[Editor] Update the freetext annotation dictionary instead of creating a new one when updating an existing freetext

src/core/annotation.js

@@ -1711,18 +1711,28 @@ class MarkupAnnotation extends Annotation {
   }
 
   static async createNewAnnotation(xref, annotation, dependencies, params) {
-    const annotationRef = (annotation.ref ||= xref.getNewTemporaryRef());
+    let oldAnnotation;
+    if (annotation.ref) {
+      oldAnnotation = (await xref.fetchIfRefAsync(annotation.ref)).clone();
+    } else {
+      annotation.ref = xref.getNewTemporaryRef();
+    }
+
+    const annotationRef = annotation.ref;
     const ap = await this.createNewAppearanceStream(annotation, xref, params);
     const buffer = [];
     let annotationDict;
 
     if (ap) {
       const apRef = xref.getNewTemporaryRef();
-      annotationDict = this.createNewDict(annotation, xref, { apRef });
+      annotationDict = this.createNewDict(annotation, xref, {
+        apRef,
+        oldAnnotation,
+      });
       await writeObject(apRef, ap, buffer, xref);
       dependencies.push({ ref: apRef, data: buffer.join("") });
     } else {
-      annotationDict = this.createNewDict(annotation, xref, {});
+      annotationDict = this.createNewDict(annotation, xref, { oldAnnotation });
     }
     if (Number.isInteger(annotation.parentTreeId)) {
       annotationDict.set("StructParent", annotation.parentTreeId);
@@ -3826,12 +3836,19 @@ class FreeTextAnnotation extends MarkupAnnotation {
     return this._hasAppearance;
   }
 
-  static createNewDict(annotation, xref, { apRef, ap }) {
+  static createNewDict(annotation, xref, { apRef, ap, oldAnnotation }) {
     const { color, fontSize, rect, rotation, user, value } = annotation;
-    const freetext = new Dict(xref);
+    const freetext = oldAnnotation || new Dict(xref);
     freetext.set("Type", Name.get("Annot"));
     freetext.set("Subtype", Name.get("FreeText"));
+    if (oldAnnotation) {
+      freetext.set("M", `D:${getModificationDate()}`);
+      // TODO: We should try to generate a new RC from the content we've.
+      // For now we can just remove it to avoid any issues.
+      freetext.delete("RC");
+    } else {
       freetext.set("CreationDate", `D:${getModificationDate()}`);
+    }
     freetext.set("Rect", rect);
     const da = `/Helv ${fontSize} Tf ${getPdfColor(color, /* isFill */ true)}`;
     freetext.set("DA", da);

src/core/primitives.js

@@ -270,6 +270,10 @@ class Dict {
     }
     return dict;
   }
+
+  delete(key) {
+    delete this._map[key];
+  }
 }
 
 class Ref {

test/unit/annotation_spec.js

@@ -4257,6 +4257,46 @@ describe("annotation", function () {
       ]);
     });
 
+    it("should update an existing FreeText annotation", async function () {
+      const freeTextDict = new Dict();
+      freeTextDict.set("Type", Name.get("Annot"));
+      freeTextDict.set("Subtype", Name.get("FreeText"));
+      freeTextDict.set("CreationDate", "D:20190423");
+      freeTextDict.set("Foo", Name.get("Bar"));
+
+      const freeTextRef = Ref.get(143, 0);
+      partialEvaluator.xref = new XRefMock([
+        { ref: freeTextRef, data: freeTextDict },
+      ]);
+
+      const task = new WorkerTask("test FreeText update");
+      const data = await AnnotationFactory.saveNewAnnotations(
+        partialEvaluator,
+        task,
+        [
+          {
+            annotationType: AnnotationEditorType.FREETEXT,
+            rect: [12, 34, 56, 78],
+            rotation: 0,
+            fontSize: 10,
+            color: [0, 0, 0],
+            value: "Hello PDF.js World !",
+            id: "143R",
+            ref: freeTextRef,
+          },
+        ]
+      );
+
+      const base = data.annotations[0].data.replaceAll(/\(D:\d+\)/g, "(date)");
+      expect(base).toEqual(
+        "143 0 obj\n" +
+          "<< /Type /Annot /Subtype /FreeText /CreationDate (date) /Foo /Bar /M (date) " +
+          "/Rect [12 34 56 78] /DA (/Helv 10 Tf 0 g) /Contents (Hello PDF.js World !) " +
+          "/F 4 /Border [0 0 0] /Rotate 0 /AP << /N 2 0 R>>>>\n" +
+          "endobj\n"
+      );
+    });
+
     it("should extract the text from a FreeText annotation", async function () {
       partialEvaluator.xref = new XRefMock();
       const task = new WorkerTask("test FreeText text extraction");