thi-ng/umbrella

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packages/color/src/is-black.ts

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import { DEFAULT, defmulti } from "@thi.ng/defmulti/defmulti";
import type { ReadonlyColor, TypedColor } from "./api.js";
import { EPS } from "./api/constants.js";
import { __dispatch0 } from "./internal/dispatch.js";
import { rgb } from "./rgb/rgb.js";

const isBlackHsv = (x: ReadonlyColor, eps = EPS) => x[2] <= eps;

const isBlackRgb = (x: ReadonlyColor, eps = EPS) =>
    x[0] <= eps && x[1] <= eps && x[2] <= eps;

const isBlackLch = (x: ReadonlyColor, eps = EPS) => x[0] <= eps;

export const isBlack = defmulti<TypedColor<any>, number | undefined, boolean>(
    __dispatch0,
    {
        hcy: "hsv",
        hsi: "hsv",
        hsl: "hsv",
        labD50: "lch",
        labD65: "lch",
        srgb: "rgb",
        ycc: "rgb",
    },
    {
        hsv: isBlackHsv,
        lch: isBlackLch,
        rgb: isBlackRgb,
        [DEFAULT]: (x: any) => isBlackRgb(rgb(x)),
    }
);