CURSES_COLOR(3)

NAME
curses_color, has_colors, can_change_color, start_color, init_pair, pair_content, COLOR_PAIR, PAIR_NUMBER, init_color, color_content, no_color_video - curses color manipulation routines

LIBRARY
libcurses

SYNOPSIS
#include <curses.h>
bool
has_colors(void);
bool
can_change_color(void);
int
start_color(void);
int
init_pair(short pair, short fore, short back);
int
pair_content(short pair, short *fore, short *back);
int
COLOR_PAIR(int n);
int
PAIR_NUMBER(int val);
int
init_color(short color, short red, short green, short blue);
int
color_content(short color, short *red, short *green, short *blue);
attr_t
no_color_video(void);

extern int COLOR_PAIRS;

extern int COLORS;

DESCRIPTION
These functions manipulate color on terminals that support color attributes.

The function has_colors() indicates whether a terminal is capable of displaying color attributes. It returns TRUE if the terminal is capable of displaying color attributes and FALSE otherwise.

The function can_change_color() indicates whether a terminal is capable of redefining colors. It returns TRUE if colors can be redefined and FALSE if they can not.

The function start_color() initializes the curses color support on a terminal. It must be called before any color manipulation functions are called on that terminal. The function initializes the eight basic colors (black, red, green, yellow, blue, magenta, cyan and white) that are specified using the color macros (such as COLOR_BLACK) defined in curses.h. start_color() also initializes the global external variables COLORS and COLOR_PAIRS. COLORS defines the number of colors that the terminal supports and COLOR_PAIRS defines the number of color-pairs that the terminal supports. These color-pairs are initialized to white foreground on black background. start_color() sets the colors on the terminal to the curses defaults of white foreground on black background unless the functions assume_default_colors() or use_default_colors() have been called previously.

The function init_pair(pair, fore, back) sets foreground color fore and background color back for color-pair number pair. The valid range for the color-pair pair is from 1 to COLOR_PAIRS - 1 and the valid range for the colors is any number less than COLORS. Specifying a negative number will set that color to the default foreground or background color. The 8 initial colors are defined as:
COLOR_BLACK
COLOR_RED
COLOR_GREEN
COLOR_YELLOW
COLOR_BLUE
COLOR_MAGENTA
COLOR_CYAN
COLOR_WHITE
Color-pair 0 is used as the default color pair, so changing this will have no effect. Use the function assume_default_colors() to change the default colors.

The function pair_content(pair, *fore, *back) stores the foreground and background color numbers of color-pair pair in the variables fore and back, respectively.

The macro COLOR_PAIR(n) gives the attribute value of color-pair number n. This is the value that is used to set the attribute of a character to this color-pair. For example,
    attrset(COLOR_PAIR(2))
will display characters using color-pair 2.

The macro PAIR_NUMBER(val) gives the color-pair number associated with the attribute value val.

The function init_color(color, red, green, blue) sets the red, green and blue intensity components of color color to the values red, green and blue, respectively. The minimum intensity value is 0 and the maximum intensity value is 1000.

The function color_content(color, *red, *green, *blue) stores the red, green and blue intensity components of color color in the variables red, green, and blue, respectively.

The function no_color_video() returns those attributes that a terminal is unable to combine with color.

RETURN VALUES
The functions start_color(), init_pair(), pair_content(), init_color() and color_content() return OK on success and ERR on failure.

SEE ALSO
curses_attributes(3), curses_background(3), curses_default_colors(3)

STANDARDS
The NetBSD Curses library complies with the X/Open Curses specification, part of the Single Unix Specification.

The function no_color_video() and the use of negative color numbers are extensions to the X/Open Curses specification.

HISTORY
These functions first appeared in NetBSD 1.5.