Toot toot, it's the refactor tractor

- Introduces the concept of a "BarcodeHandler"
- Re-uses most of the code
- Custom handlers for barcode success / failure

lib/widget/dialogs.dart

@@ -9,6 +9,28 @@ void showMessage(BuildContext context, String message) {
   ));
 }
 
+Future<void> showInfoDialog(BuildContext context, String title, String description, {IconData icon = FontAwesomeIcons.info, String info = "Info", Function onDismissed}) async {
+  showDialog(
+    context: context,
+    child: SimpleDialog(
+      title: ListTile(
+        title: Text(info),
+        leading: FaIcon(icon),
+      ),
+      children: <Widget>[
+        ListTile(
+          title: Text(title),
+          subtitle: Text(description)
+        )
+      ]
+    )
+  ).then((value) {
+    if (onDismissed != null) {
+      onDismissed();
+    }
+  });
+}
+
 Future<void> showErrorDialog(BuildContext context, String title, String description, {IconData icon = FontAwesomeIcons.exclamationCircle, String error = "Error", Function onDismissed}) async {
   showDialog(
     context: context,

lib/widget/stock_detail.dart

@@ -1,5 +1,6 @@
 
 
+import 'package:InvenTree/barcode.dart';
 import 'package:InvenTree/inventree/stock.dart';
 import 'package:InvenTree/inventree/part.dart';
 import 'package:InvenTree/widget/dialogs.dart';
@@ -374,9 +375,22 @@ class _StockItemDisplayState extends RefreshableState<StockDetailWidget> {
             trailing: Text("${item.quantity}"),
           )
       );
-
     }
 
+    tiles.add(
+      ListTile(
+        title: Text("Add Barcode"),
+        leading: FaIcon(FontAwesomeIcons.qrcode),
+        onTap: () {
+          Navigator.push(
+            context,
+            MaterialPageRoute(builder: (context) => InvenTreeQRView(StockItemBarcodeAssignmentHandler(item)))  
+          );
+          //Navigator.push(context, MaterialPageRoute(builder: (context) => AssignBarcodeToStockItemView(item)));
+        },
+      )
+    );
+
     // Location information
     if ((item.locationId > 0) && (item.locationName != null) && (item.locationName.isNotEmpty)) {
       tiles.add(