feat(gallery-web): create a DerivedLoaderController for gallery

Author: samuelreichert

packages/pluggableWidgets/gallery-web/src/controllers/DerivedLoaderController.ts

@@ -0,0 +1,25 @@
+type DerivedLoaderControllerSpec = {
+    refreshIndicator: boolean;
+    query: {
+        isRefreshing: boolean;
+        isSilentRefresh: boolean;
+    };
+};
+
+export class DerivedLoaderController {
+    constructor(private spec: DerivedLoaderControllerSpec) {}
+
+    get isRefreshing(): boolean {
+        const { isSilentRefresh, isRefreshing } = this.spec.query;
+
+        return !isSilentRefresh && isRefreshing;
+    }
+
+    get showRefreshIndicator(): boolean {
+        if (!this.spec.refreshIndicator) {
+            return false;
+        }
+
+        return this.isRefreshing;
+    }
+}