bug: fixed hot reload not working

@@ -24,7 +24,6 @@ import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.PluginRegistry
 import io.flutter.view.TextureRegistry
 import java.io.File
-import java.net.URI
 
 
 class MobileScanner(private val activity: Activity, private val textureRegistry: TextureRegistry)
@@ -39,6 +38,7 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
 
     private var cameraProvider: ProcessCameraProvider? = null
     private var camera: Camera? = null
+    private var preview: Preview? = null
     private var textureEntry: TextureRegistry.SurfaceTextureEntry? = null
 
 //    @AnalyzeMode
@@ -120,11 +120,15 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
 
     @ExperimentalGetImage
     private fun start(call: MethodCall, result: MethodChannel.Result) {
-        if (camera != null) {
-            result.error(TAG, "Called start() while already started!", null)
-            return
-        }
-
+        if (camera != null && preview != null) {
+            val resolution = preview!!.resolutionInfo!!.resolution
+            val portrait = camera!!.cameraInfo.sensorRotationDegrees % 180 == 0
+            val width = resolution.width.toDouble()
+            val height = resolution.height.toDouble()
+            val size = if (portrait) mapOf("width" to width, "height" to height) else mapOf("width" to height, "height" to width)
+            val answer = mapOf("textureId" to textureEntry!!.id(), "size" to size, "torchable" to camera!!.cameraInfo.hasFlashUnit())
+            result.success(answer)
+        } else {
             val facing: Int = call.argument<Int>("facing") ?: 0
             val ratio: Int? = call.argument<Int>("ratio")
             val torch: Boolean = call.argument<Boolean>("torch") ?: false
@@ -136,9 +140,9 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
                     formatsList.add(BarcodeFormats.values()[index].intValue)
                 }
                 scanner = if (formatsList.size == 1) {
-                BarcodeScanning.getClient( BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first()).build());
+                    BarcodeScanning.getClient(BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first()).build())
                 } else {
-                BarcodeScanning.getClient( BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first(), *formatsList.subList(1, formatsList.size).toIntArray() ).build());
+                    BarcodeScanning.getClient(BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first(), *formatsList.subList(1, formatsList.size).toIntArray()).build())
                 }
             }
 
@@ -163,7 +167,7 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
                 if (ratio != null) {
                     previewBuilder.setTargetAspectRatio(ratio)
                 }
-            val preview = previewBuilder.build().apply { setSurfaceProvider(surfaceProvider) }
+                preview = previewBuilder.build().apply { setSurfaceProvider(surfaceProvider) }
 
                 // Build the analyzer to be passed on to MLKit
                 val analysisBuilder = ImageAnalysis.Builder()
@@ -179,7 +183,7 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
                 camera = cameraProvider!!.bindToLifecycle(activity as LifecycleOwner, selector, preview, analysis)
 
                 val analysisSize = analysis.resolutionInfo?.resolution ?: Size(0, 0)
-            val previewSize = preview.resolutionInfo?.resolution ?: Size(0, 0)
+                val previewSize = preview!!.resolutionInfo?.resolution ?: Size(0, 0)
                 Log.i("LOG", "Analyzer: $analysisSize")
                 Log.i("LOG", "Preview: $previewSize")
 
@@ -192,7 +196,7 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
                 // Enable torch if provided
                 camera!!.cameraControl.enableTorch(torch)
 
-            val resolution = preview.resolutionInfo!!.resolution
+                val resolution = preview!!.resolutionInfo!!.resolution
                 val portrait = camera!!.cameraInfo.sensorRotationDegrees % 180 == 0
                 val width = resolution.width.toDouble()
                 val height = resolution.height.toDouble()
@@ -201,6 +205,7 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
                 result.success(answer)
             }, executor)
         }
+    }
 
     private fun toggleTorch(call: MethodCall, result: MethodChannel.Result) {
         if (camera == null) {
@@ -235,18 +240,19 @@ class MobileScanner(private val activity: Activity, private val textureRegistry:
     }
 
     private fun stop(result: MethodChannel.Result) {
-        if (camera == null) {
+        if (camera == null && preview == null) {
             result.error(TAG,"Called stop() while already stopped!", null)
             return
         }
 
         val owner = activity as LifecycleOwner
-        camera!!.cameraInfo.torchState.removeObservers(owner)
-        cameraProvider!!.unbindAll()
-        textureEntry!!.release()
+        camera?.cameraInfo?.torchState?.removeObservers(owner)
+        cameraProvider?.unbindAll()
+        textureEntry?.release()
 
 //        analyzeMode = AnalyzeMode.NONE
         camera = null
+        preview = null
         textureEntry = null
         cameraProvider = null