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fix: keep full alpha precision when parsing hex colors #137

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fix: keep full alpha precision when parsing hex colors #137

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5 changes: 3 additions & 2 deletions src/colorModels/hex.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
import { RgbaColor } from "../types";
import { clamp, round } from "../helpers";
import { ALPHA_PRECISION } from "../constants";
import { roundRgba } from "./rgb";

const hexMatcher = /^#([0-9a-f]{3,8})$/i;
Expand Down Expand Up @@ -38,7 +39,7 @@ export const parseHex = (hex: string): RgbaColor | null => {
r: digitAt(hex, 1) * 0x11,
g: digitAt(hex, 2) * 0x11,
b: digitAt(hex, 3) * 0x11,
a: length === 5 ? round((digitAt(hex, 4) * 0x11) / 255, 2) : 1,
a: length === 5 ? round((digitAt(hex, 4) * 0x11) / 255, ALPHA_PRECISION) : 1,
};
}

Expand All @@ -47,7 +48,7 @@ export const parseHex = (hex: string): RgbaColor | null => {
r: byteAt(hex, 1),
g: byteAt(hex, 3),
b: byteAt(hex, 5),
a: length === 9 ? round(byteAt(hex, 7) / 255, 2) : 1,
a: length === 9 ? round(byteAt(hex, 7) / 255, ALPHA_PRECISION) : 1,
};
}

Expand Down
15 changes: 12 additions & 3 deletions tests/colord.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
import { colord, random, getFormat, Colord, AnyColor } from "../src/";
import { fixtures, lime, saturationLevels } from "./fixtures";
import { clampHue, round, roundHue } from "../src/helpers";
import { ALPHA_PRECISION } from "../src/constants";

it("Converts between HEX, RGB, HSL and HSV color models properly", () => {
for (const fixture of fixtures) {
Expand Down Expand Up @@ -126,7 +127,7 @@ it("Parses modern HSL functional notations", () => {

it("Supports HEX4 and HEX8 color models", () => {
expect(colord("#ffffffff").toRgb()).toMatchObject({ r: 255, g: 255, b: 255, a: 1 });
expect(colord("#80808080").toRgb()).toMatchObject({ r: 128, g: 128, b: 128, a: 0.5 });
expect(colord("#80808080").toRgb()).toMatchObject({ r: 128, g: 128, b: 128, a: 0.502 });
expect(colord("#AAAF").toRgb()).toMatchObject({ r: 170, g: 170, b: 170, a: 1 });
expect(colord("#5550").toRgb()).toMatchObject({ r: 85, g: 85, b: 85, a: 0 });
expect(colord({ r: 255, g: 255, b: 255, a: 1 }).toHex()).toBe("#ffffff");
Expand All @@ -146,7 +147,7 @@ it("Parses and serializes every HEX digit exactly", () => {
r: byte,
g: byte,
b: byte,
a: round(byte / 255, 2),
a: round(byte / 255, ALPHA_PRECISION),
});
}

Expand All @@ -164,7 +165,7 @@ it("Parses and serializes every HEX digit exactly", () => {
r: 0,
g: 0,
b: 0,
a: round(byte / 255, 2),
a: round(byte / 255, ALPHA_PRECISION),
});
}

Expand All @@ -181,6 +182,14 @@ it("Parses and serializes every HEX digit exactly", () => {
expect(colord("# 12345").isValid()).toBe(false);
});

it("Round-trips a HEX8 alpha channel without drifting", () => {
// The alpha byte of a HEX8 string is 8-bit; parsing must keep enough
// precision (ALPHA_PRECISION) to re-encode the very same byte.
["#476d5e55", "#80808080", "#0a141e7f", "#ffffff01", "#000000fe"].forEach((hex) => {
expect(colord(hex).toHex()).toBe(hex);
});
});

it("Ignores a case and extra whitespace", () => {
expect(colord(" #0a0a0a ").toRgb()).toMatchObject({ r: 10, g: 10, b: 10, a: 1 });
expect(colord("RGB( 10, 10, 10 )").toRgb()).toMatchObject({ r: 10, g: 10, b: 10, a: 1 });
Expand Down
12 changes: 6 additions & 6 deletions tests/plugins.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,7 @@ describe("cmyk", () => {
// https://en.wikipedia.org/wiki/CMYK_color_model
expect(colord("#999966").toCmykString()).toBe("device-cmyk(0% 0% 33% 40%)");
expect(colord("#99ffff").toCmykString()).toBe("device-cmyk(40% 0% 0% 0%)");
expect(colord("#00336680").toCmykString()).toBe("device-cmyk(100% 50% 0% 60% / 0.5)");
expect(colord("#00336680").toCmykString()).toBe("device-cmyk(100% 50% 0% 60% / 0.502)");
});

it("Supported by `getFormat`", () => {
Expand Down Expand Up @@ -196,7 +196,7 @@ describe("hwb", () => {
// https://en.wikipedia.org/wiki/HWB_color_model
expect(colord("#999966").toHwbString()).toBe("hwb(60 40% 40%)");
expect(colord("#99ffff").toHwbString()).toBe("hwb(180 60% 0%)");
expect(colord("#00336680").toHwbString()).toBe("hwb(210 0% 60% / 0.5)");
expect(colord("#00336680").toHwbString()).toBe("hwb(210 0% 60% / 0.502)");
});

it("Supports all valid CSS angle units", () => {
Expand Down Expand Up @@ -233,7 +233,7 @@ describe("lab", () => {
expect(colord("#00ff00").toLab()).toMatchObject({ l: 87.82, a: -79.29, b: 80.99, alpha: 1 });
expect(colord("#ffff00").toLab()).toMatchObject({ l: 97.61, a: -15.75, b: 93.39, alpha: 1 });
expect(colord("#aabbcc").toLab()).toMatchObject({ l: 74.97, a: -3.4, b: -10.7, alpha: 1 });
expect(colord("#33221180").toLab()).toMatchObject({ l: 15.05, a: 6.68, b: 14.59, alpha: 0.5 });
expect(colord("#33221180").toLab()).toMatchObject({ l: 15.05, a: 6.68, b: 14.59, alpha: 0.502 });
expect(colord("#d53987").toLab()).toMatchObject({ l: 50.93, a: 64.96, b: -6.38, alpha: 1 });
});

Expand Down Expand Up @@ -298,7 +298,7 @@ describe("lch", () => {
expect(colord("#c65d06").toLch()).toMatchObject({ l: 52.31, c: 72.21, h: 56.33, a: 1 });
expect(colord("#9d9318").toLch()).toMatchObject({ l: 60.31, c: 59.2, h: 95.46, a: 1 });
expect(colord("#68a639").toLch()).toMatchObject({ l: 62.22, c: 59.15, h: 126.15, a: 1 });
expect(colord("#62acef80").toLch()).toMatchObject({ l: 67.67, c: 42.18, h: 257.79, a: 0.5 });
expect(colord("#62acef80").toLch()).toMatchObject({ l: 67.67, c: 42.18, h: 257.79, a: 0.502 });
});

it("Keeps the LCH hue within [0, 360)", () => {
Expand All @@ -311,9 +311,9 @@ describe("lch", () => {

it("Converts a color to CIE LCH string (CSS functional notation)", () => {
// https://cielab.xyz/colorconv/
expect(colord("#00000080").toLchString()).toBe("lch(0% 0 0 / 0.5)");
expect(colord("#00000080").toLchString()).toBe("lch(0% 0 0 / 0.502)");
expect(colord("#ffffff").toLchString()).toBe("lch(100% 0 0)");
expect(colord("#c65d06ed").toLchString()).toBe("lch(52.31% 72.21 56.33 / 0.93)");
expect(colord("#c65d06ed").toLchString()).toBe("lch(52.31% 72.21 56.33 / 0.929)");
expect(colord("#aabbcc").toLchString()).toBe("lch(74.97% 11.22 252.37)");
});

Expand Down
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