Angular 2向上和向下滑动动画

import { Component,Input,ElementRef,AfterViewInit } from '@angular/core';

@Component({
    selector: 'read-more',template: `
        <div [innerHTML]="text" [class.collapsed]="isCollapsed" [style.height]="isCollapsed ? maxHeight+'px' : 'auto'">
        </div>
            <a *ngIf="isCollapsable" (click)="isCollapsed =! isCollapsed">Read {{isCollapsed? 'more':'less'}}</a>
    `,styles: [`
        div.collapsed {
            overflow: hidden;
        }
    `]
})
export class ReadMoreComponent implements AfterViewInit {

    //the text that need to be put in the container
    @Input() text: string;

    //maximum height of the container
    @Input() maxHeight: number = 100;

    //set these to false to get the height of the expended container 
    public isCollapsed: boolean = false;
    public isCollapsable: boolean = false;

    constructor(private elementRef: ElementRef) {
    }

    ngAfterViewInit() {
        let currentHeight = this.elementRef.nativeElement.getElementsByTagName('div')[0].offsetHeight;
       //collapsable only if the contents make container exceed the max height
        if (currentHeight > this.maxHeight) {
            this.isCollapsed = true;
            this.isCollapsable = true;
        }
    }
}

使用如下：

<read-more [text]="details" [maxHeight]="250"></read-more>

该组件运作良好.现在我需要向组件添加一些向上/向下滑动动画,以便在单击“阅读更多”链接时向下滑动内容,单击“阅读更少”时,内容将向上滑动到指定的最大高度.

任何人都可以指导如何实现这一目标？