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