使用锚定图像（来自 MemoryStream）调整表单大小会导致 'System.ArgumentException' 和 'The application is in break mode'

Question

我有一个 TcpListener 得到源源不断的 byte array。由此，我将 byte() 转换为 MemoryStream 并提供一个 PictureBox 来显示图像。那很好用。如果我将 PictureBox 上的锚点设置为 top/right/bottom/left，这意味着图像将在表单展开时展开，然后 然后我实际展开 表单，我会收到以下错误：

An unhandled exception of type 'System.ArgumentException' occurred in System.Drawing.dll

Additional information: Parameter is not valid.

此外，

The application is in break mode

代码

 ' Enter the listening loop.
        While True
            Dim client As TcpClient = Await server.AcceptTcpClientAsync()
            Dim stream As NetworkStream = client.GetStream
            Dim MS As New MemoryStream
            Await stream.CopyToAsync(MS)
            Await ViewImage(MS)
            client.Close()
        End While

查看图片功能：

   Public Async Function ViewImage(ms As MemoryStream) As Task
        Try
            Dim myimage As Bitmap
            myimage = New Bitmap(ms)
            PictureBox1.Image = myimage
            PictureBox1.Refresh()
            myimage.Dispose()
        Catch ex As Exception
            MessageBox.Show(ex.ToString)
        End Try

    End Function

请注意，我的代码中没有捕获异常。有什么想法吗？

Answer 1

这个问题很可能与您 dispose myimage 在 ViewImage()方法。

这个：

PictureBox1.Image = myimage
...
myimage.Dispose()

使myimage和PictureBox1.Image指向同一个Bitmap对象。位图是引用类型 (类)，这意味着当您将其分配给不同的变量时，您只是在传递它们的引用指针。

因此，当您处理 myimage 时，您处理的是 PictureBox 中显示的相同图像，当 GDI+ 尝试重绘它的拉伸版本时，这可能会导致您的错误（事实上，即使是原始图像也不会在您处理后显示出来。

有关详细信息，请参阅：Value Types and Reference Types - Microsoft Docs。

引用类型和值类型如何工作的基本示例

引用类型：

Dim A As New Bitmap("image.bmp")

Dim B As Bitmap = A 'Points to A.
PictureBox1.Image = A 'Points to A.
PictureBox2.Image = B 'Still points to A.

'Calling Dispose() on any of the above will result in none of them having an image since you will ultimately dispose bitmap A.

值类型：

Dim A As Integer = 3

Dim B As Integer = A 'Copy of A.
Dim C As Integer = B 'Copy of B.

C = 4 'Results in A = 3, B = 3, C = 4.

使用锚定图像（来自 MemoryStream）调整表单大小会导致 'System.ArgumentException' 和 'The application is in break mode'

Resizing form with anchored image (from MemoryStream) causes 'System.ArgumentException' and 'The application is in break mode'

vb.net

tcpclient

tcplistener