feat: handle more facing directions

CHANGELOG.md

@@ -1,7 +1,12 @@
 ## NEXT
 
+**BREAKING CHANGES:**
+
+* The initial state of the `MobileScannerState` camera facing direction is changed to `CameraFacing.unknown`.
+
 Improvements:
 * [Android] Turn off logging for CameraX, except for the `Log.ERROR` logging level.
+* Added `CameraFacing.external` and `CameraFacing.unknown` enum values.
 
 ## 7.0.0-beta.6
 

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

@@ -22,6 +22,7 @@ import androidx.camera.core.Camera
 import androidx.camera.core.CameraSelector
 import androidx.camera.core.CameraXConfig
 import androidx.camera.core.ExperimentalGetImage
+import androidx.camera.core.ExperimentalLensFacing
 import androidx.camera.core.ImageAnalysis
 import androidx.camera.core.ImageProxy
 import androidx.camera.core.Preview
@@ -278,6 +279,17 @@ class MobileScanner(
         }
     }
 
+    @ExperimentalLensFacing
+    private fun getCameraLensFacing(camera: Camera?): Int? {
+        return when(camera?.cameraInfo?.lensFacing) {
+            CameraSelector.LENS_FACING_BACK -> 1
+            CameraSelector.LENS_FACING_FRONT -> 0
+            CameraSelector.LENS_FACING_EXTERNAL -> 2
+            CameraSelector.LENS_FACING_UNKNOWN -> null
+            else -> null
+        }
+    }
+
     private fun rotateBitmap(bitmap: Bitmap, degrees: Float): Bitmap {
         val matrix = Matrix()
         matrix.postRotate(degrees)
@@ -318,6 +330,7 @@ class MobileScanner(
     /**
      * Start barcode scanning by initializing the camera and barcode scanner.
      */
+    @ExperimentalLensFacing
     @ExperimentalGetImage
     fun start(
         barcodeScannerOptions: BarcodeScannerOptions?,
@@ -343,6 +356,7 @@ class MobileScanner(
 // TODO: resume here for seamless transition
 //            if (isPaused) {
 //                resumeCamera()
+//                val cameraDirection = getCameraLensFacing(camera)
 //                mobileScannerStartedCallback(
 //                  MobileScannerStartParameters(
 //                    if (portrait) width else height,
@@ -352,7 +366,8 @@ class MobileScanner(
 //                    surfaceProducer!!.handlesCropAndRotation(),
 //                    currentTorchState,
 //                    surfaceProducer!!.id(),
-//                    numberOfCameras ?: 0
+//                    numberOfCameras ?: 0,
+//                    cameraDirection
 //                  )
 //                )
 //                return
@@ -465,6 +480,7 @@ class MobileScanner(
             val height = resolution.height.toDouble()
             val sensorRotationDegrees = camera?.cameraInfo?.sensorRotationDegrees ?: 0
             val portrait = sensorRotationDegrees % 180 == 0
+            val cameraDirection = getCameraLensFacing(camera)
 
             // Start with 'unavailable' torch state.
             var currentTorchState: Int = -1
@@ -488,7 +504,8 @@ class MobileScanner(
                     surfaceProducer!!.handlesCropAndRotation(),
                     currentTorchState,
                     surfaceProducer!!.id(),
-                    numberOfCameras ?: 0
+                    numberOfCameras ?: 0,
+                    cameraDirection,
                 )
             )
         }, executor)

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

@@ -10,6 +10,7 @@ import android.os.Looper
 import android.util.Size
 import androidx.camera.core.CameraSelector
 import androidx.camera.core.ExperimentalGetImage
+import androidx.camera.core.ExperimentalLensFacing
 import com.google.mlkit.vision.barcode.BarcodeScannerOptions
 import dev.steenbakker.mobile_scanner.objects.BarcodeFormats
 import dev.steenbakker.mobile_scanner.objects.DetectionSpeed
@@ -114,6 +115,7 @@ class MobileScannerHandler(
         }
     }
 
+    @ExperimentalLensFacing
     @ExperimentalGetImage
     override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
         when (call.method) {
@@ -146,6 +148,7 @@ class MobileScannerHandler(
         }
     }
 
+    @ExperimentalLensFacing
     @ExperimentalGetImage
     private fun start(call: MethodCall, result: MethodChannel.Result) {
         val torch: Boolean = call.argument<Boolean>("torch") ?: false
@@ -191,7 +194,8 @@ class MobileScannerHandler(
                         "isPreviewPreTransformed" to it.isPreviewPreTransformed,
                         "sensorOrientation" to it.sensorOrientation,
                         "currentTorchState" to it.currentTorchState,
-                        "numberOfCameras" to it.numberOfCameras
+                        "numberOfCameras" to it.numberOfCameras,
+                        "cameraDirection" to it.cameraDirection
                     ))
                 }
             },

android/src/main/kotlin/dev/steenbakker/mobile_scanner/objects/MobileScannerStartParameters.kt

@@ -8,5 +8,6 @@ class MobileScannerStartParameters(
     val isPreviewPreTransformed: Boolean,
     val currentTorchState: Int,
     val id: Long,
-    val numberOfCameras: Int
+    val numberOfCameras: Int,
+    val cameraDirection: Int?,
 )

darwin/mobile_scanner/Sources/mobile_scanner/MobileScannerPlugin.swift

@@ -434,10 +434,18 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHandler,
                 let answer: [String : Any?]
 
                 if let device = self.device {
+                    let cameraDirection: Int? = switch(device.position) {
+                        case .back: 1
+                        case .unspecified: nil
+                        case .front: 0
+                        @unknown default: nil
+                    }
+
                     answer = [
                         "textureId": self.textureId,
                         "size": size,
                         "currentTorchState": device.hasTorch ? device.torchMode.rawValue : -1,
+                        "cameraDirection": cameraDirection,
                     ]
                 } else {
                     answer = [

example/lib/scanner_button_widgets.dart

@@ -109,6 +109,10 @@ class SwitchCameraButton extends StatelessWidget {
             icon = const Icon(Icons.camera_front);
           case CameraFacing.back:
             icon = const Icon(Icons.camera_rear);
+          case CameraFacing.external:
+            icon = const Icon(Icons.usb);
+          case CameraFacing.unknown:
+            icon = const Icon(Icons.device_unknown);
         }
 
         return IconButton(

lib/src/enums/camera_facing.dart

@@ -1,21 +1,35 @@
 /// The facing of a camera.
 enum CameraFacing {
-  /// Front facing camera.
+  /// The camera is a front facing camera.
+  ///
+  /// This type of camera always faces the user.
   front(0),
 
-  /// Back facing camera.
-  back(1);
+  /// The camera is a back facing camera.
+  ///
+  /// This type of camera always faces away from the user.
+  back(1),
+
+  /// The camera is an external camera.
+  ///
+  /// For example a USB-camera.
+  external(2),
+
+  /// The camera facing direction is unknown.
+  unknown(-1);
 
   const CameraFacing(this.rawValue);
 
-  factory CameraFacing.fromRawValue(int value) {
+  factory CameraFacing.fromRawValue(int? value) {
     switch (value) {
       case 0:
-        return CameraFacing.front;
+        return front;
       case 1:
-        return CameraFacing.back;
+        return back;
+      case 2:
+        return external;
       default:
-        throw ArgumentError.value(value, 'value', 'Invalid raw value.');
+        return unknown;
     }
   }
 

lib/src/method_channel/mobile_scanner_method_channel.dart

@@ -4,6 +4,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:mobile_scanner/src/enums/barcode_format.dart';
+import 'package:mobile_scanner/src/enums/camera_facing.dart';
 import 'package:mobile_scanner/src/enums/mobile_scanner_authorization_state.dart';
 import 'package:mobile_scanner/src/enums/mobile_scanner_error_code.dart';
 import 'package:mobile_scanner/src/enums/torch_state.dart';
@@ -307,13 +308,16 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
       );
     }
 
+    final CameraFacing cameraDirection =
+        CameraFacing.fromRawValue(startResult['cameraDirection'] as int?);
+
     _textureId = textureId;
 
     if (defaultTargetPlatform == TargetPlatform.android) {
       _surfaceProducerDelegate =
           AndroidSurfaceProducerDelegate.fromConfiguration(
         startResult,
-        startOptions.cameraDirection,
+        cameraDirection,
       );
       _surfaceProducerDelegate?.startListeningToDeviceOrientation(
         deviceOrientationChangedStream,
@@ -337,6 +341,7 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
     _pausing = false;
 
     return MobileScannerViewAttributes(
+      cameraDirection: cameraDirection,
       currentTorchMode: currentTorchState,
       numberOfCameras: numberOfCameras,
       size: size,

lib/src/mobile_scanner_controller.dart

@@ -36,7 +36,11 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
           detectionTimeoutMs >= 0,
           'The detection timeout must be greater than or equal to 0.',
         ),
-        super(MobileScannerState.uninitialized(facing));
+        assert(
+          facing != CameraFacing.unknown,
+          'CameraFacing.unknown is not a valid camera direction.',
+        ),
+        super(const MobileScannerState.uninitialized());
 
   /// The desired resolution for the camera.
   ///
@@ -303,15 +307,22 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       );
     }
 
+    if (cameraDirection == CameraFacing.unknown) {
+      throw const MobileScannerException(
+        errorCode: MobileScannerErrorCode.genericError,
+        errorDetails: MobileScannerErrorDetails(
+          message: 'CameraFacing.unknown is not a valid camera direction.',
+        ),
+      );
+    }
+
     // Do nothing if the camera is already running.
     if (value.isRunning) {
       return;
     }
 
-    final CameraFacing effectiveDirection = cameraDirection ?? facing;
-
     final StartOptions options = StartOptions(
-      cameraDirection: effectiveDirection,
+      cameraDirection: cameraDirection ?? facing,
       cameraResolution: cameraResolution,
       detectionSpeed: detectionSpeed,
       detectionTimeoutMs: detectionTimeoutMs,
@@ -333,7 +344,7 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       if (!_isDisposed) {
         value = value.copyWith(
           availableCameras: viewAttributes.numberOfCameras,
-          cameraDirection: effectiveDirection,
+          cameraDirection: viewAttributes.cameraDirection,
           isInitialized: true,
           isRunning: true,
           size: viewAttributes.size,
@@ -351,11 +362,11 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       }
 
       // The initialization finished with an error.
-      // To avoid stale values, reset the output size,
-      // torch state and zoom scale to the defaults.
+      // To avoid stale values, reset the camera direction,
+      // output size, torch state and zoom scale to the defaults.
       if (!_isDisposed) {
         value = value.copyWith(
-          cameraDirection: facing,
+          cameraDirection: CameraFacing.unknown,
           isInitialized: true,
           isRunning: false,
           error: error,
@@ -392,11 +403,13 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
 
   /// Switch between the front and back camera.
   ///
-  /// Does nothing if the device has less than 2 cameras.
+  /// Does nothing if the device has less than 2 cameras,
+  /// or if the current camera is an external camera.
   Future<void> switchCamera() async {
     _throwIfNotInitialized();
 
     final int? availableCameras = value.availableCameras;
+    final CameraFacing cameraDirection = value.cameraDirection;
 
     // Do nothing if the amount of cameras is less than 2 cameras.
     // If the the current platform does not provide the amount of cameras,
@@ -405,15 +418,24 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       return;
     }
 
-    await stop();
+    // If the camera direction is not known,
+    // or if the camera is an external camera, do not allow switching cameras.
+    if (cameraDirection == CameraFacing.unknown ||
+        cameraDirection == CameraFacing.external) {
+      return;
+    }
 
-    final CameraFacing cameraDirection = value.cameraDirection;
+    await stop();
 
-    await start(
-      cameraDirection: cameraDirection == CameraFacing.front
-          ? CameraFacing.back
-          : CameraFacing.front,
-    );
+    switch (value.cameraDirection) {
+      case CameraFacing.front:
+        return start(cameraDirection: CameraFacing.back);
+      case CameraFacing.back:
+        return start(cameraDirection: CameraFacing.front);
+      case CameraFacing.external:
+      case CameraFacing.unknown:
+        return;
+    }
   }
 
   /// Switches the flashlight on or off.

lib/src/mobile_scanner_view_attributes.dart

@@ -1,16 +1,21 @@
 import 'dart:ui';
 
+import 'package:mobile_scanner/src/enums/camera_facing.dart';
 import 'package:mobile_scanner/src/enums/torch_state.dart';
 
 /// This class defines the attributes for the mobile scanner view.
 class MobileScannerViewAttributes {
   /// Construct a new [MobileScannerViewAttributes] instance.
   const MobileScannerViewAttributes({
+    required this.cameraDirection,
     required this.currentTorchMode,
-    this.numberOfCameras,
     required this.size,
+    this.numberOfCameras,
   });
 
+  /// The direction of the active camera.
+  final CameraFacing cameraDirection;
+
   /// The current torch state of the active camera.
   final TorchState currentTorchMode;
 

lib/src/objects/mobile_scanner_state.dart

@@ -23,10 +23,10 @@ class MobileScannerState {
   });
 
   /// Create a new [MobileScannerState] instance that is uninitialized.
-  const MobileScannerState.uninitialized(CameraFacing facing)
+  const MobileScannerState.uninitialized()
       : this(
           availableCameras: null,
-          cameraDirection: facing,
+          cameraDirection: CameraFacing.unknown,
           isInitialized: false,
           isRunning: false,
           size: Size.zero,