astro/dist/assets/fonts/core/collect-font-assets-from-faces.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { FONT_FORMATS } from "../constants.js";
import { renderFontWeight } from "../utils.js";
export function collectFontAssetsFromFaces({ fonts, fontFileIdGenerator, family, fontFilesIds, collectedFontsIds, hasher, defaults }) {
	const fontFileById = new Map();
	const collectedFontsForMetricsByUniqueKey = new Map();
	const preloads = [];
	for (const font of fonts) {
		// The index keeps track of encountered URLs. We can't use a regular for loop
		// below because it may contain sources without urls, which would prevent preloading completely
		let index = 0;
		for (const source of font.src) {
			if ("name" in source) {
				continue;
			}
			const format = FONT_FORMATS.find((e) => e.format === source.format);
			const originalUrl = source.originalURL;
			const id = fontFileIdGenerator.generate({
				cssVariable: family.cssVariable,
				font,
				originalUrl,
				type: format.type
			});
			if (!fontFilesIds.has(id) && !fontFileById.has(id)) {
				fontFileById.set(id, {
					url: originalUrl,
					init: font.meta?.init
				});
				// We only collect the first URL to avoid preloading fallback sources (eg. we only
				// preload woff2 if woff is available)
				if (index === 0) {
					preloads.push({
						style: font.style,
						subset: font.meta?.subset,
						type: format.type,
						url: source.url,
						weight: renderFontWeight(font.weight)
					});
				}
			}
			const collected = {
				id,
				url: originalUrl,
				init: font.meta?.init,
				data: {
					weight: font.weight,
					style: font.style,
					meta: { subset: font.meta?.subset }
				}
			};
			const collectedKey = hasher.hashObject(collected.data);
			const fallbacks = family.fallbacks ?? defaults.fallbacks;
			if (fallbacks.length > 0 && !collectedFontsIds.has(collectedKey) && !collectedFontsForMetricsByUniqueKey.has(collectedKey)) {
				// If a family has fallbacks, we store the first url we get that may
				// be used for the fallback generation.
				collectedFontsForMetricsByUniqueKey.set(collectedKey, collected);
			}
			index++;
		}
	}
	return {
		fontFileById,
		preloads,
		collectedFontsForMetricsByUniqueKey
	};
}