.\"***************************************************************************
-.\" Copyright (c) 1998-2010,2015 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2018,2019 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 1.37 2015/04/04 19:42:47 tom Exp $
+.\" $Id: curs_color.3x,v 1.61 2019/01/20 17:04:08 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
.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,
+\fBinit_extended_pair\fR,
+\fBinit_extended_color\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
-\fB# include <curses.h>\fR
+\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.
+\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.
+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.
initialized color.
The routine \fBpair_content\fR allows a programmer to find
out how a given color-pair is currently defined.
-.SS Routine Descriptions
+.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.
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 "ANSI") 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.
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\fP capability,
-which is typically a signed 16-bit integer (see \fBterminfo\fR(\*n)).
+\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).
+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,
-which is typically a signed 16-bit integer (see \fBterminfo\fR(\*n)).
+\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.
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
+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
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
+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 routine.
+\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;
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 init_extended_color
.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
of the red, green, and blue (RGB) components in a color.
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.
+\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
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 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.
+.SS extended_pair_content
.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
-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
-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 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 \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
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
-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
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).
.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.
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 PORTABILITY
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),
projects / ncurses.git / blobdiff