UWP QR-Code Scanner Exception

Question

Hallo Leute,

ich habe gerade erst mit UWP angefangen und bekomme bei meinem Code dauernd Exceptions. Es wäre super, wenn mir jemand einen Tipp geben könnte, wie ich die Probleme lösen könnte, denn ich bin echt am Ende. Entschuldigt den schlechten Code :-).

' Die Vorlage "Leere Seite" ist unter http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409 dokumentiert.

Imports System.Threading
Imports Windows.Devices.Enumeration
'Imports Windows.Devices.Sensors
Imports Windows.Media
Imports Windows.Media.Capture
Imports Windows.System.Display
Imports Windows.UI.Core
Imports Windows.UI.Popups
Imports ZXing
Imports System.Windows
Imports Windows.Graphics.Imaging
Imports Windows.Media.MediaProperties
''' <summary>
''' Eine leere Seite, die eigenständig verwendet oder zu der innerhalb eines Rahmens navigiert werden kann.
''' </summary>
Public NotInheritable Class MainPage
    Inherits Page
    Private ReadOnly _displayRequest As DisplayRequest = New DisplayRequest()
    Private ReadOnly _systemMediaControls As SystemMediaTransportControls = SystemMediaTransportControls.GetForCurrentView()
    '  Private ReadOnly _displayInformation As DisplayInformation = DisplayInformation.GetForCurrentView
    Private _mediaCapture As MediaCapture
    Dim stateTimer As Timer
    Private _isInitialized As Boolean
    Private _isPreviewing As Boolean
    Private _isRecording As Boolean
    'Private _deviceOrientation As SimpleOrientation = SimpleOrientation.NotRotated
    'Private _displayOrientation As DisplayOrientations = DisplayOrientations.Portrait
    Private _mirroringPreview As Boolean
    Private Shared ReadOnly RotationKey As Guid = New Guid("C380465D-2271-428C-9B83-ECEA3B4A85C1")
    Private _externalCamera As Boolean
    Dim localSettings As Windows.Storage.ApplicationDataContainer = Windows.Storage.ApplicationData.Current.LocalSettings
    Dim scanner As BarcodeReader
    Dim Timercallback As New TimerCallback(Async Sub() Await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, Async Sub() Await scanforbarcode()))
    Public Sub New()
        Me.InitializeComponent()
        NavigationCacheMode = NavigationCacheMode.Enabled
        AddHandler Application.Current.Suspending, AddressOf Application_Suspending
        AddHandler Application.Current.Resuming, AddressOf Application_Resuming
    End Sub
    Private Async Sub Application_Suspending(sender As Object, e As SuspendingEventArgs)
        If Frame.CurrentSourcePageType Is GetType(MainPage) Then
            Dim deferral = e.SuspendingOperation.GetDeferral()
            Await CleanupCameraAsync()
            CleanupUi()
            deferral.Complete()
        End If
    End Sub

    Private Async Sub Application_Resuming(sender As Object, o As Object)
        If Frame.CurrentSourcePageType Is GetType(MainPage) Then
            Await InitializeCameraAsync()
        End If
    End Sub
    Private Sub MainPage_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
        CheckForSettings()

    End Sub

    Private Sub MainPage_Loading(sender As FrameworkElement, args As Object) Handles Me.Loading


    End Sub


    Private Sub button_Click(sender As Object, e As RoutedEventArgs) Handles button.Click
        Frame.Navigate(GetType(SettingsPage))
    End Sub
    Private Async Sub HasToSetSettings()
        Dim Message1 As New MessageDialog("Sie starten die App zum ersten Mal. Sie werden nun zu den Einstellungen weitergeleitet!", "Weiterleiten?")
        Message1.Commands.Add(New UICommand("Einstellungen", Nothing, 0))
        Message1.Commands.Add(New UICommand("App beenden", Nothing, 1))
        Message1.DefaultCommandIndex = 0
        Message1.CancelCommandIndex = 1
        Dim result = Await Message1.ShowAsync()
        If Convert.ToInt32(result.Id) = 0 Then
            Frame.Navigate(GetType(SettingsPage))
        Else
            Application.Current.Exit()
        End If
    End Sub
    Private Sub CheckForSettings()
        If localSettings.Values.ContainsKey("CAM") = False OrElse localSettings.Values.ContainsKey("Password") = False _
            OrElse localSettings.Values.ContainsKey("Username") = False OrElse localSettings.Values.ContainsKey("ServiceURL") = False Then
            HasToSetSettings()
        End If
    End Sub
    Private Async Function StartPreviewAsync() As Task
        _displayRequest.RequestActive()
        PreviewControl.Source = _mediaCapture
        PreviewControl.FlowDirection = If(_mirroringPreview, FlowDirection.RightToLeft, FlowDirection.LeftToRight)
        Await _mediaCapture.StartPreviewAsync()
        _isPreviewing = True
        If _isPreviewing Then
            Await SetPreviewRotationAsync()
            scanner = New BarcodeReader
            AddHandler scanner.ResultFound, AddressOf scannerresultfound
            stateTimer = New Timer(Timercallback, New AutoResetEvent(False), 1500, 250)
        End If
    End Function
    Private Async Function StopPreviewAsync() As Task
        If stateTimer IsNot Nothing Then
            stateTimer.Dispose()
        End If
        RemoveHandler scanner.ResultFound, AddressOf scannerresultfound
        scanner = Nothing
        _isPreviewing = False
        Await _mediaCapture.StopPreviewAsync()
        Await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, Sub()
                                                                     PreviewControl.Source = Nothing
                                                                     _displayRequest.RequestRelease()
                                                                 End Sub)
    End Function
    Private Async Function InitializeCameraAsync() As Task

        If _mediaCapture Is Nothing Then
            If localSettings.Values.ContainsKey("CAM") = False Then
                Return
            End If
            If localSettings.Values.ContainsKey("CAM") = False Or localSettings.Values("CAM").ToString = "" Or localSettings.Values("CAM").ToString = "NOCAM" Then
                Return
            End If


            Dim cameraDevice = Await DeviceInformation.CreateFromIdAsync(localSettings.Values("CAM").ToString)
            _mediaCapture = New MediaCapture()
            Dim settings = New MediaCaptureInitializationSettings With {.VideoDeviceId = localSettings.Values("CAM").ToString}
            Try
                Await _mediaCapture.InitializeAsync(settings)
                _isInitialized = True
            Catch ex As UnauthorizedAccessException

            End Try

            If _isInitialized Then
                If cameraDevice.EnclosureLocation Is Nothing OrElse cameraDevice.EnclosureLocation.Panel = Windows.Devices.Enumeration.Panel.Unknown Then
                    _externalCamera = True
                Else
                    _externalCamera = False
                    _mirroringPreview = (cameraDevice.EnclosureLocation.Panel = Windows.Devices.Enumeration.Panel.Front)
                End If

                Await StartPreviewAsync()
            End If
        End If
    End Function
    Private Async Function SetPreviewRotationAsync() As Task
        If _externalCamera Then
            Return
        End If

        ' Calculate which way and how far to rotate the preview
        Dim rotationDegrees As Integer = 90 '= ConvertDisplayOrientationToDegrees(_displayOrientation)
        If _mirroringPreview Then
            rotationDegrees = (360 - rotationDegrees) Mod 360
        End If

        ' Add rotation metadata to the preview stream to make sure the aspect ratio / dimensions match when rendering and getting preview frames
        Dim props = _mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview)
        props.Properties.Add(RotationKey, rotationDegrees)
        Await _mediaCapture.SetEncodingPropertiesAsync(MediaStreamType.VideoPreview, props, Nothing)
    End Function
    'Private Shared Function ConvertDeviceOrientationToDegrees(orientation As SimpleOrientation) As Integer
    '    Select Case orientation
    '        Case SimpleOrientation.Rotated90DegreesCounterclockwise
    '            Return 90
    '        Case SimpleOrientation.Rotated180DegreesCounterclockwise
    '            Return 180
    '        Case SimpleOrientation.Rotated270DegreesCounterclockwise
    '            Return 270
    '        Case Else
    '            Return 0
    '    End Select
    'End Function
    'Private Shared Function ConvertDisplayOrientationToDegrees(orientation As DisplayOrientations) As Integer
    '    Select Case orientation
    '        Case DisplayOrientations.Portrait
    '            Return 90
    '        Case DisplayOrientations.LandscapeFlipped
    '            Return 180
    '        Case DisplayOrientations.PortraitFlipped
    '            Return 270
    '        Case Else
    '            Return 0
    '    End Select
    'End Function
    'Private Async Sub DisplayInformation_OrientationChanged(sender As DisplayInformation, args As Object)
    '    _displayOrientation = sender.CurrentOrientation
    '    If _isPreviewing Then
    '        Await SetPreviewRotationAsync()
    '    End If
    'End Sub
    Protected Overrides Async Sub OnNavigatedTo(e As NavigationEventArgs)
        If Pivot1.SelectedIndex = 0 Then
            Await InitializeCameraAsync()
        End If
    End Sub
    Protected Overrides Async Sub OnNavigatingFrom(e As NavigatingCancelEventArgs)
        If Pivot1.SelectedIndex = 0 Then
            Await CleanupCameraAsync()
            CleanupUi()
        End If
    End Sub
    Private Async Function CleanupCameraAsync() As Task
        If _isInitialized Then
            If _isPreviewing Then
                Await StopPreviewAsync()
            End If
            _isInitialized = False
        End If

        If _mediaCapture IsNot Nothing Then
            _mediaCapture.Dispose()
            _mediaCapture = Nothing
        End If
    End Function
    Private Sub CleanupUi()
        UnregisterEventHandlers()
        '  DisplayInformation.AutoRotationPreferences = DisplayOrientations.None
    End Sub
    Private Sub UnregisterEventHandlers()
        '   RemoveHandler _displayInformation.OrientationChanged, AddressOf DisplayInformation_OrientationChanged
    End Sub
    Private Async Function scanforbarcode() As Task
        Try
            Dim Frame As VideoFrame
            Dim previewProperties = TryCast(_mediaCapture.VideoDeviceController.GetMediaStreamProperties(MediaStreamType.VideoPreview), VideoEncodingProperties)
            Dim VideoFrame As New VideoFrame(BitmapPixelFormat.Bgra8, Convert.ToInt32(previewProperties.Width), Convert.ToInt32(previewProperties.Height))
            Frame = Await _mediaCapture.GetPreviewFrameAsync(VideoFrame)
            If Frame Is Nothing Then
                Exit Function
            End If

            Dim previewFrame As SoftwareBitmap = Frame.SoftwareBitmap
            Dim sbSource = Frame.SoftwareBitmap
            Dim BMP As New WriteableBitmap(Convert.ToInt32(previewProperties.Width), Convert.ToInt32(previewProperties.Height))
            sbSource.CopyToBuffer(BMP.PixelBuffer)
            image.Source = BMP
            scanner.Decode(BMP)
        Catch ex As Exception
            Debug.WriteLine("MESSAGE FROM SCANFORBARCODE():" & ex.Message)
        End Try
    End Function
    Private Sub scannerresultfound(ByVal result As Result)
        Debug.WriteLine("RESULT: " & result.Text)
        If result.Text = "call:settings" Then
            Frame.Navigate(GetType(SettingsPage))
        End If
    End Sub
    Private Async Sub Pivot1_SelectionChanged(sender As Object, e As SelectionChangedEventArgs) Handles Pivot1.SelectionChanged
        If Pivot1.SelectedIndex = 0 Then
            Await InitializeCameraAsync()
        Else
            Await CleanupCameraAsync()
            CleanupUi()
        End If
    End Sub
End Class

Hier noch die Exceptions:

Ausnahme ausgelöst: "System.OutOfMemoryException" in mscorlib.ni.dll
MESSAGE FROM SCANFORBARCODE():Insufficient memory to continue the execution of the program.
Ausnahme ausgelöst: "<Unbekannt>" in Unbekanntes Modul.
Das Programm "[5192] Event_APP.exe" wurde mit Code -1 (0xffffffff) beendet.

Ausnahme ausgelöst: "System.Exception" in mscorlib.ni.dll
MESSAGE FROM SCANFORBARCODE():The request is invalid in the current state. (Exception from HRESULT: 0xC00D36B2)

Ausnahme ausgelöst: "System.NullReferenceException" in Event_APP.exe
MESSAGE FROM SCANFORBARCODE():Object reference not set to an instance of an object.

Vielen Dank,

Bodenseecoder

Answer 1

Wenn du so tust als ob du dein Problem vernünftig beschrieben hast, dann tue ich mal so als ob ich da vernünftig drauf antworte :-)

Setz mal einen Breakpoint und debugge das durch. Dann weist du zumindest wo der Fehler wirklich entsteht.

Answer 2

Wenn du so tust als ob du dein Problem vernünftig beschrieben hast, dann tue ich mal so als ob ich da vernünftig drauf antworte :-)

YMMD :)

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Gruß, Stefan
Microsoft MVP - Visual Developer ASP/ASP.NET
http://www.asp-solutions.de/ - Consulting, Development
http://www.aspnetzone.de/ - ASP.NET Zone, die ASP.NET Community