Fixes #360

plugs/markdown/markdown_render.ts

@@ -13,6 +13,8 @@ type MarkdownRenderOptions = {
   annotationPositions?: true;
   renderFrontMatter?: true;
   attachmentUrlPrefix?: string;
+  // When defined, use to inline images as data: urls
+  inlineAttachments?: (url: string) => Promise<string>;
 };
 
 function cleanTags(values: (Tag | null)[]): Tag[] {
@@ -390,11 +392,36 @@ function render(
   }
 }
 
-export function renderMarkdownToHtml(
+async function traverseTag(
+  t: Tag,
+  fn: (t: Tag) => Promise<void>,
+): Promise<void> {
+  await fn(t);
+  if (typeof t === "string") {
+    return;
+  }
+  if (t.body) {
+    for (const child of t.body) {
+      await traverseTag(child, fn);
+    }
+  }
+}
+
+export async function renderMarkdownToHtml(
   t: ParseTree,
   options: MarkdownRenderOptions = {},
 ) {
   preprocess(t, options);
   const htmlTree = posPreservingRender(t, options);
+  if (htmlTree && options.inlineAttachments) {
+    await traverseTag(htmlTree, async (t) => {
+      if (typeof t === "string") {
+        return;
+      }
+      if (t.name === "img") {
+        t.attrs!.src = await options.inlineAttachments!(t.attrs!.src!);
+      }
+    });
+  }
   return renderHtml(htmlTree);
 }