问如何在angular中通过标题按钮隐藏/显示

EN

@Injectable()
export class GlobalDataService {
  private showNavigationBar = new Subject<boolean>();

  constructor() {

  }

  public getNavigationbarState(): Observable<boolean> {
    return this.showNavigationBar.asObservable();
  }

  public setNavigationbarState(value: boolean) {
    return this.showNavigationBar.next(notification);
  }
}

constructor(private globalDatServce:GlobalDataService) {

}

public onButtonClick(): void {
  this.globalDataService.setNavigationbarState(true); // pass true or false as needed
}

constructor(private globalDatServce:GlobalDataService) {
   this.globalDatServce.getNavigationbarState().subscribe((res) => {
     this.shownavigation = res;
   });
}

<div *ngIf="shownavigation">
  // navigation content goes here
</div>

//in header
<div *ngIf="shownavigation">....</div>

constructor(private globalDataService:GlobalDataService){}
get shownavigationn()
{
   return this.globalDataService.shownavigation
}

//In component
<button (click)="click()">Click me!</button>

constructor(private globalDataService:GlobalDataService){}
set shownavigationn(value)
{
   this.globalDataService.shownavigation=value
}
click()
{
    this.showNavigation=!this.showNavigation
}