MDX remark image props

.changeset/quick-cars-kneel.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/mdx": minor
+---
+
+Allows remark plugins to pass options specifying how images in .mdx files will be optimized

packages/integrations/mdx/src/plugins.ts

@@ -43,7 +43,7 @@ export function createMdxProcessor(mdxOptions: MdxOptions, extraOptions: MdxProc
 }
 
 function getRemarkPlugins(mdxOptions: MdxOptions): PluggableList {
-	let remarkPlugins: PluggableList = [remarkCollectImages, remarkImageToComponent];
+	let remarkPlugins: PluggableList = [];
 
 	if (!isPerformanceBenchmark) {
 		if (mdxOptions.gfm) {
@@ -54,7 +54,7 @@ function getRemarkPlugins(mdxOptions: MdxOptions): PluggableList {
 		}
 	}
 
-	remarkPlugins = [...remarkPlugins, ...mdxOptions.remarkPlugins];
+	remarkPlugins = [...remarkPlugins, ...mdxOptions.remarkPlugins, remarkCollectImages, remarkImageToComponent];
 
 	if (!isPerformanceBenchmark) {
 		// Apply syntax highlighters after user plugins to match `markdown/remark` behavior

packages/integrations/mdx/src/remark-images-to-component.ts

@@ -1,6 +1,6 @@
 import type { MarkdownVFile } from '@astrojs/markdown-remark';
 import type { Image, Parent } from 'mdast';
-import type { MdxJsxFlowElement, MdxjsEsm } from 'mdast-util-mdx';
+import type { MdxJsxFlowElement, MdxjsEsm, MdxJsxAttribute } from 'mdast-util-mdx';
 import { visit } from 'unist-util-visit';
 import { jsToTreeNode } from './utils.js';
 
@@ -89,6 +89,53 @@ export function remarkImageToComponent() {
 					});
 				}
 
+				if (node.data && node.data.hProperties) {
+					const createArrayAttribute = (name: string, values: string[]): MdxJsxAttribute => {
+						return {
+							type: 'mdxJsxAttribute',
+							name: name,
+							value: {
+								type: 'mdxJsxAttributeValueExpression',
+								value: name,
+								data: {
+									estree: {
+										type: 'Program',
+										body: [
+											{
+												type: 'ExpressionStatement',
+												expression: {
+													type: 'ArrayExpression',
+													elements: values.map((value) => ({
+														type: 'Literal',
+														value: value,
+														raw: String(value),
+													})),
+												},
+											},
+										],
+										sourceType: 'module',
+										comments: [],
+									},
+								},
+							},
+						};
+					};
+					// Go through every hProperty and add it as an attribute of the <Image>
+					Object.entries(node.data.hProperties as Record<string, string | string[]>).forEach(
+						([key, value]) => {
+							if (Array.isArray(value)) {
+								componentElement.attributes.push(createArrayAttribute(key, value));
+							} else {
+								componentElement.attributes.push({
+									name: key,
+									type: 'mdxJsxAttribute',
+									value: String(value),
+								});
+							}
+						}
+					);
+				}
+
 				parent!.children.splice(index!, 1, componentElement);
 			}
 		});

packages/integrations/mdx/test/fixtures/image-remark-imgattr/astro.config.mjs

@@ -0,0 +1,8 @@
+import { defineConfig } from 'astro/config';
+import mdx from '@astrojs/mdx';
+import plugin from "./remarkPlugin"
+
+// https://astro.build/config
+export default defineConfig({
+	integrations: [mdx({remarkPlugins:[plugin]})],
+});

packages/integrations/mdx/test/fixtures/image-remark-imgattr/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "@test/image-remark-imgattr",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/mdx": "workspace:*",
+    "astro": "workspace:*"
+  },
+  "scripts": {
+    "dev": "astro dev"
+  }
+}

packages/integrations/mdx/test/fixtures/image-remark-imgattr/remarkPlugin.js

@@ -0,0 +1,22 @@
+export default function plugin() {
+	return transformer;
+
+	function transformer(tree) {
+		function traverse(node) {
+			if (node.type === "image") {
+				node.data = node.data || {};
+				node.data.hProperties = node.data.hProperties || {};
+				node.data.hProperties.id = "test";
+				node.data.hProperties.width = "300";
+				node.data.hProperties.widths = [300,600];
+				node.data.hProperties.sizes = "(min-width: 600px) 600w, 300w";
+			}
+
+			if (node.children) {
+				node.children.forEach(traverse);
+			}
+		}
+
+		traverse(tree);
+	}
+}

packages/integrations/mdx/test/fixtures/image-remark-imgattr/src/pages/index.mdx

@@ -0,0 +1 @@
+![alt](../assets/penguin2.jpg)

packages/integrations/mdx/test/remark-imgattr.test.js

@@ -0,0 +1,50 @@
+import { expect } from 'chai';
+import * as cheerio from 'cheerio';
+import { loadFixture } from '../../../astro/test/test-utils.js';
+
+const FIXTURE_ROOT = new URL('./fixtures/image-remark-imgattr/', import.meta.url);
+
+describe('Testing remark plugins for image processing', () => {
+	/** @type {import('./test-utils').Fixture} */
+	let fixture;
+
+	describe('start dev server', () => {
+		/** @type {import('./test-utils').DevServer} */
+		let devServer;
+
+		before(async () => {
+			fixture = await loadFixture({
+				root: FIXTURE_ROOT,
+			});
+
+			devServer = await fixture.startDevServer();
+		});
+
+		after(async () => {
+			await devServer.stop();
+		});
+
+		describe('Test image attributes can be added by remark plugins', () => {
+			let $;
+			before(async () => {
+				let res = await fixture.fetch('/');
+				let html = await res.text();
+				$ = cheerio.load(html);
+			});
+
+			it('<img> has correct attributes', async () => {
+				let $img = $('img');
+				expect($img.attr('id')).to.equal('test');
+				expect($img.attr('sizes')).to.equal('(min-width: 600px) 600w, 300w');
+				expect($img.attr('srcset')).to.not.be.empty;
+			});
+
+			it('<img> was processed properly', async () => {
+				let $img = $('img');
+				expect(new URL($img.attr('src'), 'http://example.com').searchParams.get('w')).to.equal(
+					'300'
+				);
+			});
+		});
+	});
+});