43 lines
1.4 KiB
TypeScript
43 lines
1.4 KiB
TypeScript
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/**
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* ThumbHash utilities for generating blur placeholders and dominant colors.
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* Uses the thumbhash package to decode Immich's base64-encoded ThumbHash strings
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* into data URLs and hex color values.
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*/
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import { thumbHashToRGBA, thumbHashToDataURL } from 'thumbhash';
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/**
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* Convert an Immich base64-encoded ThumbHash into a tiny data URL
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* suitable for next/image's blurDataURL prop.
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*/
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export function thumbHashToBlurDataUrl(base64: string): string {
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const bytes = Uint8Array.from(atob(base64), (c) => c.charCodeAt(0));
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return thumbHashToDataURL(bytes);
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}
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/**
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* Extract the dominant/average color from a ThumbHash as a hex string.
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* Computes the weighted average of all non-transparent pixels.
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*/
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export function thumbHashToDominantHex(base64: string): string {
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const bytes = Uint8Array.from(atob(base64), (c) => c.charCodeAt(0));
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const { w, h, rgba } = thumbHashToRGBA(bytes);
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let r = 0, g = 0, b = 0, total = 0;
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for (let i = 0; i < w * h; i++) {
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const a = rgba[i * 4 + 3];
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if (a > 0) {
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const weight = a / 255;
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r += rgba[i * 4] * weight;
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g += rgba[i * 4 + 1] * weight;
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b += rgba[i * 4 + 2] * weight;
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total += weight;
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}
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}
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if (total === 0) return '#888888';
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const avg = (v: number) => Math.round(v / total).toString(16).padStart(2, '0');
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return `#${avg(r)}${avg(g)}${avg(b)}`;
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}
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