Implemented async barcode generation using async helpers

ref #13

src/asyncHelpers.ts

@@ -0,0 +1,32 @@
+import AsyncHelpers from "async-helpers";
+import bwipjs from "bwip-js";
+
+export const asyncHelpers = new AsyncHelpers();
+async function generateBarcode(str, options, emtpy, cb) {
+    let res = await generateBase64Barcode(options.toString(), str.toString());
+    cb(null, res);
+}
+generateBarcode.async = true;
+asyncHelpers.set('--bc', generateBarcode);
+export const helpers = asyncHelpers.get({ wrap: true });
+
+export async function generateBase64Barcode(type: string, content: string): Promise<String> {
+    let barcode: Buffer = await bwipjs.toBuffer({
+        bcid: type,
+        text: content,
+        scale: 3,
+        height: 10,
+        includetext: true,
+        textxalign: 'center',
+    });
+    return `data:image/png;base64,${barcode.toString('base64')}`;
+}
+
+export async function awaitAsyncHandlebarHelpers(input: string): Promise<string> {
+    return await new Promise((resolve, reject) => {
+        asyncHelpers.resolveIds(input, (err, data) => {
+            if (err) { reject(err) }
+            resolve(data)
+        });
+    });
+}