Làm thế nào để tạo custom directive?

import { Directive, ElementRef, Renderer2, HostListener } from '@angular/core';

@Directive({
  selector: '[appCustomDirective]'
})
export class CustomDirective {
  constructor(private el: ElementRef, private renderer: Renderer2) {}

  @HostListener('mouseenter') onMouseEnter() {
    this.changeBackgroundColor('yellow');
  }

  @HostListener('mouseleave') onMouseLeave() {
    this.changeBackgroundColor('white');
  }

  private changeBackgroundColor(color: string) {
    th...