curs_color(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_color(3X)
NAME
curscolor: startcolor, initpair, initcolor, hascolors,
canchangecolor, colorcontent, paircontent - curses color
manipulation routines
SYNOPSIS
# include <curses.h>
int startcolor(void);
int initpair(short pair, short f, short b);
int initcolor(short color, short r, short g, short b);
bool hascolors(void);
bool canchangecolor(void);
int colorcontent(short color, short *r, short *g, short *b);
int paircontent(short pair, short *f, short *b);
DESCRIPTION
Overview
curses provides routines that manipulate color on color
alphanumeric terminals. To use these routines startcolor
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 charac-
ters are displayed). A programmer initializes a color-pair
with the routine initpair. After it has been initialized,
COLORPAIR(n), a macro defined in <curses.h>, can be used in
the same ways other video attributes can be used. If a ter-
minal is capable of redefining colors, the programmer can
use the routine initcolor to change the definition of a
color. The routines hascolors and canchangecolor return
TRUE or FALSE, depending on whether the terminal has color
capabilities and whether the programmer can change the
colors. The routine colorcontent allows a programmer to
identify the amounts of red, green, and blue components in
an initialized color. The routine paircontent allows a
programmer to find out how a given color-pair is currently
defined.
Routine Descriptions
The startcolor 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.
startcolor initializes eight basic colors (black, red,
green, yellow, blue, magenta, cyan, and white), and two glo-
bal variables, COLORS and COLORPAIRS (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.
The initpair 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
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curs_color(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_color(3X)
background color number. The value of the first argument
must be between 1 and COLORPAIRS-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 initcolor 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 section Colors for the default color index.) Each of
the last three arguments must be a value between 0 and 1000.
When initcolor is used, all occurrences of that color on
the screen immediately change to the new definition. The
hascolors 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 attri-
bute. The canchangecolor 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 colorcontent 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). The
paircontent 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 stor-
ing the foreground and the background color numbers. The
value of the first argument must be between 1 and
COLORPAIRS-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 COLORBLACK is
the default background color for all terminals.
COLORBLACK
COLORRED
COLORGREEN
COLORYELLOW
COLORBLUE
COLORMAGENTA
COLORCYAN
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curs_color(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_color(3X)
COLORWHITE
RETURN VALUE
All routines that return an integer return ERR upon failure
and OK upon successful completion.
NOTES
The header file <curses.h> automatically includes the header
files <stdio.h> and <unctrl.h>.
SEE ALSO
curses(3X), cursinitscr(3X), cursattr(3X).
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