ncurses 6.2 - patch 20201219

[ncurses.git] / man / curs_color.3x

diff --git a/man/curs_color.3x b/man/curs_color.3x
index 64689a29b4eb6c147ac292bcc2fdaa6010baf701..02defb6a793c58f1de8cd966e030fe21678d7c64 100644 (file)
--- a/man/curs_color.3x
+++ b/man/curs_color.3x
@@ -1,5 +1,6 @@
 .\"***************************************************************************
 .\"***************************************************************************

-.\" Copyright (c) 1998-2009,2010 Free Software Foundation, Inc.              *
+.\" Copyright 2018-2019,2020 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            *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *


@@ -26,197 +27,444 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"

-.\" $Id: curs_color.3x,v 1.32 2010/09/18 20:27:38 tom Exp $
+.\" $Id: curs_color.3x,v 1.63 2020/10/24 09:35:23 tom Exp $

 .TH curs_color 3X ""
 .TH curs_color 3X ""

+.ie \n(.g .ds `` \(lq
+.el       .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el       .ds '' ''

 .de bP
 .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,
 .na
 .hy 0
 .SH NAME
 \fBstart_color\fR,

-\fBinit_pair\fR,
-\fBinit_color\fR,

 \fBhas_colors\fR,
 \fBcan_change_color\fR,
 \fBhas_colors\fR,
 \fBcan_change_color\fR,

+\fBinit_pair\fR,
+\fBinit_color\fR,
+\fBinit_extended_pair\fR,
+\fBinit_extended_color\fR,

 \fBcolor_content\fR,
 \fBpair_content\fR,
 \fBcolor_content\fR,
 \fBpair_content\fR,

-\fBCOLOR_PAIR\fR \- \fBcurses\fR color manipulation routines
+\fBextended_color_content\fR,
+\fBextended_pair_content\fR,
+\fBreset_color_pairs\fR,
+\fBCOLOR_PAIR\fR,
+\fBPAIR_NUMBER\fR \- \fBcurses\fR color manipulation routines

 .ad
 .hy
 .SH SYNOPSIS
 .ad
 .hy
 .SH SYNOPSIS

-\fB# include <curses.h>\fR
+\fB#include <curses.h>\fR

 .sp
 \fBint start_color(void);\fR
 .sp
 \fBint start_color(void);\fR

+.sp
+\fBbool has_colors(void);\fR

 .br
 .br

-\fBint init_pair(short pair, short f, short b);\fR
+\fBbool can_change_color(void);\fR
+.sp
+\fBint init_pair(short \fP\fIpair\fP\fB, short \fP\fIf\fP\fB, short \fP\fIb\fP\fB);\fR

 .br
 .br

-\fBint init_color(short color, short r, short g, short b);\fR
+\fBint init_color(short \fP\fIcolor\fP\fB, short \fP\fIr\fP\fB, short \fP\fIg\fP\fB, short \fP\fIb\fP\fB);\fR

 .br
 .br

-\fBbool has_colors(void);\fR
+/* extensions */

 .br
 .br

-\fBbool can_change_color(void);\fR
+\fBint init_extended_pair(int \fP\fIpair\fP\fB, int \fP\fIf\fP\fB, int \fP\fIb\fP\fB);\fR
+.br
+\fBint init_extended_color(int \fP\fIcolor\fP\fB, int \fP\fIr\fP\fB, int \fP\fIg\fP\fB, int \fP\fIb\fP\fB);\fR
+.sp
+\fBint color_content(short \fP\fIcolor\fP\fB, short *\fP\fIr\fP\fB, short *\fP\fIg\fP\fB, short *\fP\fIb\fP\fB);\fR

 .br
 .br

-\fBint color_content(short color, short *r, short *g, short *b);\fR
+\fBint pair_content(short \fP\fIpair\fP\fB, short *\fP\fIf\fP\fB, short *\fP\fIb\fP\fB);\fR

 .br
 .br

-\fBint pair_content(short pair, short *f, short *b);\fR
+/* extensions */
+.br
+\fBint extended_color_content(int \fP\fIcolor\fP\fB, int *\fP\fIr\fP\fB, int *\fP\fIg\fP\fB, int *\fP\fIb\fP\fB);\fR
+.br
+\fBint extended_pair_content(int \fP\fIpair\fP\fB, int *\fP\fIf\fP\fB, int *\fP\fIb\fP\fB);\fR
+.sp
+/* extensions */
+.br
+\fBvoid reset_color_pairs(void);\fR
+.sp
+\fBint COLOR_PAIR(int \fP\fIn\fP\fB);\fR
+.br
+\fBPAIR_NUMBER(\fR\fIattrs\fR\fB);\fP

 .br
 .SH DESCRIPTION
 .SS Overview
 .br
 .SH DESCRIPTION
 .SS Overview

-\fBcurses\fR support 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).
+\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
 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.
+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)
+can be used to convert the pair to a video attribute.

 .PP
 If a terminal is capable of redefining colors, the programmer can use the
 .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,
+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
 depending on whether the terminal has color capabilities and whether the

-programmer can change the colors.  The routine \fBcolor_content\fR allows a
+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
 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
+initialized color.
+The routine \fBpair_content\fR allows a programmer to find

 out how a given color-pair is currently defined.
 out how a given color-pair is currently defined.

-.SS Routine Descriptions
-The \fBstart_color\fR 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 initializes
-eight basic colors (black, red, green, yellow, blue, magenta, cyan,
-and white), and two global variables, \fBCOLORS\fR and
+.SS Color Rendering
+The \fBcurses\fP library combines these inputs to produce the
+actual foreground and background colors shown on the screen:
+.bP
+per-character video attributes (e.g., via \fBwaddch\fP),
+.bP
+the window attribute (e.g., by \fBwattrset\fP), and
+.bP
+the background character (e.g., \fBwbkgdset\fP).
+.PP
+Per-character and window attributes are usually set by a parameter containing
+video attributes including a color pair value.
+Some functions such as \fBwattr_set\fP use a separate parameter which
+is the color pair number.
+.PP
+The background character is a special case: it includes a character value,
+just as if it were passed to \fBwaddch\fP.
+.PP
+The \fBcurses\fP library does the actual work of combining these color
+pairs in an internal function called from \fBwaddch\fP:
+.bP
+If the parameter passed to \fBwaddch\fP is \fIblank\fP,
+and it uses the special color pair 0,
+.RS
+.bP
+\fBcurses\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.
+.bP
+Otherwise, \fBcurses\fP uses the background character.
+.RE
+.bP
+If the parameter passed to \fBwaddch\fP is \fInot blank\fP,
+or it does not use the special color pair 0,
+\fBcurses\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.
+Those do not combine its parameter with a color pair.
+Consequently those calls use only the window attribute or
+the background character.
+.SH CONSTANTS
+.PP
+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
+.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 \fBstart_color\fP to the maximum number of colors
+the terminal can support.
+.SS COLOR_PAIRS
+is initialized by \fBstart_color\fP to the maximum number of color pairs
+the terminal can support.
+.SH FUNCTIONS
+.SS start_color
+The \fBstart_color\fR 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:
+.bP
+It initializes two global variables, \fBCOLORS\fR and

 \fBCOLOR_PAIRS\fR (respectively defining the maximum number of colors
 \fBCOLOR_PAIRS\fR (respectively defining the maximum number of colors

-and color-pairs the terminal can support).  It also restores the
-colors on the terminal to the values they had when the terminal was
-just turned on.
+and color-pairs the terminal can support).
+.bP
+It initializes the special color pair \fB0\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
+initializes its internal table representing the
+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).
+The table is initialized first for eight basic colors
+(black, red, green, yellow, blue, magenta, cyan, and white),
+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
+to match its built-in table.
+An application may use \fBinit_color\fP to alter the internal table
+along with the terminal's color.

 .PP
 .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
+These limits apply to color values and color pairs.
+Values outside these limits are not legal, and may result in a runtime error:
+.bP
+\fBCOLORS\fP corresponds to the terminal database's \fBmax_colors\fR capability,
+(see \fBterminfo\fR(\*n)).
+.bP
+color values are expected to be in the range \fB0\fP to \fBCOLORS\-1\fP,
+inclusive (including \fB0\fP and \fBCOLORS\-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(3X)).
+.bP
+\fBCOLOR_PAIRS\fP corresponds to
+the terminal database's \fBmax_pairs\fP capability,
+(see \fBterminfo\fR(\*n)).
+.bP
+legal color pair values are in the range \fB1\fP to \fBCOLOR_PAIRS\-1\fP,
+inclusive.
+.bP
+color pair \fB0\fP is special; it denotes \*(``no color\*(''.
+.IP
+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.
+.SS has_colors
+.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.
+.SS can_change_color
+.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.
+.SS init_pair
+.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

 color number, and the background color number.
 For portable applications:
 .bP
 color number, and the background color number.
 For portable applications:
 .bP

-The value of the first argument
-must be between \fB1\fR and \fBCOLOR_PAIRS\-1\fR,
-except that if default colors are used (see \fBuse_default_colors\fP)
+The first argument must be a legal color pair value.
+If default colors are used (see \fBuse_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 upper limit is adjusted to allow for extra pairs which use
 a default color in foreground and/or background.
 .bP

-The value of the second and
-third arguments must be between 0 and \fBCOLORS\fR.
-Color pair 0 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.
+The second and third arguments must be legal color values.

 .PP
 .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
 are changed to the new definition.
 .PP

-As an extension, ncurses allows you to set color pair 0 via
-the \fBassume_default_colors\fR routine, or to specify the use of
+As an extension, ncurses allows you to set color pair \fB0\fP via
+the \fBassume_default_colors\fR(3X) routine, or to specify the use of

 default colors (color number \fB\-1\fR) if you first invoke the
 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
-(for the amounts of red, green, and blue components).  The value of the first
-argument must be between \fB0\fR and \fBCOLORS\fR.  (See the section
-\fBColors\fR for the default color index.)  Each of the last three arguments
-must be a value between 0 and 1000.  When \fBinit_color\fR is used, all
+\fBuse_default_colors\fR(3X) routine.
+.SS init_extended_pair
+.PP
+Because \fBinit_pair\fP uses signed \fBshort\fPs for its parameters,
+that limits color-pairs and color-values
+to 32767 on modern hardware.
+The extension \fBinit_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
+.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
+(for the amounts of red, green, and blue components).
+.bP
+The first argument must be a legal color value;
+default colors are not allowed here.
+(See the section \fBColors\fR for the default color index.)
+.bP
+Each of the last three arguments
+must be a value in the range \fB0\fP through \fB1000\fP.
+.PP
+When \fBinit_color\fR is used, all

 occurrences of that color on the screen immediately change to the new
 definition.
 occurrences of that color on the screen immediately change to the new
 definition.

+.SS init_extended_color

 .PP
 .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.
+Because \fBinit_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 \fBinit_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

 .PP
 The \fBcolor_content\fR routine gives programmers a way to find the intensity
 .PP
 The \fBcolor_content\fR 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
+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
 the information about the amounts of red, green, and blue components in the

-given color.  The value of the first argument must be between 0 and
-\fBCOLORS\fR.  The values that are stored at the addresses pointed to by the
-last three arguments are between 0 (no component) and 1000 (maximum amount of
-component).
+given color.
+.bP
+The first argument must be a legal color value, i.e.,
+\fB0\fP through \fBCOLORS\-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.
+.SS extended_color_content
+.PP
+Because \fBcolor_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 \fBextended_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

 .PP
 The \fBpair_content\fR routine allows programmers to find out what colors a
 .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
+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
 number, and two addresses of \fBshort\fRs for storing the foreground and the

-background color numbers.  The value of the first argument must be between 1
-and \fBCOLOR_PAIRS\-1\fR.  The values that are stored at the addresses pointed
-to by the second and third arguments are between 0 and \fBCOLORS\fR.
-.SS Colors
-In \fB<curses.h>\fR the following macros are defined.  These are the default
-colors.  \fBcurses\fR also assumes that \fBCOLOR_BLACK\fR is the default
-background color for all terminals.
+background color numbers.
+.bP
+The first argument must be a legal color value,
+i.e., in the range \fB1\fP through \fBCOLOR_PAIRS\-1\fR, 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 extended_pair_content

 .PP
 .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
+Because \fBpair_content\fP uses signed \fBshort\fPs for its parameters,
+that limits color-pair and color-values to 32767 on modern hardware.
+The extension \fBextended_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
+.PP
+The extension \fBreset_color_pairs\fP tells ncurses to discard all
+of the color-pair information which was set with \fBinit_pair\fP.
+It also touches the current- and standard-screens, allowing an application to
+switch color palettes rapidly.
+.SS PAIR_NUMBER
+.PP
+\fBPAIR_NUMBER(\fR\fIattrs\fR) extracts the color
+value from its \fIattrs\fP parameter and returns it as a color pair number.
+.SS COLOR_PAIR
+Its inverse \fBCOLOR_PAIR(\fR\fIn\fR\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 \fBattr_set\fP (which pass the color pair as a separate parameter)
+rather than the legacy functions such as \fBattrset\fP.

 .SH RETURN VALUE
 .SH RETURN VALUE

-The routines \fBcan_change_color()\fR and \fBhas_colors()\fR return \fBTRUE\fR
+The routines \fBcan_change_color\fR and \fBhas_colors\fR return \fBTRUE\fR

 or \fBFALSE\fR.
 .PP
 All other routines return the integer \fBERR\fR upon failure and an \fBOK\fR
 or \fBFALSE\fR.
 .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.
+(SVr4 specifies only \*(``an integer value
+other than \fBERR\fR\*('') upon successful completion.

 .PP
 X/Open defines no error conditions.
 .PP
 X/Open defines no error conditions.

+SVr4 does document some error conditions which apply in general:
+.bP

 This implementation will return \fBERR\fR on attempts to
 This implementation will return \fBERR\fR on attempts to

-use color values outside the range 0 to COLORS\-1
+use color values outside the range \fB0\fP to \fBCOLORS\fP\-1

 (except for the default colors extension),
 (except for the default colors extension),

-or use color pairs outside the range 0 to COLOR_PAIR\-1.
-Color values used in \fBinit_color\fP must be in the range 0 to 1000.
+or use color pairs outside the range \fB0\fP to \fBCOLOR_PAIRS\-1\fP.
+.IP
+Color values used in \fBinit_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 all functions
 if the terminal has not been initialized.

+.IP

 An error is returned from secondary functions such as \fBinit_pair\fP
 if \fBstart_color\fP was not called.
 An error is returned from secondary functions such as \fBinit_pair\fP
 if \fBstart_color\fP was not called.

+.bP
+SVr4 does much the same, except that
+it returns \fBERR\fP from \fBpair_content\fP if the pair was not initialized
+using \fBinit_pairs\fP
+and 
+it returns \fBERR\fP from \fBcolor_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
 returns an error if the terminal does not support
 .RS 3
 .TP 5
 \fBinit_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 \fBinitialize_color\fP capability is absent

 from the terminal description.
 .TP 5
 \fBstart_color\fP
 returns an error if the color table cannot be allocated.
 .RE
 .SH NOTES
 from the terminal description.
 .TP 5
 \fBstart_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
+In the \fBncurses\fR implementation, there is a separate color activation flag,
+color palette, color pairs table,
+and associated \fBCOLORS\fP and \fBCOLOR_PAIRS\fP counts

 for each screen; the \fBstart_color\fR function only affects the current
 for each screen; the \fBstart_color\fR function only affects the current

-screen.  The SVr4/XSI interface is not really designed with this in mind, and
+screen.
+The SVr4/XSI interface is not really designed with this in mind, and

 historical implementations may use a single shared color palette.
 .PP
 historical implementations may use a single shared color palette.
 .PP

-Note that setting an implicit background color via a color pair affects only
-character cells that a character write operation explicitly touches.  To change
+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).
 .PP
 the background color used when parts of a window are blanked by erasing or
 scrolling operations, see \fBcurs_bkgd\fR(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
 .bP

-COLOR_YELLOW is actually brown.  To get yellow, use COLOR_YELLOW combined with
-the \fBA_BOLD\fR attribute.
+COLOR_YELLOW is actually brown.
+To get yellow, use COLOR_YELLOW combined with the \fBA_BOLD\fR attribute.

 .bP
 .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
+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
 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 PORTABILITY
 .bP
 Color RGB values are not settable.
 .SH PORTABILITY


@@ -224,25 +472,31 @@ This implementation satisfies XSI Curses's minimum maximums
 for \fBCOLORS\fR and \fBCOLOR_PAIRS\fR.
 .PP
 The \fBinit_pair\fP routine accepts negative values of foreground
 for \fBCOLORS\fR and \fBCOLOR_PAIRS\fR.
 .PP
 The \fBinit_pair\fP routine accepts negative values of foreground

-and background color to support the \fBuse_default_colors\fP extension,
+and background color to support the \fBuse_default_colors\fR(3X) extension,

 but only if that routine has been first invoked.
 .PP
 The assumption that \fBCOLOR_BLACK\fR is the default
 background color for all terminals can be modified using the
 but only if that routine has been first invoked.
 .PP
 The assumption that \fBCOLOR_BLACK\fR is the default
 background color for all terminals can be modified using the

-\fBassume_default_colors\fP extension.
+\fBassume_default_colors\fR(3X) extension.

 .PP
 This implementation checks the pointers,
 e.g., for the values returned by
 \fBcolor_content\fP and \fBpair_content\fP,
 and will treat those as optional parameters when null.
 .PP
 This implementation checks the pointers,
 e.g., for the values returned by
 \fBcolor_content\fP and \fBpair_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 \fBreset_color_pairs\fP function is an extension of ncurses.

 .SH SEE ALSO
 \fBcurses\fR(3X),
 \fBcurs_initscr\fR(3X),
 \fBcurs_attr\fR(3X),
 .SH SEE ALSO
 \fBcurses\fR(3X),
 \fBcurs_initscr\fR(3X),
 \fBcurs_attr\fR(3X),

+\fBcurs_variables\fR(3X),

 \fBdefault_colors\fR(3X)
 \fBdefault_colors\fR(3X)

-.\"#
-.\"# The following sets edit modes for GNU EMACS
-.\"# Local Variables:
-.\"# mode:nroff
-.\"# fill-column:79
-.\"# End: