fix(material/list): add opt-out for radio indicators

Add an opt-out for radio indicators for single-selection. Adds both an
Input and DI token to specify if radio indicators are hidden. By
default, display radio indicators. If both DI token and Input are
specified, the Input wins.

PR #25933 added radio toggles for single-selection. Add an opt-out to
provide a way to have same appearance as before #25933.

API changes
 - add `@Input hideSingleSelectionIndicator` to specify if radio
   indicators are displayed
 - add MAT_LIST_CONFIG token to specify default value for
   `hideSingleSelectionIndicator`

Author: zarend

src/dev-app/list/list-demo.html

@@ -123,6 +123,7 @@ <h2>Selection list</h2>
                         (selectionChange)="changeEventCount = changeEventCount + 1"
                         [disabled]="selectionListDisabled"
                         [disableRipple]="selectionListRippleDisabled"
+                        [hideSingleSelectionIndicator]="selectionListSingleSelectionIndicatorHidden"
                         color="primary">
       <div mat-subheader>Groceries</div>
 
@@ -161,6 +162,12 @@ <h2>Selection list</h2>
         <input type="checkbox" [(ngModel)]="selectionListRippleDisabled">
       </label>
     </p>
+    <p>
+      <label>
+        Hide Single-Selection indicators
+        <input type="checkbox" [(ngModel)]="selectionListSingleSelectionIndicatorHidden">
+      </label>
+    </p>
     <p>
       <button mat-raised-button (click)="groceries.selectAll()">Select all</button>
       <button mat-raised-button (click)="groceries.deselectAll()">Deselect all</button>
@@ -173,6 +180,7 @@ <h2>Single Selection list</h2>
     <mat-selection-list #favorite
                         [(ngModel)]="favoriteOptions"
                         [multiple]="false"
+                        [hideSingleSelectionIndicator]="selectionListSingleSelectionIndicatorHidden"
                         color="primary">
       <div mat-subheader>Favorite Grocery</div>
 

src/dev-app/list/list-demo.ts

@@ -64,6 +64,7 @@ export class ListDemo {
   infoClicked = false;
   selectionListDisabled = false;
   selectionListRippleDisabled = false;
+  selectionListSingleSelectionIndicatorHidden = false;
 
   selectedOptions: string[] = ['apples'];
   changeEventCount = 0;

src/material/list/_interactive-list-theme.scss

@@ -1,11 +1,13 @@
 @use 'sass:map';
 @use '@material/ripple' as mdc-ripple;
+@use '../core/theming/theming';
 
 // Mixin that provides colors for the various states of an interactive list-item. MDC
 // has integrated styles for these states but relies on their complex ripples for it.
 @mixin private-interactive-list-item-state-colors($config) {
   $is-dark-theme: map.get($config, is-dark);
   $active-base-color: if($is-dark-theme, white, black);
+  $selected-color: theming.get-color-from-palette(map.get($config, primary));
 
   .mat-mdc-list-item-interactive {
     &::before {
@@ -19,5 +21,20 @@
     &:focus::before {
       opacity: mdc-ripple.states-opacity($active-base-color, focus);
     }
+
+    &.mdc-list-item--selected {
+      &::before {
+        background: $selected-color;
+        opacity: mdc-ripple.states-opacity($selected-color, selected);
+      }
+
+      &:not(:focus):not(.mdc-list-item--disabled):hover::before {
+        // The hover and selected opacities need to be combined to match with what the MDC
+        // ripple state would render. More details here:
+        // https://github.com/material-components/material-components-web/blob/348665978ce73694ad4518626dd70cdf5b984113/packages/mdc-ripple/_ripple-theme.scss#L450.
+        opacity: mdc-ripple.states-opacity($selected-color, hover) +
+                 mdc-ripple.states-opacity($selected-color, selected);
+      }
+    }
   }
 }

src/material/list/list-base.ts

@@ -13,6 +13,7 @@ import {
   ContentChildren,
   Directive,
   ElementRef,
+  inject,
   Inject,
   Input,
   NgZone,
@@ -35,6 +36,7 @@ import {
   MatListItemIcon,
   MatListItemAvatar,
 } from './list-item-sections';
+import {MAT_LIST_CONFIG} from './tokens';
 
 @Directive({
   host: {
@@ -67,6 +69,8 @@ export abstract class MatListBase {
     this._disabled = coerceBooleanProperty(value);
   }
   private _disabled = false;
+
+  protected _defaultOptions = inject(MAT_LIST_CONFIG, {optional: true});
 }
 
 @Directive({

src/material/list/list-option.ts

@@ -50,6 +50,7 @@ export interface SelectionList extends MatListBase {
   multiple: boolean;
   color: ThemePalette;
   selectedOptions: SelectionModel<MatListOption>;
+  hideSingleSelectionIndicator: boolean;
   compareWith: (o1: any, o2: any) => boolean;
   _value: string[] | null;
   _reportValueChange(): void;
@@ -64,6 +65,10 @@ export interface SelectionList extends MatListBase {
   host: {
     'class': 'mat-mdc-list-item mat-mdc-list-option mdc-list-item',
     'role': 'option',
+    // As per MDC, only list items without checkbox or radio indicator should receive the
+    // `--selected` class.
+    '[class.mdc-list-item--selected]':
+      'selected && !_selectionList.multiple && _selectionList.hideSingleSelectionIndicator',
     // Based on the checkbox/radio position and whether there are icons or avatars, we apply MDC's
     // list-item `--leading` and `--trailing` classes.
     '[class.mdc-list-item--with-leading-avatar]': '_hasProjected("avatars", "before")',
@@ -243,7 +248,11 @@ export class MatListOption extends MatListItemBase implements ListOption, OnInit
 
   /** Where a radio indicator is shown at the given position. */
   _hasRadioAt(position: MatListOptionTogglePosition): boolean {
-    return !this._selectionList.multiple && this._getTogglePosition() === position;
+    return (
+      !this._selectionList.multiple &&
+      this._getTogglePosition() === position &&
+      !this._selectionList.hideSingleSelectionIndicator
+    );
   }
 
   /** Whether icons or avatars are shown at the given position. */

src/material/list/public-api.ts

@@ -14,6 +14,7 @@ export * from './selection-list';
 export * from './list-option';
 export * from './subheader';
 export * from './list-item-sections';
+export * from './tokens';
 
 export {MatListOption} from './list-option';
 

src/material/list/selection-list.spec.ts

@@ -30,6 +30,8 @@ import {
   MatListOptionTogglePosition,
   MatSelectionList,
   MatSelectionListChange,
+  MatListConfig,
+  MAT_LIST_CONFIG,
 } from './index';
 
 describe('MDC-based MatSelectionList without forms', () => {
@@ -663,7 +665,7 @@ describe('MDC-based MatSelectionList without forms', () => {
     });
   });
 
-  describe('with list option selected', () => {
+  describe('multiple-selection with list option selected', () => {
     let fixture: ComponentFixture<SelectionListWithSelectedOption>;
     let listOptionElements: DebugElement[];
     let selectionList: DebugElement;
@@ -703,6 +705,79 @@ describe('MDC-based MatSelectionList without forms', () => {
     }));
   });
 
+  describe('single-selection with list option selected', () => {
+    let fixture: ComponentFixture<SingleSelectionListWithSelectedOption>;
+    let listOptionElements: DebugElement[];
+
+    beforeEach(waitForAsync(() => {
+      TestBed.configureTestingModule({
+        imports: [MatListModule],
+        declarations: [SingleSelectionListWithSelectedOption],
+      });
+
+      TestBed.compileComponents();
+    }));
+
+    beforeEach(waitForAsync(() => {
+      fixture = TestBed.createComponent(SingleSelectionListWithSelectedOption);
+      listOptionElements = fixture.debugElement.queryAll(By.directive(MatListOption))!;
+      fixture.detectChanges();
+    }));
+
+    it('displays radio indicators by default', () => {
+      expect(
+        listOptionElements[0].nativeElement.querySelector('input[type="radio"]'),
+      ).not.toBeNull();
+      expect(
+        listOptionElements[1].nativeElement.querySelector('input[type="radio"]'),
+      ).not.toBeNull();
+
+      expect(listOptionElements[0].nativeElement.classList).not.toContain(
+        'mdc-list-item--selected',
+      );
+      expect(listOptionElements[1].nativeElement.classList).not.toContain(
+        'mdc-list-item--selected',
+      );
+    });
+  });
+
+  describe('with token to hide radio indicators', () => {
+    let fixture: ComponentFixture<SingleSelectionListWithSelectedOption>;
+    let listOptionElements: DebugElement[];
+
+    beforeEach(waitForAsync(() => {
+      const matListConfig: MatListConfig = {hideSingleSelectionIndicator: true};
+
+      TestBed.configureTestingModule({
+        imports: [MatListModule],
+        declarations: [SingleSelectionListWithSelectedOption],
+        providers: [{provide: MAT_LIST_CONFIG, useValue: matListConfig}],
+      });
+
+      TestBed.compileComponents();
+    }));
+
+    beforeEach(waitForAsync(() => {
+      fixture = TestBed.createComponent(SingleSelectionListWithSelectedOption);
+      listOptionElements = fixture.debugElement.queryAll(By.directive(MatListOption))!;
+      fixture.detectChanges();
+    }));
+
+    it('does not display radio indicators', () => {
+      expect(listOptionElements[0].nativeElement.querySelector('input[type="radio"]')).toBeNull();
+      expect(listOptionElements[1].nativeElement.querySelector('input[type="radio"]')).toBeNull();
+
+      expect(listOptionElements[0].nativeElement.classList).not.toContain(
+        'mdc-list-item--selected',
+      );
+
+      expect(listOptionElements[1].nativeElement.getAttribute('aria-selected'))
+        .withContext('Expected second option to be selected')
+        .toBe('true');
+      expect(listOptionElements[1].nativeElement.classList).toContain('mdc-list-item--selected');
+    });
+  });
+
   describe('with option disabled', () => {
     let fixture: ComponentFixture<SelectionListWithDisabledOption>;
     let listOptionEl: HTMLElement;
@@ -1727,6 +1802,15 @@ class SelectionListWithDisabledOption {
 })
 class SelectionListWithSelectedOption {}
 
+@Component({
+  template: `
+  <mat-selection-list [multiple]="false">
+    <mat-list-option>Not selected - Item #1</mat-list-option>
+    <mat-list-option [selected]="true">Pre-selected - Item #2</mat-list-option>
+  </mat-selection-list>`,
+})
+class SingleSelectionListWithSelectedOption {}
+
 @Component({
   template: `
   <mat-selection-list>

src/material/list/selection-list.ts

@@ -123,6 +123,17 @@ export class MatSelectionList
   }
   private _multiple = true;
 
+  /** Whether radio indicator for all list items is hidden. */
+  @Input()
+  get hideSingleSelectionIndicator(): boolean {
+    return this._hideSingleSelectionIndicator;
+  }
+  set hideSingleSelectionIndicator(value: BooleanInput) {
+    this._hideSingleSelectionIndicator = coerceBooleanProperty(value);
+  }
+  private _hideSingleSelectionIndicator: boolean =
+    this._defaultOptions?.hideSingleSelectionIndicator ?? false;
+
   /** The currently selected options. */
   selectedOptions = new SelectionModel<MatListOption>(this._multiple);
 
@@ -160,10 +171,12 @@ export class MatSelectionList
   ngOnChanges(changes: SimpleChanges) {
     const disabledChanges = changes['disabled'];
     const disableRippleChanges = changes['disableRipple'];
+    const hideSingleSelectionIndicatorChanges = changes['hideSingleSelectionIndicator'];
 
     if (
       (disableRippleChanges && !disableRippleChanges.firstChange) ||
-      (disabledChanges && !disabledChanges.firstChange)
+      (disabledChanges && !disabledChanges.firstChange) ||
+      (hideSingleSelectionIndicatorChanges && !hideSingleSelectionIndicatorChanges.firstChange)
     ) {
       this._markOptionsForCheck();
     }

src/material/list/tokens.ts

@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {InjectionToken} from '@angular/core';
+
+/** Object that can be used to configure the default options for the list module. */
+export interface MatListConfig {
+  /** Wheter icon indicators should be hidden for single-selection. */
+  hideSingleSelectionIndicator?: boolean;
+}
+
+/** Injection token that can be used to provide the default options the list module. */
+export const MAT_LIST_CONFIG = new InjectionToken<MatListConfig>('MAT_LIST_CONFIG');

tools/public_api_guard/material/list.md

@@ -32,6 +32,9 @@ import { ThemePalette } from '@angular/material/core';
 // @public
 export const MAT_LIST: InjectionToken<MatList>;
 
+// @public
+export const MAT_LIST_CONFIG: InjectionToken<MatListConfig>;
+
 // @public
 export const MAT_NAV_LIST: InjectionToken<MatNavList>;
 
@@ -56,6 +59,11 @@ export class MatList extends MatListBase {
     static ɵfac: i0.ɵɵFactoryDeclaration<MatList, never>;
 }
 
+// @public
+export interface MatListConfig {
+    hideSingleSelectionIndicator?: boolean;
+}
+
 // @public (undocumented)
 export class MatListItem extends MatListItemBase {
     constructor(element: ElementRef, ngZone: NgZone, listBase: MatListBase | null, platform: Platform, globalRippleOptions?: RippleGlobalOptions, animationMode?: string);
@@ -229,6 +237,8 @@ export class MatSelectionList extends MatListBase implements SelectionList, Cont
     _emitChangeEvent(options: MatListOption[]): void;
     focus(options?: FocusOptions): void;
     _handleKeydown(event: KeyboardEvent): void;
+    get hideSingleSelectionIndicator(): boolean;
+    set hideSingleSelectionIndicator(value: BooleanInput);
     // (undocumented)
     _items: QueryList<MatListOption>;
     get multiple(): boolean;
@@ -251,7 +261,7 @@ export class MatSelectionList extends MatListBase implements SelectionList, Cont
     _value: string[] | null;
     writeValue(values: string[]): void;
     // (undocumented)
-    static ɵcmp: i0.ɵɵComponentDeclaration<MatSelectionList, "mat-selection-list", ["matSelectionList"], { "color": "color"; "compareWith": "compareWith"; "multiple": "multiple"; "disabled": "disabled"; }, { "selectionChange": "selectionChange"; }, ["_items"], ["*"], false, never>;
+    static ɵcmp: i0.ɵɵComponentDeclaration<MatSelectionList, "mat-selection-list", ["matSelectionList"], { "color": "color"; "compareWith": "compareWith"; "multiple": "multiple"; "hideSingleSelectionIndicator": "hideSingleSelectionIndicator"; "disabled": "disabled"; }, { "selectionChange": "selectionChange"; }, ["_items"], ["*"], false, never>;
     // (undocumented)
     static ɵfac: i0.ɵɵFactoryDeclaration<MatSelectionList, never>;
 }
@@ -277,6 +287,8 @@ export interface SelectionList extends MatListBase {
     // (undocumented)
     _emitChangeEvent(options: MatListOption[]): void;
     // (undocumented)
+    hideSingleSelectionIndicator: boolean;
+    // (undocumented)
     multiple: boolean;
     // (undocumented)
     _onTouched(): void;