Function resolveFontFaces

packages/core/src/utils/faces.ts:21–127

(
	config: FontConfig,
	axisKeys?: VariableAxisKey[],
)

 * Omit axisKeys for every published bundle; an empty list selects none.
 */
export const resolveFontFaces = (
	config: FontConfig,
	axisKeys?: VariableAxisKey[],
): FontFace[] => {
	const {
		id,
		family,
		subsets,
		weights,
		styles,
		unicodeRange = {},
		subsetSlices = {},
		variable,
		formats = ['woff2'],
	} = config;

	const faces: FontFace[] = [];
	const isVariable = !!variable;
	const familyId = id ?? normalizeKebabCase(family);

	if (isVariable) {
		const requestedAxes = axisKeys ?? getVariableAxisKeys(variable);

		// Filter out ttf formats for variable fonts.
		const variableFormats = formats.filter(
			(format): format is WebFontFormat => format !== 'ttf',
		);

		// Generate one face per axis key, with the weight set to the closest available weight.
		for (const axisKey of requestedAxes) {
			const axisConfig = pickAxisConfig(variable, axisKey);
			const cssWeight = axisConfig.wght
				? formatAxisValue(axisConfig.wght)
				: `${findClosestWeight(weights)}`;

			const stretch = getFaceStretch(axisKey, axisConfig);

			for (const subset of subsets) {
				const characterSets = subsetSlices[subset]?.length
					? subsetSlices[subset]
					: [{ id: 0, unicodeRange: unicodeRange[subset] ?? '' }];
				for (const {
					id: sliceIndex,
					unicodeRange: faceRange,
				} of characterSets) {
					for (const style of styles) {
						faces.push({
							subset,
							weight: cssWeight,
							style: getFaceStyle(axisKey, style, axisConfig),
							isVariable: true,
							unicodeRange: faceRange,
							sources: variableFormats.map((format) => ({
								format,
								filename: generateVariableFilename(
									familyId,
									subset,
									axisKey,