angular 2 ngIf and CSS transition/animation

问题

I want a div to slide in from the right in angular 2 using css.

  <div class=\"note\" [ngClass]=\"{\'transition\':show}\" *ngIf=\"show\">
    <p> Notes</p>
  </div>
  <button class=\"btn btn-default\" (click)=\"toggle(show)\">Toggle</button>

I works fine if i only use [ngClass] to toggle class and utilise opacity. But li don\'t want that element to be rendered from the beginning so I \"hide\" it with ngIf first, but then the transition wont\'t work.

.transition{
  -webkit-transition: opacity 1000ms ease-in-out,margin-left 500ms ease-in-out;
  -moz-transition: opacity 1000ms ease-in-out,margin-left 500ms ease-in-out;
  -ms-transition: opacity 1000ms ease-in-out,margin-left 500ms ease-in-out ;
  -o-transition: opacity 1000ms ease-in-out,margin-left 500ms ease-in-out;
  transition: opacity 1000ms ease-in-out,margin-left 500ms ease-in-out;
  margin-left: 1500px;
  width: 200px;
  opacity: 0;
}

.transition{
  opacity: 100;
  margin-left: 0;
}

回答1:

update 4.1.0

Plunker

See also https://github.com/angular/angular/blob/master/CHANGELOG.md#400-rc1-2017-02-24

update 2.1.0

Plunker

For more details see Animations at angular.io

import { trigger, style, animate, transition } from '@angular/animations';

@Component({
  selector: 'my-app',
  animations: [
    trigger(
      'enterAnimation', [
        transition(':enter', [
          style({transform: 'translateX(100%)', opacity: 0}),
          animate('500ms', style({transform: 'translateX(0)', opacity: 1}))
        ]),
        transition(':leave', [
          style({transform: 'translateX(0)', opacity: 1}),
          animate('500ms', style({transform: 'translateX(100%)', opacity: 0}))
        ])
      ]
    )
  ],
  template: `
    <button (click)="show = !show">toggle show ({{show}})</button>

    <div *ngIf="show" [@enterAnimation]>xxx</div>
  `
})
export class App {
  show:boolean = false;
}

original

*ngIf removes the element from the DOM when the expression becomes false. You can't have a transition on a non-existing element.

Use instead hidden:

<div class="note" [ngClass]="{'transition':show}" [hidden]="!show">

回答2:

According to the latest angular 2 documentation you can animate "Entering and Leaving" elements (like in angular 1).

Example of simple fade animation:

In relevant @Component add:

animations: [
  trigger('fadeInOut', [
    transition(':enter', [   // :enter is alias to 'void => *'
      style({opacity:0}),
      animate(500, style({opacity:1})) 
    ]),
    transition(':leave', [   // :leave is alias to '* => void'
      animate(500, style({opacity:0})) 
    ])
  ])
]

Do not forget to add imports

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

The relevant component's html's element should look like:

<div *ngIf="toggle" [@fadeInOut]>element</div>

I built example of slide and fade animation here.

Explanation on 'void' and '*':

void is the state when ngIf is set to false (it applies when the element is not attached to a view).
* - There can be many animation states (read more in docs). The * state takes precedence over all of them as a "wildcard" (in my example this is the state when ngIf is set to true).

Notice (taken from angular docs):

Extra declare inside the app module, import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

Angular animations are built on top of the standard Web Animations API and run natively on browsers that support it. For other browsers, a polyfill is required. Grab web-animations.min.js from GitHub and add it to your page.

回答3:

    trigger('slideIn', [
      state('*', style({ 'overflow-y': 'hidden' })),
      state('void', style({ 'overflow-y': 'hidden' })),
      transition('* => void', [
        style({ height: '*' }),
        animate(250, style({ height: 0 }))
      ]),
      transition('void => *', [
        style({ height: '0' }),
        animate(250, style({ height: '*' }))
      ])
    ])

回答4:

CSS only solution for modern browsers

@keyframes slidein {
    0%   {margin-left:1500px;}
    100% {margin-left:0px;}
}
.note {
    animation-name: slidein;
    animation-duration: .9s;
    display: block;
}

回答5:

Am using angular 5 and for an ngif to work for me that is in a ngfor, I had to use animateChild and in the user-detail component I used the *ngIf="user.expanded" to show hide user and it worked for entering a leaving

 <div *ngFor="let user of users" @flyInParent>
  <ly-user-detail [user]= "user" @flyIn></user-detail>
</div>

//the animation file


export const FLIP_TRANSITION = [ 
trigger('flyInParent', [
    transition(':enter, :leave', [
      query('@*', animateChild())
    ])
  ]),
  trigger('flyIn', [
    state('void', style({width: '100%', height: '100%'})),
    state('*', style({width: '100%', height: '100%'})),
    transition(':enter', [
      style({
        transform: 'translateY(100%)',
        position: 'fixed'
      }),
      animate('0.5s cubic-bezier(0.35, 0, 0.25, 1)', style({transform: 'translateY(0%)'}))
    ]),
    transition(':leave', [
      style({
        transform: 'translateY(0%)',
        position: 'fixed'
      }),
      animate('0.5s cubic-bezier(0.35, 0, 0.25, 1)', style({transform: 'translateY(100%)'}))
    ])
  ])
];

回答6:

One way is to use a setter for the ngIf property and set the state as part of updating the value.

StackBlitz example

fade.component.ts

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

  export type FadeState = 'visible' | 'hidden';

  @Component({
    selector: 'app-fade',
    templateUrl: './fade.component.html',
    styleUrls: ['./fade.component.scss'],
    animations: [
      trigger('state', [
        state(
          'visible',
          style({
            opacity: '1'
          })
        ),
        state(
          'hidden',
          style({
            opacity: '0'
          })
        ),
        transition('* => visible', [animate('500ms ease-out')]),
        transition('visible => hidden', [animate('500ms ease-out')])
      ])
    ],
    changeDetection: ChangeDetectionStrategy.OnPush
  })
  export class FadeComponent {
    state: FadeState;
    // tslint:disable-next-line: variable-name
    private _show: boolean;
    get show() {
      return this._show;
    }
    @Input()
    set show(value: boolean) {
      if (value) {
        this._show = value;
        this.state = 'visible';
      } else {
        this.state = 'hidden';
      }
    }

    animationDone(event: AnimationEvent) {
      if (event.fromState === 'visible' && event.toState === 'hidden') {
        this._show = false;
      }
    }
  }

fade.component.html

 <div
    *ngIf="show"
    class="fade"
    [@state]="state"
    (@state.done)="animationDone($event)"
  >
    <button mat-raised-button color="primary">test</button>
  </div>

example.component.css

:host {
  display: block;
}
.fade {
  opacity: 0;
}

回答7:

In my case I declared the animation on the wrong component by mistake.

app.component.html

  <app-order-details *ngIf="orderDetails" [@fadeInOut] [orderDetails]="orderDetails">
  </app-order-details>

The animation needs to be declared on the component where the element is used in (appComponent.ts). I was declaring the animation on OrderDetailsComponent.ts instead.

Hopefully it will help someone making the same mistake

来源：https://stackoverflow.com/questions/36417931/angular-2-ngif-and-css-transition-animation

标签

css

angular

angular-animations