/* * Copyright (C) 2021 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 used for loading and validating media during the dictionary import process. */ class DictionaryImporterMediaLoader { /** * Attempts to load an image using an ArrayBuffer and a media type to return details about it. * @param content The binary content for the image, encoded as an ArrayBuffer. * @param mediaType The media type for the image content. * @returns A Promise which resolves with {content, width, height} on success, otherwise an error is thrown. */ getImageDetails(content, mediaType, transfer) { return new Promise((resolve, reject) => { const image = new Image(); const eventListeners = new EventListenerCollection(); const cleanup = () => { image.removeAttribute('src'); URL.revokeObjectURL(url); eventListeners.removeAllEventListeners(); }; eventListeners.addEventListener(image, 'load', () => { const {naturalWidth: width, naturalHeight: height} = image; if (Array.isArray(transfer)) { transfer.push(content); } cleanup(); resolve({content, width, height}); }, false); eventListeners.addEventListener(image, 'error', () => { cleanup(); reject(new Error('Image failed to load')); }, false); const blob = new Blob([content], {type: mediaType}); const url = URL.createObjectURL(blob); image.src = url; }); } }