单击时来自组件的 Angular2 触发指令

Question

我有一个指令可以将框阴影添加到页面上的任何悬停元素，但我需要它在单击按钮后开始应用阴影。我遇到的问题是它只适用于单个元素。

Here is an image of the box shadow

它仅适用于我悬停后的页眉。我需要它应用于任何悬停元素。

我的app.component:

@Component({
  moduleId: module.id,
  selector: 'my-app',
  template: `
    <h1 myHighlight="orange">{{title}} {{clickedElement | async}}</h1>
    <nav>
      <a routerLink="/dashboard" routerLinkActive="active">Dashboard</a>
      <a routerLink="/heroes" routerLinkActive="active">Heroes</a>
      <a routerLink="/secret-heroes" *ngIf="authService.loggedIn()" routerLinkActive="active">Secret Heroes</a>
      <a (click)=authService.login() *ngIf="!authService.loggedIn()">Log In</a>
      <a (click)=authService.logout() *ngIf="authService.loggedIn()">Log Out</a>
      <a (click)=giveFeedback()>Give Feedback</a>
      <a (click)="listening = !listening" >Give Feedback2</a>

      <button id="modalButton" type="button" (click)="feedbackModal.show()">test</button>
      <my-feedback-modal>
      </my-feedback-modal>

    </nav>
    <router-outlet></router-outlet>
  `,
  styleUrls: ['app.component.css']
})
export class AppComponent {
  //@Input() highlight: boolean = false;
  title = 'Tour of Heroes';

  @ViewChild(ModalComponent) modal: ModalComponent;
  @ViewChild(HighlightDirective) highlightDir: HighlightDirective;

  @ViewChild(FeedbackModalComponent) feedbackModal: FeedbackModalComponent;

  constructor(private authService: AuthService, private el: ElementRef, private cdr: ChangeDetectorRef) {
    this.cdr = cdr;
  }

  clickedElement:BehaviorSubject<ElementRef> = new BehaviorSubject(this.el);

  ngAfterViewInit() {
    //this.clickedElement.next(this.highlightDir.getElement().nativeElement.nodeName);
  }

  ngDoCheck() {

  }

  giveFeedback(): void {

        this.highlightDir.startFeedback();
        this.cdr.detectChanges();
        //this.highlight = true;
  }
}

我的highlight.directive:

@Directive({
  selector: 'a, abbr, address, article, body, br, button, div, h1, h2, h3, h4, h5, h6, header, hr, i, iframe, img, ' +
  'input, label, li, link, meta, nav, object, ol, option, output, p, param, pre, section, select, small, source, span,' +
  'summary, table, tbody, td, textarea, tfoot, th, thead, time, title, tr, u, ul, video'
})
export class HighlightDirective {
    elementsArray: string[];
    listening: boolean = false;

    constructor(private el: ElementRef, private cdr: ChangeDetectorRef) {
        this.cdr = cdr;
        this.elementsArray = ["a", 'abbr', 'address', 'article', 'body', 'br', 'button', 'div', 'h1', 'h2', 'h3', 'h4', 'h5'
        , 'h6', 'header', 'hr', 'i', 'iframe', 'img', 'input', 'label', 'li', 'link', 'meta', 'nav', 'object', 'ol', 'option'
        , 'output', 'p', 'param', 'pre', 'section', 'select', 'small', 'source', 'span', 'summary', 'table', 'tbody', 'td'
        , 'textarea', 'tfoot', 'th', 'thead', 'time', 'title', 'tr', 'u', 'ul', 'video'];
    }

    //@Input() defaultColor: string;
    //@Input() listening: boolean = false;
    //check: boolean = false;

    public getElement(): ElementRef {
        return this.el;
    }

    public startFeedback(): boolean {
        this.listening = true;
        this.cdr.detectChanges();

        return true;
    }

    @HostListener('click') onClick() {
        if(this.listening) {

            document.getElementById('modalButton').click();

            this.listening = false;
        }
    }

    @HostListener('mouseenter') onMouseEnter() {
        if(this.listening) {

            this.el.nativeElement.style.boxShadow = '0 0 0 5px yellow';
            this.el.nativeElement.parentNode.style.boxShadow = null;
        }
    }

    @HostListener('mouseleave') onMouseLeave() {
        if(this.listening) {

            this.el.nativeElement.style.boxShadow = null;
            this.el.nativeElement.parentNode.style.boxShadow = '0 0 0 5px yellow';

            let check = false;

            for (let entry of this.elementsArray) {
                if (this.el.nativeElement.parentNode.nodeName == entry.toUpperCase()) {
                    check = true;
                    break;
                }
            }

          if (!check)
            this.el.nativeElement.parentNode.style.boxShadow = null;
        }
    }
}

如有任何帮助，我们将不胜感激。

Answer 1

问题是您使用 @ViewChild 而不是 @ViewChildren。使用 ViewChild 时，它仅处理可以在模板中找到的 HighlightDirective 的第一个实例。

除了你在这里做出的其他一些模糊的选择之外，我会说你必须改成这样：

@ViewChildren(HighlightDirective) highlightDirs: QueryList<HighlightDirective>;

然后您必须将 giveFeedback 函数更改为：

giveFeedback(): void {
    this.highlightDirs.forEach((highlightDir: HightlightDirective) => {
       highlightDir.startFeedback();
    });
}

您的任何代码中都不需要 changeDetectionRef。仅当您将 changeDetection: ChangeDetectionStrategy.OnPush 放在 component/directive

上时才需要这样做

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