add invert scan feature for android

android/src/main/kotlin/net/touchcapture/qr/flutterqr/QRView.kt

@@ -90,6 +90,7 @@ class QRView(private val context: Context, messenger: BinaryMessenger, private v
                 call.argument<Double>("cutOutBottomOffset")!!,
                 result,
             )
+            "invertScan" -> setInvertScan(call.argument<Boolean>("isInvertScan")!!, result)
             else -> result.notImplemented()
         }
     }
@@ -259,6 +260,14 @@ class QRView(private val context: Context, messenger: BinaryMessenger, private v
         result.success(true)
     }
 
+    private fun setInvertScan(isInvert: Boolean, result: MethodChannel.Result) {
+        barcodeView!!.pause()
+        val settings = barcodeView!!.cameraSettings
+        settings.isScanInverted = isInvert
+        barcodeView!!.cameraSettings = settings
+        barcodeView!!.resume();
+    }
+
     private fun setScanAreaSize(
         dpScanAreaWidth: Double,
         dpScanAreaHeight: Double,

lib/src/qr_code_scanner.dart

@@ -357,4 +357,16 @@ class QRViewController {
     }
     return false;
   }
+
+  //Starts/Stops invert scanning.
+  Future<void> scanInvert(bool isScanInvert) async {
+    if (defaultTargetPlatform == TargetPlatform.android) {
+      try {
+        await _channel
+            .invokeMethod('invertScan', {"isInvertScan": isScanInvert});
+      } on PlatformException catch (e) {
+        throw CameraException(e.code, e.message);
+      }
+    }
+  }
 }