fix(web): profile image load (#2434)

web/src/lib/utils/image-load.ts

@@ -0,0 +1,38 @@
+import { tick } from 'svelte';
+import type { ActionReturn } from 'svelte/action';
+
+interface Attributes {
+	'on:image-error'?: (e: CustomEvent) => void;
+	'on:image-load'?: (e: CustomEvent) => void;
+}
+
+export function imageLoad(img: HTMLImageElement): ActionReturn<void, Attributes> {
+	const onImageError = () => img.dispatchEvent(new CustomEvent('image-error'));
+	const onImageLoaded = () => img.dispatchEvent(new CustomEvent('image-load'));
+
+	if (img.complete) {
+		// Browser has fetched the image, naturalHeight is used to check
+		// if any loading errors have occurred.
+		const loadingError = img.naturalHeight === 0;
+
+		// Report status after a tick, to make sure event listeners are registered.
+		if (loadingError) {
+			tick().then(onImageError);
+		} else {
+			tick().then(onImageLoaded);
+		}
+
+		return {};
+	}
+
+	// Image has not been loaded yet, report status with event listeners.
+	img.addEventListener('load', onImageLoaded, { once: true });
+	img.addEventListener('error', onImageError, { once: true });
+
+	return {
+		destroy() {
+			img.removeEventListener('load', onImageLoaded);
+			img.removeEventListener('error', onImageError);
+		}
+	};
+}