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Merged
romainmenke merged 1 commit into from
Apr 11, 2026
Merged

css-color-parser: add support for analogous set in color interpolations #1808

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4 changes: 4 additions & 0 deletions packages/css-color-parser/CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,9 @@
# Changes to CSS Color Parser

### Unreleased (minor)

- Add support for analogous set in color interpolations

### 4.0.2

_February 21, 2026_
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2 changes: 1 addition & 1 deletion packages/css-color-parser/dist/index.mjs
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53 changes: 37 additions & 16 deletions packages/css-color-parser/src/color-data.ts
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Expand Up @@ -281,79 +281,90 @@ export function colorDataTo(colorData: ColorData, toNotation: ColorNotation): Co

// 2. Carry forward missing components
if (toNotation === colorData.colorNotation) {
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [0, 1, 2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [0, 1, 2], []);
} else if (
predefinedRGB_or_XYZ_Spaces.has(toNotation) &&
predefinedRGB_or_XYZ_Spaces.has(colorData.colorNotation)
) {
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [0, 1, 2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [0, 1, 2], []);
} else {
switch (toNotation) {
case ColorNotation.HSL:
switch (colorData.colorNotation) {
case ColorNotation.HWB:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [0], [1, 2]);
break;
case ColorNotation.Lab:
case ColorNotation.OKLab:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [2], outputColorData.channels, [0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [2], [0, 1], outputColorData.channels, [0], [1, 2]);
break;
case ColorNotation.LCH:
case ColorNotation.OKLCH:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [2, 1, 0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [2, 1, 0], []);
break;
default:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [], [], outputColorData.channels, [], []);
}

break;
case ColorNotation.HWB:
switch (colorData.colorNotation) {
case ColorNotation.HSL:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [0], [1, 2]);
break;
case ColorNotation.LCH:
case ColorNotation.OKLCH:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [2], [0, 1]);
break;
default:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [], [], outputColorData.channels, [], []);
}

break;
case ColorNotation.Lab:
case ColorNotation.OKLab:
switch (colorData.colorNotation) {
case ColorNotation.HSL:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [2], [0, 1]);
break;
case ColorNotation.Lab:
case ColorNotation.OKLab:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [0, 1, 2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [0, 1, 2], []);
break;
case ColorNotation.LCH:
case ColorNotation.OKLCH:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [0], [1, 2]);
break;
default:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [], [], outputColorData.channels, [], []);
}

break;
case ColorNotation.LCH:
case ColorNotation.OKLCH:
switch (colorData.colorNotation) {
case ColorNotation.HSL:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [2, 1, 0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [2, 1, 0], []);
break;
case ColorNotation.HWB:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [2], [0, 1]);
break;
case ColorNotation.Lab:
case ColorNotation.OKLab:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], outputColorData.channels, [0]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0], [1, 2], outputColorData.channels, [0], [1, 2]);
break;
case ColorNotation.LCH:
case ColorNotation.OKLCH:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], outputColorData.channels, [0, 1, 2]);
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [0, 1, 2], [], outputColorData.channels, [0, 1, 2], []);
break;
default:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [], [], outputColorData.channels, [], []);
}

break;

default:
outputColorData.channels = carryForwardMissingComponents(colorData.channels, [], [], outputColorData.channels, [], []);
}
}

Expand Down Expand Up @@ -452,15 +463,25 @@ export function convertPowerlessComponentsToZeroValuesForDisplay(a: Color, color
return out;
}

function carryForwardMissingComponents(a: Color, aIndices: Array<number>, b: Color, bIndices: Array<number>): Color {
function carryForwardMissingComponents(a: Color, aIndices: Array<number>, aSet: Array<number>, b: Color, bIndices: Array<number>, bSet: Array<number>): Color {
if (aIndices.length < 3 && a.every(Number.isNaN)) {
return [Number.NaN, Number.NaN, Number.NaN];
}

const output: Color = [...b];

for (const i of aIndices) {
for (let i = 0; i < aIndices.length; i++) {
if (Number.isNaN(a[aIndices[i]])) {
output[bIndices[i]] = Number.NaN;
}
}

if (aSet.length && aSet.every((i) => Number.isNaN(a[i]))) {
for (let i = 0; i < bSet.length; i++) {
output[bSet[i]] = Number.NaN;
}
}

return output;
}

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5 changes: 5 additions & 0 deletions packages/css-color-parser/test/basic/color-mix-function-oklch.mjs
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Expand Up @@ -9,6 +9,11 @@ const tests = [
['color-mix(in lch, oklch(75% 0% 60deg), oklch(75% 50% 0deg))', 'oklch(0.74979 0.09824 0.10588)'],
['color-mix(in oklch, oklch(100% 0% none), oklch(50% 50% 0deg))', 'oklch(0.75 0.1 0)'],
['color-mix(in oklch, oklch(100% none 60deg), oklch(50% 50% 0deg))', 'oklch(0.75 0.2 30)'],

// Analogous sets
['color-mix(in oklch, rgb(none none none), oklch(0.5 0.2 50))', 'oklch(0.5 0.2 50)'],
['color-mix(in oklch, hwb(100deg none none), oklch(0.5 0.2 50deg))', 'oklch(0.5 0.2 94.8876)'],
['color-mix(in oklch, lab(100 none none), oklch(0.5 0.2 50deg))', 'oklch(0.75 0.2 50)'],
];

for (const test of tests) {
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5 changes: 5 additions & 0 deletions packages/css-color-parser/test/basic/color-mix-function.mjs
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Expand Up @@ -135,6 +135,11 @@ const tests = [
['color-mix(in oklab, red 5%,)', ''],
['color-mix(in oklab, red, blue, green,)', ''],
['color-mix(in oklab, red, , green)', ''],

// Analogous sets
['color-mix(in oklch, rgb(200, 100, 50), oklch(none none none))', 'rgb(200, 100, 50)'],
['color-mix(in oklch, rgb(200, 100, 50), lab(none none none))', 'rgb(200, 100, 50)'],
['color-mix(in oklch, lab(40% 20% 10%), lab(40% 20% 10%))', 'rgb(136, 77, 75)'],
];

for (const test of tests) {
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