如何使用值转换器将字节数组绑定到 WPF 中的图像？

Question

我正在尝试将 Byte 数组从我的数据库绑定到 WPF 图像。

我的 XAML：

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

我已经修改了Ryan Cromwell 发布的代码，用于值转换器：

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

BinaryImageConverter 的 Convert() 函数的 image.EndInit() 行抛出此 NotSupportedException：

"没有适合的成像组件 完成此操作已找到。”

InnerException: "异常来自 HRESULT: 0x88982F50"

我不明白我做错了什么。我怎样才能让它工作？

---

更新

问题似乎出在数据库中的字节数上。我放入它们的方式一定有问题。

在下面查看我的工作代码。

Answer 1

您可以将 byte[] 绑定到 Image。

这里是一个示例：

Xaml：

<Image Source="{Binding UserImage}"/>

代码：

private byte[] userImage;

public byte[] UserImage
   {
       get { return userImage; }
       set
       {
           if (value != userImage)
           {
               userImage = value;
               OnPropertyChanged("UserImage");
           }
       }
   }

Answer 2

感谢您的所有帮助。我现在已经开始工作了。我仍然不确定到底是什么问题。

这就是我将图像放入数据库的方式……

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

这是我用来将字节数组绑定到图像的值转换器……

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

这是我使用转换器显示图像的 XAML……

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

Answer 3

试试这个

Dim imageSource as ImageSource
Dim bitmapDecoder = new PngBitmapDecoder(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
imageSource = bitmapDecoder.Frames[0];
imageSource.Freeze();
Return imageSource

Answer 4

我的猜测是字节不是合法的图像格式。我认为错误码对应WINCODEC_ERR_COMPONENTNOTFOUND，这将与无效字节一致。

字节数组应该采用什么格式？你能把它保存到磁盘上，然后尝试用另一个图像程序打开它吗？

Answer 5

我相信这实际上是一个安全权限问题。尝试以管理员权限运行，看看是否可行，然后从那里开始。

编辑：我不同意反对票和评论。看看这个链接：

http://social.expression.microsoft.com/Forums/en-US/wpf/thread/617f6711-0373-44cc-b72c-aeae20f0f7a8/

这个用户有完全相同的错误，它是由安全设置引起的。因此，我坚持我的回答（这可能不是原因，但肯定值得一试）