feat: read inverted datamatrix

android/build.gradle

@@ -80,6 +80,9 @@ dependencies {
     implementation 'androidx.camera:camera-lifecycle:1.3.3'
     implementation 'androidx.camera:camera-camera2:1.3.3'
 
+    // opencv
+    implementation 'com.quickbirdstudios:opencv:3.4.15'
+
     testImplementation 'org.jetbrains.kotlin:kotlin-test'
     testImplementation 'org.mockito:mockito-core:5.12.0'    
 }

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

@@ -36,7 +36,12 @@ import dev.steenbakker.mobile_scanner.utils.YuvToRgbConverter
 import io.flutter.view.TextureRegistry
 import java.io.ByteArrayOutputStream
 import kotlin.math.roundToInt
-
+import com.google.mlkit.vision.common.internal.ImageConvertUtils
+import org.opencv.core.Mat
+import org.opencv.core.CvType
+import org.opencv.core.Core
+import org.opencv.android.Utils
+import org.opencv.android.OpenCVLoader
 
 class MobileScanner(
     private val activity: Activity,
@@ -57,6 +62,7 @@ class MobileScanner(
 
     /// Configurable variables
     var scanWindow: List<Float>? = null
+    var invertImage: Boolean = false
     private var detectionSpeed: DetectionSpeed = DetectionSpeed.NO_DUPLICATES
     private var detectionTimeout: Long = 250
     private var returnImage = false
@@ -67,7 +73,12 @@ class MobileScanner(
     @ExperimentalGetImage
     val captureOutput = ImageAnalysis.Analyzer { imageProxy -> // YUV_420_888 format
         val mediaImage = imageProxy.image ?: return@Analyzer
-        val inputImage = InputImage.fromMediaImage(mediaImage, imageProxy.imageInfo.rotationDegrees)
+        var inputImage = InputImage.fromMediaImage(mediaImage, imageProxy.imageInfo.rotationDegrees)
+
+        // Invert
+        if (invertImage) {
+            inputImage = invertInputImage(inputImage)
+        }
 
         if (detectionSpeed == DetectionSpeed.NORMAL && scannerTimeout) {
             imageProxy.close()
@@ -218,6 +229,7 @@ class MobileScanner(
     fun start(
         barcodeScannerOptions: BarcodeScannerOptions?,
         returnImage: Boolean,
+        invertImage: Boolean,
         cameraPosition: CameraSelector,
         torch: Boolean,
         detectionSpeed: DetectionSpeed,
@@ -229,9 +241,13 @@ class MobileScanner(
         cameraResolution: Size?,
         newCameraResolutionSelector: Boolean
     ) {
+
+        OpenCVLoader.initDebug()
+
         this.detectionSpeed = detectionSpeed
         this.detectionTimeout = detectionTimeout
         this.returnImage = returnImage
+        this.invertImage = invertImage
 
         if (camera?.cameraInfo != null && preview != null && textureEntry != null) {
             mobileScannerErrorCallback(AlreadyStarted())
@@ -473,5 +489,16 @@ class MobileScanner(
         if (camera == null) throw ZoomWhenStopped()
         camera?.cameraControl?.setZoomRatio(1f)
     }
-
+    /**
+     * Invert the input image.
+     */
+    fun invertInputImage(image: InputImage): InputImage {
+        val bitmap = ImageConvertUtils.getInstance().getUpRightBitmap(image);
+        val tmp = Mat(bitmap.getWidth(), bitmap.getHeight(), CvType.CV_8UC1);
+        Utils.bitmapToMat(bitmap, tmp);
+        Core.bitwise_not(tmp, tmp);
+        Utils.matToBitmap(tmp, bitmap);
+        val newImage = InputImage.fromBitmap(bitmap, 0);
+        return newImage
+    }
 }

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

@@ -128,6 +128,7 @@ class MobileScannerHandler(
             "setScale" -> setScale(call, result)
             "resetScale" -> resetScale(result)
             "updateScanWindow" -> updateScanWindow(call, result)
+            "setInvertImage" -> setInvertImage(call, result)
             else -> result.notImplemented()
         }
     }
@@ -138,6 +139,7 @@ class MobileScannerHandler(
         val facing: Int = call.argument<Int>("facing") ?: 0
         val formats: List<Int>? = call.argument<List<Int>>("formats")
         val returnImage: Boolean = call.argument<Boolean>("returnImage") ?: false
+        val invertImage: Boolean = call.argument<Boolean>("invertImage") ?: false
         val speed: Int = call.argument<Int>("speed") ?: 1
         val timeout: Int = call.argument<Int>("timeout") ?: 250
         val cameraResolutionValues: List<Int>? = call.argument<List<Int>>("cameraResolution")
@@ -174,6 +176,7 @@ class MobileScannerHandler(
         mobileScanner!!.start(
             barcodeScannerOptions,
             returnImage,
+            invertImage,
             position,
             torch,
             detectionSpeed,
@@ -275,4 +278,13 @@ class MobileScannerHandler(
 
         result.success(null)
     }
+
+    private fun setInvertImage(call: MethodCall, result: MethodChannel.Result) {
+        val invert = call.argument<Boolean?>("invertImage")
+
+        if (invert != null)
+            mobileScanner?.invertImage = invert
+
+        result.success(null)
+    }
 }

ios/Classes/MobileScanner.swift

@@ -28,6 +28,9 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
     /// Return image buffer with the Barcode event
     var returnImage: Bool = false
 
+    /// Analyze inverted image (useful for scanning white barcodes on black background)
+    var invertImage: Bool = false
+
     /// Default position of camera
     var videoPosition: AVCaptureDevice.Position = AVCaptureDevice.Position.back
 
@@ -124,6 +127,14 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         AVCaptureDevice.requestAccess(for: .video, completionHandler: { result($0) })
     }
 
+    func convertCIImageToCGImage(inputImage: CIImage) -> CGImage? {
+        let context = CIContext(options: nil)
+        if let cgImage = context.createCGImage(inputImage, from: inputImage.extent) {
+            return cgImage
+        }
+        return nil
+    }
+
     /// Gets called when a new image is added to the buffer
     public func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
         guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
@@ -141,9 +152,18 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
             nextScanTime = currentTime + timeoutSeconds
             imagesCurrentlyBeingProcessed = true
 
-            let ciImage = latestBuffer.image
+            let uiImage : UIImage
+            if (invertImage) {
+                let temp_image = self.invertImage(image: latestBuffer.image)
+                uiImage = temp_image
+            }
+            else
+            {
+                uiImage = latestBuffer.image
+            }
 
-            let image = VisionImage(image: ciImage)
+            var image = VisionImage(image: uiImage)
+
             image.orientation = imageOrientation(
                 deviceOrientation: UIDevice.current.orientation,
                 defaultOrientation: .portrait,
@@ -165,19 +185,20 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
                     }
                 }
 
-                mobileScannerCallback(barcodes, error, ciImage)
+                mobileScannerCallback(barcodes, error, uiImage)
             }
         }
     }
 
     /// Start scanning for barcodes
-    func start(barcodeScannerOptions: BarcodeScannerOptions?, returnImage: Bool, cameraPosition: AVCaptureDevice.Position, torch: Bool, detectionSpeed: DetectionSpeed, completion: @escaping (MobileScannerStartParameters) -> ()) throws {
+    func start(barcodeScannerOptions: BarcodeScannerOptions?, returnImage: Bool, invertImage: Bool, cameraPosition: AVCaptureDevice.Position, torch: Bool, detectionSpeed: DetectionSpeed, completion: @escaping (MobileScannerStartParameters) -> ()) throws {
         self.detectionSpeed = detectionSpeed
         if (device != nil || captureSession != nil) {
             throw MobileScannerError.alreadyStarted
         }
 
         barcodesString = nil
+        self.invertImage = invertImage
         scanner = barcodeScannerOptions != nil ? BarcodeScanner.barcodeScanner(options: barcodeScannerOptions!) : BarcodeScanner.barcodeScanner()
         captureSession = AVCaptureSession()
         textureId = registry?.register(self)
@@ -390,6 +411,10 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         }
     }
 
+    func setInvertImage(_ invertImage: Bool) {
+        self.invertImage = invertImage
+    }
+
     /// Set the zoom factor of the camera
     func setScale(_ scale: CGFloat) throws {
         if (device == nil) {
@@ -434,14 +459,27 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
 
     /// Analyze a single image
     func analyzeImage(image: UIImage, position: AVCaptureDevice.Position, callback: @escaping BarcodeScanningCallback) {
-        let image = VisionImage(image: image)
-        image.orientation = imageOrientation(
+        var uiimage = image
+        if (invertImage) {
+            uiimage = self.invertImage(image: uiimage)
+        }
+        let visImage = VisionImage(image: uiimage)
+        visImage.orientation = imageOrientation(
             deviceOrientation: UIDevice.current.orientation,
             defaultOrientation: .portrait,
             position: position
         )
+        scanner.process(visImage, completion: callback)
+    }
 
-        scanner.process(image, completion: callback)
+    func invertImage(image: UIImage) -> UIImage {
+        let ciImage = CIImage(image: image)
+        let filter = CIFilter(name: "CIColorInvert")
+        filter?.setValue(ciImage, forKey: kCIInputImageKey)
+        let outputImage = filter?.outputImage
+        let cgImage = convertCIImageToCGImage(inputImage: outputImage!)
+
+        return UIImage(cgImage: cgImage!, scale: image.scale, orientation: image.imageOrientation)
     }
 
     var barcodesString: Array<String?>?

ios/Classes/MobileScannerPlugin.swift

@@ -84,6 +84,8 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin {
             toggleTorch(result)
         case "analyzeImage":
             analyzeImage(call, result)
+        case "setInvertImage":
+            setInvertImage(call, result)
         case "setScale":
             setScale(call, result)
         case "resetScale":
@@ -101,6 +103,7 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin {
         let facing: Int = (call.arguments as! Dictionary<String, Any?>)["facing"] as? Int ?? 1
         let formats: Array<Int> = (call.arguments as! Dictionary<String, Any?>)["formats"] as? Array ?? []
         let returnImage: Bool = (call.arguments as! Dictionary<String, Any?>)["returnImage"] as? Bool ?? false
+        let invertImage: Bool = (call.arguments as! Dictionary<String, Any?>)["invertImage"] as? Bool ?? false
         let speed: Int = (call.arguments as! Dictionary<String, Any?>)["speed"] as? Int ?? 0
         let timeoutMs: Int = (call.arguments as! Dictionary<String, Any?>)["timeout"] as? Int ?? 0
         self.mobileScanner.timeoutSeconds = Double(timeoutMs) / Double(1000)
@@ -120,7 +123,7 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin {
         let detectionSpeed: DetectionSpeed = DetectionSpeed(rawValue: speed)!
 
         do {
-            try mobileScanner.start(barcodeScannerOptions: barcodeOptions, returnImage: returnImage, cameraPosition: position, torch: torch, detectionSpeed: detectionSpeed) { parameters in
+            try mobileScanner.start(barcodeScannerOptions: barcodeOptions, returnImage: returnImage, invertImage: invertImage, cameraPosition: position, torch: torch, detectionSpeed: detectionSpeed) { parameters in
                 DispatchQueue.main.async {
                     result([
                         "textureId": parameters.textureId,
@@ -162,6 +165,20 @@ public class MobileScannerPlugin: NSObject, FlutterPlugin {
         result(nil)
     }
 
+
+    /// Sets the zoomScale.
+    private func setInvertImage(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
+        let invert = call.arguments as? Bool
+        if (invert == nil) {
+            result(FlutterError(code: "MobileScanner",
+                                message: "You must provide a invert (bool) when calling setInvertImage",
+                                details: nil))
+            return
+        }
+        mobileScanner.setInvertImage(invert!)
+        result(nil)
+    }
+
     /// Sets the zoomScale.
     private func setScale(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
         let scale = call.arguments as? CGFloat

lib/src/method_channel/mobile_scanner_method_channel.dart

@@ -295,6 +295,14 @@ class MethodChannelMobileScanner extends MobileScannerPlatform {
     );
   }
 
+  @override
+  Future<void> setInvertImage(bool invertImage) async {
+    await methodChannel.invokeMethod<void>(
+      'setInvertImage',
+      {'invertImage': invertImage},
+    );
+  }
+
   @override
   Future<void> dispose() async {
     await stop();

lib/src/mobile_scanner_controller.dart

@@ -25,6 +25,7 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
     this.formats = const <BarcodeFormat>[],
     this.returnImage = false,
     this.torchEnabled = false,
+    this.invertImage = false,
     this.useNewCameraSelector = false,
   })  : detectionTimeoutMs =
             detectionSpeed == DetectionSpeed.normal ? detectionTimeoutMs : 0,
@@ -88,6 +89,11 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
   /// Defaults to false.
   final bool torchEnabled;
 
+  /// Whether the image should be inverted before scanning.
+  ///
+  /// Defaults to false.
+  final bool invertImage;
+
   /// Use the new resolution selector.
   ///
   /// This feature is experimental and not fully tested yet.
@@ -268,6 +274,7 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       formats: formats,
       returnImage: returnImage,
       torchEnabled: torchEnabled,
+      invertImage: invertImage,
     );
 
     try {

lib/src/mobile_scanner_platform_interface.dart

@@ -104,6 +104,11 @@ abstract class MobileScannerPlatform extends PlatformInterface {
     throw UnimplementedError('updateScanWindow() has not been implemented.');
   }
 
+  /// Set inverting image colors (for negative Data Matrixes).
+  Future<void> setInvertImage(bool invert) {
+    throw UnimplementedError('setInvertImage() has not been implemented.');
+  }
+
   /// Dispose of this [MobileScannerPlatform] instance.
   Future<void> dispose() {
     throw UnimplementedError('dispose() has not been implemented.');

lib/src/objects/start_options.dart

@@ -14,6 +14,7 @@ class StartOptions {
     required this.formats,
     required this.returnImage,
     required this.torchEnabled,
+    required this.invertImage,
   });
 
   /// The direction for the camera.
@@ -37,6 +38,9 @@ class StartOptions {
   /// Whether the torch should be turned on when the scanner starts.
   final bool torchEnabled;
 
+  /// Whether the image should be inverted.
+  final bool invertImage;
+
   Map<String, Object?> toMap() {
     return <String, Object?>{
       if (cameraResolution != null)
@@ -51,6 +55,7 @@ class StartOptions {
       'speed': detectionSpeed.rawValue,
       'timeout': detectionTimeoutMs,
       'torch': torchEnabled,
+      'invertImage': invertImage,
     };
   }
 }