[Editor] Restore pinch-to-resize on an editor which came back from an undo

`AnnotationEditor.remove()` destroys the editor's `TouchManager`, but `remove()`
is also the undo half of an edit: deleting a drawing and undoing it, or undoing
the drawing itself and redoing it, brings the very same editor back.

src/display/editor/editor.js

@@ -1359,16 +1359,7 @@ class AnnotationEditor {
 
     bindEvents(this, div, ["keydown", "pointerdown", "dblclick"]);
 
-    if (this.isResizable && this._uiManager._supportsPinchToZoom) {
+    this.#addTouchManager();
-      this.#touchManager ||= new TouchManager({
-        container: div,
-        isPinchingDisabled: () => !this.isSelected,
-        onPinchStart: this.#touchPinchStartCallback.bind(this),
-        onPinching: this.#touchPinchCallback.bind(this),
-        onPinchEnd: this.#touchPinchEndCallback.bind(this),
-        signal: this._uiManager._signal,
-      });
-    }
 
     this.addStandaloneCommentButton();
     this._uiManager._editorUndoBar?.hide();
@@ -1803,6 +1794,25 @@ class AnnotationEditor {
     this.div.addEventListener("focusout", this.focusout.bind(this), { signal });
   }
 
+  #addTouchManager() {
+    if (
+      this.#touchManager ||
+      !this.div ||
+      !this.isResizable ||
+      !this._uiManager._supportsPinchToZoom
+    ) {
+      return;
+    }
+    this.#touchManager = new TouchManager({
+      container: this.div,
+      isPinchingDisabled: () => !this.isSelected,
+      onPinchStart: this.#touchPinchStartCallback.bind(this),
+      onPinching: this.#touchPinchCallback.bind(this),
+      onPinchEnd: this.#touchPinchEndCallback.bind(this),
+      signal: this._uiManager._signal,
+    });
+  }
+
   /**
    * Rebuild the editor in case it has been removed on undo.
    *
@@ -1810,6 +1820,7 @@ class AnnotationEditor {
    */
   rebuild() {
     this.#addFocusListeners();
+    this.#addTouchManager();
   }
 
   /**

test/integration/ink_editor_spec.mjs

@@ -1407,3 +1407,67 @@ describe("Ink must be committed when the document is saved", () => {
     );
   });
 });
+
+describe("Pinch to resize a drawing", () => {
+  let pages;
+
+  beforeEach(async () => {
+    pages = await loadAndWait("empty.pdf", ".annotationEditorLayer");
+  });
+
+  afterEach(async () => {
+    await closePages(pages);
+  });
+
+  // Spread two fingers apart, centered on the editor.
+  async function pinchOut(page, selector) {
+    const { x, y, width, height } = await getRect(page, selector);
+    const centerX = x + width / 2;
+    const centerY = y + height / 2;
+    const finger0 = await page.touchscreen.touchStart(centerX - 25, centerY);
+    const finger1 = await page.touchscreen.touchStart(centerX + 25, centerY);
+    for (let i = 1; i <= 12; i++) {
+      const gap = 25 + i * 12;
+      await finger0.move(centerX - gap, centerY);
+      await finger1.move(centerX + gap, centerY);
+    }
+    await finger0.end();
+    await finger1.end();
+  }
+
+  it("must keep resizing a drawing which came back with an undo", async () => {
+    await Promise.all(
+      pages.map(async ([browserName, page]) => {
+        if (browserName === "firefox") {
+          pending(
+            "Touch events are not supported on devices without touch screen in Firefox."
+          );
+        }
+        await switchToInk(page);
+
+        const rect = await getRect(page, ".annotationEditorLayer");
+        await drawLine(
+          page,
+          rect.x + 200,
+          rect.y + 200,
+          rect.x + 300,
+          rect.y + 260
+        );
+        await commit(page);
+
+        const editorSelector = getEditorSelector(0);
+        await clearAll(page);
+        await waitForNoElement(page, editorSelector);
+        await kbUndo(page);
+        await page.waitForSelector(editorSelector);
+        await selectEditor(page, editorSelector);
+
+        const { width: before } = await getRect(page, editorSelector);
+        await pinchOut(page, editorSelector);
+        const { width: after } = await getRect(page, editorSelector);
+
+        expect(after).withContext(`In ${browserName}`).toBeGreaterThan(before);
+      })
+    );
+  });
+});