VB.NET跨线程操作无效

Question

我有一个循环(BackgroundWorker)，它非常频繁地更改图片框的位置，但我得到了一个错误-

Cross-thread operation not valid: Control 'box1' accessed from a thread other than the
  thread it was created on.

我一点也不明白，所以我希望有人能帮助我解决这个问题。

代码：

  box1.Location = New Point(posx, posy)

Answer 1

当您尝试从创建控制的线程以外的线程访问控制时，将引发此异常。

要解决此问题，您需要使用控件的InvokeRequired属性来查看是否需要更新，而要更新控件，则需要使用委托。我认为您需要在backgroundWorker_DoWork方法中执行此操作

Private Delegate Sub UpdatePictureBoxDelegate(Point p)

Dim del As New UpdatePictureBoxDelegate(AddressOf UpdatePictureBox)

Private Sub UpdatePictureBox(Point p)
    If pictureBoxVariable.InvokeRequired Then

        Dim del As New UpdatePictureBoxDelegate(AddressOf UpdatePictureBox)
        pictureBoxVariable.Invoke(del, New Object() {p})
    Else
        ' this is UI thread     
    End If
End Sub

Answer 2

对于遇到此错误的其他人：

尝试dispatcher对象：MSDN

我的代码：

Private _dispatcher As Dispatcher

Private Sub ThisAddIn_Startup(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Startup
    _dispatcher = Dispatcher.CurrentDispatcher
End Sub

Private Sub otherFunction()
    ' Place where you want to make the cross thread call
   _dispatcher.BeginInvoke(Sub() ThreadSafe())
End Sub

Private Sub ThreadSafe()
    ' here you can make the required calls
End Sub