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curs_color(3) Library Functions Manual curs_color(3) NAME curs_color, start_color, init_pair, init_color, has_colors, can_change_color, color_content, pair_content, COLOR_PAIR, COLOR_PAIRS, COLORS, PAIR_NUMBER - Curses color-manipulation routines and variables LIBRARY Curses Library (libcurses.a, libcurses.so) SYNOPSIS # 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); int COLOR_PAIR(int n); int PAIR_NUMBER(int value); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: start_color, init_pair, init_color, has_colors, can_change_color, color_content, pair_content, COLOR_PAIR, PAIR_NUMBER: XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. DESCRIPTION The Curses library includes routines that manipulate color-on-color al- phanumeric terminals. To use these routines, applications must call start_color, usually right after initscr. Colors are always used in pairs (referred to as color-pairs). A color-pair consists of a fore- ground color (for characters) and a background color (for the field on which the characters are displayed). An application calls init_pair to initialize a color-pair. After the color-pair is initialized, applica- tions can call COLOR_PAIR(n) to use color attributes. If a terminal is capable of redefining colors, applications 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 application can change the colors. The routine color_content allows an application to identify the amounts of red, green, and blue components in an ini- tialized color. The routine pair_content allows the application 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 application uses colors, and before the application calls any other color manipulation routine. It is good practice to call this routine right after initscr. The start_color routine initializes eight basic colors (black, red, green, yellow, blue, magenta, cyan, and white) and two global variables (COLORS and COLOR_PAIRS, which respectively define the maximum number of colors and color-pairs the terminal can support). The start_color routine also restores the colors on the terminal to the values they had when the terminal was turned on. The init_pair routine changes the definition of a color-pair. This routine takes three arguments that are identification numbers for the following: The color-pair to be changed The foreground color The back- ground color The value of the first argument must be between 1 and the smaller of either 63 or COLOR_PAIRS-1. The values of the second and third argu- ments must be between 0 and COLORS. If the color-pair was previously initialized, the screen is refreshed and all occurrences of that color- pair are changed to the new definition. The init_color routine changes the definition of a color. This routine 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, respectively). 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 immedi- ately change to the new definition. The has_colors routine requires no arguments. It returns TRUE if the terminal can manipulate colors; otherwise, the routine 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- wise, the routine returns FALSE. This routine facilitates writing ter- minal-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. This routine re- quires four arguments: the color number, and three addresses (of short data type) for storing the information about the amounts of red, green, and blue components in the given color. The value of the first argu- ment 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 com- ponent) and 1000 (maximum amount of component). The pair_content routine allows users to find out which colors a given color-pair consists of. This routine requires three arguments: the color-pair number, and two addresses (of short data type) for storing the numbers for the foreground and background colors. The value of the first argument must be between 1 and the smaller of 63 or COLOR_PAIRS-1. The values that are stored at the addresses pointed to by the second and third arguments are between 0 and COLORS. The COLOR_PAIR(n) macro returns the value of the color-pair whose num- ber is n. This value is the color attribute as it would be extracted from a chtype variable. Conversely, the macro PAIR_NUMBER(value) re- turns the number of the color-pair associated with the color attribute value. 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 NOTES The header file curses.h automatically includes the header file stdio.h. Note that COLOR_PAIR and PAIR_NUMBER may be macros. RETURN VALUES The COLOR_PAIR, PAIR_NUMBER, can_change_color, and has_colors routines return values as indicated in the DESCRIPTION. All other routines return ERR upon failure and OK upon successful com- pletion. RELATED INFORMATION Functions: curses(3), curs_attr_get(3), curs_initscr(3) Others: standards(5) delim off curs_color(3)