Barcode refactor (#363)

* Move barcode.dart

* Fix

* Refactoring barcode scanner code:

- Abstract the "controller" class (for future development)
- Break barcode scanning code out into multiple files
- Add CameraBarcodeController class (qr_code_scanner)

* Add await

* Make barcode scan delay configurable

* remove unused import

* Handle camera exceptions

* Improve sequencing for camera scanner

- Show loading overlay
- Prevent reload if view is no longer mounted

* Update docstring

* Update release notes

assets/release_notes.md

@@ -1,3 +1,9 @@
+### -
+---
+- Improvements to barcode scanning
+- Translation updates
+
+
 ### 0.12.1 - May 2023
 
 - Fixes bug in purchase order form

lib/api_form.dart

@@ -9,7 +9,8 @@ import "package:flutter/material.dart";
 
 import "package:inventree/api.dart";
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
+import "package:inventree/barcode/tones.dart";
 import "package:inventree/helpers.dart";
 import "package:inventree/l10.dart";
 
@@ -349,7 +350,7 @@ class APIFormField {
 
             Navigator.push(
               context,
-              MaterialPageRoute(builder: (context) => InvenTreeQRView(handler)
+              MaterialPageRoute(builder: (context) => barcodeController(handler)
               )
             );
           },

lib/barcode/barcode.dart

@@ -1,155 +1,42 @@
-import "dart:io";
 import "package:flutter/material.dart";
+
 import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:font_awesome_flutter/font_awesome_flutter.dart";
-import "package:inventree/inventree/purchase_order.dart";
-import "package:inventree/widget/purchase_order_detail.dart";
 import "package:one_context/one_context.dart";
-import "package:qr_code_scanner/qr_code_scanner.dart";
+
 
 import "package:inventree/api.dart";
 import "package:inventree/helpers.dart";
 import "package:inventree/l10.dart";
-import "package:inventree/preferences.dart";
+
+import "package:inventree/barcode/camera_controller.dart";
+import "package:inventree/barcode/controller.dart";
+import "package:inventree/barcode/handler.dart";
+import "package:inventree/barcode/tones.dart";
 
 import "package:inventree/inventree/company.dart";
 import "package:inventree/inventree/part.dart";
-import "package:inventree/inventree/sentry.dart";
+import "package:inventree/inventree/purchase_order.dart";
 import "package:inventree/inventree/stock.dart";
 
-import "package:inventree/widget/refreshable_state.dart";
-import "package:inventree/widget/supplier_part_detail.dart";
 import "package:inventree/widget/dialogs.dart";
-import "package:inventree/widget/snacks.dart";
 import "package:inventree/widget/location_display.dart";
 import "package:inventree/widget/part_detail.dart";
+import "package:inventree/widget/purchase_order_detail.dart";
+import "package:inventree/widget/refreshable_state.dart";
+import "package:inventree/widget/snacks.dart";
 import "package:inventree/widget/stock_detail.dart";
+import "package:inventree/widget/supplier_part_detail.dart";
 
 
 /*
- * Play an audible 'success' alert to the user.
+ * Return a new BarcodeController instance
  */
-Future<void> barcodeSuccessTone() async {
-
-  final bool en = await InvenTreeSettingsManager().getValue(INV_SOUNDS_BARCODE, true) as bool;
-
-  if (en) {
-    playAudioFile("sounds/barcode_scan.mp3");
-  }
+InvenTreeBarcodeController barcodeController(BarcodeHandler handler) {
+  // TODO: Make this configurable
+  return CameraBarcodeController(handler);
 }
 
-Future <void> barcodeFailureTone() async {
-
-  final bool en = await InvenTreeSettingsManager().getValue(INV_SOUNDS_BARCODE, true) as bool;
-
-  if (en) {
-    playAudioFile("sounds/barcode_error.mp3");
-  }
-}
-
-
-/* Generic class which "handles" a barcode, by communicating with the InvenTree server,
- * and handling match / unknown / error cases.
- *
- * Override functionality of this class to perform custom actions,
- * based on the response returned from the InvenTree server
- */
-class BarcodeHandler {
-
-  BarcodeHandler();
-
-  String getOverlayText(BuildContext context) => "Barcode Overlay";
-
-    Future<void> onBarcodeMatched(Map<String, dynamic> data) async {
-      // Called when the server "matches" a barcode
-      // Override this function
-    }
-
-    Future<void> onBarcodeUnknown(Map<String, dynamic> data) async {
-      // Called when the server does not know about a barcode
-      // Override this function
-
-      barcodeFailureTone();
-
-      showSnackIcon(
-        L10().barcodeNoMatch,
-        success: false,
-        icon: Icons.qr_code,
-      );
-    }
-
-  // Called when the server returns an unhandled response
-  Future<void> onBarcodeUnhandled(Map<String, dynamic> data) async {
-      barcodeFailureTone();
-      showServerError("barcode/", L10().responseUnknown, data.toString());
-    }
-
-    /*
-     * Base function to capture and process barcode data.
-     *
-     * Returns true only if the barcode scanner should remain open
-     */
-    Future<void> processBarcode(QRViewController? _controller, String barcode, {String url = "barcode/"}) async {
-
-      debug("Scanned barcode data: '${barcode}'");
-
-      barcode = barcode.trim();
-
-      // Empty barcode is invalid
-      if (barcode.isEmpty) {
-
-        barcodeFailureTone();
-
-        showSnackIcon(
-          L10().barcodeError,
-          icon: FontAwesomeIcons.circleExclamation,
-          success: false
-        );
-
-        return;
-      }
-
-      var response = await InvenTreeAPI().post(
-          url,
-          body: {
-            "barcode": barcode,
-          },
-          expectedStatusCode: null,  // Do not show an error on "unexpected code"
-      );
-
-      debug("Barcode scan response" + response.data.toString());
-
-      Map<String, dynamic> data = response.asMap();
-
-      // Handle strange response from the server
-      if (!response.isValid() || !response.isMap()) {
-        onBarcodeUnknown({});
-
-        showSnackIcon(L10().serverError, success: false);
-
-        // We want to know about this one!
-        await sentryReportMessage(
-            "BarcodeHandler.processBarcode returned unexpected value",
-            context: {
-              "data": response.data?.toString() ?? "null",
-              "barcode": barcode,
-              "url": url,
-              "statusCode": response.statusCode.toString(),
-              "valid": response.isValid().toString(),
-              "error": response.error,
-              "errorDetail": response.errorDetail,
-              "className": "${this}",
-            }
-        );
-      } else if (data.containsKey("success")) {
-        await onBarcodeMatched(data);
-      } else if ((response.statusCode >= 400) || data.containsKey("error")) {
-        await onBarcodeUnknown(data);
-      } else {
-        await onBarcodeUnhandled(data);
-      }
-    }
-}
 
 /*
  * Class for general barcode scanning.
@@ -638,168 +525,8 @@ class UniqueBarcodeHandler extends BarcodeHandler {
 }
 
 
-class InvenTreeQRView extends StatefulWidget {
-
-  const InvenTreeQRView(this._handler, {Key? key}) : super(key: key);
-
-  final BarcodeHandler _handler;
-
-  @override
-  State<StatefulWidget> createState() => _QRViewState();
-}
-
-
-class _QRViewState extends State<InvenTreeQRView> {
-
-  _QRViewState() : super();
-
-  final GlobalKey qrKey = GlobalKey(debugLabel: "QR");
-
-  QRViewController? _controller;
-
-  bool flash_status = false;
-
-  bool currently_processing = false;
-
-  Future<void> updateFlashStatus() async {
-    final bool? status = await _controller?.getFlashStatus();
-
-    flash_status = status != null && status;
-
-    // Reload
-    if (mounted) {
-      setState(() {});
-    }
-  }
-
-  // In order to get hot reload to work we need to pause the camera if the platform
-  // is android, or resume the camera if the platform is iOS.
-  @override
-  void reassemble() {
-    super.reassemble();
-
-    if (mounted) {
-      if (Platform.isAndroid) {
-        _controller!.pauseCamera();
-      }
-
-      _controller!.resumeCamera();
-    }
-  }
-
-  /* Callback function when the Barcode scanner view is initially created */
-  void _onViewCreated(BuildContext context, QRViewController controller) {
-    _controller = controller;
-
-    controller.scannedDataStream.listen((barcode) {
-      handleBarcode(barcode.code);
-    });
-  }
-
-  /* Handle scanned data */
-  Future<void> handleBarcode(String? data) async {
-
-    // Empty or missing data, or we have navigated away
-    if (!mounted || data == null || data.isEmpty) {
-      return;
-    }
-
-    // Currently processing a barcode - return!
-    if (currently_processing) {
-      return;
-    }
-
-    setState(() {
-      currently_processing = true;
-    });
-
-    // Pause camera functionality until we are done processing
-    _controller?.pauseCamera();
-
-    // processBarcode returns true if the scanner window is to remain open
-    widget._handler.processBarcode(_controller, data).then((value) {
-      // Re-start the process after some delay
-      Future.delayed(Duration(milliseconds: 500)).then((value) {
-        if (mounted) {
-          _controller?.resumeCamera();
-          currently_processing = false;
-        }
-      });
-    });
-  }
-
-  @override
-  void dispose() {
-    _controller?.dispose();
-    super.dispose();
-  }
-
-  @override
-  Widget build(BuildContext context) {
-
-    return Scaffold(
-        appBar: AppBar(
-          title: Text(L10().scanBarcode),
-          actions: [
-            IconButton(
-              icon: Icon(Icons.flip_camera_android),
-              onPressed: () {
-                _controller?.flipCamera();
-              }
-            ),
-            IconButton(
-              icon: flash_status ? Icon(Icons.flash_off) : Icon(Icons.flash_on),
-              onPressed: () {
-                _controller?.toggleFlash();
-                updateFlashStatus();
-              },
-            )
-          ],
-        ),
-        body: Stack(
-          children: <Widget>[
-            Column(
-              children: [
-                Expanded(
-                  child: QRView(
-                    key: qrKey,
-                    onQRViewCreated: (QRViewController controller) {
-                      _onViewCreated(context, controller);
-                    },
-                    overlay: QrScannerOverlayShape(
-                      borderColor: Colors.red,
-                      borderRadius: 10,
-                      borderLength: 30,
-                      borderWidth: 10,
-                      cutOutSize: 300,
-                    ),
-                  )
-                )
-              ]
-            ),
-            Center(
-                child: Column(
-                    children: [
-                      Spacer(),
-                      Padding(
-                        child: Text(widget._handler.getOverlayText(context),
-                          style: TextStyle(
-                              fontWeight: FontWeight.bold,
-                              color: Colors.white),
-                        ),
-                        padding: EdgeInsets.all(20),
-                      ),
-                    ]
-                )
-            )
-          ],
-        )
-    );
-  }
-}
-
 Future<void> scanQrCode(BuildContext context) async {
-  Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeQRView(BarcodeScanHandler())));
+  Navigator.push(context, MaterialPageRoute(builder: (context) => barcodeController(BarcodeScanHandler())));
 
   return;
 }
@@ -829,7 +556,7 @@ SpeedDialChild customBarcodeAction(BuildContext context, RefreshableState state,
         Navigator.push(
             context,
             MaterialPageRoute(
-                builder: (context) => InvenTreeQRView(handler)
+                builder: (context) => barcodeController(handler)
             )
         );
       }

lib/barcode/camera_controller.dart

@@ -0,0 +1,154 @@
+import "dart:io";
+import "package:flutter/material.dart";
+
+import "package:qr_code_scanner/qr_code_scanner.dart";
+
+import "package:inventree/l10.dart";
+
+import "package:inventree/barcode/handler.dart";
+import "package:inventree/barcode/controller.dart";
+
+/*
+ * Barcode controller which uses the device's camera to scan barcodes.
+ * Under the hood it uses the qr_code_scanner package.
+ */
+class CameraBarcodeController extends InvenTreeBarcodeController {
+
+  const CameraBarcodeController(BarcodeHandler handler, {Key? key}) : super(handler, key: key);
+
+  @override
+  State<StatefulWidget> createState() => _CameraBarcodeControllerState();
+
+}
+
+
+class _CameraBarcodeControllerState extends InvenTreeBarcodeControllerState {
+
+  _CameraBarcodeControllerState() : super();
+
+  QRViewController? _controller;
+
+  bool flash_status = false;
+
+  /* Callback function when the Barcode scanner view is initially created */
+  void _onViewCreated(BuildContext context, QRViewController controller) {
+    _controller = controller;
+
+    controller.scannedDataStream.listen((barcode) {
+      handleBarcodeData(barcode.code);
+    });
+  }
+
+  // In order to get hot reload to work we need to pause the camera if the platform
+  // is android, or resume the camera if the platform is iOS.
+  @override
+  void reassemble() {
+    super.reassemble();
+
+    if (mounted) {
+      if (Platform.isAndroid) {
+        _controller!.pauseCamera();
+      }
+
+      _controller!.resumeCamera();
+    }
+  }
+
+  @override
+  void dispose() {
+    _controller?.dispose();
+    super.dispose();
+  }
+
+  @override
+  Future<void> pauseScan() async {
+    try {
+      await _controller?.pauseCamera();
+    } on CameraException {
+      // do nothing
+    }
+  }
+
+  @override
+  Future<void> resumeScan() async {
+    try {
+      await _controller?.resumeCamera();
+    } on CameraException {
+      // do nothing
+    }
+  }
+
+  // Toggle the status of the camera flash
+  Future<void> updateFlashStatus() async {
+    final bool? status = await _controller?.getFlashStatus();
+
+    if (mounted) {
+      setState(() {
+        flash_status = status != null && status;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+
+    return Scaffold(
+        appBar: AppBar(
+          title: Text(L10().scanBarcode),
+          actions: [
+            IconButton(
+              icon: Icon(Icons.flip_camera_android),
+              onPressed: () {
+                _controller?.flipCamera();
+              }
+            ),
+            IconButton(
+              icon: flash_status ? Icon(Icons.flash_off) : Icon(Icons.flash_on),
+              onPressed: () {
+                _controller?.toggleFlash();
+                updateFlashStatus();
+              },
+            )
+          ],
+        ),
+        body: Stack(
+          children: <Widget>[
+            Column(
+              children: [
+                Expanded(
+                  child: QRView(
+                    key: barcodeControllerKey,
+                    onQRViewCreated: (QRViewController controller) {
+                      _onViewCreated(context, controller);
+                    },
+                    overlay: QrScannerOverlayShape(
+                      borderColor: Colors.red,
+                      borderRadius: 10,
+                      borderLength: 30,
+                      borderWidth: 10,
+                      cutOutSize: 300,
+                    ),
+                  )
+                )
+              ]
+            ),
+            Center(
+                child: Column(
+                    children: [
+                      Spacer(),
+                      Padding(
+                        child: Text(widget.handler.getOverlayText(context),
+                          style: TextStyle(
+                              fontWeight: FontWeight.bold,
+                              color: Colors.white),
+                        ),
+                        padding: EdgeInsets.all(20),
+                      ),
+                    ]
+                )
+            )
+          ],
+        )
+    );
+  }
+}

lib/barcode/controller.dart

@@ -0,0 +1,108 @@
+import "package:flutter/material.dart";
+import "package:one_context/one_context.dart";
+
+import "package:inventree/preferences.dart";
+
+import "package:inventree/barcode/handler.dart";
+
+import "package:inventree/widget/progress.dart";
+
+/*
+ * Generic class which provides a barcode scanner interface.
+ * 
+ * When the controller is instantiated, it is passed a "handler" class,
+ * which is used to process the scanned barcode.
+ */
+class InvenTreeBarcodeController extends StatefulWidget {
+
+  const InvenTreeBarcodeController(this.handler, {Key? key}) : super(key: key);
+
+  final BarcodeHandler handler;
+
+  @override
+  State<StatefulWidget> createState() => InvenTreeBarcodeControllerState();
+}
+
+
+/*
+ * Base state widget for the barcode controller.
+ * This defines the basic interface for the barcode controller.
+ */
+class InvenTreeBarcodeControllerState extends State<InvenTreeBarcodeController> {
+
+  InvenTreeBarcodeControllerState() : super();
+
+  final GlobalKey barcodeControllerKey = GlobalKey(debugLabel: "barcodeController");
+
+  // Internal state flag to test if we are currently processing a barcode
+  bool processingBarcode = false;
+
+  /*
+   * Method to handle scanned data.
+   * Any implementing class should call this method when a barcode is scanned.
+   * Barcode data should be passed as a string
+   */
+  Future<void> handleBarcodeData(String? data) async {
+    
+    // Check that the data is valid, and this view is still mounted
+    if (!mounted || data == null || data.isEmpty) {
+      return;
+    }
+
+    // Currently processing a barcode - ignore this one
+    if (processingBarcode) {
+      return;
+    }
+
+    setState(() {
+      processingBarcode = true;
+    });
+
+    BuildContext? context = OneContext().context;
+
+    showLoadingOverlay(context!);
+    await pauseScan();
+
+    await widget.handler.processBarcode(data);
+
+    // processBarcode may have popped the context
+    if (!mounted) {
+      hideLoadingOverlay();
+      return;
+    }
+
+    int delay = await InvenTreeSettingsManager().getValue(INV_BARCODE_SCAN_DELAY, 500) as int;
+
+    Future.delayed(Duration(milliseconds: delay), () {
+      hideLoadingOverlay();
+      if (mounted) {
+        resumeScan().then((_) {
+          if (mounted) {
+            setState(() {
+              processingBarcode = false;
+            });
+          }
+        });
+      }
+    });
+  }
+
+  // Hook function to "pause" the barcode scanner
+  Future<void> pauseScan() async {
+    // Implement this function in subclass
+  }
+
+  // Hook function to "resume" the barcode scanner
+  Future<void> resumeScan() async {
+    // Implement this function in subclass
+  }
+
+  /*
+   * Implementing classes are in control of building out the widget
+   */
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+
+}

lib/barcode/handler.dart

@@ -0,0 +1,121 @@
+
+import "package:flutter/material.dart";
+
+import "package:font_awesome_flutter/font_awesome_flutter.dart";
+
+import "package:inventree/api.dart";
+import "package:inventree/helpers.dart";
+import "package:inventree/l10.dart";
+
+import "package:inventree/barcode/tones.dart";
+
+import "package:inventree/inventree/sentry.dart";
+
+import "package:inventree/widget/dialogs.dart";
+import "package:inventree/widget/snacks.dart";
+
+
+/* Generic class which "handles" a barcode, by communicating with the InvenTree server,
+ * and handling match / unknown / error cases.
+ *
+ * Override functionality of this class to perform custom actions,
+ * based on the response returned from the InvenTree server
+ */
+class BarcodeHandler {
+
+  BarcodeHandler();
+
+  // Return the text to display on the barcode overlay
+  // Note: Will be overridden by child classes
+  String getOverlayText(BuildContext context) => "Barcode Overlay";
+
+  // Called when the server "matches" a barcode
+  Future<void> onBarcodeMatched(Map<String, dynamic> data) async {
+    // Override this function
+  }
+
+  // Called when the server does not know about a barcode
+  Future<void> onBarcodeUnknown(Map<String, dynamic> data) async {
+    // Override this function
+
+    barcodeFailureTone();
+
+    showSnackIcon(
+      L10().barcodeNoMatch,
+      success: false,
+      icon: Icons.qr_code,
+    );
+  }
+
+  // Called when the server returns an unhandled response
+  Future<void> onBarcodeUnhandled(Map<String, dynamic> data) async {
+    barcodeFailureTone();
+    showServerError("barcode/", L10().responseUnknown, data.toString());
+  }
+
+  /*
+    * Base function to capture and process barcode data.
+    *
+    * Returns true only if the barcode scanner should remain open
+    */
+  Future<void> processBarcode(String barcode, {String url = "barcode/"}) async {
+
+    debug("Scanned barcode data: '${barcode}'");
+
+    barcode = barcode.trim();
+
+    // Empty barcode is invalid
+    if (barcode.isEmpty) {
+
+      barcodeFailureTone();
+
+      showSnackIcon(
+        L10().barcodeError,
+        icon: FontAwesomeIcons.circleExclamation,
+        success: false
+      );
+
+      return;
+    }
+
+    var response = await InvenTreeAPI().post(
+        url,
+        body: {
+          "barcode": barcode,
+        },
+        expectedStatusCode: null,  // Do not show an error on "unexpected code"
+    );
+
+    debug("Barcode scan response" + response.data.toString());
+
+    Map<String, dynamic> data = response.asMap();
+
+    // Handle strange response from the server
+    if (!response.isValid() || !response.isMap()) {
+      onBarcodeUnknown({});
+
+      showSnackIcon(L10().serverError, success: false);
+
+      // We want to know about this one!
+      await sentryReportMessage(
+          "BarcodeHandler.processBarcode returned unexpected value",
+          context: {
+            "data": response.data?.toString() ?? "null",
+            "barcode": barcode,
+            "url": url,
+            "statusCode": response.statusCode.toString(),
+            "valid": response.isValid().toString(),
+            "error": response.error,
+            "errorDetail": response.errorDetail,
+            "className": "${this}",
+          }
+      );
+    } else if (data.containsKey("success")) {
+      await onBarcodeMatched(data);
+    } else if ((response.statusCode >= 400) || data.containsKey("error")) {
+      await onBarcodeUnknown(data);
+    } else {
+      await onBarcodeUnhandled(data);
+    }
+  }
+}

lib/barcode/tones.dart

@@ -0,0 +1,23 @@
+import "package:inventree/helpers.dart";
+import "package:inventree/preferences.dart";
+
+/*
+ * Play an audible 'success' alert to the user.
+ */
+Future<void> barcodeSuccessTone() async {
+
+  final bool en = await InvenTreeSettingsManager().getValue(INV_SOUNDS_BARCODE, true) as bool;
+
+  if (en) {
+    playAudioFile("sounds/barcode_scan.mp3");
+  }
+}
+
+Future <void> barcodeFailureTone() async {
+
+  final bool en = await InvenTreeSettingsManager().getValue(INV_SOUNDS_BARCODE, true) as bool;
+
+  if (en) {
+    playAudioFile("sounds/barcode_error.mp3");
+  }
+}

lib/l10n/app_en.arb

@@ -79,6 +79,12 @@
   "availableStock": "Available Stock",
   "@availableStock": {},
 
+  "barcodes": "Barcodes",
+  "@barcodes": {},
+
+  "barcodeSettings": "Barcode Settings",
+  "@barcodeSettings": {},
+
   "barcodeAssign": "Assign Barcode",
   "@barcodeAssign": {},
 
@@ -106,6 +112,12 @@
   "barcodeScanAssign": "Scan to assign barcode",
   "@barcodeScanAssign": {},
 
+  "barcodeScanDelay": "Barcode Scan Delay",
+  "@barcodeScanDelay": {},
+
+  "barcodeScanDelayDetail": "Delay between barcode scans",
+  "@barcodeScanDelayDetail": {},
+
   "barcodeScanGeneral":  "Scan an InvenTree barcode",
   "@barcodeScanGeneral": {},
 

lib/preferences.dart

@@ -29,6 +29,9 @@ const String INV_STOCK_SHOW_TESTS = "stockShowTests";
 const String INV_REPORT_ERRORS = "reportErrors";
 const String INV_STRICT_HTTPS = "strictHttps";
 
+// Barcode settings
+const String INV_BARCODE_SCAN_DELAY = "barcodeScanDelay";
+
 /*
  * Class for storing InvenTree preferences in a NoSql DB
  */

lib/settings/barcode_settings.dart

@@ -0,0 +1,114 @@
+import "package:flutter/material.dart";
+import "package:font_awesome_flutter/font_awesome_flutter.dart";
+import "package:inventree/l10.dart";
+import "package:inventree/preferences.dart";
+
+
+class InvenTreeBarcodeSettingsWidget extends StatefulWidget {
+  @override
+  _InvenTreeBarcodeSettingsState createState() => _InvenTreeBarcodeSettingsState();
+}
+
+
+class _InvenTreeBarcodeSettingsState extends State<InvenTreeBarcodeSettingsWidget> {
+
+ _InvenTreeBarcodeSettingsState();
+
+ int barcodeScanDelay = 500;
+
+ final TextEditingController _barcodeScanDelayController = TextEditingController();
+
+ @override
+ void initState() {
+  super.initState();
+  loadSettings();
+ }
+
+  Future<void> loadSettings() async {
+    barcodeScanDelay = await InvenTreeSettingsManager().getValue(INV_BARCODE_SCAN_DELAY, 500) as int;
+
+    if (mounted) {
+      setState(() {
+      });
+    }
+  }
+
+  // Callback function to edit the barcode scan delay value
+  // TODO: Next time any new settings are added, refactor this into a generic function
+  Future<void> _editBarcodeScanDelay(BuildContext context) async {
+
+    _barcodeScanDelayController.text = barcodeScanDelay.toString();
+
+    return showDialog(
+      context: context,
+      builder: (context) {
+        return AlertDialog(
+          title: Text(L10().barcodeScanDelay),
+          content: TextField(
+            onChanged: (value) {},
+            controller: _barcodeScanDelayController,
+            keyboardType: TextInputType.number,
+            decoration: InputDecoration(
+              hintText: L10().barcodeScanDelayDetail,
+            ),
+          ),
+          actions: <Widget>[
+            MaterialButton(
+              color: Colors.red,
+              textColor: Colors.white,
+              child: Text(L10().cancel),
+              onPressed: () {
+                setState(() {
+                  Navigator.pop(context);
+                });
+              },
+            ),
+            MaterialButton(
+              color: Colors.green,
+              textColor: Colors.white,
+              child: Text(L10().ok),
+              onPressed: () async {
+                int delay = int.tryParse(_barcodeScanDelayController.text) ?? barcodeScanDelay;
+
+                // Apply limits
+                if (delay < 100) delay = 100;
+                if (delay > 2500) delay = 2500;
+
+                InvenTreeSettingsManager().setValue(INV_BARCODE_SCAN_DELAY, delay);
+                setState(() {
+                  barcodeScanDelay = delay;
+                  Navigator.pop(context);
+                });
+              },
+            ),
+          ],
+        );
+      }
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: Text(L10().barcodes)),
+      body: Container(
+        child: ListView(
+          children: [
+            ListTile(
+              title: Text(L10().barcodeScanDelay),
+              subtitle: Text(L10().barcodeScanDelayDetail),
+              leading: FaIcon(FontAwesomeIcons.stopwatch),
+              trailing: GestureDetector(
+                child: Text("${barcodeScanDelay} ms"),
+                onTap: () {
+                  _editBarcodeScanDelay(context);
+                },
+              ),
+            )
+          ],
+        )
+      )
+    );
+  }
+
+}

lib/settings/settings.dart

@@ -4,8 +4,10 @@ import "package:package_info_plus/package_info_plus.dart";
 
 import "package:inventree/app_colors.dart";
 import "package:inventree/l10.dart";
+
 import "package:inventree/settings/about.dart";
 import "package:inventree/settings/app_settings.dart";
+import "package:inventree/settings/barcode_settings.dart";
 import "package:inventree/settings/home_settings.dart";
 import "package:inventree/settings/login.dart";
 import "package:inventree/settings/part_settings.dart";
@@ -68,6 +70,14 @@ class _InvenTreeSettingsState extends State<InvenTreeSettingsWidget> {
                   Navigator.push(context, MaterialPageRoute(builder: (context) => HomeScreenSettingsWidget()));
                 }
               ),
+              ListTile(
+                title: Text(L10().barcodes),
+                subtitle: Text(L10().barcodeSettings),
+                leading: FaIcon(FontAwesomeIcons.barcode, color: COLOR_ACTION),
+                onTap: () {
+                  Navigator.push(context, MaterialPageRoute(builder: (context) => InvenTreeBarcodeSettingsWidget()));
+                }
+              ),
               ListTile(
                 title: Text(L10().part),
                 subtitle: Text(L10().partSettings),

lib/widget/location_display.dart

@@ -4,7 +4,7 @@ import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:font_awesome_flutter/font_awesome_flutter.dart";
 
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 import "package:inventree/l10.dart";
 
 import "package:inventree/inventree/stock.dart";
@@ -94,7 +94,7 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
                   Navigator.push(
                       context,
                       MaterialPageRoute(builder: (context) =>
-                          InvenTreeQRView(
+                          barcodeController(
                               StockLocationScanInItemsHandler(location!)))
                   ).then((value) {
                     refresh(context);
@@ -114,8 +114,8 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
                   Navigator.push(
                       context,
                       MaterialPageRoute(builder: (context) =>
-                          InvenTreeQRView(
-                              ScanParentLocationHandler(location!)))
+                        barcodeController(ScanParentLocationHandler(location!))
+                      )
                   ).then((value) {
                     refresh(context);
                   });

lib/widget/part_detail.dart

@@ -4,7 +4,7 @@ import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:font_awesome_flutter/font_awesome_flutter.dart";
 
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 import "package:inventree/l10.dart";
 import "package:inventree/helpers.dart";
 

lib/widget/refreshable_state.dart

@@ -3,7 +3,7 @@ import "package:flutter_speed_dial/flutter_speed_dial.dart";
 
 import "package:inventree/api.dart";
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 
 import "package:inventree/widget/back.dart";
 import "package:inventree/widget/drawer.dart";

lib/widget/stock_detail.dart

@@ -4,7 +4,7 @@ import "package:flutter_speed_dial/flutter_speed_dial.dart";
 import "package:font_awesome_flutter/font_awesome_flutter.dart";
 
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 import "package:inventree/helpers.dart";
 import "package:inventree/l10.dart";
 import "package:inventree/api.dart";
@@ -168,8 +168,9 @@ class _StockItemDisplayState extends RefreshableState<StockDetailWidget> {
                 Navigator.push(
                     context,
                     MaterialPageRoute(builder: (context) =>
-                        InvenTreeQRView(
-                            StockItemScanIntoLocationHandler(widget.item)))
+                      barcodeController(
+                        StockItemScanIntoLocationHandler(widget.item))
+                      )
                 ).then((ctx) {
                   refresh(context);
                 });

lib/widget/supplier_part_detail.dart

@@ -4,7 +4,7 @@ import "package:font_awesome_flutter/font_awesome_flutter.dart";
 
 import "package:inventree/api.dart";
 import "package:inventree/app_colors.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 import "package:inventree/l10.dart";
 
 import "package:inventree/inventree/part.dart";

test/barcode_test.dart

@@ -8,7 +8,7 @@
 import "package:flutter_test/flutter_test.dart";
 
 import "package:inventree/api.dart";
-import "package:inventree/barcode.dart";
+import "package:inventree/barcode/barcode.dart";
 import "package:inventree/helpers.dart";
 import "package:inventree/user_profile.dart";
 
@@ -57,7 +57,7 @@ void main() {
 
     test("Empty Barcode", () async {
       // Handle an 'empty' barcode
-      await handler.processBarcode(null, "");
+      await handler.processBarcode("");
 
       debugContains("Scanned barcode data: ''");
       debugContains("showSnackIcon: 'Barcode scan error'");
@@ -68,7 +68,7 @@ void main() {
     test("Junk Data", () async {
       // test scanning 'junk' data
 
-      await handler.processBarcode(null, "abcdefg");
+      await handler.processBarcode("abcdefg");
 
       debugContains("Scanned barcode data: 'abcdefg'");
       debugContains("showSnackIcon: 'No match for barcode'");
@@ -76,7 +76,7 @@ void main() {
 
     test("Invalid StockLocation", () async {
       // Scan an invalid stock location
-      await handler.processBarcode(null, '{"stocklocation": 999999}');
+      await handler.processBarcode('{"stocklocation": 999999}');
 
       debugContains("Scanned barcode data: '{\"stocklocation\": 999999}'");
       debugContains("showSnackIcon: 'No match for barcode'");
@@ -97,7 +97,7 @@ void main() {
 
       var handler = StockItemScanIntoLocationHandler(item!);
 
-      await handler.processBarcode(null, '{"stocklocation": 7}');
+      await handler.processBarcode('{"stocklocation": 7}');
       // Check the location has been updated
       await item.reload();
       assert(item.locationId == 7);
@@ -105,7 +105,7 @@ void main() {
       debugContains("Scanned stock location 7");
 
       // Scan into a new location
-      await handler.processBarcode(null, '{"stocklocation": 1}');
+      await handler.processBarcode('{"stocklocation": 1}');
       await item.reload();
       assert(item.locationId == 1);
 
@@ -125,7 +125,7 @@ void main() {
 
       // Scan multiple items into this location
       for (int id in [1, 2, 11]) {
-        await handler.processBarcode(null, '{"stockitem": ${id}}');
+        await handler.processBarcode('{"stockitem": ${id}}');
 
         var item = await InvenTreeStockItem().get(id) as InvenTreeStockItem?;
 
@@ -150,12 +150,12 @@ void main() {
       var handler = ScanParentLocationHandler(location!);
 
       // Scan into new parent location
-      await handler.processBarcode(null, '{"stocklocation": 1}');
+      await handler.processBarcode('{"stocklocation": 1}');
       await location.reload();
       assert(location.parentId == 1);
 
       // Scan back into old parent location
-      await handler.processBarcode(null, '{"stocklocation": 4}');
+      await handler.processBarcode('{"stocklocation": 4}');
       await location.reload();
       assert(location.parentId == 4);