How to control what Camera sees

[ThunZEN]

How to make the camera see only those objects that are in the frame

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Hi @ThunZEN
thankyou to let me know the problem I will fix it in the next version

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Hi @ThunZEN Keep it open that will remind me for this

[ButasButora]

hello, i have the same question. I cropped the screen scan preview, but the scanner reads the codes outside this area. How to fix this?

[tomasf71]

The same problem, is there any way how to detect codes only from the frame? It would be very useful

[ButasButora]

Try this setupCamera function:

func setupCamera() {
let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: cameraPosition)

    if let selectedCamera = deviceDiscoverySession.devices.first {
        if let input = try? AVCaptureDeviceInput(device: selectedCamera) {
           
            let session = AVCaptureSession()
            session.sessionPreset = .hd1920x1080//.vga640x480
            if session.canAddInput(input) {
                session.addInput(input)
                cameraInput = input
            }
            
            if session.canAddOutput(metadataOutput) {
                session.addOutput(metadataOutput)
        
                metadataOutput.metadataObjectTypes = supportBarcode
                metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            }
            
            previewLayer?.removeFromSuperlayer()
            self.session = session
          
            self.selectedCamera = selectedCamera
           
            self.backgroundColor = UIColor.gray
            
            // calculate a centered square rectangle with red border
            //let size = 200
            let screenWidth = CGFloat(1080) //bounds.size.width
            let screenHeight = CGFloat(1920)
            
           // let xPos = (CGFloat(screenWidth) / CGFloat(2)) - (CGFloat(size) / CGFloat(2))
            //let scanRect = CGRect(x: Int(xPos), y: 150, width: size, height: size)
            //width is height :-)
            /// windows height 
            let w = screenWidth / 2.5

            /// window width 
            let h = screenHeight

            /// Middle on window height 
            let ws = screenWidth / 2 - w / 2
            
            let scanRect = CGRect(x: ws , y: 0, width: w, height: h)
            
            let x = scanRect.origin.x/screenWidth
            let y = scanRect.origin.y/screenHeight
            let width = scanRect.width/screenWidth
            let height = scanRect.height/screenHeight
            let scanRectTransformed = CGRect(x: x, y: y, width: width, height: height)
            
            //create area for scanning 
            let scanAreaView = UIView()
            scanAreaView.layer.borderColor = UIColor.red.cgColor
            scanAreaView.layer.borderWidth = 4
            scanAreaView.frame = scanRect
            //   self.addSubview(scanAreaView)
   
                DispatchQueue.global().async {
                    Thread.sleep(forTimeInterval: 0.2)
                    session.startRunning()
                    
                    DispatchQueue.main.async {
                        let previewLayer = AVCaptureVideoPreviewLayer(session: session)
                        //Preview layer je 0x0 = nelze použít metadataOutputRectConverted
                        //let rectOfInterest = self.previewLayer?.metadataOutputRectConverted(fromLayerRect: CGRect(x: 0, y: 0, width: 300, height: 300)) //  videoPreviewLayer is AVCaptureVideoPreviewLayer
                        //print ("width: \(rectOfInterest?.width); heght: \(rectOfInterest?.height)")
                        
                        // print ("rect of int :\(self.metadataOutput.rectOfInterest)")
                        self.metadataOutput.rectOfInterest = scanRectTransformed
                        
                        try? selectedCamera.lockForConfiguration()
                    
                            do {
                                self.selectedCamera!.focusMode = .continuousAutoFocus
                            }
                        
                        selectedCamera.unlockForConfiguration()
                      
                        //rectOfInterest ?? CGRect(x: 0, y: 0, width: 1, height: 1)
                        //   print ("rect of int 2:\(self.metadataOutput.rectOfInterest)")
                        previewLayer.videoGravity = .resizeAspectFill
                        //  print ("previewLayer: width: \(previewLayer.frame.width); heght: \(previewLayer.frame.height)")
                        self.layer.addSublayer(previewLayer)
                        
                        self.previewLayer = previewLayer
                        self.updateCameraView()
                    }
                }
        }
    }
}