let MobileScanner manage Method Channel internally

Author: navaronbracke

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScanner.kt

@@ -44,6 +44,9 @@ import dev.steenbakker.mobile_scanner.objects.MobileScannerStartParameters
 import dev.steenbakker.mobile_scanner.utils.invertBitmapColors
 import dev.steenbakker.mobile_scanner.utils.rotateBitmap
 import dev.steenbakker.mobile_scanner.utils.serialize
+import io.flutter.plugin.common.BinaryMessenger
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.MethodChannel
 import io.flutter.view.TextureRegistry
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -55,16 +58,37 @@ import kotlin.math.roundToInt
 
 @ExperimentalGetImage
 class MobileScanner(
+    binaryMessenger: BinaryMessenger,
+    methodCallHandler: MethodChannel.MethodCallHandler,
     private val activity: Activity,
     private val textureRegistry: TextureRegistry,
     private val mobileScannerCallback: MobileScannerCallback,
     private val mobileScannerErrorCallback: MobileScannerErrorCallback,
-    private val deviceOrientationListener: DeviceOrientationListener,
     private val barcodeScannerFactory: (options: BarcodeScannerOptions?) -> BarcodeScanner = ::defaultBarcodeScannerFactory,
 ) {
 
+    private val methodChannel: MethodChannel
+    private val deviceOrientationChannel: EventChannel
+
     init {
         configureCameraProcessProvider()
+        methodChannel = MethodChannel(binaryMessenger,
+            "dev.steenbakker.mobile_scanner/scanner/method")
+        methodChannel.setMethodCallHandler(methodCallHandler)
+        deviceOrientationChannel = EventChannel(binaryMessenger,
+            "dev.steenbakker.mobile_scanner/scanner/deviceOrientation")
+    }
+
+    // The device orientation listener is a lazy property,
+    // because eagerly initializing it during `init {}`
+    // leads to privacy warnings with more restrictive Play Store vendors.
+    private val deviceOrientationListener by lazy {
+        val listener = DeviceOrientationListener(activity)
+
+        // Only attach the listener to the event channel when it actually exists.
+        deviceOrientationChannel.setStreamHandler(listener)
+
+        return@lazy listener
     }
 
     /// Internal variables
@@ -718,6 +742,9 @@ class MobileScanner(
      * Dispose of this scanner instance.
      */
     fun dispose() {
+        methodChannel.setMethodCallHandler(null)
+        deviceOrientationChannel.setStreamHandler(null)
+
         if (isStopped()) {
             return
         }

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScannerHandler.kt

@@ -21,7 +21,6 @@ import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
-import io.flutter.plugin.common.EventChannel
 import io.flutter.view.TextureRegistry
 import java.io.File
 import com.google.mlkit.vision.barcode.ZoomSuggestionOptions
@@ -79,9 +78,6 @@ class MobileScannerHandler(
         barcodeHandler.publishError(MobileScannerErrorCodes.BARCODE_ERROR, error, null)
     }
 
-    private var methodChannel: MethodChannel? = null
-    private var deviceOrientationChannel: EventChannel? = null
-
     private var mobileScanner: MobileScanner? = null
 
     private val torchStateCallback: TorchStateCallback = {state: Int ->
@@ -94,25 +90,17 @@ class MobileScannerHandler(
     }
 
     init {
-        methodChannel = MethodChannel(binaryMessenger,
-            "dev.steenbakker.mobile_scanner/scanner/method")
-        methodChannel!!.setMethodCallHandler(this)
-
-        val deviceOrientationListener = DeviceOrientationListener(activity)
-
-        deviceOrientationChannel = EventChannel(binaryMessenger,
-            "dev.steenbakker.mobile_scanner/scanner/deviceOrientation")
-        deviceOrientationChannel!!.setStreamHandler(deviceOrientationListener)
-
         mobileScanner = MobileScanner(
-            activity, textureRegistry, callback, errorCallback, deviceOrientationListener)
+            binaryMessenger,
+            this,
+            activity,
+            textureRegistry,
+            callback,
+            errorCallback
+        )
     }
 
     fun dispose(activityPluginBinding: ActivityPluginBinding) {
-        methodChannel?.setMethodCallHandler(null)
-        methodChannel = null
-        deviceOrientationChannel?.setStreamHandler(null)
-        deviceOrientationChannel = null
         barcodeHandler.dispose()
         mobileScanner?.dispose()
         mobileScanner = null