yomichan/ext/js/data/sandbox/array-buffer-util.js

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/*
* 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/>.
*/
/**
* Class containing generic ArrayBuffer utility functions.
*/
class ArrayBufferUtil {
/**
* Decodes the contents of an ArrayBuffer using UTF8.
* @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
* @returns {string} A UTF8-decoded string.
*/
static arrayBufferUtf8Decode(arrayBuffer) {
try {
return new TextDecoder('utf-8').decode(arrayBuffer);
} catch (e) {
return decodeURIComponent(escape(this.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.
*/
static arrayBufferToBase64(arrayBuffer) {
return btoa(this.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.
*/
static 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.
*/
static 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;
}
}