[Editor] Add the ability to create/update the structure tree when saving a pdf containing newly added annotations (bug 1845087)

When there is no tree, the tags for the new annotions are just put under the root element.
When there is a tree, we insert the new tags at the right place in using the value
of structTreeParentId (added in PR #16916).

test/unit/api_spec.js

@@ -2297,6 +2297,114 @@ describe("api", function () {
       await loadingTask.destroy();
     });
 
+    it("write a new stamp annotation in a tagged pdf, save and check that the structure tree", async function () {
+      if (isNodeJS) {
+        pending("Cannot create a bitmap from Node.js.");
+      }
+
+      const TEST_IMAGES_PATH = "../images/";
+      const filename = "firefox_logo.png";
+      const path = new URL(TEST_IMAGES_PATH + filename, window.location).href;
+
+      const response = await fetch(path);
+      const blob = await response.blob();
+      const bitmap = await createImageBitmap(blob);
+
+      let loadingTask = getDocument(buildGetDocumentParams("bug1823296.pdf"));
+      let pdfDoc = await loadingTask.promise;
+      pdfDoc.annotationStorage.setValue("pdfjs_internal_editor_0", {
+        annotationType: AnnotationEditorType.STAMP,
+        rect: [128, 400, 148, 420],
+        rotation: 0,
+        bitmap,
+        bitmapId: "im1",
+        pageIndex: 0,
+        structTreeParentId: "p3R_mc12",
+        accessibilityData: {
+          type: "Figure",
+          alt: "Hello World",
+        },
+      });
+
+      const data = await pdfDoc.saveDocument();
+      await loadingTask.destroy();
+
+      loadingTask = getDocument(data);
+      pdfDoc = await loadingTask.promise;
+      const page = await pdfDoc.getPage(1);
+      const tree = await page.getStructTree();
+      const leaf = tree.children[0].children[6].children[1];
+
+      expect(leaf).toEqual({
+        role: "Figure",
+        children: [
+          {
+            type: "annotation",
+            id: "pdfjs_internal_id_477R",
+          },
+        ],
+        alt: "Hello World",
+      });
+
+      await loadingTask.destroy();
+    });
+
+    it("write a new stamp annotation in a non-tagged pdf, save and check that the structure tree", async function () {
+      if (isNodeJS) {
+        pending("Cannot create a bitmap from Node.js.");
+      }
+
+      const TEST_IMAGES_PATH = "../images/";
+      const filename = "firefox_logo.png";
+      const path = new URL(TEST_IMAGES_PATH + filename, window.location).href;
+
+      const response = await fetch(path);
+      const blob = await response.blob();
+      const bitmap = await createImageBitmap(blob);
+
+      let loadingTask = getDocument(buildGetDocumentParams("empty.pdf"));
+      let pdfDoc = await loadingTask.promise;
+      pdfDoc.annotationStorage.setValue("pdfjs_internal_editor_0", {
+        annotationType: AnnotationEditorType.STAMP,
+        rect: [128, 400, 148, 420],
+        rotation: 0,
+        bitmap,
+        bitmapId: "im1",
+        pageIndex: 0,
+        structTreeParentId: null,
+        accessibilityData: {
+          type: "Figure",
+          alt: "Hello World",
+        },
+      });
+
+      const data = await pdfDoc.saveDocument();
+      await loadingTask.destroy();
+
+      loadingTask = getDocument(data);
+      pdfDoc = await loadingTask.promise;
+      const page = await pdfDoc.getPage(1);
+      const tree = await page.getStructTree();
+
+      expect(tree).toEqual({
+        children: [
+          {
+            role: "Figure",
+            children: [
+              {
+                type: "annotation",
+                id: "pdfjs_internal_id_18R",
+              },
+            ],
+            alt: "Hello World",
+          },
+        ],
+        role: "Root",
+      });
+
+      await loadingTask.destroy();
+    });
+
     describe("Cross-origin", function () {
       let loadingTask;
       function _checkCanLoad(expectSuccess, filename, options) {