Angular2 Height Animation - Same State Transition

Angular Animation For Dynamically Changing Height

I've written a component that smoothly animates the height of projected content if that content changes.
It's used like this:

<smooth-height [trigger]="content">
  {{content}}
</smooth-height>

Here's a stackblitz: https://stackblitz.com/edit/angular4-kugxw7

This is the component:

import {ElementRef, HostBinding, Component, Input, OnChanges} from '@angular/core';
import {animate, style, transition, trigger} from "@angular/animations";

@Component({
  selector: 'smooth-height',
  template: `
    <ng-content></ng-content>
  `,
  styles: [`
    :host {
      display: block;
      overflow: hidden;
    }
  `],
  animations: [
    trigger('grow', [
      transition('void <=> *', []),
      transition('* <=> *', [
        style({height: '{{startHeight}}px', opacity: 0}),
        animate('.5s ease'),
      ], {params: {startHeight: 0}})
    ])
  ]
})
export class SmoothHeightComponent implements OnChanges {
  @Input()
  trigger: any;

  startHeight: number;

  @HostBinding('@grow') grow: any;

  constructor(private element: ElementRef) {}  
              
  ngOnChanges(){
    this.startHeight = this.element.nativeElement.clientHeight;

    this.grow = {
      value: this.trigger,
      params: {startHeight: this.startHeight}
    };
  }
}

Angular 2/4 Animation on div height

You don't have any states defined in your trigger() function.

trigger creates a named animation trigger, containing a list of state() and transition() entries to be evaluated when the expression bound to the trigger changes (the expression being [@slideInOut]="helpMenu" in example below).

@Component({
  ...
  animations: [
    trigger('slideInOut', [
      state('in', style({
        overflow: 'hidden',
        height: '*',
        width: '300px'
      })),
      state('out', style({
        opacity: '0',
        overflow: 'hidden',
        height: '0px',
        width: '0px'
      })),
      transition('in => out', animate('400ms ease-in-out')),
      transition('out => in', animate('400ms ease-in-out'))
    ])
  ]
})
export class AComponent implements OnInit {

  helpMenu: string;

  constructor() { }

  ngOnInit() {
    this.helpMenu = 'out';
  }

  toggleHelpMenu(): void {
    this.helpMenu = this.helpMenu === 'out' ? 'in' : 'out';
  }

}

Then use it in your view like this:

<div [@slideInOut]="helpMenu">
   <h1>My Title</h1>
   <p>My paragraph</p>
</div>
<button (click)="toggleHelpMenu()">help</button>

How to animate :enter & :leave transitions conditionally in Angular?

According to Angular IO:

When true, the special animation control binding @.disabled binding prevents all animations from rendering. Place the @.disabled binding on an element to disable animations on the element itself, as well as any inner animation triggers within the element.

The following example shows how to use this feature:

@Component({
    selector: 'my-component',
    template: `
    <div [@.disabled]="isDisabled">
        <div [@childAnimation]="exp"></div>
    </div>
    `,
    animations: [
        trigger("childAnimation", [
            // ...
        ])
    ]
})
class MyComponent {
      isDisabled = true;
  exp = '...';
}

When @.disabled is true, it prevents the @childAnimation trigger from animating, along with any inner animations.

angular 2 ngIf and CSS transition/animation

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">

Angular2. Animating left to right movement

The solution I came up with: instead of right use calculated left value:

    state('true', style({
        left: 'calc(100% - 200px - 10px)',
    })),
    state('false', style({
        left: '10px',
    })),

plunker

Get height of an element in Angular 2

This should work AFAIK.

 height: '*'

Just checked. It works !

You can read more here : https://angular.io/docs/ts/latest/guide/animations.html#!#automatic-property-calculation

Angular Animation Performance State/Transition vs Query

Angular uses the web animations api, so it's not changing style properties through JavaScript and is therefore quite performant. You can check the performance of different animation frameworks (javascript-based) vs CSS with the HTML 5 Animation Speed Test.

The performance in different browsers is therefore dependent on the browser compatibility of the web animations api (unfortunately the section is not being maintained yet). But, according to the comment here, it is not fully supported yet across common browsers and is being polyfilled for Edge/Safari.

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