feat: emit null image on reset

When viewer is reset, no current image is set anymore
so emit null for clarity.

declarations/mapillary.js.flow

@@ -1723,6 +1723,18 @@ declare class Image {
    */
   id: string;
 
+  /**
+   * Get is disposed.
+   *
+   * @description If the image has been disposed no properties
+   * are acessible. Image are disposed when the {@link Viewer}
+   * is reset or a new data provider is set.
+   *
+   * @returns {boolean} Value indicating that this image
+   * has been disposed.
+   */
+  isDisposed: boolean;
+
   /**
    * Get lngLat.
    * @description If the SfM computed longitude, latitude exist
@@ -3466,7 +3478,7 @@ export type ViewerImageEvent = {
   /**
    * The viewer's current image.
    */
-  image: Image,
+  image: Image | null,
   type: "image",
   ...
 } & ViewerEvent;
@@ -3974,9 +3986,8 @@ declare class Viewer implements IEventEmitter, IViewer {
 
   /**
    * Reset the viewer's cache.
-   * @description All images in the viewer's cache at the moment when
-   * reset is called will eventually be removed if not navigated to
-   * again.
+   * @description All images in the viewer's cache at the moment of the
+   * reset will be disposed.
    * @returns {Promise<void>} Promise that resolves when viewer's cache
    * has been reset.
    * @throws When viewer is not navigable.
@@ -4029,7 +4040,7 @@ declare class Viewer implements IEventEmitter, IViewer {
 
   /**
    * Set a new data provider instance.
-   * @description [object Object],[object Object],[object Object]
+   * @description Resets the viewer's cache (see Viewer.reset).
    * @returns {Promise<void>} Promise that resolves when viewer's data
    * provider has been set.
    * @throws When viewer is not navigable.

examples/debug/reset.html

@@ -64,6 +64,9 @@
                 };
                 viewer = new Viewer(options);
                 viewer.on("reset", (event) => console.log(event.type));
+                viewer.on("image", (event) =>
+                    console.log(event.image ? event.image.id : null)
+                );
                 viewer
                     .moveTo(dataProvider.images.keys().next().value)
                     .catch((error) => console.error(error));

src/graph/Image.ts

@@ -317,6 +317,20 @@ export class Image {
         return this._core.id;
     }
 
+    /**
+     * Get is disposed.
+     *
+     * @description If the image has been disposed no properties
+     * are acessible. Image are disposed when the {@link Viewer}
+     * is reset or a new data provider is set.
+     *
+     * @returns {boolean} Value indicating that this image
+     * has been disposed.
+     */
+    public get isDisposed(): boolean {
+        return !this._core;
+    }
+
     /**
      * Get lngLat.
      *

src/state/StateService.ts

@@ -33,7 +33,6 @@ import { Transform } from "../geo/Transform";
 import { LngLatAlt } from "../api/interfaces/LngLatAlt";
 import { SubscriptionHolder } from "../util/SubscriptionHolder";
 import { Clock } from "three";
-import { isNullImageId } from "../util/Common";
 
 interface IContextOperation {
     (context: IStateContext): IStateContext;
@@ -193,10 +192,6 @@ export class StateService {
             refCount());
 
         this._currentImageExternal$ = imageChanged$.pipe(
-            filter(
-                (f: AnimationFrame): boolean => {
-                    return !isNullImageId(f.state.currentImage.id);
-                }),
             map(
                 (f: AnimationFrame): Image => {
                     return f.state.currentImage;

src/viewer/Observer.ts

@@ -41,6 +41,7 @@ import { ViewerLoadEvent } from "./events/ViewerLoadEvent";
 import { ViewerReferenceEvent } from "./events/ViewerReferenceEvent";
 import { ViewerResetEvent } from "./events/ViewerResetEvent";
 import { ViewerDragEndEvent } from "./events/ViewerDragEndEvent";
+import { isNullImageId } from "../util/Common";
 
 type UnprojectionParams = [
     [
@@ -200,7 +201,7 @@ export class Observer {
             .subscribe((image: Image): void => {
                 const type: ViewerEventType = "image";
                 const event: ViewerImageEvent = {
-                    image,
+                    image: isNullImageId(image.id) ? null : image,
                     target: this._viewer,
                     type,
                 };

src/viewer/PanService.ts

@@ -12,6 +12,7 @@ import {
 import {
     catchError,
     distinctUntilChanged,
+    filter,
     map,
     publishReplay,
     refCount,
@@ -37,6 +38,7 @@ import { isSpherical } from "../geo/Geo";
 import { geodeticToEnu } from "../geo/GeoCoords";
 import { State } from "../state/State";
 import { ICameraFactory } from "../geometry/interfaces/ICameraFactory";
+import { isNullImageId } from "../util/Common";
 
 enum PanMode {
     Disabled,
@@ -126,6 +128,7 @@ export class PanService {
         }
 
         const panImages$ = this._stateService.currentImage$.pipe(
+            filter((image: Image) => { return !isNullImageId(image.id); }),
             switchMap(
                 (current: Image): Observable<[Image, Transform, number][]> => {
                     if (!current.merged || isSpherical(current.cameraType)) {

src/viewer/Viewer.ts

@@ -1431,9 +1431,8 @@ export class Viewer extends EventEmitter implements IViewer {
     /**
      * Reset the viewer's cache.
      *
-     * @description All images in the viewer's cache at the moment when
-     * reset is called will eventually be removed if not navigated to
-     * again.
+     * @description All images in the viewer's cache at the moment of the
+     * reset will be disposed.
      *
      * @returns {Promise<void>} Promise that resolves when viewer's cache
      * has been reset.

src/viewer/events/ViewerImageEvent.ts

@@ -7,8 +7,11 @@ import { Image } from "../../graph/Image";
 export interface ViewerImageEvent extends ViewerEvent {
     /**
      * The viewer's current image.
+     *
+     * @description If the viewer is reset, the emitted
+     * image will be null.
      */
-    image: Image;
+    image: Image | null;
 
     type: "image";
 }