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/*
* Copyright (C) 2020-2022 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/>.
*/
/* global
* StringUtil
*/
/**
* A callback used when a media file has been loaded.
* @callback DisplayContentManager.OnLoadCallback
* @param {string} url The URL of the media that was loaded.
*/
/**
* A callback used when a media file should be unloaded.
* @callback DisplayContentManager.OnUnloadCallback
* @param {boolean} fullyLoaded Whether or not the media was fully loaded.
*/
/**
* The content manager which is used when generating HTML display content.
*/
class DisplayContentManager {
/**
* Creates a new instance of the class.
*/
constructor() {
this._token = {};
this._mediaCache = new Map();
this._loadMediaData = [];
}
/**
* Attempts to load the media file from a given dictionary.
* @param {string} path The path to the media file in the dictionary.
* @param {string} dictionary The name of the dictionary.
* @param {DisplayContentManager.OnLoadCallback} onLoad The callback that is executed if the media was loaded successfully.
* No assumptions should be made about the synchronicity of this callback.
* @param {DisplayContentManager.OnUnloadCallback} onUnload The callback that is executed when the media should be unloaded.
*/
loadMedia(path, dictionary, onLoad, onUnload) {
this._loadMedia(path, dictionary, onLoad, onUnload);
}
/**
* Unloads all media that has been loaded.
*/
unloadAll() {
for (const {onUnload, loaded} of this._loadMediaData) {
if (typeof onUnload === 'function') {
onUnload(loaded);
}
}
this._loadMediaData = [];
for (const map of this._mediaCache.values()) {
for (const {url} of map.values()) {
if (url !== null) {
URL.revokeObjectURL(url);
}
}
}
this._mediaCache.clear();
this._token = {};
}
async _loadMedia(path, dictionary, onLoad, onUnload) {
const token = this._token;
const data = {onUnload, loaded: false};
this._loadMediaData.push(data);
const media = await this._getMedia(path, dictionary);
if (token !== this._token) { return; }
onLoad(media.url);
data.loaded = true;
}
async _getMedia(path, dictionary) {
let cachedData;
let dictionaryCache = this._mediaCache.get(dictionary);
if (typeof dictionaryCache !== 'undefined') {
cachedData = dictionaryCache.get(path);
} else {
dictionaryCache = new Map();
this._mediaCache.set(dictionary, dictionaryCache);
}
if (typeof cachedData === 'undefined') {
cachedData = {
promise: null,
data: null,
url: null
};
dictionaryCache.set(path, cachedData);
cachedData.promise = this._getMediaData(path, dictionary, cachedData);
}
return cachedData.promise;
}
async _getMediaData(path, dictionary, cachedData) {
const token = this._token;
const data = (await yomichan.api.getMedia([{path, dictionary}]))[0];
if (token === this._token && data !== null) {
const buffer = StringUtil.base64ToArrayBuffer(data.content);
const blob = new Blob([buffer], {type: data.mediaType});
const url = URL.createObjectURL(blob);
cachedData.data = data;
cachedData.url = url;
}
return cachedData;
}
}
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