Angular 2 animate *ngFor list item one after other using new Animation support in RC 5

问题

I have a component that fetches list of items from server and then display that list using *ngFor in template.

I want the list to be displayed with some animation, but one after other. I mean each list item should animate in after other.

I am trying something like this:

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

@Component({
    selector: 'list-item',
    template: ` <li  @flyInOut="'in'">{{item}}</li>`,
    animations: [
        trigger('flyInOut', [
            state('in', style({ transform: 'translateX(0)' })),
            transition('void => *', [
                style({ transform: 'translateX(-100%)' }),
                animate(100)
            ]),
            transition('* => void', [
                animate(100, style({ transform: 'translateX(100%)' }))
            ])
        ])
    ]
})
export class ListItemComponent {
    @Input() item: any;
}

and in my list component template I am using it like:

<ul>
    <li *ngFor="let item of list;">
     <list-item [item]="item"></list-item>
    </li>
</ul>

What it does is displays whole list at once. I want items to enter one by one with some animation.

回答1:

I couldn't find stagger support on ngFor in the documentation, but there's now animation.done events, which can be used to make staggering ngFor

see@PLUNKER

@Component({
  selector: 'my-app',
  template: `
    <ul>
    <li *ngFor="let hero of staggeringHeroes; let i = index"
        (@flyInOut.done)="doNext()"
        [@flyInOut]="'in'" (click)="removeMe(i)">
      {{hero}}
    </li>
  </ul>
  `,
  animations: [
  trigger('flyInOut', [
    state('in', style({transform: 'translateX(0)'})),
    transition('void => *', [
      animate(300, keyframes([
        style({opacity: 0, transform: 'translateX(-100%)', offset: 0}),
        style({opacity: 1, transform: 'translateX(15px)',  offset: 0.3}),
        style({opacity: 1, transform: 'translateX(0)',     offset: 1.0})
      ]))
    ]),
    transition('* => void', [
      animate(300, keyframes([
        style({opacity: 1, transform: 'translateX(0)',     offset: 0}),
        style({opacity: 1, transform: 'translateX(-15px)', offset: 0.7}),
        style({opacity: 0, transform: 'translateX(100%)',  offset: 1.0})
      ]))
    ])
  ])
]
})
export class App {
  heroes: any[] = ['Alpha', 'Bravo', 'Charlie', 'Delta', 'Echo', 'Foxtrot', 'Golf', 'Hotel', 'India'];

  next: number = 0;
  staggeringHeroes: any[] = [];

  constructor(){
    this.doNext();
  }

  doNext() {
    if(this.next < this.heroes.length) {
      this.staggeringHeroes.push(this.heroes[this.next++]);
    }
  }

  removeMe(i) {
    this.staggeringHeroes.splice(i, 1);
  }
}

回答2:

To use the angular2 animations I set a state property to the iterated item and then just setup a toggle function for the mouseover and mouseout functions. This way each item encapsulated it's animated state and then I could change it as needed

<li
   *ngFor="let item of itemsList"
   (mouseover)="toogleAnimation(item)"
   (mouseout)="toogleAnimation(item)"
>{{ item.name }}
  <div class="animation_wrapper" [@slideInOut]="item.state">
    <span class="glyphicon glyphicon-refresh"></span>
    <span class="glyphicon glyphicon-trash"></span>
  </div>
</li>

回答3:

what you want, of the time between each item in the list, see this code. change the file .css to .scss

like this https://codepen.io/jhenriquez856/pen/baPagq

$total-items: 5;

body {
  font-family: sans-serif;
  background: #111;
  color: #fff;
}

ul {
  width: 300px;
  left: 50%;
  margin-top: 25px;
  margin-left: -150px;
  
  position: absolute;
}

li {
  position: relative;
  display: block;
  border: 1px solid hotpink;
  margin-bottom: 5px;
  padding: 10px;
  text-align: center;
  text-transform: uppercase;
  animation: fadeIn 0.5s linear;
  animation-fill-mode: both;
}

// Set delay per List Item
@for $i from 1 through $total-items {
  li:nth-child(#{$i}) {
    animation-delay: .25s * $i;
  }
}

// Keyframe animation
@-webkit-keyframes fadeIn {
  0% {
    opacity: 0;
  }
  75% {
    opacity: 0.5;
  }
  100% {
    opacity: 1;
  }
}

<ul>
  <li>item 1</li>
  <li>item 2</li>
  <li>item 3</li>
  <li>item 4</li>
  <li>item 5</li>
</ul>

来源：https://stackoverflow.com/questions/38085837/angular-2-animate-ngfor-list-item-one-after-other-using-new-animation-support-i