make scanner nullable to prevent leak; use early returns in process image callback; format

@@ -20,12 +20,12 @@ import androidx.camera.core.ImageAnalysis
 import androidx.camera.core.ImageProxy
 import androidx.camera.core.Preview
 import androidx.camera.core.TorchState
-import androidx.camera.core.resolutionselector.AspectRatioStrategy
 import androidx.camera.core.resolutionselector.ResolutionSelector
 import androidx.camera.core.resolutionselector.ResolutionStrategy
 import androidx.camera.lifecycle.ProcessCameraProvider
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.LifecycleOwner
+import com.google.mlkit.vision.barcode.BarcodeScanner
 import com.google.mlkit.vision.barcode.BarcodeScannerOptions
 import com.google.mlkit.vision.barcode.BarcodeScanning
 import com.google.mlkit.vision.barcode.common.Barcode
@@ -37,7 +37,6 @@ import io.flutter.view.TextureRegistry
 import java.io.ByteArrayOutputStream
 import kotlin.math.roundToInt
 
-
 class MobileScanner(
     private val activity: Activity,
     private val textureRegistry: TextureRegistry,
@@ -50,7 +49,7 @@ class MobileScanner(
     private var camera: Camera? = null
     private var preview: Preview? = null
     private var textureEntry: TextureRegistry.SurfaceTextureEntry? = null
-    private var scanner = BarcodeScanning.getClient()
+    private var scanner: BarcodeScanner? = null
     private var lastScanned: List<String?>? = null
     private var scannerTimeout = false
     private var displayListener: DisplayManager.DisplayListener? = null
@@ -76,76 +75,75 @@ class MobileScanner(
             scannerTimeout = true
         }
 
-        scanner.process(inputImage)
-            .addOnSuccessListener { barcodes ->
+        scanner?.let {
+            it.process(inputImage).addOnSuccessListener { barcodes ->
                 if (detectionSpeed == DetectionSpeed.NO_DUPLICATES) {
-                    val newScannedBarcodes = barcodes.mapNotNull { barcode -> barcode.rawValue }.sorted()
+                    val newScannedBarcodes = barcodes.mapNotNull {
+                        barcode -> barcode.rawValue
+                    }.sorted()
+
                     if (newScannedBarcodes == lastScanned) {
                         // New scanned is duplicate, returning
                         return@addOnSuccessListener
                     }
-                    if (newScannedBarcodes.isNotEmpty()) lastScanned = newScannedBarcodes
+                    if (newScannedBarcodes.isNotEmpty()) {
+                        lastScanned = newScannedBarcodes
+                    }
                 }
 
                 val barcodeMap: MutableList<Map<String, Any?>> = mutableListOf()
 
                 for (barcode in barcodes) {
-                    if (scanWindow != null) {
-                        val match = isBarcodeInScanWindow(scanWindow!!, barcode, imageProxy)
-                        if (!match) {
-                            continue
-                        } else {
-                            barcodeMap.add(barcode.data)
-                        }
-                    } else {
+                    if (scanWindow == null) {
                         barcodeMap.add(barcode.data)
+                        continue
                     }
-                }
 
+                    if (isBarcodeInScanWindow(scanWindow!!, barcode, imageProxy)) {
+                        barcodeMap.add(barcode.data)
+                    }
+                }
 
-                if (barcodeMap.isNotEmpty()) {
-                    if (returnImage) {
-
-                        val bitmap = Bitmap.createBitmap(mediaImage.width, mediaImage.height, Bitmap.Config.ARGB_8888)
-
-                        val imageFormat = YuvToRgbConverter(activity.applicationContext)
-
-                        imageFormat.yuvToRgb(mediaImage, bitmap)
+                if (barcodeMap.isEmpty()) {
+                    return@addOnSuccessListener
+                }
 
-                        val bmResult = rotateBitmap(bitmap, camera?.cameraInfo?.sensorRotationDegrees?.toFloat() ?: 90f)
+                if (!returnImage) {
+                    mobileScannerCallback(
+                        barcodeMap,
+                        null,
+                        null,
+                        null
+                    )
+                    return@addOnSuccessListener
+                }
 
-                        val stream = ByteArrayOutputStream()
-                        bmResult.compress(Bitmap.CompressFormat.PNG, 100, stream)
-                        val byteArray = stream.toByteArray()
-                        val bmWidth = bmResult.width
-                        val bmHeight = bmResult.height
-                        bmResult.recycle()
+                val bitmap = Bitmap.createBitmap(mediaImage.width, mediaImage.height, Bitmap.Config.ARGB_8888)
+                val imageFormat = YuvToRgbConverter(activity.applicationContext)
 
+                imageFormat.yuvToRgb(mediaImage, bitmap)
 
-                        mobileScannerCallback(
-                            barcodeMap,
-                            byteArray,
-                            bmWidth,
-                            bmHeight
-                        )
+                val bmResult = rotateBitmap(bitmap, camera?.cameraInfo?.sensorRotationDegrees?.toFloat() ?: 90f)
 
-                    } else {
+                val stream = ByteArrayOutputStream()
+                bmResult.compress(Bitmap.CompressFormat.PNG, 100, stream)
+                val byteArray = stream.toByteArray()
+                val bmWidth = bmResult.width
+                val bmHeight = bmResult.height
+                bmResult.recycle()
 
-                        mobileScannerCallback(
-                            barcodeMap,
-                            null,
-                            null,
-                            null
-                        )
-                    }
-                }
-            }
-            .addOnFailureListener { e ->
+                mobileScannerCallback(
+                    barcodeMap,
+                    byteArray,
+                    bmWidth,
+                    bmHeight
+                )
+            }.addOnFailureListener { e ->
                 mobileScannerErrorCallback(
                     e.localizedMessage ?: e.toString()
                 )
-            }
-            .addOnCompleteListener { imageProxy.close() }
+            }.addOnCompleteListener { imageProxy.close() }
+        }
 
         if (detectionSpeed == DetectionSpeed.NORMAL) {
             // Set timer and continue