fix(material/timepicker): TimepickerInput component in shadow DOM (#30642)

Fixes an issue where the value of the input element referenced by a
TimepickerInput component inside a shadow DOM was getting formatted too
often due to `TimepickerInput._hasFocus()` assuming the component wasn't
in the shadow DOM.

Fixes #30641

Co-authored-by: Caleb Kish <j69674031@gmail.com>

Author: calebkish

src/material/timepicker/timepicker-input.ts

@@ -41,7 +41,7 @@ import {MAT_INPUT_VALUE_ACCESSOR} from '../input';
 import {Subscription} from 'rxjs';
 import {DOWN_ARROW, ESCAPE, hasModifierKey, UP_ARROW} from '@angular/cdk/keycodes';
 import {validateAdapter} from './util';
-import {DOCUMENT} from '@angular/common';
+import {_getFocusedElementPierceShadowDom} from '@angular/cdk/platform';
 
 /**
  * Input that can be used to enter time and connect to a `mat-timepicker`.
@@ -82,7 +82,6 @@ import {DOCUMENT} from '@angular/common';
 })
 export class MatTimepickerInput<D> implements ControlValueAccessor, Validator, OnDestroy {
   private _elementRef = inject<ElementRef<HTMLInputElement>>(ElementRef);
-  private _document = inject(DOCUMENT);
   private _dateAdapter = inject<DateAdapter<D>>(DateAdapter, {optional: true})!;
   private _dateFormats = inject(MAT_DATE_FORMATS, {optional: true})!;
   private _formField = inject(MAT_FORM_FIELD, {optional: true});
@@ -406,7 +405,7 @@ export class MatTimepickerInput<D> implements ControlValueAccessor, Validator, O
 
   /** Whether the input is currently focused. */
   private _hasFocus(): boolean {
-    return this._document.activeElement === this._elementRef.nativeElement;
+    return _getFocusedElementPierceShadowDom() === this._elementRef.nativeElement;
   }
 
   /** Gets a function that can be used to validate the input. */

src/material/timepicker/timepicker.spec.ts

@@ -1,4 +1,4 @@
-import {Component, inject, Provider, signal, ViewChild} from '@angular/core';
+import {Component, inject, Provider, signal, ViewChild, ViewEncapsulation} from '@angular/core';
 import {ComponentFixture, fakeAsync, flush, TestBed} from '@angular/core/testing';
 import {NoopAnimationsModule} from '@angular/platform-browser/animations';
 import {DateAdapter, provideNativeDateAdapter} from '../core';
@@ -299,6 +299,15 @@ describe('MatTimepicker', () => {
         fixture.detectChanges();
       }).toThrowError(/MatTimepicker can only be registered with one input at a time/);
     });
+
+    it('input should be properly formatted when in shadow DOM', () => {
+      const fixture = TestBed.createComponent(TimepickerInShadowDom);
+      fixture.detectChanges(); // So that TimepickerInput.timepicker gets set.
+      const input = fixture.nativeElement.shadowRoot.querySelector('.mat-timepicker-input');
+      typeInElement(input, '13:37');
+      fixture.detectChanges();
+      expect(input.value).toBe('13:37');
+    });
   });
 
   describe('opening and closing', () => {
@@ -1413,3 +1422,13 @@ class TimepickerWithMultipleInputs {}
 class TimepickerWithoutInput {
   @ViewChild(MatTimepicker) timepicker: MatTimepicker<Date>;
 }
+
+@Component({
+  template: `
+    <input [matTimepicker]="picker" />
+    <mat-timepicker #picker />
+  `,
+  imports: [MatTimepicker, MatTimepickerInput],
+  encapsulation: ViewEncapsulation.ShadowDom,
+})
+class TimepickerInShadowDom {}