.\"***************************************************************************
-.\" Copyright (c) 1998-2004,2005 Free Software Foundation, Inc. *
+.\" Copyright (c) 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 1.28 2005/12/18 00:00:37 tom Exp $
+.\" $Id: curs_color.3x,v 1.52 2017/11/18 23:47:37 tom Exp $
.TH curs_color 3X ""
+.ie \n(.g .ds `` \(lq
+.el .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el .ds '' ''
+.de bP
+.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,
+\fBinit_pair\fR,
+\fBinit_color\fR,
\fBcolor_content\fR,
\fBpair_content\fR,
-\fBCOLOR_PAIR\fR - \fBcurses\fR color manipulation routines
+\fBreset_color_pairs\fR,
+\fBCOLOR_PAIR\fR,
+\fBPAIR_NUMBER\fR \- \fBcurses\fR color manipulation routines
.ad
.hy
.SH SYNOPSIS
-\fB# include <curses.h>\fR
-.br
+\fB#include <curses.h>\fR
+.sp
\fBint start_color(void);\fR
+.sp
+\fBbool has_colors(void);\fR
.br
+\fBbool can_change_color(void);\fR
+.sp
\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
+/* extensions */
.br
-\fBbool can_change_color(void);\fR
+\fBint init_extended_pair(int pair, int f, int b);\fR
.br
+\fBint init_extended_color(int color, int r, int g, int b);\fR
+.sp
\fBint color_content(short color, short *r, short *g, short *b);\fR
.br
\fBint pair_content(short pair, short *f, short *b);\fR
.br
+/* extensions */
+.br
+\fBint extended_color_content(int color, int *r, int *g, int *b);\fR
+.br
+\fBint extended_pair_content(int pair, int *f, int *b);\fR
+.sp
+/* extensions */
+.br
+\fBvoid reset_color_pairs(void);\fR
+.sp
+\fBint COLOR_PAIR(int n);\fR
+.br
+\fBPAIR_NUMBER(\fR\fIattrs\fR\fB);\fP
+.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
-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
-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
-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
-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.
-.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
-\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.
-.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:
-.TP 5
--
-The value of the first argument
-must be between \fB1\fR and \fBCOLOR_PAIRS-1\fR.
-.TP 5
--
-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.
-.PP
-If the color-pair was previously
-initialized, the screen is refreshed and all occurrences of that color-pair
-are changed to the new definition.
+.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
-As an extension, ncurses allows you to set color pair 0 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
-(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
-occurrences of that color on the screen immediately change to the new
-definition.
+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 \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.
+The background character is a special case: it includes a character value,
+just as if it were passed to \fBwaddch\fP.
.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.
+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
-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
-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).
+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
-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
-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
+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_CYAN\fR
\fBCOLOR_WHITE\fR
.fi
+.PP
+Some terminals support more than the eight (8) \*(lqANSI\*(rq 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
+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 \*(lqANSI\*(rq) 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.
+.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
+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).
+.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
+The first argument must be a legal color pair value.
+If default colors are used (see \fBuse_default_colors\fP)
+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.
+.PP
+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(3X) routine, or to specify the use of
+default colors (color number \fB\-1\fR) if you first invoke the
+\fBuse_default_colors\fR(3X) routine.
+.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 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.
+.SS color_content
+.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
+the information about the amounts of red, green, and blue components in the
+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 pair_content
+.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
+number, and two addresses of \fBshort\fRs for storing the foreground and the
+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 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
-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
-(SVr4 specifies only "an integer value other than \fBERR\fR") upon successful
+(SVr4 specifies only \*(lqan integer value other than \fBERR\fR\*(rq) 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 0 to COLORS-1
+use color values outside the range \fB0\fP to \fBCOLORS\fP\-1
(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.
+Color values used in \fBinit_color\fP must be in the range \fB0\fP to \fB1000\fP.
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.
-.RS
+.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.
+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
-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
-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
-Several caveats apply on 386 and 486 machines with VGA-compatible graphics:
-.TP 5
--
-COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW combined with
-the \fBA_BOLD\fR attribute.
-.TP 5
--
-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
+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.
+.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).
-.TP 5
--
+\*(lqyellow\*(rq background (you get a blinking yellow foreground instead).
+.bP
Color RGB values are not settable.
.SH PORTABILITY
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
-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
-\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
+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),
+\fBcurs_variables\fR(3X),
\fBdefault_colors\fR(3X)
-.\"#
-.\"# The following sets edit modes for GNU EMACS
-.\"# Local Variables:
-.\"# mode:nroff
-.\"# fill-column:79
-.\"# End:
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