Ng-zone optimization

demo/app/samples/test.component.html

@@ -22,7 +22,7 @@
     <input [(ngModel)]="sizeIndex" style="width: 50px">
     <button (click)="doChangeSize()">Size</button>
     <br>
-    <small>ngx-ui-scroll version: {{datasource.adapter.version}}</small>
+    <small>ngx-ui-scroll version: {{datasource.adapter.packageInfo.consumer.version}}</small>
     <br>
     <small>isLoading:
       {{datasource.adapter.isLoading}}
@@ -47,14 +47,9 @@
   </div>
   <br><br>
 </div>
-
 <div class="viewport" #viewport style="height: 600px" id="my-viewport">
   <div *ngIf="show">
-    <div
-      *uiScroll="let item of datasource"
-      (click)="doToggleItem(item)"
-      [style.height]="item.size + 'px'"
-    >
+    <div *uiScroll="let item of datasource" (click)="doToggleItem(item)" [style.height]="item.size + 'px'">
       <app-samples-test-inner>
         {{item.text}}
         <span [style.color]="item.color">
@@ -63,4 +58,4 @@
       </app-samples-test-inner>
     </div>
   </div>
-</div>
+</div>

package.json

@@ -34,7 +34,7 @@
     "ngx-bootstrap": "^8.0.0-RC.5",
     "rxjs": "~7.5.1",
     "tslib": "^2.3.1",
-    "vscroll": "^1.5.4",
+    "vscroll": "^1.5.5",
     "zone.js": "~0.11.4"
   },
   "devDependencies": {
@@ -56,4 +56,4 @@
     "puppeteer": "^13.0.1",
     "typescript": "~4.5.4"
   }
-}
+}

scroller/package.json

@@ -1,13 +1,10 @@
 {
   "name": "ngx-ui-scroll",
-  "version": "3.0.2",
+  "version": "3.1.0",
   "license": "MIT",
   "peerDependencies": {
     "@angular/common": ">=12.0.0",
     "@angular/core": ">=12.0.0",
-    "vscroll": "^1.5.4"
-  },
-  "dependencies": {
-    "tslib": "^2.3.1"
+    "vscroll": "^1.5.5"
   }
 }

scroller/src/ui-scroll.component.ts

@@ -1,7 +1,7 @@
 import {
   Component, OnInit, OnDestroy,
   TemplateRef, ElementRef,
-  ChangeDetectionStrategy, ChangeDetectorRef
+  ChangeDetectionStrategy, ChangeDetectorRef, NgZone
 } from '@angular/core';
 
 import { IDatasource, Workflow, Item } from './vscroll';
@@ -43,25 +43,43 @@ export class UiScrollComponent<Data = unknown> implements OnInit, OnDestroy {
   public workflow!: Workflow<Data>;
 
   constructor(
-    public changeDetector: ChangeDetectorRef,
-    public elementRef: ElementRef) { }
+    private changeDetector: ChangeDetectorRef,
+    private elementRef: ElementRef,
+    private ngZone: NgZone
+  ) {}
 
   ngOnInit(): void {
-    this.workflow = new Workflow<Data>({
-      consumer,
-      element: this.elementRef.nativeElement,
-      datasource: this.datasource as IDatasource<Data>,
-      run: (items: Item<Data>[]) => {
-        if (!items.length && !this.items.length) {
-          return;
-        }
-        this.items = items;
-        this.changeDetector.detectChanges();
-      }
-    });
+    // The workflow should be created outside of the Angular zone because it's causing many
+    // change detection cycles. It runs its `init()` function in a `setTimeout` task, which
+    // then sets up the `scroll` listener. The `scroll` event listener would force Angular to
+    // run `tick()` any time the `scroll` task is invoked. We don't care about `scroll` events
+    // since they're handled internally by `vscroll`. We still run change detection manually
+    // tho when the `run` function is invoked.
+    // `scroll` events may be also unpatched through zone.js flags:
+    // `(window as any).__zone_symbol__UNPATCHED_EVENTS = ['scroll']`.
+    // Having `runOutsideAngular` guarantees we're responsible for running change detection
+    // only when it's "required" (when `items` are updated and the template should be updated too).
+    this.workflow = this.ngZone.runOutsideAngular(
+      () =>
+        new Workflow<Data>({
+          consumer,
+          element: this.elementRef.nativeElement,
+          datasource: this.datasource as IDatasource<Data>,
+          run: (items: Item<Data>[]) => {
+            if (!items.length && !this.items.length) {
+              return;
+            }
+            // Re-enter the Angular zone only when items are set and when we have to run the local change detection.
+            this.ngZone.run(() => {
+              this.items = items;
+              this.changeDetector.detectChanges();
+            });
+          },
+        })
+    );
   }
 
   ngOnDestroy(): void {
-    this.workflow && this.workflow.dispose();
+    this.workflow?.dispose();
   }
 }

scroller/src/ui-scroll.directive.ts

@@ -1,4 +1,10 @@
-import { Directive, Input, TemplateRef, ViewContainerRef, ComponentFactoryResolver, OnInit } from '@angular/core';
+import {
+  Directive,
+  Input,
+  TemplateRef,
+  ViewContainerRef,
+  OnInit,
+} from '@angular/core';
 
 import { UiScrollComponent } from './ui-scroll.component';
 import { IDatasource } from './ui-scroll.datasource';
@@ -9,20 +15,15 @@ export class UiScrollDirective<ItemData = unknown> implements OnInit {
 
   constructor(
     private templateRef: TemplateRef<unknown>,
-    private viewContainer: ViewContainerRef,
-    private resolver: ComponentFactoryResolver
-  ) {
-  }
+    private viewContainer: ViewContainerRef
+  ) {}
 
   @Input() set uiScrollOf(datasource: IDatasource<ItemData>) {
     this.datasource = datasource;
   }
 
   ngOnInit(): void {
-    const compFactory = this.resolver.resolveComponentFactory(UiScrollComponent);
-    const componentRef = this.viewContainer.createComponent(
-      compFactory, void 0, this.viewContainer.injector
-    );
+    const componentRef = this.viewContainer.createComponent(UiScrollComponent);
     componentRef.instance.datasource = this.datasource as IDatasource;
     componentRef.instance.template = this.templateRef;
   }

scroller/src/ui-scroll.module.ts

@@ -12,6 +12,5 @@ import { UiScrollDirective } from './ui-scroll.directive';
   imports: [CommonModule],
   entryComponents: [UiScrollComponent],
   exports: [UiScrollDirective],
-  providers: []
 })
 export class UiScrollModule { }

scroller/src/ui-scroll.version.ts

@@ -1,4 +1,4 @@
 export default {
   name: 'ngx-ui-scroll',
-  version: '3.0.2'
+  version: '3.1.0'
 };

tests/recreation.spec.ts

@@ -38,18 +38,25 @@ describe('Recreation Spec', () => {
       adapterId = misc.adapter.id;
     });
 
-    const init = (flag: boolean): Promise<boolean> =>
-      firstValueFrom(
-        misc.testComponent.datasource.adapter.init$.pipe(
-          filter(v => flag ? v : !v), take(1)
-        ));
+    const init = (flag: boolean): boolean | Promise<boolean> =>
+      (flag !== misc.testComponent.datasource.adapter.init) ?
+        firstValueFrom(
+          misc.testComponent.datasource.adapter.init$.pipe(
+            filter(v => flag ? v : !v), take(1)
+          ))
+        : Promise.resolve(flag);
 
     const ngIfReload = async (onBeforeHide?: () => void): Promise<void> => {
       await init(true);
       await misc.adapter.relax();
+
+      // hide test component
       onBeforeHide && onBeforeHide();
       misc.testComponent.show = false;
+      misc.fixture.changeDetectorRef.detectChanges();
       await init(false);
+
+      // show test component
       misc.testComponent.show = true;
       misc.fixture.changeDetectorRef.detectChanges();
       await init(true);