[IIIF-148] Retrieve canvas index from query param and provide to mirador

Author: atarix83

src/app/item-page/viewer-provider/viewers/item-viewers/iiif-item-viewer/iiif-item-viewer.component.html

@@ -5,5 +5,6 @@
     [searchable]="isSearchable$ | async"
     [query]="query$ | async"
     [canvasId]="canvasId$ | async"
+    [canvasIndex]="canvasIndex$ | async"
   ></ds-mirador-viewer>
 </div>

src/app/item-page/viewer-provider/viewers/item-viewers/iiif-item-viewer/iiif-item-viewer.component.ts

@@ -14,11 +14,13 @@ import { ActivatedRoute, ParamMap } from '@angular/router';
 export class IIIFItemViewerComponent extends BaseItemViewerComponent implements OnInit {
 
   private readonly CANVAS_PARAM: string = 'canvasId';
+  private readonly CANVASIDX_PARAM: string = 'canvasIndex';
   private readonly QUERY_PARAM: string = 'query';
 
   isSearchable$: Observable<boolean>;
   query$: Observable<string>;
   canvasId$: Observable<string>;
+  canvasIndex$: Observable<string>;
 
   constructor(
     private readonly routeService: RouteService,
@@ -34,6 +36,9 @@ export class IIIFItemViewerComponent extends BaseItemViewerComponent implements
     this.canvasId$ = queryParams$.pipe(
       this.extractParam(queryMap => queryMap.get(this.CANVAS_PARAM))
     );
+    this.canvasIndex$ = queryParams$.pipe(
+      this.extractParam(queryMap => queryMap.get(this.CANVASIDX_PARAM))
+    );
     this.isSearchable$ = this.item$.pipe(
       map((item) => isIiifSearchEnabled(item))
     );