feat(design)!: change daffSkeletonMixin to a directive (#2923)

BREAKING CHANGE: daffSkeletonMixin has been removed in favor of DaffSkeletonableDirective. Update usage by using the hostDirective feature.

Author: xelaint

Diff for: libs/design/image/src/image/image.component.spec.ts

@@ -82,8 +82,11 @@ describe('@daffodil/design/image | DaffImageComponent', () => {
     expect(component.height).toEqual(100);
   });
 
-  it('should be able to take `skeleton` as an input', () => {
-    expect(component.skeleton).toEqual(wrapper.skeleton);
+  it('should take skeleton as an input', () => {
+    wrapper.skeleton = true;
+    fixture.detectChanges();
+
+    expect(de.nativeElement.classList.contains('daff-skeleton')).toEqual(true);
   });
 
   it('should throw an error when src is invalid', () => {

Diff for: libs/design/image/src/image/image.component.ts

@@ -4,17 +4,12 @@ import {
   Input,
   EventEmitter,
   OnInit,
-  ElementRef,
-  Renderer2,
   Output,
   HostBinding,
 } from '@angular/core';
 import { DomSanitizer } from '@angular/platform-browser';
 
-import {
-  daffSkeletonableMixin,
-  DaffSkeletonable,
-} from '@daffodil/design';
+import { DaffSkeletonableDirective } from '@daffodil/design';
 import { daffThumbnailCompatToken } from '@daffodil/design/media-gallery';
 
 const validateProperty = (object: Record<string, any>, prop: string) => {
@@ -38,15 +33,6 @@ const validateProperties = (object: Record<string, any>, props: string[]) => {
   }
 };
 
-/**
- * An _elementRef is needed for the GolfGhostable mixin
- */
-class DaffImageBase {
-  constructor(public _elementRef: ElementRef, public _renderer: Renderer2) { }
-}
-
-const _daffImageBase = daffSkeletonableMixin(DaffImageBase);
-
 @Component({
   selector: 'daff-image',
   templateUrl: './image.component.html',
@@ -58,11 +44,12 @@ const _daffImageBase = daffSkeletonableMixin(DaffImageBase);
 			 provide: daffThumbnailCompatToken, useExisting: DaffImageComponent,
     },
   ],
-  // todo(damienwebdev): remove once decorators hit stage 3 - https://github.com/microsoft/TypeScript/issues/7342
-  // eslint-disable-next-line @angular-eslint/no-inputs-metadata-property
-  inputs: ['skeleton'],
+  hostDirectives: [{
+    directive: DaffSkeletonableDirective,
+    inputs: ['skeleton'],
+  }],
 })
-export class DaffImageComponent extends _daffImageBase implements OnInit, DaffSkeletonable {
+export class DaffImageComponent implements OnInit {
 
   private _src: string;
 
@@ -119,13 +106,7 @@ export class DaffImageComponent extends _daffImageBase implements OnInit, DaffSk
 	  validateProperties(this, ['src', 'alt', 'width', 'height']);
   }
 
-  constructor(
-    private sanitizer: DomSanitizer,
-    private elementRef: ElementRef,
-    private renderer: Renderer2,
-  ) {
-	  super(elementRef, renderer);
-  }
+  constructor(private sanitizer: DomSanitizer) {}
 
   /**
    * @docs-private

Diff for: libs/design/media-gallery/src/media-gallery/media-gallery.component.spec.ts

@@ -78,8 +78,11 @@ describe('@daffodil/design/media-gallery | DaffMediaGalleryComponent', () => {
     expect(component.name).toEqual(stubName);
   });
 
-  it('should take a skeleton as input', () => {
-    expect(component.skeleton).toEqual(wrapper.skeleton);
+  it('should take skeleton as an input', () => {
+    wrapper.skeleton = true;
+    fixture.detectChanges();
+
+    expect(de.nativeElement.classList.contains('daff-skeleton')).toEqual(true);
   });
 
   it('should remove the gallery from the registry when the gallery is destroyed', () => {

Diff for: libs/design/media-gallery/src/media-gallery/media-gallery.component.ts

@@ -5,14 +5,11 @@ import {
   Input,
   OnInit,
   OnDestroy,
-  ElementRef,
-  Renderer2,
 } from '@angular/core';
 
 import {
-  daffSkeletonableMixin,
-  DaffSkeletonable,
   DaffArticleEncapsulatedDirective,
+  DaffSkeletonableDirective,
 } from '@daffodil/design';
 
 import { DaffMediaGalleryRegistration } from '../helpers/media-gallery-registration.interface';
@@ -21,15 +18,6 @@ import { DaffMediaGalleryRegistry } from '../registry/media-gallery.registry';
 
 let uniqueGalleryId = 0;
 
-/**
- * An _elementRef and an instance of renderer2 are needed for the link set mixins
- */
-class DaffMediaGalleryBase {
-  constructor(public _elementRef: ElementRef, public _renderer: Renderer2) {}
-}
-
-const _daffMediaGalleryBase = daffSkeletonableMixin((DaffMediaGalleryBase));
-
 @Component({
   selector: 'daff-media-gallery',
   templateUrl: './media-gallery.component.html',
@@ -42,11 +30,15 @@ const _daffMediaGalleryBase = daffSkeletonableMixin((DaffMediaGalleryBase));
   // todo(damienwebdev): remove once decorators hit stage 3 - https://github.com/microsoft/TypeScript/issues/7342
   // eslint-disable-next-line @angular-eslint/no-inputs-metadata-property
   inputs: ['skeleton'],
-  hostDirectives: [{
-    directive: DaffArticleEncapsulatedDirective,
-  }],
+  hostDirectives: [
+    { directive: DaffArticleEncapsulatedDirective },
+    {
+      directive: DaffSkeletonableDirective,
+      inputs: ['skeleton'],
+    },
+  ],
 })
-export class DaffMediaGalleryComponent extends _daffMediaGalleryBase implements DaffMediaGalleryRegistration, DaffSkeletonable, OnInit, OnDestroy {
+export class DaffMediaGalleryComponent implements DaffMediaGalleryRegistration, OnInit, OnDestroy {
   /**
    * Adds a class for styling the media gallery
    */
@@ -57,13 +49,8 @@ export class DaffMediaGalleryComponent extends _daffMediaGalleryBase implements
    */
   @Input() name = `${uniqueGalleryId}`;
 
-  constructor(
-    private elementRef: ElementRef,
-    private renderer: Renderer2,
-    private registry: DaffMediaGalleryRegistry,
-  ) {
-	  	super(elementRef, renderer);
-	  	uniqueGalleryId++;
+  constructor(private registry: DaffMediaGalleryRegistry) {
+    uniqueGalleryId++;
   }
 
   ngOnInit() {

Diff for: libs/design/scss/state/skeleton/_mixins.scss

@@ -28,7 +28,7 @@
 
 	&::before {
 		animation-name: loading;
-		animation-duration: 1500ms;
+		animation-duration: 1000ms;
 		animation-timing-function: linear;
 		animation-iteration-count: infinite;
 		animation-direction: alternate;

Diff for: libs/design/src/core/skeletonable/public_api.ts

@@ -1,2 +1,2 @@
 export { DaffSkeletonable } from './skeletonable';
-export { daffSkeletonableMixin } from './skeletonable-mixin';
+export { DaffSkeletonableDirective } from './skeletonable.directive';

Diff for: libs/design/src/core/skeletonable/skeletonable-mixin.ts

@@ -0,0 +1,72 @@
+import {
+  Component,
+  DebugElement,
+} from '@angular/core';
+import {
+  waitForAsync,
+  ComponentFixture,
+  TestBed,
+} from '@angular/core/testing';
+import { By } from '@angular/platform-browser';
+
+import { DaffSkeletonableDirective } from './skeletonable.directive';
+
+@Component({
+  template: `
+		<div daffSkeletonable
+			[skeleton]="skeleton">
+		</div>`,
+})
+
+class WrapperComponent {
+  skeleton: boolean;
+}
+
+describe('@daffodil/design | DaffSkeletonableDirective', () => {
+  let wrapper: WrapperComponent;
+  let de: DebugElement;
+  let fixture: ComponentFixture<WrapperComponent>;
+  let directive: DaffSkeletonableDirective;
+
+  beforeEach(waitForAsync(() => {
+    TestBed.configureTestingModule({
+      declarations: [
+        WrapperComponent,
+      ],
+      imports: [
+        DaffSkeletonableDirective,
+      ],
+    })
+      .compileComponents();
+  }));
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(WrapperComponent);
+    wrapper = fixture.componentInstance;
+    de = fixture.debugElement.query(By.css('[daffSkeletonable]'));
+    directive = de.injector.get(DaffSkeletonableDirective);
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(wrapper).toBeTruthy();
+    expect(directive).toBeTruthy();
+  });
+
+  it('should take skeleton as an input', () => {
+    expect(directive.skeleton).toEqual(wrapper.skeleton);
+  });
+
+  it('should add a class of "daff-skeleton" to the host element when skeleton is true', () => {
+    wrapper.skeleton = true;
+    fixture.detectChanges();
+
+    expect(de.classes).toEqual(jasmine.objectContaining({
+      'daff-skeleton': true,
+    }));
+  });
+
+  it('should not add a class of "daff-skeleton" to the host element when skeleton is false', () => {
+    expect(de.classes['daff-skeleton']).toBeUndefined();
+  });
+});

Diff for: libs/design/src/core/skeletonable/skeletonable.directive.spec.ts

@@ -0,0 +1,24 @@
+import {
+  Directive,
+  HostBinding,
+  Input,
+} from '@angular/core';
+
+/**
+ * The `DaffSkeletonableDirective` allows a component to display a skeleton loading
+ * state by conditionally applying a CSS class. This is useful for indicating to
+ * users that content is loading or being processed. This directive can be used to
+ * apply a skeleton loading state to any component by toggling the `skeleton`
+ * input property. When `skeleton` is `true`, the `daff-skeleton` CSS class
+ * is applied, which should style the component to look like a loading placeholder.
+ *
+ * The styles for the`daff-skeleton` class should be defined component's 
+ * stylesheets to display the loading state as desired.
+ */
+@Directive({
+  selector: '[daffSkeletonable]',
+  standalone: true,
+})
+export class DaffSkeletonableDirective {
+  @Input() @HostBinding('class.daff-skeleton') skeleton = false;
+}

Diff for: libs/design/src/core/skeletonable/skeletonable.directive.ts

@@ -1,6 +1,5 @@
 /**
  * An interface for giving a component the ability to display a skeleton/loading UI.
- * In order to be skeletonable, our class must implement this property.
  */
 export interface DaffSkeletonable {
   skeleton: boolean;