fix: focus monitor-based styles not working in some cases inside shadow dom (#19422)

A while ago event delegation was implemented for the focus monitor which has some special behavior where it has to bind its events to the closest shadow root in order for them to work correctly. The problem is that a lot of our `FocusMonitor.focus` calls are very early in the component lifecycle which means that might not have been put into the shadow DOM yet. These changes move the `monitor` calls to `ngAfterViewInit` to resolve the issue.

Fixes #19414.

Author: crisbeto

src/cdk/a11y/focus-monitor/focus-monitor.ts

@@ -18,6 +18,7 @@ import {
   OnDestroy,
   Optional,
   Output,
+  AfterViewInit,
 } from '@angular/core';
 import {Observable, of as observableOf, Subject, Subscription} from 'rxjs';
 import {coerceElement} from '@angular/cdk/coercion';
@@ -562,19 +563,24 @@ function getTarget(event: Event): HTMLElement|null {
 @Directive({
   selector: '[cdkMonitorElementFocus], [cdkMonitorSubtreeFocus]',
 })
-export class CdkMonitorFocus implements OnDestroy {
+export class CdkMonitorFocus implements AfterViewInit, OnDestroy {
   private _monitorSubscription: Subscription;
   @Output() cdkFocusChange = new EventEmitter<FocusOrigin>();
 
-  constructor(private _elementRef: ElementRef<HTMLElement>, private _focusMonitor: FocusMonitor) {
+  constructor(private _elementRef: ElementRef<HTMLElement>, private _focusMonitor: FocusMonitor) {}
+
+  ngAfterViewInit() {
     this._monitorSubscription = this._focusMonitor.monitor(
-        this._elementRef,
-        this._elementRef.nativeElement.hasAttribute('cdkMonitorSubtreeFocus'))
-        .subscribe(origin => this.cdkFocusChange.emit(origin));
+      this._elementRef,
+      this._elementRef.nativeElement.hasAttribute('cdkMonitorSubtreeFocus'))
+      .subscribe(origin => this.cdkFocusChange.emit(origin));
   }
 
   ngOnDestroy() {
     this._focusMonitor.stopMonitoring(this._elementRef);
-    this._monitorSubscription.unsubscribe();
+
+    if (this._monitorSubscription) {
+      this._monitorSubscription.unsubscribe();
+    }
   }
 }

src/material/button-toggle/button-toggle.ts

@@ -30,6 +30,7 @@ import {
   ViewEncapsulation,
   InjectionToken,
   Inject,
+  AfterViewInit,
 } from '@angular/core';
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {
@@ -394,7 +395,7 @@ const _MatButtonToggleMixinBase: CanDisableRippleCtor & typeof MatButtonToggleBa
     '(focus)': 'focus()',
   }
 })
-export class MatButtonToggle extends _MatButtonToggleMixinBase implements OnInit,
+export class MatButtonToggle extends _MatButtonToggleMixinBase implements OnInit, AfterViewInit,
   CanDisableRipple, OnDestroy {
 
   private _isSingleSelector = false;
@@ -512,7 +513,9 @@ export class MatButtonToggle extends _MatButtonToggleMixinBase implements OnInit
         group._syncButtonToggle(this, this._checked);
       }
     }
+  }
 
+  ngAfterViewInit() {
     this._focusMonitor.monitor(this._elementRef, true);
   }
 

src/material/button/button.spec.ts

@@ -72,6 +72,7 @@ describe('MatButton', () => {
 
   it('should be able to focus button with a specific focus origin', () => {
     const fixture = TestBed.createComponent(TestApp);
+    fixture.detectChanges();
     const buttonDebugEl = fixture.debugElement.query(By.css('button'));
     const buttonInstance = buttonDebugEl.componentInstance as MatButton;
 

src/material/button/button.ts

@@ -18,6 +18,7 @@ import {
   Optional,
   Inject,
   Input,
+  AfterViewInit,
 } from '@angular/core';
 import {
   CanColor,
@@ -79,7 +80,7 @@ const _MatButtonMixinBase: CanDisableRippleCtor & CanDisableCtor & CanColorCtor
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class MatButton extends _MatButtonMixinBase
-    implements OnDestroy, CanDisable, CanColor, CanDisableRipple, FocusableOption {
+    implements AfterViewInit, OnDestroy, CanDisable, CanColor, CanDisableRipple, FocusableOption {
 
   /** Whether the button is round. */
   readonly isRoundButton: boolean = this._hasHostAttributes('mat-fab', 'mat-mini-fab');
@@ -108,13 +109,15 @@ export class MatButton extends _MatButtonMixinBase
     // the class is applied to derived classes.
     elementRef.nativeElement.classList.add('mat-button-base');
 
-    this._focusMonitor.monitor(this._elementRef, true);
-
     if (this.isRoundButton) {
       this.color = DEFAULT_ROUND_BUTTON_COLOR;
     }
   }
 
+  ngAfterViewInit() {
+    this._focusMonitor.monitor(this._elementRef, true);
+  }
+
   ngOnDestroy() {
     this._focusMonitor.stopMonitoring(this._elementRef);
   }

src/material/checkbox/checkbox.ts

@@ -221,7 +221,12 @@ export class MatCheckbox extends _MatCheckboxMixinBase implements ControlValueAc
 
     this.tabIndex = parseInt(tabIndex) || 0;
 
-    this._focusMonitor.monitor(elementRef, true).subscribe(focusOrigin => {
+    // TODO: Remove this after the `_clickAction` parameter is removed as an injection parameter.
+    this._clickAction = this._clickAction || this._options.clickAction;
+  }
+
+  ngAfterViewInit() {
+    this._focusMonitor.monitor(this._elementRef, true).subscribe(focusOrigin => {
       if (!focusOrigin) {
         // When a focused element becomes disabled, the browser *immediately* fires a blur event.
         // Angular does not expect events to be raised during change detection, so any state change
@@ -230,16 +235,11 @@ export class MatCheckbox extends _MatCheckboxMixinBase implements ControlValueAc
         // telling the form control it has been touched until the next tick.
         Promise.resolve().then(() => {
           this._onTouched();
-          _changeDetectorRef.markForCheck();
+          this._changeDetectorRef.markForCheck();
         });
       }
     });
 
-    // TODO: Remove this after the `_clickAction` parameter is removed as an injection parameter.
-    this._clickAction = this._clickAction || this._options.clickAction;
-  }
-
-  ngAfterViewInit() {
     this._syncIndeterminate(this._indeterminate);
   }
 

src/material/expansion/expansion-panel-header.ts

@@ -20,6 +20,7 @@ import {
   ViewEncapsulation,
   Optional,
   Inject,
+  AfterViewInit,
 } from '@angular/core';
 import {ANIMATION_MODULE_TYPE} from '@angular/platform-browser/animations';
 import {merge, Subscription, EMPTY} from 'rxjs';
@@ -64,7 +65,7 @@ import {MatAccordionTogglePosition} from './accordion-base';
     '(keydown)': '_keydown($event)',
   },
 })
-export class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
+export class MatExpansionPanelHeader implements AfterViewInit, OnDestroy, FocusableOption {
   private _parentChangeSubscription = Subscription.EMPTY;
 
   constructor(
@@ -99,12 +100,6 @@ export class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
       .pipe(filter(() => panel._containsFocus()))
       .subscribe(() => _focusMonitor.focusVia(_element, 'program'));
 
-    _focusMonitor.monitor(_element).subscribe(origin => {
-      if (origin && panel.accordion) {
-        panel.accordion._handleHeaderFocus(this);
-      }
-    });
-
     if (defaultOptions) {
       this.expandedHeight = defaultOptions.expandedHeight;
       this.collapsedHeight = defaultOptions.collapsedHeight;
@@ -201,6 +196,14 @@ export class MatExpansionPanelHeader implements OnDestroy, FocusableOption {
     this._focusMonitor.focusVia(this._element, origin, options);
   }
 
+  ngAfterViewInit() {
+    this._focusMonitor.monitor(this._element).subscribe(origin => {
+      if (origin && this.panel.accordion) {
+        this.panel.accordion._handleHeaderFocus(this);
+      }
+    });
+  }
+
   ngOnDestroy() {
     this._parentChangeSubscription.unsubscribe();
     this._focusMonitor.stopMonitoring(this._element);

src/material/input/input.ts

@@ -18,10 +18,10 @@ import {
   NgZone,
   OnChanges,
   OnDestroy,
-  OnInit,
   Optional,
   Self,
   HostListener,
+  AfterViewInit,
 } from '@angular/core';
 import {FormGroupDirective, NgControl, NgForm} from '@angular/forms';
 import {
@@ -88,7 +88,7 @@ const _MatInputMixinBase: CanUpdateErrorStateCtor & typeof MatInputBase =
   providers: [{provide: MatFormFieldControl, useExisting: MatInput}],
 })
 export class MatInput extends _MatInputMixinBase implements MatFormFieldControl<any>, OnChanges,
-    OnDestroy, OnInit, DoCheck, CanUpdateErrorState {
+    OnDestroy, AfterViewInit, DoCheck, CanUpdateErrorState {
   protected _uid = `mat-input-${nextUniqueId++}`;
   protected _previousNativeValue: any;
   private _inputValueAccessor: {value: any};
@@ -277,7 +277,7 @@ export class MatInput extends _MatInputMixinBase implements MatFormFieldControl<
     }
   }
 
-  ngOnInit() {
+  ngAfterViewInit() {
     if (this._platform.isBrowser) {
       this._autofillMonitor.monitor(this._elementRef.nativeElement).subscribe(event => {
         this.autofilled = event.isAutofilled;

src/material/menu/menu-item.ts

@@ -18,6 +18,7 @@ import {
   Optional,
   Input,
   HostListener,
+  AfterViewInit,
 } from '@angular/core';
 import {
   CanDisable, CanDisableCtor,
@@ -57,7 +58,7 @@ const _MatMenuItemMixinBase: CanDisableRippleCtor & CanDisableCtor & typeof MatM
   templateUrl: 'menu-item.html',
 })
 export class MatMenuItem extends _MatMenuItemMixinBase
-    implements FocusableOption, CanDisable, CanDisableRipple, OnDestroy {
+    implements FocusableOption, CanDisable, CanDisableRipple, AfterViewInit, OnDestroy {
 
   /** ARIA role for the menu item. */
   @Input() role: 'menuitem' | 'menuitemradio' | 'menuitemcheckbox' = 'menuitem';
@@ -85,13 +86,6 @@ export class MatMenuItem extends _MatMenuItemMixinBase
     // @breaking-change 8.0.0 make `_focusMonitor` and `document` required params.
     super();
 
-    if (_focusMonitor) {
-      // Start monitoring the element so it gets the appropriate focused classes. We want
-      // to show the focus style for menu items only when the focus was not caused by a
-      // mouse or touch interaction.
-      _focusMonitor.monitor(this._elementRef, false);
-    }
-
     if (_parentMenu && _parentMenu.addItem) {
       _parentMenu.addItem(this);
     }
@@ -110,6 +104,15 @@ export class MatMenuItem extends _MatMenuItemMixinBase
     this._focused.next(this);
   }
 
+  ngAfterViewInit() {
+    if (this._focusMonitor) {
+      // Start monitoring the element so it gets the appropriate focused classes. We want
+      // to show the focus style for menu items only when the focus was not caused by a
+      // mouse or touch interaction.
+      this._focusMonitor.monitor(this._elementRef, false);
+    }
+  }
+
   ngOnDestroy() {
     if (this._focusMonitor) {
       this._focusMonitor.stopMonitoring(this._elementRef);

src/material/slider/slider.ts

@@ -36,12 +36,12 @@ import {
   Inject,
   Input,
   OnDestroy,
-  OnInit,
   Optional,
   Output,
   ViewChild,
   ViewEncapsulation,
   NgZone,
+  AfterViewInit,
 } from '@angular/core';
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {
@@ -156,7 +156,7 @@ const _MatSliderMixinBase:
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class MatSlider extends _MatSliderMixinBase
-    implements ControlValueAccessor, OnDestroy, CanDisable, CanColor, OnInit, HasTabIndex {
+    implements ControlValueAccessor, OnDestroy, CanDisable, CanColor, AfterViewInit, HasTabIndex {
   /** Whether the slider is inverted. */
   @Input()
   get invert(): boolean { return this._invert; }
@@ -511,7 +511,7 @@ export class MatSlider extends _MatSliderMixinBase
     });
   }
 
-  ngOnInit() {
+  ngAfterViewInit() {
     this._focusMonitor
         .monitor(this._elementRef, true)
         .subscribe((origin: FocusOrigin) => {

src/material/sort/sort-header.ts

@@ -18,6 +18,7 @@ import {
   ViewEncapsulation,
   Inject,
   ElementRef,
+  AfterViewInit,
 } from '@angular/core';
 import {CanDisable, CanDisableCtor, mixinDisabled} from '@angular/material/core';
 import {FocusMonitor} from '@angular/cdk/a11y';
@@ -95,7 +96,7 @@ interface MatSortHeaderColumnDef {
   ]
 })
 export class MatSortHeader extends _MatSortHeaderMixinBase
-    implements CanDisable, MatSortable, OnDestroy, OnInit {
+    implements CanDisable, MatSortable, OnDestroy, OnInit, AfterViewInit {
   private _rerenderSubscription: Subscription;
 
   /**
@@ -168,11 +169,6 @@ export class MatSortHeader extends _MatSortHeaderMixinBase
 
           changeDetectorRef.markForCheck();
         });
-
-    // We use the focus monitor because we also want to style
-    // things differently based on the focus origin.
-    _focusMonitor.monitor(_elementRef, true)
-        .subscribe(origin => this._setIndicatorHintVisible(!!origin));
   }
 
   ngOnInit() {
@@ -188,6 +184,13 @@ export class MatSortHeader extends _MatSortHeaderMixinBase
     this._sort.register(this);
   }
 
+  ngAfterViewInit() {
+    // We use the focus monitor because we also want to style
+    // things differently based on the focus origin.
+    this._focusMonitor.monitor(this._elementRef, true)
+        .subscribe(origin => this._setIndicatorHintVisible(!!origin));
+  }
+
   ngOnDestroy() {
     this._focusMonitor.stopMonitoring(this._elementRef);
     this._sort.deregister(this);