chore(*): Update active indexes on events. Cache result to limit pipe trigger.

Author: MKirova

projects/igniteui-angular/src/lib/grids/grid-base.directive.ts

@@ -3246,6 +3246,7 @@ export abstract class IgxGridBaseDirective implements GridType,
     private _filteredSortedData = null;
     private _filteredData = null;
     private _mergedDataInView = null;
+    private _activeRowIndexes = null;
 
     private _customDragIndicatorIconTemplate: TemplateRef<IgxGridEmptyTemplateContext>;
     private _excelStyleHeaderIconTemplate: TemplateRef<IgxGridHeaderTemplateContext>;
@@ -3907,6 +3908,14 @@ export abstract class IgxGridBaseDirective implements GridType,
                 this.autoSizeColumnsInView();
                 this._firstAutoResize = false;
             });
+
+        this.activeNodeChange.pipe(filter(() => !this._init), destructor).subscribe(() => {
+            this._activeRowIndexes = null;
+        });
+
+        this.selectionService.selectedRangeChange.pipe(filter(() => !this._init), destructor).subscribe(() => {
+            this._activeRowIndexes = null;
+        });
     }
 
     /**
@@ -4055,9 +4064,14 @@ export abstract class IgxGridBaseDirective implements GridType,
 
 
     protected get activeRowIndexes(): number[] {
-        const activeRow = this.navigation.activeNode?.row;
-        const selectedCellIndexes = (this.selectionService.selection?.keys() as any)?.toArray();
-        return [activeRow, ...selectedCellIndexes];
+        if (this._activeRowIndexes) {
+            return this._activeRowIndexes;
+        } else {
+            const activeRow = this.navigation.activeNode?.row;
+            const selectedCellIndexes = (this.selectionService.selection?.keys() as any)?.toArray();
+            this._activeRowIndexes = [activeRow, ...selectedCellIndexes];
+            return this._activeRowIndexes;
+        }
     }
 
     protected get hasCellsToMerge() {

projects/igniteui-angular/src/lib/grids/selection/selection.service.ts

@@ -35,6 +35,11 @@ export class IgxGridSelectionService {
      */
     public selectedRowsChange = new Subject<any[]>();
 
+    /**
+     * @hidden @internal
+     */
+    public selectedRangeChange = new Subject<Map<number, Set<number>>>();
+
     /**
      * Toggled when a pointerdown event is triggered inside the grid body (cells).
      * When `false` the drag select behavior is disabled.
@@ -355,6 +360,8 @@ export class IgxGridSelectionService {
                 }
             }
         }
+
+        this.selectedRangeChange.next(collection);
     }
 
     public dragSelect(node: ISelectionNode, state: SelectionState): void {
@@ -637,7 +644,7 @@ export class IgxGridSelectionService {
         if (this.areEqualCollections(currSelection, newSelection)) {
             return;
         }
-        
+
         const args: IRowSelectionEventArgs = {
             owner: this.grid,
             oldSelection: currSelection,