From ba67e47b7d657ec78c9b6b3cce8158fd4442e618 Mon Sep 17 00:00:00 2001
From: Julian Steenbakker <juliansteenbakker@outlook.com>
Date: Mon, 8 Feb 2021 08:51:41 +0100
Subject: [PATCH] Added onResume listener and updateDimensions call (#250)

---
 lib/src/lifecycle_event_handler.dart | 30 ++++++++++++++++++++++++++++
 lib/src/qr_code_scanner.dart         | 12 +++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 lib/src/lifecycle_event_handler.dart

diff --git a/lib/src/lifecycle_event_handler.dart b/lib/src/lifecycle_event_handler.dart
new file mode 100644
index 0000000..f6da736
--- /dev/null
+++ b/lib/src/lifecycle_event_handler.dart
@@ -0,0 +1,30 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/foundation.dart';
+
+class LifecycleEventHandler extends WidgetsBindingObserver {
+  LifecycleEventHandler({
+    this.resumeCallBack,
+    this.suspendingCallBack,
+  });
+
+  final AsyncCallback resumeCallBack;
+  final AsyncCallback suspendingCallBack;
+
+  @override
+  Future<void> didChangeAppLifecycleState(AppLifecycleState state) async {
+    switch (state) {
+      case AppLifecycleState.resumed:
+        if (resumeCallBack != null) {
+          await resumeCallBack();
+        }
+        break;
+      case AppLifecycleState.inactive:
+      case AppLifecycleState.paused:
+      case AppLifecycleState.detached:
+        if (suspendingCallBack != null) {
+          await suspendingCallBack();
+        }
+        break;
+    }
+  }
+}
diff --git a/lib/src/qr_code_scanner.dart b/lib/src/qr_code_scanner.dart
index ec28402..66243df 100644
--- a/lib/src/qr_code_scanner.dart
+++ b/lib/src/qr_code_scanner.dart
@@ -4,6 +4,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
+import 'lifecycle_event_handler.dart';
 import 'qr_scanner_overlay_shape.dart';
 import 'types/barcode.dart';
 import 'types/barcode_format.dart';
@@ -58,6 +59,17 @@ class QRView extends StatefulWidget {
 class _QRViewState extends State<QRView> {
   var _channel;
 
+  @override
+  void initState() {
+    super.initState();
+
+    WidgetsBinding.instance.addObserver(
+        LifecycleEventHandler(resumeCallBack: () async =>
+            QRViewController.updateDimensions(widget.key, _channel,
+            overlay: widget.overlay)
+    ));
+  }
+
   @override
   Widget build(BuildContext context) {
     return NotificationListener(