gistfile1.txt

import { Component, OnInit, ContentChild, ElementRef, Renderer2 } from '@angular/core';

@Component({
  selector: 'app-image-loader',
  template: `<h1 *ngIf="isLoaded">LOADING</h1>
  <ng-content></ng-content>`,
  styleUrls: ['./image-loader.component.css']
})
export class ImageLoaderComponent implements OnInit {
  isLoaded = true;
  @ContentChild('my') my: ElementRef;
  constructor(private renderer: Renderer2) { }

  ngOnInit() {
    console.log(this.my);
    this.renderer.listen(this.my.nativeElement, 'load', (event) => {
      this.isLoaded = false;
        console.log(event);
    })
  }

}

<app-image-loader>
  <img #my src="https://picsum.photos/1024/683?image=1074" alt="pippo">
</app-image-loader>