fix(material/badge): allow badge defaults to be configured

goldens/material/badge/index.api.md

@@ -8,9 +8,13 @@ import { AfterViewInit } from '@angular/core';
 import * as i0 from '@angular/core';
 import * as i1 from '@angular/cdk/a11y';
 import * as i2 from '@angular/cdk/bidi';
+import { InjectionToken } from '@angular/core';
 import { OnDestroy } from '@angular/core';
 import { OnInit } from '@angular/core';
 
+// @public
+export const MAT_BADGE_CONFIG: InjectionToken<MatBadgeConfig>;
+
 // @public
 export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
     constructor();
@@ -46,6 +50,14 @@ export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
     static ɵfac: i0.ɵɵFactoryDeclaration<MatBadge, never>;
 }
 
+// @public
+export interface MatBadgeConfig {
+    color?: ThemePalette;
+    overlap?: boolean;
+    position?: MatBadgePosition;
+    size?: MatBadgeSize;
+}
+
 // @public (undocumented)
 export class MatBadgeModule {
     // (undocumented)

src/material/badge/badge.spec.ts

@@ -10,6 +10,7 @@ import {
 import {By} from '@angular/platform-browser';
 import {MatBadge, MatBadgeModule, MatBadgePosition, MatBadgeSize} from './index';
 import {ThemePalette} from '../core';
+import {MAT_BADGE_CONFIG, MatBadgeConfig} from './badge';
 
 describe('MatBadge', () => {
   let fixture: ComponentFixture<any>;
@@ -265,6 +266,31 @@ describe('MatBadge', () => {
         .toBeFalse();
     });
   });
+
+  it('should be able to specify default values through DI', () => {
+    TestBed.configureTestingModule({
+      providers: [
+        {
+          provide: MAT_BADGE_CONFIG,
+          useValue: {
+            color: 'accent',
+            overlap: false,
+            position: 'below before',
+            size: 'large',
+          } satisfies MatBadgeConfig,
+        },
+      ],
+    });
+
+    const fixture = TestBed.createComponent(SimpleBadge);
+    fixture.detectChanges();
+    const badge = fixture.componentInstance.badgeInstance;
+
+    expect(badge.color).toBe('accent');
+    expect(badge.overlap).toBe(false);
+    expect(badge.position).toBe('below before');
+    expect(badge.size).toBe('large');
+  });
 });
 
 /** Test component that contains a MatBadge. */
@@ -333,9 +359,20 @@ class PreExistingBadge {}
 class NestedBadge {}
 
 @Component({
-  template: `
-    <ng-template matBadge="1">Notifications</ng-template>`,
+  template: `<ng-template matBadge="1">Notifications</ng-template>`,
   imports: [MatBadgeModule],
   changeDetection: ChangeDetectionStrategy.Eager,
 })
 class BadgeOnTemplate {}
+
+@Component({
+  template: `
+    <button matBadge="Hello">
+      home
+    </button>
+  `,
+  imports: [MatBadgeModule],
+})
+class SimpleBadge {
+  @ViewChild(MatBadge) badgeInstance!: MatBadge;
+}

src/material/badge/badge.ts

@@ -22,6 +22,7 @@ import {
   ViewEncapsulation,
   DOCUMENT,
   AfterViewInit,
+  InjectionToken,
 } from '@angular/core';
 import {_animationsDisabled, ThemePalette} from '../core';
 import {_CdkPrivateStyleLoader, _VisuallyHiddenLoader} from '@angular/cdk/private';
@@ -40,6 +41,24 @@ export type MatBadgePosition =
 /** Allowed size options for matBadgeSize */
 export type MatBadgeSize = 'small' | 'medium' | 'large';
 
+/** Object that can be used to configure the default options for the badge component. */
+export interface MatBadgeConfig {
+  /** Default position for badges. */
+  position?: MatBadgePosition;
+
+  /** Default size for badges. */
+  size?: MatBadgeSize;
+
+  /** Default color to apply to all badges. */
+  color?: ThemePalette;
+
+  /** Whether badges should overlap by default. */
+  overlap?: boolean;
+}
+
+/** Injection token that can be used to configure the default options for the badge component. */
+export const MAT_BADGE_CONFIG = new InjectionToken<MatBadgeConfig>('MAT_BADGE_CONFIG');
+
 const BADGE_CONTENT_CLASS = 'mat-badge-content';
 
 /**
@@ -93,10 +112,10 @@ export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
     this._setColor(value);
     this._color = value;
   }
-  private _color: ThemePalette = 'primary';
+  private _color: ThemePalette;
 
   /** Whether the badge should overlap its contents or not */
-  @Input({alias: 'matBadgeOverlap', transform: booleanAttribute}) overlap: boolean = true;
+  @Input({alias: 'matBadgeOverlap', transform: booleanAttribute}) overlap: boolean;
 
   /** Whether the badge is disabled. */
   @Input({alias: 'matBadgeDisabled', transform: booleanAttribute}) disabled: boolean = false;
@@ -105,7 +124,7 @@ export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
    * Position the badge should reside.
    * Accepts any combination of 'above'|'below' and 'before'|'after'
    */
-  @Input('matBadgePosition') position: MatBadgePosition = 'above after';
+  @Input('matBadgePosition') position: MatBadgePosition;
 
   /** The content for the badge */
   @Input('matBadge')
@@ -128,7 +147,7 @@ export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
   private _description!: string;
 
   /** Size of the badge. Can be 'small', 'medium', or 'large'. */
-  @Input('matBadgeSize') size: MatBadgeSize = 'medium';
+  @Input('matBadgeSize') size: MatBadgeSize;
 
   /** Whether the badge is hidden. */
   @Input({alias: 'matBadgeHidden', transform: booleanAttribute}) hidden: boolean = false;
@@ -148,10 +167,16 @@ export class MatBadge implements OnInit, AfterViewInit, OnDestroy {
   private _document = inject(DOCUMENT);
 
   constructor() {
+    const config = inject(MAT_BADGE_CONFIG, {optional: true});
     const styleLoader = inject(_CdkPrivateStyleLoader);
     styleLoader.load(_MatBadgeStyleLoader);
     styleLoader.load(_VisuallyHiddenLoader);
 
+    this._color = config?.color || 'primary';
+    this.overlap = config?.overlap ?? true;
+    this.position = config?.position || 'above after';
+    this.size = config?.size || 'medium';
+
     if (typeof ngDevMode === 'undefined' || ngDevMode) {
       const nativeElement = this._elementRef.nativeElement;
 

src/material/badge/public-api.ts

@@ -7,4 +7,4 @@
  */
 
 export * from './badge-module';
-export {MatBadge, MatBadgePosition, MatBadgeSize} from './badge';
+export {MatBadge, MatBadgePosition, MatBadgeSize, MAT_BADGE_CONFIG, MatBadgeConfig} from './badge';