Reduced uses of Buffer

shockpkg · Sep 24, 2023 · f68b587 · f68b587
1 parent 8de04e1
commit f68b587
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Showing 3 changed files with 32 additions and 20 deletions.
diff --git a/src/icon.ts b/src/icon.ts
@@ -18,7 +18,7 @@ export abstract class Icon {
 	 * @returns Image data.
 	 */
 	protected _decodePngToRgba(data: Readonly<Buffer>) {
-		const image = UPNG.decode(data as Buffer);
+		const image = UPNG.decode(data);
 		return {
 			width: image.width,
 			height: image.height,

diff --git a/src/util.test.ts b/src/util.test.ts
@@ -11,7 +11,7 @@ void describe('util', () => {
 			// eslint-disable-next-line no-loop-func
 			void it(`${name}: ${size}`, async () => {
 				const info = pngIhdr(
-					await readFile(specIconFilePng(name, size))
+					new Uint8Array(await readFile(specIconFilePng(name, size)))
 				);
 
 				strictEqual(info.width, size);

diff --git a/src/util.ts b/src/util.ts
@@ -6,31 +6,43 @@ import {IPngIhdr} from './types';
  * @param data PNG data.
  * @returns PNG IHDR.
  */
-export function pngIhdr(data: Readonly<Buffer>): IPngIhdr {
-	if (data.toString('ascii', 0, 8) !== '\tPNG\r\n\x1a\n') {
+export function pngIhdr(data: Readonly<Uint8Array>): IPngIhdr {
+	let i = 0;
+	if (
+		data[i++] !== 137 ||
+		data[i++] !== 80 ||
+		data[i++] !== 78 ||
+		data[i++] !== 71 ||
+		data[i++] !== 13 ||
+		data[i++] !== 10 ||
+		data[i++] !== 26 ||
+		data[i++] !== 10
+	) {
 		throw new Error('Invalid PNG header signature');
 	}
 
 	// Seek out IHDR tag, which should be first (spec requires, some ignore).
-	let offset = 8;
-	while (offset < data.length) {
-		const size = data.readUInt32BE(offset);
-		offset += 4;
-		const name = data.toString('ascii', offset, offset + 4);
-		offset += 4;
-		if (name === 'IHDR') {
-			const d = data.subarray(offset, offset + size);
+	const dv = new DataView(data.buffer, data.byteOffset, data.byteLength);
+	while (i < data.length) {
+		const size = dv.getUint32(i, false);
+		i += 4;
+		const na = data[i++];
+		const nb = data[i++];
+		const nc = data[i++];
+		const nd = data[i++];
+		if (na === 73 && nb === 72 && nc === 68 && nd === 82) {
+			const d = new DataView(dv.buffer, dv.byteOffset + i, size);
 			return {
-				width: d.readUInt32BE(0),
-				height: d.readUInt32BE(4),
-				bitDepth: d.readUInt8(8),
-				colorType: d.readUInt8(9),
-				compressionMethod: d.readUInt8(10),
-				filterMethod: d.readUInt8(11),
-				interlacemethod: d.readUInt8(12)
+				width: d.getUint32(0, false),
+				height: d.getUint32(4, false),
+				bitDepth: d.getUint8(8),
+				colorType: d.getUint8(9),
+				compressionMethod: d.getUint8(10),
+				filterMethod: d.getUint8(11),
+				interlacemethod: d.getUint8(12)
 			};
 		}
-		offset += size;
+		i += size;
 	}
 
 	throw new Error('Missing PNG IHDR tag');