Class CdkVirtualForOf

src/cdk/scrolling/virtual-for-of.ts:83–396

  selector: '[cdkVirtualFor][cdkVirtualForOf]',
})
export class CdkVirtualForOf<T>
  implements CdkVirtualScrollRepeater<T>, CollectionViewer, DoCheck, OnDestroy
{
  private _viewContainerRef = inject(ViewContainerRef);
  private _template = inject<TemplateRef<CdkVirtualForOfContext<T>>>(TemplateRef);
  private _differs = inject(IterableDiffers);
  private _viewRepeater = new _RecycleViewRepeaterStrategy<T, T, CdkVirtualForOfContext<T>>();
  private _viewport = inject(CDK_VIRTUAL_SCROLL_VIEWPORT, {skipSelf: true});

  /** Emits when the rendered view of the data changes. */
  readonly viewChange = new Subject<ListRange>();

  /** Subject that emits when a new DataSource instance is given. */
  private readonly _dataSourceChanges = new Subject<DataSource<T>>();

  /** The DataSource to display. */
  @Input()
  get cdkVirtualForOf(): DataSource<T> | Observable<T[]> | NgIterable<T> | null | undefined {
    return this._cdkVirtualForOf;
  }
  set cdkVirtualForOf(value: DataSource<T> | Observable<T[]> | NgIterable<T> | null | undefined) {
    this._cdkVirtualForOf = value;
    if (isDataSource(value)) {
      this._dataSourceChanges.next(value);
    } else {
      // If value is an an NgIterable, convert it to an array.
      this._dataSourceChanges.next(
        new ArrayDataSource<T>(isObservable(value) ? value : Array.from(value || [])),
      );
    }
  }

  _cdkVirtualForOf: DataSource<T> | Observable<T[]> | NgIterable<T> | null | undefined;

  /**
   * The `TrackByFunction` to use for tracking changes. The `TrackByFunction` takes the index and
   * the item and produces a value to be used as the item's identity when tracking changes.
   */
  @Input()
  get cdkVirtualForTrackBy(): TrackByFunction<T> | undefined {
    return this._cdkVirtualForTrackBy;
  }
  set cdkVirtualForTrackBy(fn: TrackByFunction<T> | undefined) {
    this._needsUpdate = true;
    this._cdkVirtualForTrackBy = fn
      ? (index, item) => fn(index + (this._renderedRange ? this._renderedRange.start : 0), item)
      : undefined;
  }
  private _cdkVirtualForTrackBy: TrackByFunction<T> | undefined;

  /** The template used to stamp out new elements. */
  @Input()
  set cdkVirtualForTemplate(value: TemplateRef<CdkVirtualForOfContext<T>>) {
    if (value) {
      this._needsUpdate = true;
      this._template = value;
    }
  }