Creating a transition when changing properties in angular 2/4

问题

I want to create a transition effect whenever I change the value of a property.

I tried doing the following

    @Component({   
    selector: 'image-holder',
    template: `
        <div class="carousel-image">
            <img src="{{ image }}" [@slideInRight]="slide" />
            <span>{{ text }}</span>
        </div>
    `,
    styleUrls: ['../greenscreen.scss'],
    animations: [
        trigger(
            'slideInRight',
            [
                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}))
                ]
            )
            ])
    ]
})
export class ImageHolderComponent implements OnChanges {
    @Input()
        image: string;
    @Input()
        text: string;

    public slide: boolean = true;

    public ngOnChanges(changes: { [propKey: string]: SimpleChange }){
        this.slide = !this.slide;
    }
}

What I assumed was changing the property would trigger the component to start the animation effect again but that doesn't work as expected

回答1:

You can use *ngFor for those use cases, even if it's just a single object.

@Component({
  selector: 'image-holder',
  template: `
    <div class="carousel-image">
      <img [src]="image" *ngFor="let image of [image]" [@slideInRight]/>
      <span>{{ text }}</span>
    </div>
  `,
  styleUrls: ['../greenscreen.scss'],
  animations: [
    trigger(
      'slideInRight',
      [
        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}))
          ]
        )
      ])
  ]
})
export class ImageHolderComponent {
  @Input()
  image: string;
  @Input()
  text: string;

}

回答2:

this.slide = !this.slide would be true and false but when I look at your trigger you are saying [@slideInRight]="slide"

so basically, true or false.

but when I look in your animations I see :enter and :leave

what if instead you did 'true' and 'false' or try 1 and 0

then your animations would work when slideInRight is true or false and it would trigger the corresponding animation for true and false.

    trigger('work', [
  state('*', style({transform: 'translateX(0)', opacity: 1})),
  state('true', style({'border-right': '50px solid #72BF44', opacity: 1})),
  state('false', style({'border-right': '20px solid #72BF44', opacity: 1})),
  transition('1 => 0', animate('.125s .1s cubic-bezier(0.29, 0.06, 0.43, 0.92)')),
  transition('0 => 1', animate('.125s 0s cubic-bezier(0.29, 0.06, 0.43, 0.92)')),
  transition('void => *', [
    style({transform: 'translateX(-100%)', opacity: 0}),
    animate('1s 1.1s cubic-bezier(0.29, 0.06, 0.43, 0.92)')
  ])
])

I've included a sample trigger that I have used in a application.

you need to setup your states for on and off / true and false or whatever variable values you want (string, etc).

then you have a transition that goes from... true to false, or false to true, or void to true, whatever your previous state and current state are, that transition will trigger.

来源：https://stackoverflow.com/questions/43967392/creating-a-transition-when-changing-properties-in-angular-2-4

标签

angular

animation

web-animations