Add dishworker

src/web/workers/DishWorker.mjs

@@ -0,0 +1,69 @@
+/**
+ * Web worker to handle dish conversion operations.
+ *
+ * @author j433866 [j433866@gmail.com]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Dish from "../../core/Dish";
+
+self.addEventListener("message", function(e) {
+    // Handle message from the main thread
+    const r = e.data;
+    log.debug(`DishWorker receiving command '${r.action}'`);
+
+    switch (r.action) {
+        case "getDishAs":
+            getDishAs(r.data);
+            break;
+        case "getDishTitle":
+            getDishTitle(r.data);
+            break;
+        default:
+            log.error(`DishWorker sent invalid action: '${r.action}'`);
+    }
+});
+
+/**
+ * Translates the dish to a given type
+ *
+ * @param {object} data
+ * @param {Dish} data.dish
+ * @param {string} data.type
+ * @param {number} data.id
+ */
+async function getDishAs(data) {
+    const newDish = new Dish(data.dish),
+        value = await newDish.get(data.type),
+        transferable = (data.type === "ArrayBuffer") ? [value] : undefined;
+
+    self.postMessage({
+        action: "dishReturned",
+        data: {
+            value: value,
+            id: data.id
+        }
+    }, transferable);
+}
+
+/**
+ * Gets the title of the given dish
+ *
+ * @param {object} data
+ * @param {Dish} data.dish
+ * @param {number} data.id
+ * @param {number} data.maxLength
+ */
+async function getDishTitle(data) {
+    const newDish = new Dish(data.dish),
+        title = await newDish.getTitle(data.maxLength);
+
+    self.postMessage({
+        action: "dishReturned",
+        data: {
+            value: title,
+            id: data.id
+        }
+    });
+}