feat(Base64): fromArrayBuffer impl

- Updates XMLWriter to use Base64 module

Author: floryst

Sources/Common/Core/Base64/index.d.ts

@@ -4,7 +4,19 @@
 
 /**
  * Convert a Base64 string to an ArrayBuffer.
- * @param {string} b64Str 
+ * @param {string} b64Str
  * @return An ArrayBuffer object.
  */
-export default function toArrayBuffer(b64Str: string): ArrayBuffer;
+export function toArrayBuffer(b64Str: string): ArrayBuffer;
+
+/**
+ * Convert a Base64 string to an ArrayBuffer.
+ * @param {string} b64Str
+ * @return An ArrayBuffer object.
+ */
+export function fromArrayBuffer(ab: ArrayBuffer): string;
+
+export default {
+  toArrayBuffer,
+  fromArrayBuffer,
+};

Sources/Common/Core/Base64/index.js

@@ -119,7 +119,7 @@ function writeChunk(b64Str, chunk, dstOffset, uint8) {
   return offset;
 }
 
-function toArrayBuffer(b64Str) {
+export function toArrayBuffer(b64Str) {
   const chunks = extractChunks(b64Str);
   const totalEncodedLength = chunks[chunks.length - 1].end + 1;
   const padding = (4 - (totalEncodedLength % 4)) % 4; // -length mod 4
@@ -138,6 +138,45 @@ function toArrayBuffer(b64Str) {
   return arrayBuffer;
 }
 
+function encodeTriplet(v1, v2, v3) {
+  const triplet = (v1 << 16) + (v2 << 8) + v3;
+  return (
+    BASE64_CODE[triplet >> 18] +
+    BASE64_CODE[(triplet >> 12) & 0x3f] +
+    BASE64_CODE[(triplet >> 6) & 0x3f] +
+    BASE64_CODE[triplet & 0x3f]
+  );
+}
+
+export function fromArrayBuffer(ab) {
+  const uint8 = new Uint8Array(ab);
+  const leftoverLength = ab.byteLength % 3;
+  const maxTripletIndex = ab.byteLength - leftoverLength;
+  const segments = Array(maxTripletIndex / 3);
+  for (let i = 0; i < segments.length; i++) {
+    const bufOffset = i * 3;
+    segments[i] = encodeTriplet(
+      uint8[bufOffset],
+      uint8[bufOffset + 1],
+      uint8[bufOffset + 2]
+    );
+  }
+  if (leftoverLength > 0) {
+    const segment = encodeTriplet(
+      uint8[maxTripletIndex],
+      uint8[maxTripletIndex + 1] || 0,
+      uint8[maxTripletIndex + 2] || 0
+    );
+    if (leftoverLength === 1) {
+      segments.push(`${segment.substr(0, 2)}==`);
+    } else if (leftoverLength === 2) {
+      segments.push(`${segment.substr(0, 3)}=`);
+    }
+  }
+  return segments.join('');
+}
+
 export default {
   toArrayBuffer,
+  fromArrayBuffer,
 };

Sources/IO/XML/XMLWriter/index.js

@@ -1,8 +1,8 @@
 import { create } from 'xmlbuilder2';
-import { fromByteArray } from 'base64-js';
 import pako from 'pako';
 
 import macro from 'vtk.js/Sources/macros';
+import { fromArrayBuffer } from 'vtk.js/Sources/Common/Core/Base64';
 import {
   FormatTypes,
   TYPED_ARRAY,
@@ -75,7 +75,9 @@ function processDataArray(
         uint8.set(blocks[blockId], uint8Offset);
         uint8Offset += header[3 + blockId];
       }
-      return fromByteArray(headerUint8) + fromByteArray(uint8);
+      return (
+        fromArrayBuffer(headerUint8.buffer) + fromArrayBuffer(uint8.buffer)
+      );
     }
     throw new Error('Only vtkZLibDataCompressor is supported');
   }

package-lock.json

@@ -31,7 +31,6 @@
   "module": "./dist/esm/index.js",
   "dependencies": {
     "@babel/runtime": "7.15.4",
-    "base64-js": "1.5.1",
     "blueimp-md5": "2.18.0",
     "commander": "8.2.0",
     "d3-scale": "4.0.0",