From 59a2d0759116e38866554b4015a76dde4c5c1ae4 Mon Sep 17 00:00:00 2001
From: JrMasterModelBuilder <legojrmastermodelbuilder@gmail.com>
Date: Sun, 24 Sep 2023 03:35:05 -0400
Subject: [PATCH] Custom optimized packbits encoder

---
 package-lock.json |  9 ---------
 package.json      |  1 -
 src/icon/icns.ts  | 12 ++----------
 src/util.ts       | 44 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+), 20 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 8948225..50a0996 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,6 @@
 			"version": "2.1.3",
 			"license": "MPL-2.0",
 			"dependencies": {
-				"@fiahfy/packbits": "0.0.6",
 				"upng-js": "^2.1.0"
 			},
 			"bin": {
@@ -1880,14 +1879,6 @@
 				"node": "^12.22.0 || ^14.17.0 || >=16.0.0"
 			}
 		},
-		"node_modules/@fiahfy/packbits": {
-			"version": "0.0.6",
-			"resolved": "https://registry.npmjs.org/@fiahfy/packbits/-/packbits-0.0.6.tgz",
-			"integrity": "sha512-XuhF/edg+iIvXjkCWgfj6fWtRi/KrEPg2ILXj1l86EN4EssuOiPcLKgkMDr9cL8jTGtVd/MKUWW6Y0/ZVf1PGA==",
-			"engines": {
-				"node": ">=8"
-			}
-		},
 		"node_modules/@humanwhocodes/config-array": {
 			"version": "0.11.11",
 			"resolved": "https://registry.npmjs.org/@humanwhocodes/config-array/-/config-array-0.11.11.tgz",
diff --git a/package.json b/package.json
index c474b1b..3539047 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,6 @@
 	"copyright": "Copyright (c) 2019-2023 JrMasterModelBuilder",
 	"license": "MPL-2.0",
 	"dependencies": {
-		"@fiahfy/packbits": "0.0.6",
 		"upng-js": "^2.1.0"
 	},
 	"devDependencies": {
diff --git a/src/icon/icns.ts b/src/icon/icns.ts
index 6549141..ab97527 100644
--- a/src/icon/icns.ts
+++ b/src/icon/icns.ts
@@ -1,8 +1,6 @@
-import {encode as packbitsEncode} from '@fiahfy/packbits';
-
 import {IImageData} from '../types';
 import {Icon} from '../icon';
-import {concatUint8Arrays} from '../util';
+import {concatUint8Arrays, packBitsIcns} from '../util';
 
 const typeArgb = ['ic04', 'ic05'];
 
@@ -343,12 +341,6 @@ export class IconIcns extends Icon {
 	 * @returns Compressed data.
 	 */
 	protected _encodePackBitsIcns(data: Readonly<Uint8Array>) {
-		const b = packbitsEncode(
-			Buffer.from(data.buffer, data.byteOffset, data.byteLength),
-			{
-				format: 'icns'
-			}
-		);
-		return new Uint8Array(b.buffer, b.byteOffset, b.byteLength);
+		return packBitsIcns(data);
 	}
 }
diff --git a/src/util.ts b/src/util.ts
index a9c1cc8..d268e46 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -67,3 +67,47 @@ export function pngIhdr(data: Readonly<Uint8Array>): IPngIhdr {
 
 	throw new Error('Missing PNG IHDR tag');
 }
+
+/**
+ * Encode data using PackBits ICNS compression.
+ *
+ * @param data Data to be compressed.
+ * @returns Compressed data.
+ */
+export function packBitsIcns(data: Readonly<Uint8Array>) {
+	const chunks = [];
+	const l = data.length;
+	for (let i = 0; i < l; ) {
+		const b = data[i];
+		if (i + 2 >= l) {
+			// Not enough left for anything but literal data.
+			chunks.push(new Uint8Array([l - i - 1]), data.subarray(i, l));
+			break;
+		}
+		if (b === data[i + 1] && b === data[i + 2]) {
+			// 3+ bytes repeat RLE.
+			i += 2;
+			let c = 3;
+			for (; ++i < l && b === data[i] && c < 130; c++);
+			chunks.push(new Uint8Array([c + 125, b]));
+		} else {
+			// Literal until next 3 bytes repeat.
+			let e = i + 2;
+			let c = 3;
+			for (let r = 1, p = data[e]; ++e < l && c < 128; c++) {
+				const b = data[e];
+				if (p !== b) {
+					p = b;
+					r = 1;
+				} else if (++r > 2) {
+					e -= 2;
+					c -= 2;
+					break;
+				}
+			}
+			chunks.push(new Uint8Array([c - 1]), data.subarray(i, e));
+			i = e;
+		}
+	}
+	return concatUint8Arrays(chunks);
+}