Most terminals don’t support defining new colors or changing the
colors that already exist. For those terminals that do, the function
init-color! can be used to change the definition of colors by
adjusting the amount of red, green, and blue in each. To set the red
to a darker red, you could use this function
;; Param 1: color name ;; Param 2, 3, 4; RGB content, min=0 max=1000 (init-color! COLOR_RED 300 0 0)
If your terminal cannot change the color definitions, the procedure
will throw and error. The function
can-change-color? can be
used to find out whether that terminal has the capability of changing
color content or not. The RGB content is scaled from 0 to 1000.
Initially, red is likely defined with content 680 (r), 0 (g), 0 (b).
pair-content can be used
to find the color content of a given color and foreground/background
combination of a color pair.