.\"***************************************************************************
-.\" Copyright (c) 1998-2010,2015 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2015,2016 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 1.42 2016/07/24 00:02:15 tom Exp $
.TH curs_color 3X ""
.ie \n(.g .ds `` \(lq
.el .ds `` ``
\fBstart_color\fR,
\fBinit_pair\fR,
\fBinit_color\fR,
+.\" .br
\fBhas_colors\fR,
\fBcan_change_color\fR,
+.\" .br
\fBcolor_content\fR,
\fBpair_content\fR,
-\fBCOLOR_PAIR\fR \- \fBcurses\fR color manipulation routines
+.\" .br
+\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
.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
+.sp
\fBbool has_colors(void);\fR
.br
\fBbool can_change_color(void);\fR
-.br
+.sp
\fBint color_content(short color, short *r, short *g, short *b);\fR
.br
\fBint pair_content(short pair, short *f, short *b);\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 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.
.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
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.
+.PP
+\fBPAIR_NUMBER(\fR\fIattrs\fR) extracts the color
+value from its \fIattrs\fP parameter and returns it as a color pair number.
+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.
.SS Colors
In \fB<curses.h>\fR the following macros are defined.
-These are the default colors.
+These are the standard colors (ISO-6429).
\fBcurses\fR also assumes that \fBCOLOR_BLACK\fR is the default
background color for all terminals.
.PP
projects / ncurses.git / blobdiff