Styjun

I'm trying to write an app with an integrated barcode scanner.
I followed this tutorial:
https://www.c-sharpcorner.com/article/xamarin-android-qr-code-reader-by-mobile-camera/

The scan works fine and very fast (before I used ZXing.Net.Mobile and it is horrible slow).
Now I need some help to integrate that the app only detects one barcode when the user presses a button and not the whole time. Maybe a delay would solve the problem too.

protected override void OnCreate(Bundle savedInstanceState)
 BarcodeFormat.QrCode)
 .Build();
 cameraSource = new CameraSource
 .Builder(this, barcodeDetector)
 .SetRequestedPreviewSize(320, 480)
 .SetAutoFocusEnabled(true)
 .Build();

 surfaceView.Click += StartScanning;
 surfaceView.Holder.AddCallback(this);
 //barcodeDetector.SetProcessor(this);
 

private void StartScanning(object sender, EventArgs e)

 barcodeDetector.SetProcessor(this);

public void ReceiveDetections(Detections detections)
 
 SparseArray qrcodes = detections.DetectedItems;
 if (qrcodes.Size() != 0)
 
 txtResult.Post(() => 
 //Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
 //vibrator.Vibrate(1000);
 txtResult.Text = ((Barcode)qrcodes.ValueAt(0)).RawValue;
 );
 
 

At the moment the user presses the SurfaceView and the scanner starts and never stops.

Is it possible, that it just scans one after pressing the "button"?

r3d007

1 Uncomment this line in OnCreate method

barcodeDetector.SetProcessor(this);

2 Remove or comment this line from SurfaceCreated and OnRequestPermissionsResult methods

cameraSource.Start(surfaceView.Holder);

3 Your StartScanning method should call the Start

private void StartScanning(object sender, EventArgs e)

 cameraSource.Start(surfaceView.Holder);

4 Once you read and validate a code, stop the scanner

public void ReceiveDetections(Detections detections)

 SparseArray qrcodes = detections.DetectedItems;
 if (qrcodes.Size() != 0)
 
 txtResult.Post(() => 
 //Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
 //vibrator.Vibrate(1000);
 txtResult.Text = ((Barcode)qrcodes.ValueAt(0)).RawValue;
 );

 using (var h = new Handler (Looper.MainLooper))
 h.Post (() => 
 cameraSource.Stop();
 );

 

To prevent crashes, consider also to hide or disable the button until you get the camera permissions, and when the scanner is already started.

You need add this after scan process triggered. "-" operator must be added to prevent non-stop working.You plugged-in event in this line

//adds the handler
surfaceView.Click += StartScanning;

after that you need this.

 // removes the handler
surfaceView.Click -= StartScanning;

Also look here