Camera.MAUI.ZXing (.Net 8) The function does not detect my cameras

Question

I'm using Camera.MAUI.ZXing and Camera.MAUI in my .Net MAUI project. On my xaml.cs I have the following code:

private async void InitializeCamera()
{
    // barcode detection
    cameraView.BarcodeDetected += Camera_OnDetected;
    // Inicializar ZXing Barcode Decoder
    cameraView.BarCodeDecoder = new ZXingBarcodeDecoder();

    // Configurar las opciones del decodificador de códigos de barras
    cameraView.BarCodeOptions = new BarcodeDecodeOptions
    {
        AutoRotate = true,
        PossibleFormats = { BarcodeFormat.QR_CODE },
        ReadMultipleCodes = false,
        TryHarder = true,
        TryInverted = true
    };

    // Configurar otras opciones de detección
    cameraView.BarCodeDetectionFrameRate = 10;
    cameraView.BarCodeDetectionMaxThreads = 5;
    cameraView.ControlBarcodeResultDuplicate = true;
    cameraView.BarCodeDetectionEnabled = true;

    // Iniciar la cámara de forma asíncrona
    if (cameraView.NumCamerasDetected > 0)
    {
        //if (cameraView.NumMicrophonesDetected > 0)
        //   cameraView.Microphone = cameraView.Microphones.First();
        cameraView.Camera = cameraView.Cameras.FirstOrDefault();
        MainThread.BeginInvokeOnMainThread(async () =>
        {
            if (await cameraView.StartCameraAsync() == CameraResult.Success)
            {
                playing = true;
            }
        });
    }
    else
        await DisplayAlert("Warning", "No cameras detected.", "OK");
}

protected override async void OnAppearing()
{
    base.OnAppearing();

    // Verificar el estado del permiso de la cámara
    var cameraStatus = await Permissions.CheckStatusAsync<Permissions.Camera>();
    if (cameraStatus != PermissionStatus.Granted)
    {
        var results = await Permissions.RequestAsync<Permissions.Camera>();
        if (results != PermissionStatus.Granted)
        {
            await Application.Current.MainPage.DisplayAlert("Permisos de cámara", "Los permisos de la cámara han sido denegados, active manualmente los permisos para usar esta funcionalidad", "OK");
            return;
        }
    }

    // Inicializar la cámara después de obtener los permisos
    InitializeCamera();
}

private async void Camera_OnDetected(object sender, Camera.MAUI.ZXingHelper.BarcodeEventArgs e)
{
    
    string result = e.Result[0].Text;

    if (result is null) return;

    if (viewModel.ValidaCodigo(result))
    {
        // Navegar a la página de inicio
        Shell.Current.GoToAsync("//HomePage");
        //await StopCameraAsync();
    }

}

The problem I have is the InitializeCamera, when I make the condition to detect the cameras (NumCamerasDetected) the first time I enter the view and accept the permissions, it tells me that my device has 4 cameras and that is fine, but when I enter for the second time it appears that I have 0.

It's as if the app will stop detecting them.

Is there any way to refresh or not lose the 4 cameras?

Answer 1

I can reproduce your problem. The cameraView.NumCamerasDetected will always be 0 when you enter it second. So you can use the cameraView.CamerasLoaded to get the camera.

cameraView.BarcodeDetected += Camera_OnDetected;
 // Inicializar ZXing Barcode Decoder
 cameraView.BarCodeDecoder = new ZXingBarcodeDecoder();
 cameraView.CamerasLoaded += (s, e) =>
 {
     if (cameraView.Cameras.Count > 0)
     {
         //if (cameraView.NumMicrophonesDetected > 0)
         // the cameraView.NumMicrophonesDetected is still 0 here 
         cameraView.Camera = cameraView.Cameras.FirstOrDefault();
         MainThread.BeginInvokeOnMainThread(async () =>
         {
             if (await cameraView.StartCameraAsync() == CameraResult.Success)
             {
                 // playing = true;
             }
         });
     }
 };