Dictionary worker refactor (#1894)

* Rename dictionary worker files

* Rename classes

* Rename file

* Rename class

* Generalize the _invoke method

* Rename 'import' to 'importDictionary'

* Improve DictionaryImporterMediaLoader usage

* Refactor message handler

* Generalize onProgress event

1 files changed, 65 insertions, 0 deletions

diff --git a/ext/js/language/dictionary-worker-media-loader.js b/ext/js/language/dictionary-worker-media-loader.js
new file mode 100644
index 00000000..90ee513f
--- /dev/null
+++ b/ext/js/language/dictionary-worker-media-loader.js
@@ -0,0 +1,65 @@
+/*
+ * 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 from a worker thread
+ * during the dictionary import process.
+ */
+class DictionaryWorkerMediaLoader {
+    /**
+     * Creates a new instance of the media loader.
+     */
+    constructor() {
+        this._requests = new Map();
+    }
+
+    /**
+     * Handles a response message posted to the worker thread.
+     * @param params Details of the response.
+     */
+    handleMessage(params) {
+        const {id} = params;
+        const request = this._requests.get(id);
+        if (typeof request === 'undefined') { return; }
+        this._requests.delete(id);
+        const {error} = params;
+        if (typeof error !== 'undefined') {
+            request.reject(deserializeError(error));
+        } else {
+            request.resolve(params.result);
+        }
+    }
+
+    /**
+     * Attempts to load an image using a base64 encoded content and a media type
+     * and returns its resolution.
+     * @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 {width, height} on success,
+     *   otherwise an error is thrown.
+     */
+    getImageResolution(mediaType, content) {
+        return new Promise((resolve, reject) => {
+            const id = generateId(16);
+            this._requests.set(id, {resolve, reject});
+            self.postMessage({
+                action: 'getImageResolution',
+                params: {id, mediaType, content}
+            });
+        });
+    }
+}