[Editor] Add the ability to create/update the structure tree when sav…

…ing 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 mozilla#16916).

src/core/annotation.js

@@ -1639,7 +1639,7 @@ class MarkupAnnotation extends Annotation {
   }
 
   static async createNewAnnotation(xref, annotation, dependencies, params) {
-    const annotationRef = annotation.ref || xref.getNewTemporaryRef();
+    const annotationRef = (annotation.ref ||= xref.getNewTemporaryRef());
     const ap = await this.createNewAppearanceStream(annotation, xref, params);
     const buffer = [];
     let annotationDict;
@@ -1652,6 +1652,9 @@ class MarkupAnnotation extends Annotation {
     } else {
       annotationDict = this.createNewDict(annotation, xref, {});
     }
+    if (Number.isInteger(annotation.parentTreeId)) {
+      annotationDict.set("StructParent", annotation.parentTreeId);
+    }
 
     buffer.length = 0;
     await writeObject(annotationRef, annotationDict, buffer, xref);

src/core/catalog.js

@@ -84,6 +84,10 @@ class Catalog {
     this.systemFontCache = new Map();
   }
 
+  cloneDict() {
+    return this._catDict.clone();
+  }
+
   get version() {
     const version = this._catDict.get("Version");
     if (version instanceof Name) {
@@ -245,11 +249,13 @@ class Catalog {
    * @private
    */
   _readStructTreeRoot() {
-    const obj = this._catDict.get("StructTreeRoot");
+    const rawObj = this._catDict.getRaw("StructTreeRoot");
+    const obj = this.xref.fetchIfRef(rawObj);
     if (!(obj instanceof Dict)) {
       return null;
     }
-    const root = new StructTreeRoot(obj);
+
+    const root = new StructTreeRoot(obj, rawObj);
     root.init();
     return root;
   }

src/core/pdf_manager.js

@@ -64,6 +64,10 @@ class BasePdfManager {
     return this._docBaseUrl;
   }
 
+  get catalog() {
+    return this.pdfDocument.catalog;
+  }
+
   ensureDoc(prop, args) {
     return this.ensure(this.pdfDocument, prop, args);
   }

src/core/primitives.js

@@ -262,6 +262,14 @@ class Dict {
 
     return mergedDict.size > 0 ? mergedDict : Dict.empty;
   }
+
+  clone() {
+    const dict = new Dict(this.xref);
+    for (const key of this.getKeys()) {
+      dict.set(key, this.getRaw(key));
+    }
+    return dict;
+  }
 }
 
 class Ref {