99 lines
3.4 KiB
JavaScript
99 lines
3.4 KiB
JavaScript
/*
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* Copyright (C) 2020 Yomichan Authors
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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/**
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* mediaUtility is an object containing helper methods related to media processing.
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*/
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const mediaUtility = (() => {
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/**
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* Gets the file extension of a file path. URL search queries and hash
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* fragments are not handled.
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* @param path The path to the file.
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* @returns The file extension, including the '.', or an empty string
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* if there is no file extension.
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*/
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function getFileNameExtension(path) {
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const match = /\.[^./\\]*$/.exec(path);
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return match !== null ? match[0] : '';
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}
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/**
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* Gets an image file's media type using a file path.
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* @param path The path to the file.
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* @returns The media type string if it can be determined from the file path,
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* otherwise null.
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*/
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function getImageMediaTypeFromFileName(path) {
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switch (getFileNameExtension(path).toLowerCase()) {
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case '.apng':
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return 'image/apng';
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case '.bmp':
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return 'image/bmp';
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case '.gif':
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return 'image/gif';
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case '.ico':
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case '.cur':
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return 'image/x-icon';
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case '.jpg':
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case '.jpeg':
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case '.jfif':
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case '.pjpeg':
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case '.pjp':
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return 'image/jpeg';
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case '.png':
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return 'image/png';
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case '.svg':
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return 'image/svg+xml';
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case '.tif':
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case '.tiff':
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return 'image/tiff';
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case '.webp':
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return 'image/webp';
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default:
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return null;
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}
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}
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/**
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* Attempts to load an image using a base64 encoded content and a media type.
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* @param mediaType The media type for the image content.
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* @param content The binary content for the image, encoded in base64.
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* @returns A Promise which resolves with an HTMLImageElement instance on
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* successful load, otherwise an error is thrown.
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*/
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function loadImageBase64(mediaType, content) {
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return new Promise((resolve, reject) => {
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const image = new Image();
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const eventListeners = new EventListenerCollection();
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eventListeners.addEventListener(image, 'load', () => {
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eventListeners.removeAllEventListeners();
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resolve(image);
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}, false);
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eventListeners.addEventListener(image, 'error', () => {
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eventListeners.removeAllEventListeners();
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reject(new Error('Image failed to load'));
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}, false);
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image.src = `data:${mediaType};base64,${content}`;
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});
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}
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return {
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getImageMediaTypeFromFileName,
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loadImageBase64
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};
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})();
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