feat(scroll): emit 'annotations_initialized' when annotations first initializes.

src/@types/events.ts

@@ -1,9 +1,10 @@
 enum Event {
+    ACTIVE_CHANGE = 'annotations_active_change',
+    ACTIVE_SET = 'annotations_active_set',
     ANNOTATION_CREATE = 'annotations_create',
     ANNOTATION_FETCH_ERROR = 'annotations_fetch_error',
+    ANNOTATIONS_INITIALIZED = 'annotations_initialized',
     ANNOTATION_REMOVE = 'annotations_remove',
-    ACTIVE_CHANGE = 'annotations_active_change',
-    ACTIVE_SET = 'annotations_active_set',
     VISIBLE_SET = 'annotations_visible_set',
 }
 

src/common/BaseAnnotator.ts

@@ -5,6 +5,7 @@ import EventEmitter from './EventEmitter';
 import i18n from '../utils/i18n';
 import messages from '../messages';
 import { Event, IntlOptions, LegacyEvent, Permissions } from '../@types';
+import { getAnnotations } from '../store';
 import './BaseAnnotator.scss';
 
 export type Container = string | HTMLElement;
@@ -37,6 +38,8 @@ export type Options = {
 export default class BaseAnnotator extends EventEmitter {
     container: Container;
 
+    initialized = false;
+
     intl: IntlShape;
 
     rootEl?: HTMLElement | null;
@@ -151,4 +154,12 @@ export default class BaseAnnotator extends EventEmitter {
         this.store.dispatch<any>(store.fetchAnnotationsAction()); // eslint-disable-line @typescript-eslint/no-explicit-any
         this.store.dispatch<any>(store.fetchCollaboratorsAction()); // eslint-disable-line @typescript-eslint/no-explicit-any
     }
+
+    protected isInitialized(): void {
+        if (!this.initialized) {
+            this.initialized = true;
+
+            this.emit(Event.ANNOTATIONS_INITIALIZED, { annotations: getAnnotations(this.store.getState()) });
+        }
+    }
 }

src/document/DocumentAnnotator.ts

@@ -1,8 +1,8 @@
 import BaseAnnotator from '../common/BaseAnnotator';
 import BaseManager from '../common/BaseManager';
 import { CLASS_ANNOTATIONS_LOADED } from '../constants';
-import { getAnnotation } from '../store/annotations';
 import { centerRegion, isRegion, RegionManager } from '../region';
+import { getAnnotation } from '../store/annotations';
 import './DocumentAnnotator.scss';
 
 export const SCROLL_THRESHOLD = 1000; // pixels
@@ -63,6 +63,8 @@ export default class DocumentAnnotator extends BaseAnnotator {
         this.annotatedEl.classList.add(CLASS_ANNOTATIONS_LOADED);
 
         this.render();
+
+        this.isInitialized();
     }
 
     render(): void {

src/document/__tests__/DocumentAnnotator-test.ts

@@ -33,6 +33,14 @@ describe('DocumentAnnotator', () => {
     const getPage = (pageNumber = 1): HTMLElement => {
         return container.querySelector(`[data-page-number="${pageNumber}"]`) as HTMLElement;
     };
+
+    const payload = {
+        entries: regions as Annotation[],
+        limit: 1000,
+        next_marker: null,
+        previous_marker: null,
+    };
+
     let annotator = getAnnotator();
 
     beforeEach(() => {
@@ -135,6 +143,19 @@ describe('DocumentAnnotator', () => {
             expect(annotator.annotatedEl).toBe(container.querySelector('.bp-doc'));
             expect(annotator.annotatedEl!.className).toContain(CLASS_ANNOTATIONS_LOADED); // eslint-disable-line @typescript-eslint/no-non-null-assertion
         });
+
+        test('should emit annotations_initialized event once', () => {
+            annotator.emit = jest.fn();
+            annotator.store.dispatch(fetchAnnotationsAction.fulfilled(payload, 'test', undefined));
+
+            annotator.init(1);
+            annotator.init(1);
+            annotator.init(1);
+
+            expect(annotator.initialized).toEqual(true);
+            expect(annotator.emit).toBeCalledWith('annotations_initialized', { annotations: regions });
+            expect(annotator.emit).toBeCalledTimes(1);
+        });
     });
 
     describe('render()', () => {
@@ -168,13 +189,6 @@ describe('DocumentAnnotator', () => {
 
     describe('scrollToAnnotation()', () => {
         beforeEach(() => {
-            const payload = {
-                entries: regions as Annotation[],
-                limit: 1000,
-                next_marker: null,
-                previous_marker: null,
-            };
-
             annotator.scrollToLocation = jest.fn();
             annotator.store.dispatch(fetchAnnotationsAction.fulfilled(payload, 'test', undefined));
         });