emitImageMetadata() — astro Function Reference

Source Code

packages/astro/src/assets/utils/node.ts lines 72–139

export async function emitImageMetadata(
	id: string | undefined,
	fileEmitter?: FileEmitter,
): Promise<ImageMetadataWithContents | undefined> {
	if (!id) {
		return undefined;
	}

	const url = pathToFileURL(id);
	let fileData: Buffer;
	try {
		fileData = await fs.readFile(url);
	} catch {
		return undefined;
	}

	const fileMetadata = await imageMetadata(fileData, id);

	const emittedImage: Omit<ImageMetadataWithContents, 'fsPath'> = {
		src: '',
		...fileMetadata,
	};

	// Private for now, we generally don't want users to rely on filesystem paths, but we need it so that we can maybe remove the original asset from the build if it's unused.
	Object.defineProperty(emittedImage, 'fsPath', {
		enumerable: false,
		writable: false,
		value: fileURLToNormalizedPath(url),
	});

	// Build
	let isBuild = typeof fileEmitter === 'function';
	if (isBuild) {
		const pathname = decodeURI(url.pathname);
		const filename = path.basename(pathname, path.extname(pathname) + `.${fileMetadata.format}`);

		try {
			let handle: string;

			if (fileMetadata.format === 'svg') {
				// check if this content already exists
				handle = await handleSvgDeduplication(fileData, filename, fileEmitter!);
			} else {
				// Non-SVG assets: emit normally
				handle = fileEmitter!({
					name: filename,
					source: fileData,
					type: 'asset',
				});
			}

			emittedImage.src = `__ASTRO_ASSET_IMAGE__${handle}__`;
		} catch {
			isBuild = false;
		}
	}

	if (!isBuild) {
		// Pass the original file information through query params so we don't have to load the file twice
		url.searchParams.append('origWidth', fileMetadata.width.toString());
		url.searchParams.append('origHeight', fileMetadata.height.toString());
		url.searchParams.append('origFormat', fileMetadata.format);

		emittedImage.src = `/@fs` + prependForwardSlash(fileURLToNormalizedPath(url));
	}

	return emittedImage as ImageMetadataWithContents;
}