How do I bind a Byte array to an Image in WPF with a value converter?

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逝去的感伤
逝去的感伤 2020-12-03 05:59

I\'m trying to bind a Byte array from my databse to a WPF Image.

My XAML:


    

        
5条回答
  •  时光取名叫无心
    2020-12-03 06:07

    Thanks for all your help. I've now got it working. I'm still not sure exactly what the problem was.

    This is how I put images into my database…

    Private Sub ButtonUpload_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        Dim FileOpenStream As Stream = Nothing
        Dim FileBox As New Microsoft.Win32.OpenFileDialog()
        FileBox.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures)
        FileBox.Filter = "Pictures (*.jpg;*.jpeg;*.gif;*.png)|*.jpg;*.jpeg;*.gif;*.png|" & _
                         "All Files (*.*)|*.*"
        FileBox.FilterIndex = 1
        FileBox.Multiselect = False
        Dim FileSelected As Nullable(Of Boolean) = FileBox.ShowDialog(Me)
        If FileSelected IsNot Nothing AndAlso FileSelected.Value = True Then
            Try
                FileOpenStream = FileBox.OpenFile()
                If (FileOpenStream IsNot Nothing) Then
    
                    Dim ByteArray As Byte()
                    Using br As New BinaryReader(FileOpenStream)
                        ByteArray = br.ReadBytes(FileOpenStream.Length)
                    End Using
    
                    Dim g As New ZackGraphic
                    g.Id = Guid.NewGuid
                    g.ImageData = ByteArray
                    g.FileSize = CInt(ByteArray.Length)
                    g.FileName = FileBox.FileName.Split("\").Last
                    g.FileExtension = "." + FileBox.FileName.Split(".").Last.ToLower
                    g.DateAdded = Now
    
                    Dim bmp As New BitmapImage
                    bmp.BeginInit()
                    bmp.StreamSource = New MemoryStream(ByteArray)
                    bmp.EndInit()
                    bmp.Freeze()
    
                    g.PixelWidth = bmp.PixelWidth
                    g.PixelHeight = bmp.PixelHeight
    
                    db.AddToZackGraphic(g)
                    db.SaveChanges()
    
                End If
            Catch Ex As Exception
                MessageBox.Show("Cannot read file from disk. " & Ex.Message, "Add a New Image", MessageBoxButton.OK, MessageBoxImage.Error, MessageBoxResult.OK)
            Finally
                If (FileOpenStream IsNot Nothing) Then
                    FileOpenStream.Close()
                End If
            End Try
        End If
    End Sub
    

    This is my value converter used to bind a Byte array to an Image…

    Class BinaryImageConverter
        Implements IValueConverter
        Private Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.Convert
            If value IsNot Nothing AndAlso TypeOf value Is Byte() Then
                Dim ByteArray As Byte() = TryCast(value, Byte())
                Dim bmp As New BitmapImage()
                bmp.BeginInit()
                bmp.StreamSource = New MemoryStream(ByteArray)
                bmp.EndInit()
                Return bmp
            End If
            Return Nothing
        End Function
        Private Function ConvertBack(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack
            Throw New Exception("The method or operation is not implemented.")
        End Function
    End Class
    

    This is my XAML that uses the converter display the image…

    
        
            
        
    ...
    
    

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