From 2325de6979771781c05bc09e738f1a866c72f22d Mon Sep 17 00:00:00 2001
From: Manfred Hantschel <manfred.hantschel@gmail.com>
Date: Mon, 31 Aug 2026 15:04:48 +0200
Subject: [PATCH] Add Old Palette Chunk 0x0004

Sometimes Aseprite is still using the very old palette chunk (0x0004),
e.g. when creating an indexed file with C64 palette (no transparency).

As stated by the specs: Aseprite v1.3.5 writes this chunk if the palette
doesn't have alpha channel and contains 256 colors or less (because
this chunk is smaller)

This commit adds support for the chunk.

fixes #24
---
 Aseprite.js | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/Aseprite.js b/Aseprite.js
index c4f40a5..c5e84bb 100644
--- a/Aseprite.js
+++ b/Aseprite.js
@@ -308,10 +308,17 @@ class Aseprite {
     this.skipBytes(2);
     const newChunk = this.readNextDWord();
     let cels = [];
+    let hasNewPaletteChunk = false;
     for(let i = 0; i < newChunk; i ++) {
       let chunkData = this.readChunk();
       switch(chunkData.type) {
         case 0x0004:
+          if (!hasNewPaletteChunk) {
+            this.palette = this.readOldPaletteChunk();
+          } else {
+            this.skipBytes(chunkData.chunkSize - 6);
+          }
+          break;
         case 0x0011:
         case 0x2016:
         case 0x2017:
@@ -335,6 +342,7 @@ class Aseprite {
           this.readFrameTagsChunk();
           break;
         case 0x2019:
+          hasNewPaletteChunk = true;
           this.palette = this.readPaletteChunk();
           break;
         case 0x2023:
@@ -444,6 +452,42 @@ class Aseprite {
     return palette;
   }
 
+  /**
+   * Reads the old Palette Chunk and stores the information
+   * Old Palette Chunk is type 0x0004
+   *
+   * @returns {Palette}
+   */
+  readOldPaletteChunk() {
+    const packetCount = this.readNextWord();
+    const colors = [];
+    let colorIndex = 0;
+
+    for (let i = 0; i < packetCount; i++) {
+      colorIndex += this.readNextByte();
+      const colorCount = this.readNextByte() || 256;
+
+      for (let j = 0; j < colorCount; j++) {
+        colors[colorIndex++] = {
+          red: this.readNextByte(),
+          green: this.readNextByte(),
+          blue: this.readNextByte(),
+          alpha: 255,
+          name: 'none'
+        };
+      }
+    }
+
+    const palette = {
+      paletteSize: colors.length,
+      firstColor: 0,
+      lastColor: colors.length - 1,
+      colors
+    };
+    this.colorDepth === 8 ? palette.index = this.paletteIndex : '';
+    return palette;
+  }
+
   /**
    * Reads the Tileset Chunk and stores the information
    * Tileset Chunk is type 0x2023