.\"***************************************************************************
-.\" Copyright (c) 1998-2016,2017 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_color.3x,v 1.50 2017/04/01 19:57:19 tom Exp $
+.\" $Id: curs_color.3x,v 1.63 2020/10/24 09:35:23 tom Exp $
.TH curs_color 3X ""
.ie \n(.g .ds `` \(lq
.el .ds `` ``
.ie \n(.g .ds '' \(rq
.el .ds '' ''
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.ds n 5
.na
\fBcan_change_color\fR,
\fBinit_pair\fR,
\fBinit_color\fR,
+\fBinit_extended_pair\fR,
+\fBinit_extended_color\fR,
\fBcolor_content\fR,
\fBpair_content\fR,
+\fBextended_color_content\fR,
+\fBextended_pair_content\fR,
+\fBreset_color_pairs\fR,
\fBCOLOR_PAIR\fR,
\fBPAIR_NUMBER\fR \- \fBcurses\fR color manipulation routines
.ad
.br
\fBbool can_change_color(void);\fR
.sp
-\fBint init_pair(short pair, short f, short b);\fR
+\fBint init_pair(short \fP\fIpair\fP\fB, short \fP\fIf\fP\fB, short \fP\fIb\fP\fB);\fR
.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
/* extensions */
.br
-\fBint init_extended_pair(int pair, int f, int b);\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 color, int r, int g, int b);\fR
+\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 color, short *r, short *g, short *b);\fR
+\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
-\fBint pair_content(short pair, short *f, short *b);\fR
+\fBint pair_content(short \fP\fIpair\fP\fB, short *\fP\fIf\fP\fB, short *\fP\fIb\fP\fB);\fR
.br
/* extensions */
.br
-\fBint extended_color_content(int color, int *r, int *g, int *b);\fR
+\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 pair, int *f, int *b);\fR
+\fBint extended_pair_content(int \fP\fIpair\fP\fB, int *\fP\fIf\fP\fB, int *\fP\fIb\fP\fB);\fR
.sp
-\fBint COLOR_PAIR(int n);\fR
+/* 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
\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.
+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
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.
+red, green, and blue components of the color palette.
.IP
The components depend on whether the terminal uses
-CGA (aka \*(lqANSI\*(rq) or
+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
to match its built-in table.
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).
+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,
+\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,
.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
+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)
+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 \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.
+.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
+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;
When \fBinit_color\fR is used, all
occurrences of that color on the screen immediately change to the new
definition.
+.SS init_extended_color
+.PP
+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
.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.
+\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
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
+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
or \fBFALSE\fR.
.PP
All other routines return the integer \fBERR\fR upon failure and an \fBOK\fR
-(SVr4 specifies only \*(lqan integer value other than \fBERR\fR\*(rq) upon successful
-completion.
+(SVr4 specifies only \*(``an integer value
+other than \fBERR\fR\*('') upon successful completion.
.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
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 \fB0\fP to \fBCOLOR_PAIRS\-1\fP.
-Color values used in \fBinit_color\fP must be in the range \fB0\fP to \fB1000\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.
+.IP
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
.RE
.SH NOTES
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
+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
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 older x86 machines (e.g., i386, i486) 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.
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
-\*(lqyellow\*(rq 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
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),