显示 MDI 子窗体后等待 - DoEvents 的替代方法

Question

一位同事对我的应用程序进行了一些改进，但与此同时，他将整个应用程序更改为使用 MDI 子窗体。因此，我以前可以使用 ShowDialog() 使子例程等到新表单关闭后再继续，现在我不能了。我改编了一些旧的 VB6 代码来尝试复制相同的功能，但它使用 DoEvents() 并且我被告知要不惜一切代价避免这种情况。

在这一点上，我不禁觉得我的方法有一个根本性的缺陷，可能有更简单的方法来完成同样的任务。

    Private Sub Label_EditNode_Click(sender As Object, e As EventArgs) Handles Label_EditNode.Click
        Dim Frm As New frmVariableEditor With {
            .Tag = "FrmVariableEditor",
            .MdiParent = FrmMDIMain,
            .Dock = DockStyle.Fill,
            .Location = Me.Location,
            .Size = Me.Size,
            .myFieldName = "NodeClick",
            .myResultText = txbNodeClick.Text
        }

        Frm.Show()
        Call WaitOnFormUnload()

        txbNodeClick.Text = Frm.myResultText
    End Sub

    Public Sub WaitOnFormUnload()
        Dim bIsLoaded As Boolean = True
        Dim FormName As String = Me.MdiParent.ActiveMdiChild.Name ' Form.ActiveForm.Name
        Do While bIsLoaded
            bIsLoaded = False

            For Each f As Form In Application.OpenForms
                If f.Name = FormName Then
                    bIsLoaded = True
                    Application.DoEvents()
                    Exit For ' breaks the for loop
                End If
            Next f
        Loop
    End Sub

Answer 1

像这样：

Private Sub Label_EditNode_Click(sender As Object, e As EventArgs) Handles Label_EditNode.Click
    Dim Frm As New frmVariableEditor With {
        .Tag = "FrmVariableEditor",
        .MdiParent = FrmMDIMain,
        .Dock = DockStyle.Fill,
        .Location = Me.Location,
        .Size = Me.Size,
        .myFieldName = "NodeClick",
        .myResultText = txbNodeClick.Text
    }

    AddHandler Frm.FormClosing, AddressOf RetrieveBlahData

    Frm.Show()

End Sub

Private Sub RetrieveBlahData(sender as Object, e as FormClosingEventArgs)
   txbNodeClick.Text = DirectCast(sender, frmVariableEditor).myResultText
End Sub

可能没有比这更小的了，除了可能共享一个数据对象：

    Dim Frm As New frmVariableEditor With {
        .Tag = "FrmVariableEditor",
        .MdiParent = FrmMDIMain,
        .Dock = DockStyle.Fill,
        .Location = Me.Location,
        .Size = Me.Size,
        .myFieldName = "NodeClick",
        .DataSetToBindTo = Me.DataSetWhatever
    }

您必须重新编码您的表单，以便它接受传入的数据集（或其他数据容器）并从中获取数据（数据绑定）..然后当编辑器表单更改数据时，它实际上也在主窗体中更改原始数据集，因为它们是同一回事

显示 MDI 子窗体后等待 - DoEvents 的替代方法

Wait after showing MDI child form - alternative to DoEvents

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