如何使用值转换器将字节数组绑定到WPF中的图像？ [英] How do I bind a Byte array to an Image in WPF with a value converter?

问题描述

我正在尝试将一个Byte数组从我的数据库绑定到WPF图像。

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

我的XAML：

<Window.Resources>
    <local:BinaryImageConverter x:Key="imgConverter" />
</Window.Resources>
...
<Image Source="{Binding Path=ImageData, Converter={StaticResource imgConverter}}" />

我已修改由 Ryan Cromwell 的价值转换器： p>

I've modified code published by Ryan Cromwell for a value converter:

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 bytes As Byte() = TryCast(value, Byte())
            Dim stream As New MemoryStream(bytes)
            Dim image As New BitmapImage()
            image.BeginInit()
            image.StreamSource = stream
            image.EndInit()
            Return image
        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

我 mage.EndInit（） BinaryImageConverter的Convert（）函数的行会抛出 NotSupportedException ：

The image.EndInit() line of the BinaryImageConverter's Convert() function throws this NotSupportedException:

$ b $

InnerException：
中的异常HRESULT：0x88982F50

InnerException: "Exception from HRESULT: 0x88982F50"

我不明白我在做错什么如何获得这项工作？

I don't understand what I'm doing wrong. How can I get this working?

似乎问题是从数据库出来的字节。一定是我的方式出现问题。

It seems the problem was the bytes coming out of the database. There must have been a problem with the way I was putting them in.

请看下面的工作代码。

推荐答案

感谢您的帮助。我现在已经工作了我仍然不确定问题是什么。

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

这是我将图像放入我的数据库…

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

这是我使用的值转换器将Byte数组绑定到Image…

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

这是我的XAML，使用转换器显示图像…

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

<Window xmlns:local="clr-namespace:MyProjectName" ... >
    <Window.Resources>
        <local:BinaryImageConverter x:Key="imgConverter" />
    </Window.Resources>
...
<Image Source="{Binding Path=ImageData, Converter={StaticResource imgConverter}}" />

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