1 files changed, 72 insertions, 0 deletions
diff --git a/ext/js/data/array-buffer-util.js b/ext/js/data/array-buffer-util.js
new file mode 100644
index 00000000..487fcd24
--- /dev/null
+++ b/ext/js/data/array-buffer-util.js
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2023-2024  Yomitan Authors
+ * Copyright (C) 2021-2022  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * Decodes the contents of an ArrayBuffer using UTF8.
+ * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+ * @returns {string} A UTF8-decoded string.
+ */
+export function arrayBufferUtf8Decode(arrayBuffer) {
+    try {
+        return new TextDecoder('utf-8').decode(arrayBuffer);
+    } catch (e) {
+        return decodeURIComponent(escape(arrayBufferToBinaryString(arrayBuffer)));
+    }
+}
+
+/**
+ * Converts the contents of an ArrayBuffer to a base64 string.
+ * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+ * @returns {string} A base64 string representing the binary content.
+ */
+export function arrayBufferToBase64(arrayBuffer) {
+    return btoa(arrayBufferToBinaryString(arrayBuffer));
+}
+
+/**
+ * Converts the contents of an ArrayBuffer to a binary string.
+ * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+ * @returns {string} A string representing the binary content.
+ */
+export function arrayBufferToBinaryString(arrayBuffer) {
+    const bytes = new Uint8Array(arrayBuffer);
+    try {
+        return String.fromCharCode(...bytes);
+    } catch (e) {
+        let binary = '';
+        for (let i = 0, ii = bytes.byteLength; i < ii; ++i) {
+            binary += String.fromCharCode(bytes[i]);
+        }
+        return binary;
+    }
+}
+
+/**
+ * Converts a base64 string to an ArrayBuffer.
+ * @param {string} content The binary content string encoded in base64.
+ * @returns {ArrayBuffer} A new `ArrayBuffer` object corresponding to the specified content.
+ */
+export function base64ToArrayBuffer(content) {
+    const binaryContent = atob(content);
+    const length = binaryContent.length;
+    const array = new Uint8Array(length);
+    for (let i = 0; i < length; ++i) {
+        array[i] = binaryContent.charCodeAt(i);
+    }
+    return array.buffer;
+}