如何在组件内部手动触发动画？

Question

在Angular 9 animations中，如何从组件本身触发动画？我假设我会在组件本身中手动执行此操作，因为它会跟踪创建图形时的状态。与使用模板表达式相反，在该模板表达式中，父级将通过数据绑定和主机属性来跟踪状态。

<div class="chart-body">
  <div *ngFor="let chart of charts | async | daysFilter:7" class="last-seven-days-body">
      <line-chart
        [curve-data]="chart"
        graph-size="med"></line-chart>
  </div>
</div>

@Component({
  selector: 'line-chart',
  templateUrl: './line-chart.component.html',
  styleUrls: ['./line-chart.component.css'],
  animations: [
    trigger('fadeIn', [
      transition('void => *', [
        style({ opacity: 0 }),
        animate(2000, style({opacity: 1}))
      ])
    ])
  ],

})

export class LineChartComponent {
  @Input('curve-data') curveData: Array<object>;
  @Input('graph-size') graphSize: String;


  constructor(
    private lineChartService: LineChartService,
    private elRef: ElementRef,
    private fadeInStart: Boolean,
  ) { }    

  ngAfterViewInit() {
    this.lineChartService.makeGraph(
      this.curveData,
      this.elRef.nativeElement,
      this.graphSize,
    );

    this.fadeInStart = true; //AFTER GRAPH IS MADE, TURN ON FADE IN ANIMATION HERE
  }     
}  

Answer 1

[而不是使用转换void => *，您可以尝试提供特定的名称/布尔值，例如false => true，并将其绑定到成员变量。尝试以下操作

line-chart.component.ts

@Component({
  selector: 'line-chart',
  templateUrl: './line-chart.component.html',
  styleUrls: ['./line-chart.component.css'],
  animations: [
    trigger('fade', [
      state('false', style({ opacity: 0 })),
      state('true', style({ opacity: 1 })),
      transition('false => true', animate('2000ms ease-in')),
      transition('true => false', animate('2000ms ease-out'))
    ]),
  ],
})
export class LineChartComponent {
  @Input('curve-data') curveData: Array<object>;
  @Input('graph-size') graphSize: String;


  constructor(
    private lineChartService: LineChartService,
    private elRef: ElementRef,
    private fadeInStart: Boolean,
  ) { }    

  ngAfterViewInit() {
    this.lineChartService.makeGraph(
      this.curveData,
      this.elRef.nativeElement,
      this.graphSize,
    );

    this.fadeInStart = true; //AFTER GRAPH IS MADE, TURN ON FADE IN ANIMATION HERE
  }     
}

line-chart.component.html

<div [@fade]="fadeInStart">
  <!-- chart -->
</div>