Cleanup webp import code a bit.

web/scripts/pnginfo.js

@@ -108,37 +108,33 @@ export function getWebpMetadata(file) {
 	return new Promise((r) => {
 		const reader = new FileReader();
 		reader.onload = (event) => {
-			// Get the PNG data as a Uint8Array
-			const pngData = new Uint8Array(event.target.result);
-			const dataView = new DataView(pngData.buffer);
+			const webp = new Uint8Array(event.target.result);
+			const dataView = new DataView(webp.buffer);
 
-			// Check that the PNG signature is present
+			// Check that the WEBP signature is present
 			if (dataView.getUint32(0) !== 0x52494646 || dataView.getUint32(8) !== 0x57454250) {
 				console.error("Not a valid WEBP file");
 				r();
 				return;
 			}
 
-			// Start searching for chunks after the PNG signature
+			// Start searching for chunks after the WEBP signature
 			let offset = 12;
 			let txt_chunks = {};
-			// Loop through the chunks in the PNG file
-			while (offset < pngData.length) {
-				// Get the length of the chunk
-				const length = dataView.getUint32(offset + 4, true);
-				// Get the chunk type
-				const type = String.fromCharCode(...pngData.slice(offset, offset + 4));
-				if (type === "EXIF") {
-					// Get the keyword
-					let data = parseExifData(pngData.slice(offset + 8, offset + 8 + length));
+			// Loop through the chunks in the WEBP file
+			while (offset < webp.length) {
+				const chunk_length = dataView.getUint32(offset + 4, true);
+				const chunk_type = String.fromCharCode(...webp.slice(offset, offset + 4));
+				if (chunk_type === "EXIF") {
+					let data = parseExifData(webp.slice(offset + 8, offset + 8 + chunk_length));
 					for (var key in data) {
 						var value = data[key];
 						let index = value.indexOf(':');
 						txt_chunks[value.slice(0, index)] = value.slice(index + 1);
 					}
 				}
 
-				offset += 8 + length;
+				offset += 8 + chunk_length;
 			}
 
 			r(txt_chunks);