ark/lib/colors.nix
2022-10-04 02:08:44 +03:00

72 lines
1.5 KiB
Nix

lib:
with lib; rec {
# color-related functions
# convert rrggbb hex to #rrggbb
x = c: "#${c}";
# same as x but adds an alpha channel for transparency
xrgba = c: "${c}88";
xargb = c: "88${c}";
# convert rrggbb hex to rgba(r, g, b, a) css
rgba = c: let
r = toString (hexToDec (__substring 0 2 c));
g = toString (hexToDec (__substring 2 2 c));
b = toString (hexToDec (__substring 4 2 c));
res = "rgba(${r}, ${g}, ${b}, 0.5)";
in
res;
# general stuff
# functions copied from https://gist.github.com/corpix/f761c82c9d6fdbc1b3846b37e1020e11
# convert a hex value to an integer
hexToDec = v: let
hexToInt = {
"0" = 0;
"1" = 1;
"2" = 2;
"3" = 3;
"4" = 4;
"5" = 5;
"6" = 6;
"7" = 7;
"8" = 8;
"9" = 9;
"a" = 10;
"b" = 11;
"c" = 12;
"d" = 13;
"e" = 14;
"f" = 15;
"A" = 10;
"B" = 11;
"C" = 12;
"D" = 13;
"E" = 14;
"F" = 15;
};
chars = stringToCharacters v;
charsLen = length chars;
in
foldl
(a: v: a + v)
0
(imap0
(k: v: hexToInt."${v}" * (pow 16 (charsLen - k - 1)))
chars);
pow = let
pow' = base: exponent: value:
# FIXME: It will silently overflow on values > 2**62 :(
# The value will become negative or zero in this case
if exponent == 0
then 1
else if exponent <= 1
then value
else (pow' base (exponent - 1) (value * base));
in
base: exponent: pow' base exponent base;
}