Show images inline into the editor

packages/web/editor.tsx

@@ -60,6 +60,7 @@ import { syntaxTree } from "@codemirror/language";
 import sandboxSyscalls from "@plugos/plugos/syscalls/sandbox";
 import { eventSyscalls } from "@plugos/plugos/syscalls/event";
 import { storeSyscalls } from "./syscalls/store";
+import { inlineImagesPlugin } from "./inline_image";
 
 class PageState {
   constructor(
@@ -380,6 +381,7 @@ export class Editor {
           base: buildMarkdown(this.mdExtensions),
           addKeymap: true,
         }),
+        inlineImagesPlugin(),
         highlightSpecialChars(),
         history(),
         drawSelection(),

packages/web/inline_image.ts

@@ -0,0 +1,70 @@
+import { syntaxTree } from "@codemirror/language";
+import { Range } from "@codemirror/state";
+import { Decoration, DecorationSet, EditorView, ViewPlugin, ViewUpdate, WidgetType } from "@codemirror/view";
+
+class InlineImageWidget extends WidgetType {
+  constructor(readonly url: string) {
+    super();
+  }
+
+  eq(other: InlineImageWidget) {
+    return other.url === this.url;
+  }
+
+  toDOM() {
+    const img = document.createElement('img')
+    img.src = this.url;
+    img.style.display = 'block';
+
+    return img;
+  }
+}
+
+const inlineImages = (view: EditorView) => {
+  let widgets: Range<Decoration>[] = [];
+  const imageRegex = /!\[[^\]]*\]\((?<url>.+)\)/;
+
+  for (let {from, to} of view.visibleRanges) {
+    syntaxTree(view.state).iterate({
+      from, to,
+      enter: (node) => {
+        if (node.name !== 'Image') {
+          return
+        }
+        
+        const imageRexexResult = imageRegex.exec(view.state.sliceDoc(node.from, node.to));
+        if (imageRexexResult === null || !imageRexexResult.groups) {
+          return;
+        }
+        
+        const url = imageRexexResult.groups.url;
+        let deco = Decoration.widget({
+          widget: new InlineImageWidget(url),
+        });
+        widgets.push(deco.range(node.to));
+      }
+    });
+  }
+
+  return Decoration.set(widgets, true);
+}
+
+export const inlineImagesPlugin = () =>
+  ViewPlugin.fromClass(
+    class {
+      decorations: DecorationSet;
+
+      constructor(view: EditorView) {
+        this.decorations = inlineImages(view);
+      }
+
+      update(update: ViewUpdate) {
+        if (update.docChanged) {
+          this.decorations = inlineImages(update.view);
+        }
+      }
+    },
+    {
+      decorations: (v) => v.decorations,
+    }
+  );