暂停角度动画

Question

是否可以在 Angular 2+ 中暂停动画？我想在将鼠标悬停在元素上时暂停动画，并在鼠标移出时从停止的地方恢复动画。

我创建了一个简单的脚本来演示：https://stackblitz.com/edit/scrolling-text

这是我的组件：

import { Component, ElementRef, ViewChild } from '@angular/core';
import { trigger, state, style, animate, transition } from '@angular/animations';

@Component({
  selector: 'my-app',
  template: `
    <div class="container">
      <div class="scrolling-text" [@scroll]="state" (@scroll.done)="scrollDone()">Hover to pause!</div>
    </div>
  `,
  styles: [`
    .container {
      height: 30px;
      overflow: hidden;
      position: relative;
      width: 100%;
    }

    .scrolling-text {
      position: absolute;
      white-space: nowrap;
    }

    /* Below doesn't work to pause */

    .scrolling-text:hover, .container:hover {
      -moz-animation-play-state: paused;
      -webkit-animation-play-state: paused;
      animation-play-state: paused;
    }
  `],
  animations: [
    trigger('scroll', [
      state('on', style({left: '-100px'})),
      transition('* => *', [
        style({left: '-100px'}),
        animate(10000, style({left: '100%'}))
      ])
    ])
  ]
})
export class AppComponent  {
  state = 0;

  scrollDone() {
    this.state++;
  }

}

我试过animation-play-state: paused; 没有运气：

.scrolling-text:hover, .container:hover {
  -moz-animation-play-state: paused;
  -webkit-animation-play-state: paused;
  animation-play-state: paused;
}

有什么方法可以让它工作吗？

Answer 1

我找到了使用AnimationBuilder 的方法。

import { Component, ElementRef, ViewChild } from '@angular/core';
import { style, animate, AnimationBuilder, AnimationPlayer } from '@angular/animations';

@Component({
selector: 'my-app',
template: `
  <div class="container" (mouseover)="player.pause()" (mouseout)="player.play()">
    <div #el class="scrolling-text">Hover to pause!</div>
  </div>
`,
styles: [`
  .container {
    height: 30px;
    overflow: hidden;
    position: relative;
    width: 100%;
  }

  .scrolling-text {
    position: absolute;
    white-space: nowrap;
  }
`]
})
export class AppComponent  {

  @ViewChild('el') el: ElementRef;

  private factory = this.builder.build([
    style({left: '-100px'}),
    animate(10000, style({left: '100%'}))
  ]);
  private player;

  constructor(private builder: AnimationBuilder) { }

  ngOnInit() {
    this.player = this.factory.create(this.el.nativeElement, {});
    this.animate();
  }

  private animate() {
    this.player.reset();

    this.player.onDone(() => {
      this.animate();
    });

    this.player.play();
  }

}

Live Demo

Answer 2

虽然不是最好的解决方案。 自从

this.player = this.factory.create(this.el.nativeElement, {}); 

在 RendererAnimationPlayer 中创建另一个 WebAnimationsPlayer 实例

您可以通过以下方式自行检查：

 console.log(this.player._renderer.engine.players.length);

当然，在您的情况下，这并不重要，但仍然如此。 当您尝试在诸如 mousemove 事件中重用动画时，这就会发挥作用。然后 Angular 最多可以创建 1000 个玩家。并溢出内存。

如果您想重用动画以提高内存效率，您应该重用现有播放器。

或致电

 if (this.player) {
      this.player.destroy();
 }

之前

this.player = this.factory.create(this.el.nativeElement, {});