feat(assets): Add property to image services to control which properties to use for hashing (#8984)

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

.changeset/new-islands-lick.md

@@ -0,0 +1,5 @@
+---
+'astro': minor
+---
+
+Adds a new property `propertiesToHash` to the Image Services API to allow specifying which properties of `getImage()` / `<Image />` / `<Picture />` should be used for hashing the result files when doing local transformations. For most services, this will include properties such as `src`, `width` or `quality` that directly changes the content of the generated image.

packages/astro/src/assets/consts.ts

@@ -26,3 +26,4 @@ export const VALID_SUPPORTED_FORMATS = [
 ] as const;
 export const DEFAULT_OUTPUT_FORMAT = 'webp' as const;
 export const VALID_OUTPUT_FORMATS = ['avif', 'png', 'webp', 'jpeg', 'jpg', 'svg'] as const;
+export const DEFAULT_HASH_PROPS = ['src', 'width', 'height', 'format', 'quality'];

packages/astro/src/assets/internal.ts

@@ -1,6 +1,7 @@
 import { isRemotePath } from '@astrojs/internal-helpers/path';
 import type { AstroConfig, AstroSettings } from '../@types/astro.js';
 import { AstroError, AstroErrorData } from '../core/errors/index.js';
+import { DEFAULT_HASH_PROPS } from './consts.js';
 import { isLocalService, type ImageService } from './services/service.js';
 import type {
 	GetImageResult,
@@ -114,10 +115,11 @@ export async function getImage(
 		globalThis.astroAsset.addStaticImage &&
 		!(isRemoteImage(validatedOptions.src) && imageURL === validatedOptions.src)
 	) {
-		imageURL = globalThis.astroAsset.addStaticImage(validatedOptions);
+		const propsToHash = service.propertiesToHash ?? DEFAULT_HASH_PROPS;
+		imageURL = globalThis.astroAsset.addStaticImage(validatedOptions, propsToHash);
 		srcSets = srcSetTransforms.map((srcSet) => ({
 			transform: srcSet.transform,
-			url: globalThis.astroAsset.addStaticImage!(srcSet.transform),
+			url: globalThis.astroAsset.addStaticImage!(srcSet.transform, propsToHash),
 			descriptor: srcSet.descriptor,
 			attributes: srcSet.attributes,
 		}));

packages/astro/src/assets/services/service.ts

@@ -1,7 +1,7 @@
 import type { AstroConfig } from '../../@types/astro.js';
 import { AstroError, AstroErrorData } from '../../core/errors/index.js';
 import { isRemotePath, joinPaths } from '../../core/path.js';
-import { DEFAULT_OUTPUT_FORMAT, VALID_SUPPORTED_FORMATS } from '../consts.js';
+import { DEFAULT_HASH_PROPS, DEFAULT_OUTPUT_FORMAT, VALID_SUPPORTED_FORMATS } from '../consts.js';
 import { isESMImportedImage, isRemoteAllowed } from '../internal.js';
 import type { ImageOutputFormat, ImageTransform, UnresolvedSrcSetValue } from '../types.js';
 
@@ -100,6 +100,13 @@ export interface LocalImageService<T extends Record<string, any> = Record<string
 		transform: LocalImageTransform,
 		imageConfig: ImageConfig<T>
 	) => Promise<{ data: Buffer; format: ImageOutputFormat }>;
+
+	/**
+	 * A list of properties that should be used to generate the hash for the image.
+	 *
+	 * Generally, this should be all the properties that can change the result of the image. By default, this is `src`, `width`, `height`, `quality`, and `format`.
+	 */
+	propertiesToHash?: string[];
 }
 
 export type BaseServiceTransform = {
@@ -131,6 +138,7 @@ export type BaseServiceTransform = {
  *
  */
 export const baseService: Omit<LocalImageService, 'transform'> = {
+	propertiesToHash: DEFAULT_HASH_PROPS,
 	validateOptions(options) {
 		// `src` is missing or is `undefined`.
 		if (!options.src || (typeof options.src !== 'string' && typeof options.src !== 'object')) {

packages/astro/src/assets/types.ts

@@ -17,7 +17,7 @@ declare global {
 	// eslint-disable-next-line no-var
 	var astroAsset: {
 		imageService?: ImageService;
-		addStaticImage?: ((options: ImageTransform) => string) | undefined;
+		addStaticImage?: ((options: ImageTransform, hashProperties: string[]) => string) | undefined;
 		staticImages?: AssetsGlobalStaticImagesList;
 	};
 }

packages/astro/src/assets/utils/transformToPath.ts

@@ -16,9 +16,20 @@ export function propsToFilename(transform: ImageTransform, hash: string) {
 	return `/${filename}_${hash}${outputExt}`;
 }
 
-export function hashTransform(transform: ImageTransform, imageService: string) {
+export function hashTransform(
+	transform: ImageTransform,
+	imageService: string,
+	propertiesToHash: string[]
+) {
 	// Extract the fields we want to hash
-	const { alt, class: className, style, widths, densities, ...rest } = transform;
+	const hashFields = propertiesToHash.reduce(
-	const hashFields = { ...rest, imageService };
+		(acc, prop) => {
+			// It's possible for `transform[prop]` here to be undefined, or null, but that's fine because it's still consistent
+			// between different transforms. (ex: every transform without a height will explicitly have a `height: undefined` property)
+			acc[prop] = transform[prop];
+			return acc;
+		},
+		{ imageService } as Record<string, unknown>
+	);
 	return shorthash(deterministicString(hashFields));
 }

packages/astro/src/assets/vite-plugin-assets.ts

@@ -77,7 +77,7 @@ export default function assets({
 					return;
 				}
 
-				globalThis.astroAsset.addStaticImage = (options) => {
+				globalThis.astroAsset.addStaticImage = (options, hashProperties) => {
 					if (!globalThis.astroAsset.staticImages) {
 						globalThis.astroAsset.staticImages = new Map<
 							string,
@@ -88,7 +88,11 @@ export default function assets({
 					const originalImagePath = (
 						isESMImportedImage(options.src) ? options.src.src : options.src
 					).replace(settings.config.build.assetsPrefix || '', '');
-					const hash = hashTransform(options, settings.config.image.service.entrypoint);
+					const hash = hashTransform(
+						options,
+						settings.config.image.service.entrypoint,
+						hashProperties
+					);
 
 					let finalFilePath: string;
 					let transformsForPath = globalThis.astroAsset.staticImages.get(originalImagePath);

packages/astro/test/core-image.test.js

@@ -934,6 +934,29 @@ describe('astro:image', () => {
 
 			expect(isReusingCache).to.be.true;
 		});
+
+		describe('custom service in build', () => {
+			it('uses configured hashes properties', async () => {
+				await fixture.build();
+				const html = await fixture.readFile('/imageDeduplication/index.html');
+
+				const $ = cheerio.load(html);
+
+				const allTheSamePath = $('#all-the-same img')
+					.map((_, el) => $(el).attr('src'))
+					.get();
+
+				expect(allTheSamePath.every((path) => path === allTheSamePath[0])).to.equal(true);
+
+				const useCustomHashProperty = $('#use-data img')
+					.map((_, el) => $(el).attr('src'))
+					.get();
+				expect(useCustomHashProperty.every((path) => path === useCustomHashProperty[0])).to.equal(
+					false
+				);
+				expect(useCustomHashProperty[1]).to.not.equal(allTheSamePath[0]);
+			});
+		});
 	});
 
 	describe('dev ssr', () => {

packages/astro/test/fixtures/core-image-ssg/src/pages/imageDeduplication.astro

@@ -0,0 +1,22 @@
+---
+import { Image } from 'astro:assets';
+import myImage from "../assets/penguin1.jpg";
+---
+<html>
+<head>
+
+</head>
+<body>
+	<div id="all-the-same">
+		<Image src={myImage} alt="a penguin" />
+		<Image src={myImage} alt="a penguin" class="something" />
+		<Image src={myImage} alt="a penguin" id="something-else" class="something" />
+		<Image src={myImage} alt="a penguin" id="something-else" class="something" transition:animate={"none"} transition:name='' transition:persist style="color: red" />
+	</div>
+
+	<div id="use-data">
+		<Image src={myImage} alt="a penguin" />
+		<Image src={myImage} alt="a penguin" data-custom="value" />
+	</div>
+</body>
+</html>

packages/astro/test/test-image-service.js

@@ -15,6 +15,7 @@ export function testImageService(config = {}) {
 /** @type {import("../dist/@types/astro").LocalImageService} */
 export default {
 	...baseService,
+	propertiesToHash: [...baseService.propertiesToHash, 'data-custom'],
 	getHTMLAttributes(options, serviceConfig) {
 		options['data-service'] = 'my-custom-service';
 		if (serviceConfig.service.config.foo) {