How to dynamically set animation speed in Angular 2?

Question

JavaScript

I'm using TypeScript and Angular 2.4
I have a directive to scroll long text (something like a marquee tag).
It takes a "speed" parameter which describes the scrolling speed (pixels per second).
This allows you to maintain the same speed for any length of text.
Angular 2 has the ability to describe the animation in the @Component decorator, but you can't refer to the component's methods.
In order to convert it to normal speed in seconds, I need to know the length of the element itself.
Component code:

import {Component, Input, ElementRef, trigger, state, style, transition, animate} from '@angular/core';
import * as $ from 'jquery';

const SCROLL_SPEED_DEFAULT = 25;

@Component({
  selector: 'text-scroll',
  template: '<span><ng-content></ng-content></span>',
  animations: [
    trigger('hover', [
      state('idle', style({transformX: '0'})),
      state('scrolled', style({transformX: '-100%'})),
      transition('idle => scrolled', [
        animate(this.getAnimationSpeed())
      ])
    ])
  ]
})
export class TextScrollComponent {
  @Input('speed') speedTime: number = SCROLL_SPEED_DEFAULT;
  private element: HTMLElement;

  constructor(private el: ElementRef) {
    this.element = this.el.nativeElement;
  }
  
  public getAnimationSpeed(): number {
    let element = this.element;
    let elementWidth = $(element).width();
    let difference = this.el.nativeElement.scrollWidth - elementWidth;

    return (difference / Number(this.speedTime)) * 1000;
  }
}

Directive usage:

<text-scroll>My very <b>loooong..</b> text</text-scroll>