Usage AttachmentImageView to smartly handle attachment images

packages/gallery/src/interface/attachmentImage.js

@@ -0,0 +1,62 @@
+import { defineElement as el } from 'domvm';
+import { prop, computed, bundle } from 'frptools';
+
+import * as imageType from '../data/image.js';
+
+export function AttachmentImageView(vm, params) {
+	const model = bundle({
+		doc: prop(params.src),
+		attachmentKey: prop(params.attachmentKey || 'image')
+	});
+
+	const blobURL = prop('');
+
+	const imageID = computed(doc => doc._id, [model.doc]);
+	const imageURL = computed((doc, key, bURL) => bURL || doc.attachmentUrls[key], [
+		model.doc,
+		model.attachmentKey,
+		blobURL
+	]);
+	const imageSignature = computed((id, key) => id + ' ' + key, [imageID, model.attachmentKey]);
+
+	async function loadImageFromBlob() {
+		const id = imageID();
+		const key = model.attachmentKey();
+
+		try {
+			const data = await imageType.getAttachment(id, key);
+			if (blobURL()) {
+				URL.revokeObjectURL(blobURL());
+			}
+			blobURL(URL.createObjectURL(data));
+		} catch (err) {
+			// Probably hasn't created the thumbnail yet.
+			console.log("Probably hasn't created the thumbnail yet.", err);
+		}
+	}
+
+	function cleanup() {
+		redrawOff();
+		URL.revokeObjectURL(blobURL());
+	}
+
+	const redrawOff = imageURL.subscribe(() => vm.redraw());
+
+	return function render(vm, params) {
+		const imgSig = imageSignature();
+		model(params);
+		if (imgSig !== imageSignature()) {
+			URL.revokeObjectURL(blobURL());
+			blobURL('');
+		}
+
+		return el('img', {
+			src: imageURL(),
+			onerror: loadImageFromBlob,
+			_key: imageSignature(),
+			_hooks: {
+				didRemove: cleanup
+			}
+		});
+	};
+}

packages/gallery/src/interface/thumbnail.js

@@ -1,12 +1,11 @@
-import { defineView, defineElement as el } from 'domvm';
+import { defineView as vw, defineElement as el } from 'domvm';
 import { prop, computed } from 'frptools';
 
 import * as image from '../data/image.js';
+import { AttachmentImageView } from './attachmentImage.js';
 
 export function ThumbnailView(vm, model) {
 	const { addTag } = model;
-	const imageData = prop(null);
-	let imageId = null;
 
 	function onAddTag(image_id) {
 		addTag(prompt('Tag Name'), image_id);
@@ -17,31 +16,17 @@ export function ThumbnailView(vm, model) {
 		const { _id: id, _rev: rev, tags } = doc;
 		const _showTags = showTags !== undefined ? showTags : true;
 		const filteredTags = _showTags ? Object.entries(doc.tags).filter(([_, visible]) => visible) : [];
-		if (imageId !== id) {
-			image
-				.getAttachment(id, 'thumbnail')
-				.then(thumbnail => {
-					if (imageData()) {
-						URL.revokeObjectURL(imageData());
-					}
-					imageData(URL.createObjectURL(thumbnail));
-					vm.redraw();
-				})
-				.catch(err => {
-					// Probably hasn't created the thumbnail yet.
-					console.log("Probably hasn't created the thumbnail yet.", err);
-					imageId = null;
-				});
-			imageId = id;
-		}
 
-		if (imageData()) {
-			return el('div', { _key: id }, [
-				el(`figure#${doc._id}.image`, [
-					el('img', {
-						src: imageData(),
-						title: `${id} ${name}`,
-						onclick: [remove, id, rev]
+		return el('div', { _key: id }, [
+			el(
+				`figure#${doc._id}.image`,
+				{
+					onclick: { img: [remove, id, rev] }
+				},
+				[
+					vw(AttachmentImageView, {
+						src: doc,
+						attachmentKey: 'thumbnail'
 					}),
 					filteredTags.length
 						? el(
@@ -51,11 +36,9 @@ export function ThumbnailView(vm, model) {
 								)
 						  )
 						: null
-				]),
-				addTag ? el('button', { onclick: [onAddTag, id] }, '+') : null
-			]);
-		}
-
-		return el('span');
+				]
+			),
+			addTag ? el('button', { onclick: [onAddTag, id] }, '+') : null
+		]);
 	};
 }