update matrix by swapping canvas buffers

Webserver/src/routes/image/+page.svelte

@@ -10,6 +10,11 @@
 	let imageURL: string | null, lastImage: File;
 	let uploadData: UploadData;
 
+	async function updateMatrix() {
+		await fetch('/api/redirect?endpoint=update');
+		clearInterval(uploadData.interval);
+	}
+
 	async function placeImage() {
 		const fdata = new FormData();
 		fdata.append('x', '0');
@@ -109,8 +114,13 @@
 				<p>Placing image . . .</p>
 				<p>{uploadData.elapsed} seconds elapsed.</p>
 			{:then}
-				<p>Done!</p>
+				{#await updateMatrix()}
-				<p>{uploadData.elapsed} seconds elapsed.</p>
+					<p>Updating matrix . . .</p>
+					<p>{uploadData.elapsed} seconds elapsed.</p>
+				{:then}
+					<p>Done!</p>
+					<p>{uploadData.elapsed} seconds elapsed.</p>
+				{/await}
 			{/await}
 		{/await}
 	{/await}