Fixed permission callback on Android (#251)

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

@@ -21,7 +21,7 @@ class FlutterQrPlugin : FlutterPlugin, ActivityAware {
     }
 
     private fun onAttachedToV1(registrar: PluginRegistry.Registrar) {
-        registrar.addRequestPermissionsResultListener(CameraRequestPermissionsListener())
+        Shared.registrar = registrar
         onAttachedToEngines(registrar.platformViewRegistry(), registrar.messenger(), registrar.activity())
     }
 
@@ -45,27 +45,23 @@ class FlutterQrPlugin : FlutterPlugin, ActivityAware {
 
     override fun onAttachedToActivity(activityPluginBinding: ActivityPluginBinding) {
         Shared.activity = activityPluginBinding.activity
-        activityPluginBinding.addRequestPermissionsResultListener(CameraRequestPermissionsListener())
+        Shared.binding = activityPluginBinding
     }
 
     override fun onDetachedFromActivityForConfigChanges() {
         Shared.activity = null
+        Shared.binding = null
     }
 
     override fun onReattachedToActivityForConfigChanges(activityPluginBinding: ActivityPluginBinding) {
         Shared.activity = activityPluginBinding.activity
+        Shared.binding = activityPluginBinding
     }
 
     override fun onDetachedFromActivity() {
         Shared.activity = null
+        Shared.binding = null
     }
     
-    inner class CameraRequestPermissionsListener : PluginRegistry.RequestPermissionsResultListener {
-        override fun onRequestPermissionsResult(id: Int, permissions: Array<String>, grantResults: IntArray): Boolean {
-            if (id == Shared.CAMERA_REQUEST_ID && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-                return true
-            }
-            return false
-        }
-    }
+
 }

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

@@ -4,30 +4,40 @@ import android.Manifest
 import android.app.Activity
 import android.app.Application
 import android.content.pm.PackageManager
-import android.os.Bundle
-import android.view.View
-import com.google.zxing.ResultPoint
 import android.hardware.Camera.CameraInfo
 import android.os.Build
+import android.os.Bundle
+import android.view.View
 import com.google.zxing.BarcodeFormat
+import com.google.zxing.ResultPoint
 import com.journeyapps.barcodescanner.BarcodeCallback
 import com.journeyapps.barcodescanner.BarcodeResult
 import com.journeyapps.barcodescanner.BarcodeView
 import io.flutter.plugin.common.BinaryMessenger
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
+import io.flutter.plugin.common.PluginRegistry
 import io.flutter.plugin.platform.PlatformView
+
+
 class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<String, Any>) :
-        PlatformView, MethodChannel.MethodCallHandler {
+        PlatformView, MethodChannel.MethodCallHandler, PluginRegistry.RequestPermissionsResultListener {
 
     private var isTorchOn: Boolean = false
     private var isPaused: Boolean = false
     private var barcodeView: BarcodeView? = null
-    private val channel: MethodChannel
+    private val channel: MethodChannel = MethodChannel(messenger, "net.touchcapture.qr.flutterqr/qrview_$id")
+    private var permissionGranted: Boolean = false
 
     init {
-        checkAndRequestPermission(null)
-        channel = MethodChannel(messenger, "net.touchcapture.qr.flutterqr/qrview_$id")
+        if (Shared.binding != null) {
+            Shared.binding!!.addRequestPermissionsResultListener(this)
+        }
+
+        if (Shared.registrar != null) {
+            Shared.registrar!!.addRequestPermissionsResultListener(this)
+        }
+
         channel.setMethodCallHandler(this)
         Shared.activity?.application?.registerActivityLifecycleCallbacks(object : Application.ActivityLifecycleCallbacks {
             override fun onActivityPaused(p0: Activity) {
@@ -92,8 +102,6 @@ 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()) {
-            return cameraPermissionNotSet(result)
         }
 
         barcodeView!!.pause()
@@ -119,8 +127,6 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
     private fun toggleFlash(result: MethodChannel.Result) {
         if (barcodeView == null) {
             return barCodeViewNotSet(result)
-        } else if (!hasCameraPermission()) {
-            return cameraPermissionNotSet(result)
         }
 
         if (hasFlash()) {
@@ -136,10 +142,8 @@ 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()) {
-            return cameraPermissionNotSet(result)
         }
-
+        
         if (barcodeView!!.isPreviewActive) {
             isPaused = true
             barcodeView!!.pause()
@@ -151,7 +155,7 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
         if (barcodeView == null) {
             return barCodeViewNotSet(result)
         } else if (!hasCameraPermission()) {
-            return cameraPermissionNotSet(result)
+            checkAndRequestPermission(result)
         }
 
         if (!barcodeView!!.isPreviewActive) {
@@ -182,10 +186,6 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
         result.error("404", "No barcode view found", null)
     }
 
-    private fun cameraPermissionNotSet(result: MethodChannel.Result) {
-         result.error("cameraPermission", " Permission denied to access the camera", null)
-    }
-
     override fun getView(): View {
         return initBarCodeView().apply {}!!
     }
@@ -196,16 +196,17 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
             if (params["cameraFacing"] as Int == 1) {
                 barcodeView?.cameraSettings?.requestedCameraId = CameraInfo.CAMERA_FACING_FRONT
             }
-            barcodeView!!.resume()
+        } else {
+            if (hasCameraPermission()) {
+                barcodeView!!.resume()
+            } else {
+                checkAndRequestPermission(null)
+            }
         }
         return barcodeView
     }
 
     private fun startScan(arguments: List<Int>?, result: MethodChannel.Result) {
-        if (!hasCameraPermission()) {
-            return cameraPermissionNotSet(result)
-        }
-
         val allowedBarcodeTypes = mutableListOf<BarcodeFormat>()
         try {
             arguments?.forEach {
@@ -254,7 +255,6 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
 
     private fun checkAndRequestPermission(result: MethodChannel.Result?) {
         when {
-            hasCameraPermission() -> result?.success(true)
             Build.VERSION.SDK_INT >= Build.VERSION_CODES.M -> {
                 Shared.activity?.requestPermissions(
                         arrayOf(Manifest.permission.CAMERA),
@@ -265,5 +265,20 @@ class QRView(messenger: BinaryMessenger, id: Int, private val params: HashMap<St
             }
         }
     }
+
+    override fun onRequestPermissionsResult( requestCode: Int,
+                                             permissions: Array<out String>?,
+                                             grantResults: IntArray): Boolean {
+
+        if (requestCode == Shared.CAMERA_REQUEST_ID && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+            permissionGranted = true
+            channel.invokeMethod("onPermissionSet", true)
+            return true
+        }
+        permissionGranted = false
+        channel.invokeMethod("onPermissionSet", false)
+        return false
+    }
+
 }
 

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

@@ -1,8 +1,12 @@
 package net.touchcapture.qr.flutterqr
 
 import android.app.Activity
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
+import io.flutter.plugin.common.PluginRegistry
 
 object Shared {
     const val CAMERA_REQUEST_ID = 513469796
     var activity: Activity? = null
+    var binding: ActivityPluginBinding? = null
+    var registrar: PluginRegistry.Registrar? = null
 }

lib/src/qr_code_scanner.dart

@@ -140,7 +140,7 @@ class _QRViewState extends State<QRView> {
 
     // Start scan after creation of the view
     final controller =
-        QRViewController._(_channel, widget.key, widget.onPermissionSet)
+        QRViewController._(_channel, widget.key, widget.onPermissionSet, widget.cameraFacing)
           .._startScan(widget.key, widget.overlay, widget.formatsAllowed);
 
     // Initialize the controller for controlling the QRView
@@ -166,8 +166,8 @@ class _QrCameraSettings {
 
 class QRViewController {
   QRViewController._(MethodChannel channel, GlobalKey qrKey,
-      PermissionSetCallback onPermissionSet)
-      : _channel = channel {
+      PermissionSetCallback onPermissionSet, CameraFacing cameraFacing)
+      : _channel = channel, _cameraFacing = cameraFacing{
     _channel.setMethodCallHandler((call) async {
       switch (call.method) {
         case 'onRecognizeQR':
@@ -204,6 +204,7 @@ class QRViewController {
   }
 
   final MethodChannel _channel;
+  final CameraFacing _cameraFacing;
   final StreamController<Barcode> _scanUpdateController =
       StreamController<Barcode>();
 
@@ -232,6 +233,8 @@ class QRViewController {
   /// Gets information about which camera is active.
   Future<CameraFacing> getCameraInfo() async {
     try {
+      var cameraFacing = await _channel.invokeMethod('getCameraInfo') as int;
+      if (cameraFacing == -1) return _cameraFacing;
       return CameraFacing
           .values[await _channel.invokeMethod('getCameraInfo') as int];
     } on PlatformException catch (e) {