Function parseBackgroundPosition

packages/core/css/parser.ts:284–401

(text: string, start = 0, keyword = parseKeyword(text, start))

	bottom: 'y',
};
export function parseBackgroundPosition(text: string, start = 0, keyword = parseKeyword(text, start)): Parsed<BackgroundPosition> {
	function formatH(align: Parsed<HorizontalAlign>, offset: Parsed<LengthPercentage>) {
		if (align.value === 'center') {
			return 'center';
		}
		if (offset && offset.value.value !== 0) {
			return { align: align.value, offset: offset.value };
		}

		return align.value;
	}
	function formatV(align: Parsed<VerticalAlign>, offset: Parsed<LengthPercentage>) {
		if (align.value === 'center') {
			return 'center';
		}
		if (offset && offset.value.value !== 0) {
			return { align: align.value, offset: offset.value };
		}

		return align.value;
	}
	let end = start;
	if (keyword && backgroundPositionKeywords.has(keyword.value)) {
		end = keyword.end;
		const firstDirection = backgroundPositionKeywordsDirection[keyword.value];

		const firstLength = firstDirection !== 'center' && parsePercentageOrLength(text, end);
		if (firstLength) {
			end = firstLength.end;
		}

		const secondKeyword = parseKeyword(text, end);
		if (secondKeyword && backgroundPositionKeywords.has(secondKeyword.value)) {
			end = secondKeyword.end;
			const secondDirection = backgroundPositionKeywordsDirection[secondKeyword.end];

			if (firstDirection === secondDirection && firstDirection !== 'center') {
				return null; // Reject pair of both horizontal or both vertical alignments.
			}

			const secondLength = secondDirection !== 'center' && parsePercentageOrLength(text, end);
			if (secondLength) {
				end = secondLength.end;
			}

			if ((firstDirection === secondDirection && secondDirection === 'center') || firstDirection === 'x' || secondDirection === 'y') {
				return {
					start,
					end,
					value: {
						x: formatH(<Parsed<HorizontalAlign>>keyword, firstLength),
						y: formatV(<Parsed<VerticalAlign>>secondKeyword, secondLength),
					},
				};
			} else {
				return {
					start,
					end,