standard-screens, allowing an application to
+switch color palettes rapidly.
+.SS COLOR_PAIR
+\fB\%COLOR_PAIR(\fIn\fB)\fR converts a color pair number to an
+attribute.
+Attributes can hold color pairs in the range 0 to 255.
+If you need a color pair larger than that,
+you must use functions such as \fB\%attr_set\fP
+(which pass the color pair as a separate parameter)
+rather than the legacy functions such as \fB\%attrset\fP.
+.SS PAIR_NUMBER
+\fB\%PAIR_NUMBER(\fIattr\fR) extracts the color information from its
+\fIattr\fP parameter and returns it as a color pair number;
+it is the inverse operation of \fB\%COLOR_PAIR\fP.
.SH RETURN VALUE
-The routines \fBcan_change_color()\fR and \fBhas_colors()\fR return \fBTRUE\fR
-or \fBFALSE\fR.
+The routines \fB\%can_change_color\fP and \fB\%has_colors\fP return \fBTRUE\fP
+or \fBFALSE\fP.
.PP
-All other routines return the integer \fBERR\fR upon failure and an \fBOK\fR
-(SVr4 specifies only "an integer value other than \fBERR\fR") upon successful
-completion.
+All other routines return the integer \fBERR\fP upon failure and an \fBOK\fP
+(SVr4 specifies only \*(``an integer value
+other than \fBERR\fP\*('') upon successful completion.
.PP
X/Open defines no error conditions.
-This implementation will return \fBERR\fR on attempts to
-use color values outside the range \fB0\fP to COLORS\-1
+SVr4 does document some error conditions which apply in general:
+.bP
+This implementation will return \fBERR\fP on attempts to
+use color values outside the range \fB0\fP to \fB\%COLORS\fP\-1
(except for the default colors extension),
-or use color pairs outside the range \fB0\fP to \fBCOLOR_PAIRS\-1\fP.
-Color values used in \fBinit_color\fP must be in the range \fB0\fP to \fB1000\fP.
+or use color pairs outside the range \fB0\fP to \fB\%COLOR_PAIRS\-1\fP.
+.IP
+Color values used in \fB\%init_color\fP must be
+in the range \fB0\fP to \fB1000\fP.
+.IP
An error is returned from all functions
if the terminal has not been initialized.
-An error is returned from secondary functions such as \fBinit_pair\fP
-if \fBstart_color\fP was not called.
+.IP
+An error is returned from secondary functions such as \fB\%init_pair\fP
+if \fB\%start_color\fP was not called.
+.bP
+SVr4 does much the same, except that
+it returns \fBERR\fP from \fB\%pair_content\fP if the pair was not initialized
+using \fB\%init_pairs\fP
+and
+it returns \fBERR\fP from \fB\%color_content\fP
+if the terminal does not support changing colors.
+.IP
+This implementation does not return \fBERR\fP for either case.
+.PP
+Specific functions make additional checks:
.RS 3
.TP 5
-\fBinit_color\fP
+\fB\%init_color\fP
returns an error if the terminal does not support
-this feature, e.g., if the \fIinitialize_color\fP capability is absent
+this feature, e.g., if the \fB\%initialize_color\fP capability is absent
from the terminal description.
.TP 5
-\fBstart_color\fP
+\fB\%start_color\fP
returns an error if the color table cannot be allocated.
.RE
.SH NOTES
-In the \fIncurses\fR implementation, there is a separate color activation flag,
-color palette, color pairs table, and associated COLORS and COLOR_PAIRS counts
-for each screen; the \fBstart_color\fR function only affects the current
+In the \fI\%ncurses\fP implementation,
+there is a separate color activation flag,
+color palette, color pairs table,
+and associated \fB\%COLORS\fP and \fB\%COLOR_PAIRS\fP counts
+for each screen; the \fB\%start_color\fP function only affects the current
screen.
The SVr4/XSI interface is not really designed with this in mind, and
historical implementations may use a single shared color palette.
.PP
-Note that setting an implicit background color via a color pair affects only
+Setting an implicit background color via a color pair affects only
character cells that a character write operation explicitly touches.
To change
the background color used when parts of a window are blanked by erasing or
-scrolling operations, see \fBcurs_bkgd\fR(3X).
+scrolling operations, see \fB\%curs_bkgd\fP(3X).
.PP
-Several caveats apply on 386 and 486 machines with VGA-compatible graphics:
+Several caveats apply on older x86 machines
+(e.g., i386, i486) with VGA-compatible graphics:
.bP
COLOR_YELLOW is actually brown.
-To get yellow, use COLOR_YELLOW combined with the \fBA_BOLD\fR attribute.
+To get yellow, use COLOR_YELLOW combined with the \fBA_BOLD\fP attribute.
.bP
The A_BLINK attribute should in theory cause the background to go bright.
This often fails to work, and even some cards for which it mostly works
(such as the
Paradise and compatibles) do the wrong thing when you try to set a bright
-"yellow" background (you get a blinking yellow foreground instead).
+\*(``yellow\*('' background (you get a blinking yellow foreground instead).
.bP
Color RGB values are not settable.
+.SH EXTENSIONS
+The functions marked as extensions were designed for
+\fB\%ncurses\fP(3X),
+and are not found in SVr4
+.IR curses ,
+4.4BSD
+.IR curses ,
+or any other previous curses implementation.
.SH PORTABILITY
-This implementation satisfies XSI Curses's minimum maximums
-for \fBCOLORS\fR and \fBCOLOR_PAIRS\fR.
+Applications employing
+.I \%ncurses
+extensions should condition their use on the visibility of the
+.B \%NCURSES_VERSION
+preprocessor macro.
+.PP
+This implementation satisfies X/Open Curses's minimum maximums
+for \fB\%COLORS\fP and \fB\%COLOR_PAIRS\fP.
.PP
-The \fBinit_pair\fP routine accepts negative values of foreground
-and background color to support the \fBuse_default_colors\fP extension,
+The \fB\%init_pair\fP routine accepts negative values of foreground
+and background color to support the \fB\%use_default_colors\fP(3X) extension,
but only if that routine has been first invoked.
.PP
-The assumption that \fBCOLOR_BLACK\fR is the default
+The assumption that \fB\%COLOR_BLACK\fP is the default
background color for all terminals can be modified using the
-\fBassume_default_colors\fP extension.
+\fB\%assume_default_colors\fP(3X) extension.
.PP
This implementation checks the pointers,
e.g., for the values returned by
-\fBcolor_content\fP and \fBpair_content\fP,
+\fB\%color_content\fP and \fB\%pair_content\fP,
and will treat those as optional parameters when null.
+.PP
+X/Open Curses does not specify a limit for the number of colors and
+color pairs which a terminal can support.
+However, in its use of \fBshort\fP for the parameters,
+it carries over SVr4's implementation detail for the compiled
+terminfo database, which uses signed 16-bit numbers.
+This implementation provides extended versions of those functions
+which use \fBshort\fP parameters,
+allowing applications to use larger color- and pair-numbers.
+.PP
+The \fB\%reset_color_pairs\fP function is an extension of
+\fI\%ncurses\fP.
+.SH HISTORY
+SVr3.2 introduced color support to curses in 1987.
+.PP
+SVr4 made internal changes,
+e.g., moving the storage for the color state
+from \fBSP\fP (the \fISCREEN\fP structure)
+to \fB\%cur_term\fP (the \fI\%TERMINAL\fP structure),
+but provided the same set of library functions.
+.PP
+SVr4 curses limits the number of color pairs to 64,
+reserving color pair zero (0) as the terminal's initial uncolored state.
+This limit arises because the color pair information is a bitfield
+in the \fB\%chtype\fP data type (denoted by \fB\%A_COLOR\fP).
+.PP
+Other implementations of curses had different limits:
+.bP
+PCCurses (1987-1990) provided for only eight (8) colors.
+.bP
+PDCurses (1992-present) inherited the 8-color limitation from PCCurses,
+but changed this to 256 in version 2.5 (2001),
+along with changing \fB\%chtype\fP from 16-bits to 32-bits.
+.bP
+X/Open Curses (1992-present)
+added a new structure \fB\%cchar_t\fP to store the character,
+attributes and color pair values, allowing increased range of color pairs.
+Both color pairs and color-values used a signed \fBshort\fP,
+limiting values to 15 bits.
+.bP
+\fI\%ncurses\fP (1992-present) uses eight bits
+for \fB\%A_COLOR\fP in \fB\%chtype\fP values.
+.IP
+Version 5.3 provided a wide-character interface (2002),
+but left color pairs as part of the attributes-field.
+.IP
+Since version 6 (2015),
+ncurses uses a separate \fBint\fP for color pairs in the \fB\%cchar_t\fP values.
+When those color pair values fit in 8 bits,
+ncurses allows color pairs to be manipulated
+via the functions using \fB\%chtype\fP values.
+.bP
+NetBSD curses used 6 bits from
+2000 (when colors were first supported) until 2004.
+At that point, NetBSD changed to use 10 bits.
+As of 2021, that size is unchanged.
+Like \fI\%ncurses\fP before version 6,
+the NetBSD color pair information is stored in
+the attributes field of \fB\%cchar_t\fP, limiting the number of color pairs
+by the size of the bitfield.
.SH SEE ALSO
-\fBcurses\fR(3X),
-\fBcurs_initscr\fR(3X),
-\fBcurs_attr\fR(3X),
-\fBcurs_variables\fR(3X),
-\fBdefault_colors\fR(3X)
+\fB\%curses\fP(3X),
+\fB\%curs_attr\fP(3X),
+\fB\%curs_initscr\fP(3X),
+\fB\%curs_variables\fP(3X),
+\fB\%default_colors\fP(3X)
projects / ncurses.git / blobdiff