curs_color(3curses) curs_color(3curses)
NAME
curs_color: start_color, init_pair, init_color, has_colors,
can_change_color, color_content, pair_content - curses color
manipulation routines
SYNOPSIS
cc [flag . . .] file -lcurses [library . . .]
# include <curses.h>
int start_color(void);
int init_pair(short pair, short f, short b);
int init_color(short color, short r, short g, short b);
bool has_colors(void);
bool can_change_color(void);
int color_content(short color, short *r, short *g, short *b);
int pair_content(short pair, short *f, short *b);
DESCRIPTION
Overview
curses provides routines that manipulate color on color
alphanumeric terminals. To use these routines start_color
must be called, usually right after initscr. 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 field on which the characters are
displayed). A programmer initializes a color-pair with the
routine init_pair. After it has been initialized,
COLOR_PAIR(n), a macro defined in curses.h, can be used in the
same ways other video attributes can be used. If a terminal
is capable of redefining colors, the programmer can use the
routine init_color to change the definition of a color. The
routines has_colors and can_change_color return TRUE or FALSE,
depending on whether the terminal has color capabilities and
whether the programmer can change the colors. The routine
color_content allows a programmer to identify the amounts of
red, green, and blue components in an initialized color. The
routine pair_content allows a programmer to find out how a
given color-pair is currently defined.
Routine Descriptions
The start_color 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 initscr.
start_color initializes eight basic colors (black, red, green,
yellow, blue, magenta, cyan, and white), and two global
variables, COLORS and COLOR_PAIRS (respectively defining the
Copyright 1994 Novell, Inc. Page 1
curs_color(3curses) curs_color(3curses)
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.
The init_pair 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. The value of the first argument must be between 1 and
the smaller of 63 and COLOR_PAIRS-1. The value of the second
and third arguments must be between 0 and COLORS. If the
color-pair was previously initialized, the screen is refreshed
and all occurrences of that color-pair is changed to the new
definition.
The init_color 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 0 and COLORS. (See the subsection Colors for the
default color index.) Each of the last three arguments must
be a value between 0 and 1000. When init_color is used, all
occurrences of that color on the screen immediately change to
the new definition.
The has_colors routine requires no arguments. It returns TRUE
if the terminal can manipulate colors; otherwise, it returns
FALSE. 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 can_change_color routine requires no arguments. It
returns TRUE if the terminal supports colors and can change
their definitions; other, it returns FALSE. This routine
facilitates writing terminal-independent programs.
The color_content routine gives users 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 shorts 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
COLORS. 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).
Copyright 1994 Novell, Inc. Page 2
curs_color(3curses) curs_color(3curses)
The pair_content routine allows users to find out what colors
a given color-pair consists of. It requires three arguments:
the color-pair number, and two addresses of shorts for storing
the foreground and the background color numbers. The value of
the first argument must be between 1 and the smaller of 63 and
COLOR_PAIRS-1. The values that are stored at the addresses
pointed to by the second and third arguments are between 0 and
COLORS.
Colors
In curses.h the following macros are defined. These are the
default colors. curses also assumes that COLOR_BLACK is the
default background color for all terminals.
COLOR_BLACK
COLOR_RED
COLOR_GREEN
COLOR_YELLOW
COLOR_BLUE
COLOR_MAGENTA
COLOR_CYAN
COLOR_WHITE
Return Values
All routines that return an integer return ERR upon failure
and OK upon successful completion.
REFERENCES
curses(3curses), curs_attr(3curses), curs_initscr(3curses)
NOTICES
The header file curses.h automatically includes the header
files stdio.h and unctrl.h.
Copyright 1994 Novell, Inc. Page 3