resolve.ts

export function imgResolver(resourceProvider: ResourceProvider) {
  const preloadImgs: string[] = ['/assets/bg_color.jpg', '/assets/bg_bw.jpg'];
  return new Promise(function (resolve) {

    const preloadImage = (img: HTMLImageElement) => console.log(img.src + ' loaded!');

    const preloadError = (err: Error) => console.log('Preload Error!' + err);

    const preloadComplete = () => setTimeout(resolve, 0);

    return resourceProvider.preloadImages(preloadImgs)
      .subscribe((img: HTMLImageElement) => preloadImage(img), (err: Error) => preloadError(err), () => preloadComplete());
  });
};