implemented ios

@@ -2,6 +2,7 @@ import AVFoundation
 import Flutter
 import MLKitVision
 import MLKitBarcodeScanning
+import UIKit
 
 public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHandler, FlutterTexture, AVCaptureVideoDataOutputSampleBufferDelegate {
     
@@ -25,6 +26,9 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHan
 //    var analyzeMode: Int = 0
     var analyzing: Bool = false
     var position = AVCaptureDevice.Position.back
+
+    // optional frame to crop camera image before barcode detection
+    var scanWindow: CGRect?
     
     var scanner = BarcodeScanner.barcodeScanner()
     
@@ -99,13 +103,22 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHan
             }
             analyzing = true
             let buffer = CMSampleBufferGetImageBuffer(sampleBuffer)
-            let image = VisionImage(image: buffer!.image)
-            image.orientation = imageOrientation(
+            
+            var image: VisionImage?
+            
+            if (scanWindow != nil) {
+                let cropped = cropSampleBuffer(imageBuffer: buffer!, cropRect: scanWindow!)
+                image = VisionImage(image: cropped)
+             } else {
+                image = VisionImage(image: buffer!.image)
+             }
+
+            image!.orientation = imageOrientation(
               deviceOrientation: UIDevice.current.orientation,
               defaultOrientation: .portrait
             )
 
-            scanner.process(image) { [self] barcodes, error in
+            scanner.process(image!) { [self] barcodes, error in
                 if error == nil && barcodes != nil {
                     for barcode in barcodes! {
                         let event: [String: Any?] = ["name": "barcode", "data": barcode.data]
@@ -118,6 +131,29 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHan
 //            break
 //        }
     }
+
+    public func cropSampleBuffer(imageBuffer: CVImageBuffer, cropRect: CGRect) -> UIImage {
+        CVPixelBufferLockBaseAddress(imageBuffer, .readOnly)
+
+        let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)!
+        let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
+        let cropX = Int(cropRect.minX)
+        let cropY = Int(cropRect.minY)
+        let cropWidth = Int(cropRect.width)
+        let cropHeight = Int(cropRect.height)
+        let colorSpace = CGColorSpaceCreateDeviceRGB()
+
+        // calculate start position
+        let bytesPerPixel = 4
+        let startAddress = baseAddress + cropY * bytesPerRow + cropX * bytesPerPixel
+
+        let context = CGContext(data: startAddress, width: cropWidth, height: cropHeight, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
+        CVPixelBufferUnlockBaseAddress(imageBuffer, .readOnly)
+    
+        // create image
+        let cgImage: CGImage = context!.makeImage()!
+        return UIImage(cgImage: cgImage)
+    }
     
     func imageOrientation(
           deviceOrientation: UIDeviceOrientation,
@@ -172,6 +208,15 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin, FlutterStreamHan
         let torch: Bool = argReader.bool(key: "torch") ?? false
         let facing: Int = argReader.int(key: "facing") ?? 1
         let formats: Array = argReader.intArray(key: "formats") ?? []
+
+        let scanWindowData: Array? = argReader.intArray(key: "scanWindow")
+        if(scanWindowData != nil) {
+            scanWindow = CGRect(
+                x: scanWindowData![0],
+                y: scanWindowData![1],
+                width: scanWindowData![2] - scanWindowData![0],
+                height: scanWindowData![3] - scanWindowData![1])
+        }
         
         let formatList: NSMutableArray = []
         for index in formats {