fix(mdx): convert remark-images-to-component plugin to a rehype plugin

.changeset/sweet-goats-own.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/mdx": major
+---
+
+Replace remark-images-to-component with rehype-images-to-component to let users use additional rehype plugins for images

packages/integrations/mdx/package.json

@@ -54,13 +54,15 @@
   },
   "devDependencies": {
     "@types/estree": "^1.0.5",
+    "@types/hast": "^3.0.3",
     "@types/mdast": "^4.0.3",
     "@types/yargs-parser": "^21.0.3",
     "astro": "workspace:*",
     "astro-scripts": "workspace:*",
     "cheerio": "1.0.0-rc.12",
     "linkedom": "^0.16.11",
     "mdast-util-mdx": "^3.0.0",
+    "mdast-util-mdx-jsx": "^3.1.2",
     "mdast-util-to-string": "^4.0.0",
     "reading-time": "^1.5.0",
     "rehype-mathjax": "^6.0.0",

packages/integrations/mdx/src/plugins.ts

@@ -15,7 +15,7 @@ import { rehypeApplyFrontmatterExport } from './rehype-apply-frontmatter-export.
 import { rehypeInjectHeadingsExport } from './rehype-collect-headings.js';
 import rehypeMetaString from './rehype-meta-string.js';
 import { rehypeOptimizeStatic } from './rehype-optimize-static.js';
-import { remarkImageToComponent } from './remark-images-to-component.js';
+import { rehypeImageToComponent } from './rehype-images-to-component.js';
 
 // Skip nonessential plugins during performance benchmark runs
 const isPerformanceBenchmark = Boolean(process.env.ASTRO_PERFORMANCE_BENCHMARK);
@@ -52,7 +52,7 @@ function getRemarkPlugins(mdxOptions: MdxOptions): PluggableList {
 		}
 	}
 
-	remarkPlugins.push(...mdxOptions.remarkPlugins, remarkCollectImages, remarkImageToComponent);
+	remarkPlugins.push(...mdxOptions.remarkPlugins, remarkCollectImages);
 
 	return remarkPlugins;
 }
@@ -74,7 +74,7 @@ function getRehypePlugins(mdxOptions: MdxOptions): PluggableList {
 		}
 	}
 
-	rehypePlugins.push(...mdxOptions.rehypePlugins);
+	rehypePlugins.push(...mdxOptions.rehypePlugins, rehypeImageToComponent);
 
 	if (!isPerformanceBenchmark) {
 		// getHeadings() is guaranteed by TS, so this must be included.

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

@@ -0,0 +1,166 @@
+import type { MarkdownVFile } from '@astrojs/markdown-remark';
+import type { Properties, Root } from 'hast';
+import type { MdxJsxAttribute, MdxjsEsm } from 'mdast-util-mdx';
+import type { MdxJsxFlowElementHast } from 'mdast-util-mdx-jsx';
+import { visit } from 'unist-util-visit';
+import { jsToTreeNode } from './utils.js';
+
+export const ASTRO_IMAGE_ELEMENT = 'astro-image';
+export const ASTRO_IMAGE_IMPORT = '__AstroImage__';
+export const USES_ASTRO_IMAGE_FLAG = '__usesAstroImage';
+
+function createArrayAttribute(name: string, values: (string | number)[]): 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: [],
+				},
+			},
+		},
+	};
+}
+
+/**
+ * Convert the <img /> element properties (except `src`) to MDX JSX attributes.
+ *
+ * @param {Properties} props - The element properties
+ * @returns {MdxJsxAttribute[]} The MDX attributes
+ */
+function getImageComponentAttributes(props: Properties): MdxJsxAttribute[] {
+	const attrs: MdxJsxAttribute[] = [];
+
+	for (const [prop, value] of Object.entries(props)) {
+		if (prop === 'src') continue;
+
+		/*
+		 * <Image /> component expects an array for those attributes but the
+		 * received properties are sanitized as strings. So we need to convert them
+		 * back to an array.
+		 */
+		if (prop === 'widths' || prop === 'densities') {
+			attrs.push(createArrayAttribute(prop, String(value).split(' ')));
+		} else {
+			attrs.push({
+				name: prop,
+				type: 'mdxJsxAttribute',
+				value: String(value),
+			});
+		}
+	}
+
+	return attrs;
+}
+
+export function rehypeImageToComponent() {
+	return function (tree: Root, file: MarkdownVFile) {
+		if (!file.data.imagePaths) return;
+
+		const importsStatements: MdxjsEsm[] = [];
+		const importedImages = new Map<string, string>();
+
+		visit(tree, 'element', (node, index, parent) => {
+			if (!file.data.imagePaths || node.tagName !== 'img' || !node.properties.src) return;
+
+			const src = decodeURI(String(node.properties.src));
+
+			if (!file.data.imagePaths.has(src)) return;
+
+			let importName = importedImages.get(src);
+
+			if (!importName) {
+				importName = `__${importedImages.size}_${src.replace(/\W/g, '_')}__`;
+
+				importsStatements.push({
+					type: 'mdxjsEsm',
+					value: '',
+					data: {
+						estree: {
+							type: 'Program',
+							sourceType: 'module',
+							body: [
+								{
+									type: 'ImportDeclaration',
+									source: {
+										type: 'Literal',
+										value: src,
+										raw: JSON.stringify(src),
+									},
+									specifiers: [
+										{
+											type: 'ImportDefaultSpecifier',
+											local: { type: 'Identifier', name: importName },
+										},
+									],
+								},
+							],
+						},
+					},
+				});
+				importedImages.set(src, importName);
+			}
+
+			// Build a component that's equivalent to <Image src={importName} {...attributes} />
+			const componentElement: MdxJsxFlowElementHast = {
+				name: ASTRO_IMAGE_ELEMENT,
+				type: 'mdxJsxFlowElement',
+				attributes: [
+					...getImageComponentAttributes(node.properties),
+					{
+						name: 'src',
+						type: 'mdxJsxAttribute',
+						value: {
+							type: 'mdxJsxAttributeValueExpression',
+							value: importName,
+							data: {
+								estree: {
+									type: 'Program',
+									sourceType: 'module',
+									comments: [],
+									body: [
+										{
+											type: 'ExpressionStatement',
+											expression: { type: 'Identifier', name: importName },
+										},
+									],
+								},
+							},
+						},
+					},
+				],
+				children: [],
+			};
+
+			parent!.children.splice(index!, 1, componentElement);
+		});
+
+		// Add all the import statements to the top of the file for the images
+		tree.children.unshift(...importsStatements);
+
+		tree.children.unshift(
+			jsToTreeNode(`import { Image as ${ASTRO_IMAGE_IMPORT} } from "astro:assets";`)
+		);
+		// Export `__usesAstroImage` to pick up `astro:assets` usage in the module graph.
+		// @see the '@astrojs/mdx-postprocess' plugin
+		tree.children.push(jsToTreeNode(`export const ${USES_ASTRO_IMAGE_FLAG} = true`));
+	};
+}

packages/integrations/mdx/src/vite-plugin-mdx-postprocess.ts

@@ -5,7 +5,7 @@ import {
 	ASTRO_IMAGE_ELEMENT,
 	ASTRO_IMAGE_IMPORT,
 	USES_ASTRO_IMAGE_FLAG,
-} from './remark-images-to-component.js';
+} from './rehype-images-to-component.js';
 import { type FileInfo, getFileInfo } from './utils.js';
 
 // These transforms must happen *after* JSX runtime transformations