Move the AcroForm logic from the document to the catalog

The `AcroForm` entry is part of the catalog, not of the document, so its
logic should be placed there instead. The document should look in the
catalog to fetch it, and not have knowledge of `catDict`, which is a
member internal to the catalog.

Moreover, make the AcroForm member private on the document instance. It's
only used internally and was also never intended to be public. For users
it's exposed by the `getMetadata` API endpoint as `IsAcroFormPresent`.
Only a boolean is exposed, so we now also only store the boolean on the
document instance.

Finally, the annotation code needs access to the full AcroForm
dictionary, so it's updated to fetch the data from the catalog instead
of the document that now only holds the boolean.

src/core/annotation.js

@@ -51,7 +51,7 @@ class AnnotationFactory {
    *   instance.
    */
   static create(xref, ref, pdfManager, idFactory) {
-    return pdfManager.ensureDoc("acroForm").then(acroForm => {
+    return pdfManager.ensureCatalog("acroForm").then(acroForm => {
       return pdfManager.ensure(this, "_create", [
         xref,
         ref,

src/core/document.js

@@ -584,21 +584,13 @@ class PDFDocument {
     }
 
     // Check if AcroForms are present in the document.
-    try {
-      this.acroForm = this.catalog.catDict.get("AcroForm");
-      if (this.acroForm) {
-        this.xfa = this.acroForm.get("XFA");
-        const fields = this.acroForm.get("Fields");
-        if ((!Array.isArray(fields) || fields.length === 0) && !this.xfa) {
-          this.acroForm = null; // No fields and no XFA, so it's not a form.
-        }
+    this._hasAcroForm = !!this.catalog.acroForm;
+    if (this._hasAcroForm) {
+      this.xfa = this.catalog.acroForm.get("XFA");
+      const fields = this.catalog.acroForm.get("Fields");
+      if ((!Array.isArray(fields) || fields.length === 0) && !this.xfa) {
+        this._hasAcroForm = false; // No fields and no XFA, so it's not a form.
       }
-    } catch (ex) {
-      if (ex instanceof MissingDataException) {
-        throw ex;
-      }
-      info("Cannot fetch AcroForm entry; assuming no AcroForms are present");
-      this.acroForm = null;
     }
   }
 
@@ -730,7 +722,7 @@ class PDFDocument {
     const docInfo = {
       PDFFormatVersion: version,
       IsLinearized: !!this.linearization,
-      IsAcroFormPresent: !!this.acroForm,
+      IsAcroFormPresent: this._hasAcroForm,
       IsXFAPresent: !!this.xfa,
       IsCollectionPresent: !!this.catalog.collection,
     };

src/core/obj.js

@@ -100,6 +100,22 @@ class Catalog {
     return shadow(this, "collection", collection);
   }
 
+  get acroForm() {
+    let acroForm = null;
+    try {
+      const obj = this.catDict.get("AcroForm");
+      if (isDict(obj) && obj.size > 0) {
+        acroForm = obj;
+      }
+    } catch (ex) {
+      if (ex instanceof MissingDataException) {
+        throw ex;
+      }
+      info("Cannot fetch AcroForm entry; assuming no forms are present.");
+    }
+    return shadow(this, "acroForm", acroForm);
+  }
+
   get metadata() {
     const streamRef = this.catDict.getRaw("Metadata");
     if (!isRef(streamRef)) {

test/unit/annotation_spec.js

@@ -41,7 +41,9 @@ describe("annotation", function () {
     constructor(params) {
       this.docBaseUrl = params.docBaseUrl || null;
       this.pdfDocument = {
-        acroForm: new Dict(),
+        catalog: {
+          acroForm: new Dict(),
+        },
       };
     }
 
@@ -56,8 +58,8 @@ describe("annotation", function () {
       });
     }
 
-    ensureDoc(prop, args) {
-      return this.ensure(this.pdfDocument, prop, args);
+    ensureCatalog(prop, args) {
+      return this.ensure(this.pdfDocument.catalog, prop, args);
     }
   }