luoyangwei
94 lines
1.7 KiB
TypeScript
94 lines
1.7 KiB
TypeScript
export type GalleryColorFamily =
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| "black"
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| "blue"
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| "green"
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| "light"
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| "orange"
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| "purple"
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| "red"
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| "yellow";
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function hexToRgb(hex: string) {
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const normalized = hex.trim().replace(/^#/, "");
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if (!/^[0-9a-f]{6}$/i.test(normalized)) {
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return null;
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}
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return {
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r: parseInt(normalized.slice(0, 2), 16),
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g: parseInt(normalized.slice(2, 4), 16),
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b: parseInt(normalized.slice(4, 6), 16),
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};
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}
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export function getGalleryColorFamily(
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color: string | null | undefined,
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): GalleryColorFamily | null {
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if (!color) {
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return null;
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}
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const rgb = hexToRgb(color);
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if (!rgb) {
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return null;
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}
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const { r, g, b } = rgb;
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const max = Math.max(r, g, b);
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const min = Math.min(r, g, b);
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const lightness = (max + min) / 510;
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if (lightness > 0.78) {
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return "light";
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}
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if (lightness < 0.2) {
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return "black";
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}
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const delta = max - min;
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if (delta < 24) {
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return lightness > 0.52 ? "light" : "black";
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}
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let hue = 0;
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if (max === r) {
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hue = ((g - b) / delta) % 6;
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} else if (max === g) {
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hue = (b - r) / delta + 2;
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} else {
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hue = (r - g) / delta + 4;
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}
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hue = Math.round(hue * 60);
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if (hue < 0) {
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hue += 360;
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}
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if (hue < 18 || hue >= 345) {
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return "red";
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}
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if (hue < 45) {
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return "orange";
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}
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if (hue < 70) {
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return "yellow";
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}
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if (hue < 170) {
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return "green";
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}
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if (hue < 255) {
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return "blue";
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}
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if (hue < 345) {
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return "purple";
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}
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return null;
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}
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