Implement camera switching

fast_barcode_scanner/android/src/main/kotlin/com/jhoogstraat/fast_barcode_scanner/BarcodeReader.kt

@@ -23,7 +23,7 @@ import java.util.ArrayList
 import java.util.concurrent.ExecutorService
 import java.util.concurrent.Executors
 
-data class CameraConfig(val formats: IntArray, val mode: DetectionMode, val resolution: Resolution, val framerate: Framerate, val position: CameraPosition)
+data class CameraConfig(val formats: IntArray, val mode: DetectionMode, val resolution: Resolution, val framerate: Framerate, var position: CameraPosition)
 
 class BarcodeReader(private val flutterTextureEntry: TextureRegistry.SurfaceTextureEntry, private val listener: (List<Barcode>) -> Unit) : RequestPermissionsResultListener {
     /* Android Lifecycle */
@@ -106,6 +106,28 @@ class BarcodeReader(private val flutterTextureEntry: TextureRegistry.SurfaceText
         }, ContextCompat.getMainExecutor(activity))
     }
 
+    fun canChangeCamera(result: Result) {
+        try {
+            val cameraProviderFuture = ProcessCameraProvider.getInstance(activity!!)
+            cameraProviderFuture.addListener(Runnable {
+                val cameraProviderForChangeCamera = cameraProviderFuture.get()    
+                val hasFrontCamera = cameraProviderForChangeCamera.hasCamera(CameraSelector.DEFAULT_FRONT_CAMERA)
+                val hasBackCamera = cameraProviderForChangeCamera.hasCamera(CameraSelector.DEFAULT_BACK_CAMERA)
+                result.success(hasFrontCamera && hasBackCamera)
+            }, ContextCompat.getMainExecutor(activity!!))
+        } catch (exc: Exception) {
+            result.success(false)
+        }
+    }
+
+    fun changeCamera(position: String, result: Result) {
+        cameraConfig.position = when (position) {
+            "front" -> CameraPosition.front
+            else -> CameraPosition.back
+        }
+        initCamera()
+    }
+
     private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
         ContextCompat.checkSelfPermission(activity!!.applicationContext, it) == PackageManager.PERMISSION_GRANTED
     }
@@ -148,12 +170,8 @@ class BarcodeReader(private val flutterTextureEntry: TextureRegistry.SurfaceText
         // Select camera
         val selectorBuilder = CameraSelector.Builder()
         when (cameraConfig.position) {
-            CameraPosition.front -> {
-                selectorBuilder.requireLensFacing(CameraSelector.LENS_FACING_FRONT)
-            }
-            CameraPosition.back -> {
-                selectorBuilder.requireLensFacing(CameraSelector.LENS_FACING_BACK)
-            }
+            CameraPosition.front -> selectorBuilder.requireLensFacing(CameraSelector.LENS_FACING_FRONT)
+            CameraPosition.back -> selectorBuilder.requireLensFacing(CameraSelector.LENS_FACING_BACK)
         }
         cameraSelector = selectorBuilder.build()
 

fast_barcode_scanner/android/src/main/kotlin/com/jhoogstraat/fast_barcode_scanner/FastBarcodeScannerPlugin.kt

@@ -58,6 +58,8 @@ class FastBarcodeScannerPlugin: FlutterPlugin, MethodCallHandler, ActivityAware
       "pause" -> reader.stop(result)
       "resume" -> reader.resume(result)
       "toggleTorch" -> reader.toggleTorch(result)
+      "canChangeCamera" -> reader.canChangeCamera(result)
+      "changeCamera" -> reader.changeCamera(call.arguments as String, result)
       else -> result.notImplemented()
     }
   }

fast_barcode_scanner/example/lib/scanner_screen.dart

@@ -15,6 +15,17 @@ class ScannerScreen extends StatefulWidget {
 
 class _ScannerScreenState extends State<ScannerScreen> {
   final _torchIconState = ValueNotifier(false);
+  bool _canChangeCamera = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _checkCanChangeCamera();
+  }
+
+  Future<void> _checkCanChangeCamera() async => setState(() async {
+        _canChangeCamera = await CameraController.instance.canChangeCamera();
+      });
 
   @override
   Widget build(BuildContext context) {
@@ -42,6 +53,11 @@ class _ScannerScreenState extends State<ScannerScreen> {
               },
             ),
           ),
+          if (_canChangeCamera)
+            IconButton(
+              icon: const Icon(Icons.cameraswitch),
+              onPressed: CameraController.instance.toggleCamera,
+            ),
         ],
       ),
       body: BarcodeCamera(

fast_barcode_scanner/example/pubspec.yaml

@@ -1,6 +1,7 @@
 name: fast_barcode_scanner_example
 description: Demonstrates how to use the fast_barcode_scanner plugin.
 publish_to: 'none'
+version: 0.0.1+1
 
 environment:
   sdk: '>=2.12.0 <3.0.0'
@@ -15,5 +16,9 @@ dependencies:
 dev_dependencies:
   flutter_lints: ^1.0.4
 
+dependency_overrides: 
+  fast_barcode_scanner_platform_interface:
+    path: ../../fast_barcode_scanner_platform_interface/
+
 flutter:
   uses-material-design: true