Angular 6 - Rendering problems if BrowserAnimation

问题:

I basically have a App which renders a small map. On this page is also a "toggle" button which hides the small map with a *ngIf in the parent component and displays the map in large instead. If I now import BrowserAnimationsModule in app.module.ts the large map is not rendered if I click on the toggle button (only if i set a timeout of 1ms before the map is created in ngOnInit of map-base.component.ts).

Sorry..it's a bit hard to explain, here's the code:

App.module.ts

...
@NgModule({
  declarations: [
    AppComponent,
    MapSmallComponent,
    MapLargeComponent,
    MapBaseComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    BrowserAnimationsModule, // comment this line, to make the app work
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

app.component.ts

@Component({
  selector: 'app-root',
  template: `
  <app-map-small *ngIf="small"></app-map-small>
  <app-map-large *ngIf="!small"></app-map-large>
  <button (click)="small = !small">Toggle</button>`,
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  small = true;
}

map-base.component.ts

@Component({
  selector: 'app-map-base',
  template: `<div id="map" class="map"></div>`,
  styleUrls: ['./map-base.component.scss']
})
export class MapBaseComponent implements OnInit {
  map: OlMap;
  constructor() { }

  ngOnInit() {
    this.map = new OlMap({
      target: 'map',
      layers: [new OlTileLayer({ source: new OlOSM() })],
      view: new OlView({ zoom: 13, center: fromLonLat([13.376935, 52.516181]) }),
      controls: []
    });
  }
}

map-small.component.ts

@Component({
  selector: 'app-map-small',
  template: `
    <p>other stuff</p>
    <div style="max-width:500px">
      <app-map-base></app-map-base>
    </div>
    <p>other stuff2</p>
  `,
  styleUrls: ['./map-small.component.scss']
})
export class MapSmallComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }
}

map-large.component.ts

@Component({
  selector: 'app-map-large',
  template: `
  <p>Some other stuff</p>
  <app-map-base></app-map-base>`,
  styleUrls: ['./map-large.component.scss']
})
export class MapLargeComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }
}

dependencies

"dependencies": {
    "@angular/animations": "^6.0.9",
    "@angular/cdk": "^6.4.0",
    "@angular/common": "^6.0.2",
    "@angular/compiler": "^6.0.2",
    "@angular/core": "^6.0.2",
    "@angular/forms": "^6.0.2",
    "@angular/http": "^6.0.2",
    "@angular/material": "^6.4.0",
    "@angular/platform-browser": "^6.0.2",
    "@angular/platform-browser-dynamic": "^6.0.2",
    "@angular/router": "^6.0.2",
    "core-js": "^2.5.4",
    "ol": "^5.1.3",
    "rxjs": "^6.0.0",
    "zone.js": "^0.8.26"
  },

So why works everything fine, if I don't import BrowserAnimationsModule and it breaks if I import it? I want to use Angular Material, that's I would need it...

回答1:

Here is a solution,

Component template

<div #mapElementRef class="map"></div>

Component class implements OnInit and has the next property

@ViewChild('mapElementRef') mapElementRef: ElementRef;

finally initialize the map on ngOnInit method, you can use

this.map.setTarget(this.mapElementRef.nativeElement);

Hope it helps.

回答2:

You have to use ngAfterViewInit, then you can be 'sure' the element inside your components template is present in the DOM.

ngAfterViewInit() {
  this.map = new OlMap({
    target: 'map',
    layers: [new OlTileLayer({ source: new OlOSM() })],
    view: new OlView({ zoom: 13, center: fromLonLat([13.376935, 52.516181]) }),
    controls: []
  });
}