Question

下图显示了我的项目。

您可以在下面找到我的项目代码，以满足您的测试需求。

<Window x:Class="MainWindow" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Name="MainWindow" 
    Height="300" 
    Width="400">
<Grid>
    <Image Name="Image1" Height="100" Width="125" HorizontalAlignment="Left"/>
    <Button Name="Button1" Content="Button1" Height="30" Width="125" HorizontalAlignment="Center"/>
    <Button Name="Button2" Content="Button2" Height="30" Width="125" HorizontalAlignment="Right"/>
</Grid>
</Window>

...

Class MainWindow

Private Sub Button1_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button1.Click
    Dim myOFD As New Microsoft.Win32.OpenFileDialog
    myOFD.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
    myOFD.Filter = "Image File (*.png)|*.png"
    If myOFD.ShowDialog = True Then
        Dim myBitmap As New BitmapImage
        myBitmap.BeginInit()
        myBitmap.UriSource = New Uri(uriString:=myOFD.FileName, UriKind:=UriKind.RelativeOrAbsolute)
        myBitmap.EndInit()
        myBitmap.Freeze()
        Image1.Source = myBitmap
    End If
End Sub

Private Sub Button2_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button2.Click
    Dim myBitmapEncoder As New PngBitmapEncoder()
    myBitmapEncoder.Frames.Add(BitmapFrame.Create(Image1.Source))
End Sub

End Class

Option Strict on时，我遇到以下错误。

  

'公共共享函数Create（source As System.Windows.Media.Imaging.BitmapSource）As System.Windows.Media.Imaging.BitmapFrame'：Option Strict On禁止从System.Windows.Media.ImageSource'到'的隐式转换System.Windows.Media.Imaging.BitmapSource”。

...

  

'公共共享函数Create（bitmapStream As System.IO.Stream）As System.Windows.Media.Imaging.BitmapFrame'：'System.Windows.Media.ImageSource'类型的值无法转换为'System.IO。流”。

...

  

'公共共享函数Create（bitmapUri As System.Uri）As System.Windows.Media.Imaging.BitmapFrame'：'System.Windows.Media.ImageSource'类型的值无法转换为'System.Uri

Answer 1

使用Option Strict选项，您必须将Uri传递给BitmapFrame.Create方法，以便您的代码进行编译：

Private Sub Button2_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles Button2.Click
    Dim source = DirectCast(Image1.Source, BitmapImage)
    Dim myBitmapEncoder As New PngBitmapEncoder()
    myBitmapEncoder.Frames.Add(BitmapFrame.Create(source.UriSource))
End Sub