address comments

Author: mmalerba

src/cdk-experimental/scrolling/auto-size-virtual-scroll.ts

@@ -122,29 +122,29 @@ export class AutoSizeVirtualScrollStrategy implements VirtualScrollStrategy {
     this._viewport = null;
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onContentScrolled() {
     if (this._viewport) {
       this._updateRenderedContentAfterScroll();
     }
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onDataLengthChanged() {
     if (this._viewport) {
       // TODO(mmalebra): Do something smarter here.
       this._setScrollOffset();
     }
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onContentRendered() {
     if (this._viewport) {
       this._checkRenderedContentSize();
     }
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onRenderedOffsetChanged() {
     if (this._viewport) {
       this._checkRenderedContentOffset();
@@ -318,6 +318,7 @@ export class AutoSizeVirtualScrollStrategy implements VirtualScrollStrategy {
     this._updateTotalContentSize(this._lastRenderedContentSize);
   }
 
+  /** Checks the currently rendered content offset and saves the value for later use. */
   private _checkRenderedContentOffset() {
     const viewport = this._viewport!;
     this._lastRenderedContentOffset = viewport.getOffsetToRenderedContentStart()!;

src/cdk-experimental/scrolling/fixed-size-virtual-scroll.ts

@@ -60,21 +60,21 @@ export class FixedSizeVirtualScrollStrategy implements VirtualScrollStrategy {
     this._updateRenderedRange();
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onContentScrolled() {
     this._updateRenderedRange();
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onDataLengthChanged() {
     this._updateTotalContentSize();
     this._updateRenderedRange();
   }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onContentRendered() { /* no-op */ }
 
-  /** Implemented as part of VirtualScrollStrategy. */
+  /** @docs-private Implemented as part of VirtualScrollStrategy. */
   onRenderedOffsetChanged() { /* no-op */ }
 
   /** Update the viewport's total content size. */

src/cdk-experimental/scrolling/virtual-for-of.ts

@@ -24,7 +24,7 @@ import {
   ViewContainerRef,
 } from '@angular/core';
 import {Observable, Subject} from 'rxjs';
-import {pairwise, shareReplay, startWith, switchMap} from 'rxjs/operators';
+import {pairwise, shareReplay, startWith, switchMap, takeUntil} from 'rxjs/operators';
 import {CdkVirtualScrollViewport} from './virtual-scroll-viewport';
 
 
@@ -138,6 +138,8 @@ export class CdkVirtualForOf<T> implements CollectionViewer, DoCheck, OnDestroy
   /** Whether the rendered data should be updated during the next ngDoCheck cycle. */
   private _needsUpdate = false;
 
+  private _destroyed = new Subject<void>();
+
   constructor(
       /** The view container to add items to. */
       private _viewContainerRef: ViewContainerRef,
@@ -151,7 +153,7 @@ export class CdkVirtualForOf<T> implements CollectionViewer, DoCheck, OnDestroy
       this._data = data;
       this._onRenderedDataChange();
     });
-    this._viewport.renderedRangeStream.subscribe(range => {
+    this._viewport.renderedRangeStream.pipe(takeUntil(this._destroyed)).subscribe(range => {
       this._renderedRange = range;
       this.viewChange.next(this._renderedRange);
       this._onRenderedDataChange();
@@ -214,6 +216,9 @@ export class CdkVirtualForOf<T> implements CollectionViewer, DoCheck, OnDestroy
     this._dataSourceChanges.complete();
     this.viewChange.complete();
 
+    this._destroyed.next();
+    this._destroyed.complete();
+
     for (let view of this._templateCache) {
       view.destroy();
     }

src/cdk-experimental/scrolling/virtual-scroll-viewport.ts

@@ -257,16 +257,15 @@ export class CdkVirtualScrollViewport implements DoCheck, OnInit, OnDestroy {
 
         // If the rendered content offset was specified as an offset to the end of the content,
         // rewrite it as an offset to the start of the content.
-        if (this._renderedContentOffsetNeedsRewrite) {
-          this._ngZone.onStable.pipe(take(1)).subscribe(() => {
+        this._ngZone.onStable.pipe(take(1)).subscribe(() => {
+          if (this._renderedContentOffsetNeedsRewrite) {
             this._renderedContentOffset -= this.measureRenderedContentSize();
             this._renderedContentOffsetNeedsRewrite = false;
             this.setRenderedContentOffset(this._renderedContentOffset);
-          });
-        } else {
-          this._ngZone.onStable.pipe(take(1))
-              .subscribe(() => this._scrollStrategy.onRenderedOffsetChanged());
-        }
+          } else {
+            this._scrollStrategy.onRenderedOffsetChanged();
+          }
+        });
       });
     }
   }

src/demo-app/virtual-scroll/virtual-scroll-demo.ts

@@ -98,7 +98,12 @@ export class VirtualScrollDemo {
   sortBy(prop: 'name' | 'capital') {
     this.statesObservable.next(this.states.map(s => ({...s})).sort((a, b) => {
       const aProp = a[prop], bProp = b[prop];
-      return aProp < bProp ? -1 : (aProp > bProp ? 1 : 0);
+      if (aProp < bProp) {
+        return -1;
+      } else if (aProp > bProp) {
+        return 1;
+      }
+      return 0;
     }));
   }
 }