/* * Copyright (C) 2020 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/>. */ /** * mediaUtility is an object containing helper methods related to media processing. */ const mediaUtility = (() => { /** * Gets the file extension of a file path. URL search queries and hash * fragments are not handled. * @param path The path to the file. * @returns The file extension, including the '.', or an empty string * if there is no file extension. */ function getFileNameExtension(path) { const match = /\.[^./\\]*$/.exec(path); return match !== null ? match[0] : ''; } /** * Gets an image file's media type using a file path. * @param path The path to the file. * @returns The media type string if it can be determined from the file path, * otherwise null. */ function getImageMediaTypeFromFileName(path) { switch (getFileNameExtension(path).toLowerCase()) { case '.apng': return 'image/apng'; case '.bmp': return 'image/bmp'; case '.gif': return 'image/gif'; case '.ico': case '.cur': return 'image/x-icon'; case '.jpg': case '.jpeg': case '.jfif': case '.pjpeg': case '.pjp': return 'image/jpeg'; case '.png': return 'image/png'; case '.svg': return 'image/svg+xml'; case '.tif': case '.tiff': return 'image/tiff'; case '.webp': return 'image/webp'; default: return null; } } /** * Attempts to load an image using a base64 encoded content and a media type. * @param mediaType The media type for the image content. * @param content The binary content for the image, encoded in base64. * @returns A Promise which resolves with an HTMLImageElement instance on * successful load, otherwise an error is thrown. */ function loadImageBase64(mediaType, content) { return new Promise((resolve, reject) => { const image = new Image(); const eventListeners = new EventListenerCollection(); eventListeners.addEventListener(image, 'load', () => { eventListeners.removeAllEventListeners(); resolve(image); }, false); eventListeners.addEventListener(image, 'error', () => { eventListeners.removeAllEventListeners(); reject(new Error('Image failed to load')); }, false); image.src = `data:${mediaType};base64,${content}`; }); } return { getImageMediaTypeFromFileName, loadImageBase64 }; })();