60 lines
1.3 KiB
TypeScript
60 lines
1.3 KiB
TypeScript
// Copyright 2021 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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const LIGHTNESS_TABLE: Record<number, number> = {
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0: 45,
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60: 30,
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180: 30,
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240: 50,
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300: 40,
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360: 45,
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};
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function getLightnessFromHue(hue: number, min: number, max: number) {
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const percentage = ((hue - min) * 100) / (max - min);
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const minValue = LIGHTNESS_TABLE[min];
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const maxValue = LIGHTNESS_TABLE[max];
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return (percentage * (maxValue - minValue)) / 100 + minValue;
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}
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function calculateLightness(hue: number): number {
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let lightness = 45;
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if (hue < 60) {
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lightness = getLightnessFromHue(hue, 0, 60);
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} else if (hue < 180) {
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lightness = 30;
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} else if (hue < 240) {
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lightness = getLightnessFromHue(hue, 180, 240);
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} else if (hue < 300) {
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lightness = getLightnessFromHue(hue, 240, 300);
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} else {
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lightness = getLightnessFromHue(hue, 300, 360);
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}
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return lightness;
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}
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function adjustLightnessValue(
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lightness: number,
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percentIncrease: number
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): number {
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return lightness + lightness * percentIncrease;
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}
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export function getHSL(
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{
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hue,
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saturation,
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}: {
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hue: number;
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saturation: number;
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},
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adjustedLightness = 0
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): string {
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return `hsl(${hue}, ${saturation}%, ${adjustLightnessValue(
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calculateLightness(hue),
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adjustedLightness
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)}%)`;
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}
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