Method _applyChanges

src/cdk/scrolling/virtual-for-of.ts:325–354

Apply changes to the DOM.

(changes: IterableChanges<T>)

  /** Apply changes to the DOM. */
  private _applyChanges(changes: IterableChanges<T>) {
    this._viewRepeater.applyChanges(
      changes,
      this._viewContainerRef,
      (
        record: IterableChangeRecord<T>,
        _adjustedPreviousIndex: number | null,
        currentIndex: number | null,
      ) => this._getEmbeddedViewArgs(record, currentIndex!),
      record => record.item,
    );

    // Update $implicit for any items that had an identity change.
    changes.forEachIdentityChange((record: IterableChangeRecord<T>) => {
      const view = this._viewContainerRef.get(record.currentIndex!) as EmbeddedViewRef<
        CdkVirtualForOfContext<T>
      >;
      view.context.$implicit = record.item;
    });

    // Update the context variables on all items.
    const count = this._data.length;
    let i = this._viewContainerRef.length;
    while (i--) {
      const view = this._viewContainerRef.get(i) as EmbeddedViewRef<CdkVirtualForOfContext<T>>;
      view.context.index = this._renderedRange.start + i;
      view.context.count = count;
      this._updateComputedContextProperties(view.context);
    }
  }

  /** Update the computed properties on the `CdkVirtualForOfContext`. */
  private _updateComputedContextProperties(context: CdkVirtualForOfContext<any>) {