imp: add resetZoomScale

@@ -289,4 +289,13 @@ class MobileScanner(
         camera!!.cameraControl.setLinearZoom(scale.toFloat())
     }
 
+    /**
+     * Reset the zoom rate of the camera.
+     */
+    fun resetScale() {
+        if (camera == null) throw ZoomWhenStopped()
+        camera!!.cameraControl.setZoomRatio(1f)
+    }
+
+
 }

@@ -120,6 +120,7 @@ class MobileScannerHandler(
             "stop" -> stop(result)
             "analyzeImage" -> analyzeImage(call, result)
             "setScale" -> setScale(call, result)
+            "resetScale" -> resetScale(call, result)
             "updateScanWindow" -> updateScanWindow(call)
             else -> result.notImplemented()
         }
@@ -234,6 +235,15 @@ class MobileScannerHandler(
         }
     }
 
+    private fun resetScale(call: MethodCall, result: MethodChannel.Result) {
+        try {
+            mobileScanner!!.resetScale()
+            result.success(null)
+        } catch (e: ZoomWhenStopped) {
+            result.error("MobileScanner", "Called setScale() while stopped!", null)
+        }
+    }
+
     private fun updateScanWindow(call: MethodCall) {
         mobileScanner!!.scanWindow = call.argument<List<Float>?>("rect")
     }

@@ -52,6 +52,8 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
 
     var detectionSpeed: DetectionSpeed = DetectionSpeed.noDuplicates
 
+    var standardZoomFactor: CGFloat = 1
+
     init(registry: FlutterTextureRegistry?, mobileScannerCallback: @escaping MobileScannerCallback, torchModeChangeCallback: @escaping TorchModeChangeCallback, zoomScaleChangeCallback: @escaping ZoomScaleChangeCallback) {
         self.registry = registry
         self.mobileScannerCallback = mobileScannerCallback
@@ -140,6 +142,20 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
 
         device.addObserver(self, forKeyPath: #keyPath(AVCaptureDevice.torchMode), options: .new, context: nil)
         device.addObserver(self, forKeyPath: #keyPath(AVCaptureDevice.videoZoomFactor), options: .new, context: nil)
+
+        // Check the zoom factor at switching from ultra wide camera to wide camera.
+        standardZoomFactor = 1
+        if #available(iOS 13.0, *) {
+            for (index, actualDevice) in device.constituentDevices.enumerated() {
+                if (actualDevice.deviceType != .builtInUltraWideCamera) {
+                    if index > 0 && index <= device.virtualDeviceSwitchOverVideoZoomFactors.count {
+                        standardZoomFactor = CGFloat(truncating: device.virtualDeviceSwitchOverVideoZoomFactors[index - 1])
+                    }
+                    break
+                }
+            }
+        }
+
         do {
             try device.lockForConfiguration()
             if device.isFocusModeSupported(.continuousAutoFocus) {
@@ -272,6 +288,22 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         
     }
 
+    /// Set the zoom factor of the camera
+    func resetScale() throws {
+        if (device == nil) {
+            throw MobileScannerError.torchWhenStopped
+        }
+
+        do {
+            try device.lockForConfiguration()
+            device.videoZoomFactor = standardZoomFactor
+            device.unlockForConfiguration()
+        } catch {
+            throw MobileScannerError.zoomError(error)
+        }
+    }
+
+
     /// Analyze a single image
     func analyzeImage(image: UIImage, position: AVCaptureDevice.Position, callback: @escaping BarcodeScanningCallback) {
         let image = VisionImage(image: image)

@@ -87,6 +87,8 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
             analyzeImage(call, result)
         case "setScale":
             setScale(call, result)
+        case "resetScale":
+            resetScale(call, result)
         case "updateScanWindow":
             updateScanWindow(call, result)
         default:
@@ -189,7 +191,28 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
         }
         result(nil)
     }
-    
+
+    /// Reset the zoomScale
+    private func resetScale(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
+        do {
+            try mobileScanner.resetScale()
+        } catch MobileScannerError.zoomWhenStopped {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Called resetScale() while stopped!",
+                                details: nil))
+        } catch MobileScannerError.zoomError(let error) {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Error while zooming.",
+                                details: error))
+        } catch {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Error while zooming.",
+                                details: nil))
+        }
+        result(nil)
+    }
+
+
     /// Toggles the torch
     func updateScanWindow(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
         let scanWindowData: Array? = (call.arguments as? [String: Any])?["rect"] as? [CGFloat]

@@ -322,6 +322,12 @@ class MobileScannerController {
     await _methodChannel.invokeMethod('setScale', zoomScale);
   }
 
+  /// Reset the zoomScale of the camera to use standard scale 1x.
+  Future<void> resetZoomScale() async {
+    await _methodChannel.invokeMethod('resetScale');
+  }
+
+
   /// Disposes the MobileScannerController and closes all listeners.
   ///
   /// If you call this, you cannot use this controller object anymore.