Question

我有2个表单，1个MainForm和1个Form2。我试图将Form2显示为MainForm的模态形式和背景。这是我到目前为止所拥有的。

出现默认的MainForm，5秒后，它将从后台线程将Form2显示为Modal表单。我关闭Form2，如果使用ShowDialog再次显示相同的Form2，则表单不是模态的。如何确保显示的Form2始终是模态的？

Public Class MainForm
    Dim frm2 As Form2
    Private Sub MainForm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        frm2 = New Form2()
        Dim frmHandle As IntPtr = frm2.Handle
        frm2.Button1.Text = "test"

        System.Threading.ThreadPool.QueueUserWorkItem(New System.Threading.WaitCallback(AddressOf DoSomething), 0)
    End Sub

    Private Sub DoSomething()

        'call show dialog first time
        Threading.Thread.Sleep(5000)
        If frm2.InvokeRequired Then
            frm2.Invoke(New Action(AddressOf frm2.ShowDialog))
        Else
            frm2.ShowDialog()
        End If

        'call show dialog second time
        If frm2.InvokeRequired Then
            frm2.Invoke(New Action(AddressOf frm2.ShowDialog))
        Else
            frm2.ShowDialog()
        End If

    End Sub
End Class

Answer 1

在showDialog中，您可以设置导致子项成为模态的父窗体：

Public Class MainForm
Dim frm2 As Form2
Private Sub MainForm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    frm2 = New Form2()
    Dim frmHandle As IntPtr = frm2.Handle
    frm2.Button1.Text = "test"

    System.Threading.ThreadPool.QueueUserWorkItem(New System.Threading.WaitCallback(AddressOf DoSomething), 0)
End Sub

Private Sub DoSomething()
    Dim myAction as Action(Of System.Windows.Forms.IWin32Window)

    'call show dialog first time
    Threading.Thread.Sleep(5000)
    If Me.InvokeRequired Then
        myAction = AddressOf frm2.ShowDialog
        Me.Invoke(myAction(Me))
    Else
        frm2.ShowDialog(Me)
    End If

    'call show dialog second time
    If Me.InvokeRequired Then
        myAction = AddressOf frm2.ShowDialog
        Me.Invoke(myAction(Me))
    Else
        frm2.ShowDialog(Me)
    End If

End Sub
End Class

您可以使用以下方法缩短代码：

New Action(Of System.Windows.Forms.IWin32Window)(AddressOf frm2.ShowDialog), Me)

调用表单showdialog不是模态的

1 个答案: