Updated permission callback and added requests when permission is not granted. (#251)

android/src/main/kotlin/net/touchcapture/qr/flutterqr/QRView.kt

@@ -41,13 +41,13 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
         channel.setMethodCallHandler(this)
         Shared.activity?.application?.registerActivityLifecycleCallbacks(object : Application.ActivityLifecycleCallbacks {
             override fun onActivityPaused(p0: Activity) {
-                if (p0 == Shared.activity && !isPaused) {
+                if (p0 == Shared.activity && !isPaused && hasCameraPermission()) {
                     barcodeView?.pause()
                 }
             }
 
             override fun onActivityResumed(p0: Activity) {
-                if (p0 == Shared.activity && !isPaused) {
+                if (p0 == Shared.activity && !isPaused && hasCameraPermission()) {
                     barcodeView?.resume()
                 }
             }
@@ -102,19 +102,23 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
     private fun flipCamera(result: MethodChannel.Result) {
         if (barcodeView == null) {
             return barCodeViewNotSet(result)
-        }
+        } else if (!hasCameraPermission()) {
+            checkAndRequestPermission(result)
+        } else {
+            barcodeView!!.pause()
+            val settings = barcodeView!!.cameraSettings
 
-        barcodeView!!.pause()
-        val settings = barcodeView!!.cameraSettings
+            if(settings.requestedCameraId == CameraInfo.CAMERA_FACING_FRONT)
+                settings.requestedCameraId = CameraInfo.CAMERA_FACING_BACK
+            else
+                settings.requestedCameraId = CameraInfo.CAMERA_FACING_FRONT
+
+            barcodeView!!.cameraSettings = settings
+            barcodeView!!.resume()
+            result.success(settings.requestedCameraId)
+        }
 
-        if(settings.requestedCameraId == CameraInfo.CAMERA_FACING_FRONT)
-            settings.requestedCameraId = CameraInfo.CAMERA_FACING_BACK
-        else
-            settings.requestedCameraId = CameraInfo.CAMERA_FACING_FRONT
 
-        barcodeView!!.cameraSettings = settings
-        barcodeView!!.resume()
-        result.success(settings.requestedCameraId)
     }
 
     private fun getFlashInfo(result: MethodChannel.Result) {
@@ -142,13 +146,15 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
     private fun pauseCamera(result: MethodChannel.Result) {
         if (barcodeView == null) {
             return barCodeViewNotSet(result)
+        } else if (!hasCameraPermission()) {
+            checkAndRequestPermission(result)
+        } else {
+            if (barcodeView!!.isPreviewActive) {
+                isPaused = true
+                barcodeView!!.pause()
+            }
+            result.success(true)
         }
-        
-        if (barcodeView!!.isPreviewActive) {
-            isPaused = true
-            barcodeView!!.pause()
-        }
-        result.success(true)
     }
 
     private fun resumeCamera(result: MethodChannel.Result) {
@@ -156,13 +162,13 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
             return barCodeViewNotSet(result)
         } else if (!hasCameraPermission()) {
             checkAndRequestPermission(result)
+        } else {
+            if (!barcodeView!!.isPreviewActive) {
+                isPaused = false
+                barcodeView!!.resume()
+            }
+            result.success(true)
         }
-
-        if (!barcodeView!!.isPreviewActive) {
-            isPaused = false
-            barcodeView!!.resume()
-        }
-        result.success(true)
     }
 
     private fun hasFlash(): Boolean {
@@ -198,7 +204,7 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
             }
         } else {
             if (hasCameraPermission()) {
-                barcodeView!!.resume()
+                if (!isPaused) barcodeView!!.resume()
             } else {
                 checkAndRequestPermission(null)
             }
@@ -270,7 +276,7 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
                                              permissions: Array<out String>?,
                                              grantResults: IntArray): Boolean {
 
-        if (requestCode == Shared.CAMERA_REQUEST_ID && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+        if (requestCode == Shared.CAMERA_REQUEST_ID && grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
             permissionGranted = true
             channel.invokeMethod("onPermissionSet", true)
             return true

lib/src/qr_code_scanner.dart

@@ -64,12 +64,12 @@ class _QRViewState extends State<QRView> {
     super.initState();
     WidgetsBinding.instance.addObserver(LifecycleEventHandler(
         resumeCallBack: () async => {
-          if (_channel != null) {
-            QRViewController.updateDimensions(
-                widget.key, _channel,
-                overlay: widget.overlay)
-          }
-        }));
+              if (_channel != null)
+                {
+                  QRViewController.updateDimensions(widget.key, _channel,
+                      overlay: widget.overlay)
+                }
+            }));
   }
 
   @override
@@ -86,9 +86,9 @@ class _QRViewState extends State<QRView> {
 
   bool onNotification(notification) {
     Future.microtask(() => {
-        QRViewController.updateDimensions(widget.key, _channel,
-        overlay: widget.overlay)
-      });
+          QRViewController.updateDimensions(widget.key, _channel,
+              overlay: widget.overlay)
+        });
 
     return false;
   }
@@ -139,9 +139,9 @@ class _QRViewState extends State<QRView> {
     _channel = MethodChannel('net.touchcapture.qr.flutterqr/qrview_$id');
 
     // Start scan after creation of the view
-    final controller =
-        QRViewController._(_channel, widget.key, widget.onPermissionSet, widget.cameraFacing)
-          .._startScan(widget.key, widget.overlay, widget.formatsAllowed);
+    final controller = QRViewController._(
+        _channel, widget.key, widget.onPermissionSet, widget.cameraFacing)
+      .._startScan(widget.key, widget.overlay, widget.formatsAllowed);
 
     // Initialize the controller for controlling the QRView
     if (widget.onQRViewCreated != null) {
@@ -167,7 +167,8 @@ class _QrCameraSettings {
 class QRViewController {
   QRViewController._(MethodChannel channel, GlobalKey qrKey,
       PermissionSetCallback onPermissionSet, CameraFacing cameraFacing)
-      : _channel = channel, _cameraFacing = cameraFacing{
+      : _channel = channel,
+        _cameraFacing = cameraFacing {
     _channel.setMethodCallHandler((call) async {
       switch (call.method) {
         case 'onRecognizeQR':
@@ -323,7 +324,7 @@ class QRViewController {
         await Future.delayed(Duration(milliseconds: 300));
       }
       final RenderBox renderBox = key.currentContext.findRenderObject();
-       try {
+      try {
         await channel.invokeMethod('setDimensions', {
           'width': renderBox.size.width,
           'height': renderBox.size.height,