Replace png encode dependency with optimized CRC32 calculation

src/png/encode.js

@@ -0,0 +1,68 @@
+import { crc32 } from 'crc';
+
+/**
+ * Encodes PNG chunks into a PNG file format buffer.
+ * @param {Array<{ name: string; data: Uint8Array }>} chunks Array of PNG chunks
+ * @returns {Uint8Array} Encoded PNG data
+ * @copyright Based on https://github.com/hughsk/png-chunks-encode (MIT)
+ */
+export default function encode(chunks) {
+    const uint8 = new Uint8Array(4);
+    const int32 = new Int32Array(uint8.buffer);
+    const uint32 = new Uint32Array(uint8.buffer);
+
+    let totalSize = 8;
+    let idx = totalSize;
+
+    for (let i = 0; i < chunks.length; i++) {
+        totalSize += chunks[i].data.length;
+        totalSize += 12;
+    }
+
+    const output = new Uint8Array(totalSize);
+
+    output[0] = 0x89;
+    output[1] = 0x50;
+    output[2] = 0x4E;
+    output[3] = 0x47;
+    output[4] = 0x0D;
+    output[5] = 0x0A;
+    output[6] = 0x1A;
+    output[7] = 0x0A;
+
+    for (let i = 0; i < chunks.length; i++) {
+        const { name, data } = chunks[i];
+        const size = data.length;
+        const nameChars = [
+            name.charCodeAt(0),
+            name.charCodeAt(1),
+            name.charCodeAt(2),
+            name.charCodeAt(3),
+        ];
+
+        uint32[0] = size;
+        output[idx++] = uint8[3];
+        output[idx++] = uint8[2];
+        output[idx++] = uint8[1];
+        output[idx++] = uint8[0];
+
+        output[idx++] = nameChars[0];
+        output[idx++] = nameChars[1];
+        output[idx++] = nameChars[2];
+        output[idx++] = nameChars[3];
+
+        for (let j = 0; j < size;) {
+            output[idx++] = data[j++];
+        }
+
+        const crc = crc32(data, crc32(new Uint8Array(nameChars)));
+
+        int32[0] = crc;
+        output[idx++] = uint8[3];
+        output[idx++] = uint8[2];
+        output[idx++] = uint8[1];
+        output[idx++] = uint8[0];
+    }
+
+    return output;
+}