curs_color(3X) 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
characters 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 terminal 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 global 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 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.
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curs_color(3X) curs_color(3X)
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 attribute.
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 storing 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
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curs_color(3X) curs_color(3X)
COLORMAGENTA
COLORCYAN
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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