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. For portable applications:
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The value of the first argument must be between 1 and COLOR_PAIRS-1.
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The value of the second and third arguments must be between 0 and COLORS (the 0 color pair is wired to white on black and cannot be changed).
If the color-pair was previously initialized, the screen is refreshed and all occurrences of that color-pair are changed to the new definition.
As an extension, ncurses allows you to set color pair 0 via the assume_default_colors routine, or to specify the use of default colors (color number -1) if you first invoke the use_default_colors routine.
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 section 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 programmers 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 pair_content routine allows programmers 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 COLOR_PAIRS-1. The values that are stored at the addresses pointed to by the second and third arguments are between 0 and COLORS.
COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW combined with the A_BOLD attribute.
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The A_BLINK attribute should in theory cause the background to go bright. This often fails to work, and even some cards for which it mostly works (such as the Paradise and compatibles) do the wrong thing when you try to set a bright "yellow" background (you get a blinking yellow foreground instead).
The init_pair routine accepts negative values of foreground and background color to support the use_default_colors extension, but only if that routine has been first invoked.
The assumption that COLOR_BLACK is the default background color for all terminals can be modified using the assume_default_colors extension,
