[VB.NET]MDI子視窗清單的實作

2010-05-30

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VB.NET
2010-07-10

[VB.NET]MDI子視窗清單的實作

最近在撰寫MDI程式，碰到很多很麻煩的問題，尤其是在MDI子視窗清單功能的部分，個人覺得特別難處理。其中最麻煩的莫過於When close is cancelled on MDI Child Window and it is hidden, MDI parent's window never shows it again.這篇所提到的問題。

雖然MenuStrip內建的MDIWindowListItem十分好用，但要自行擋住為數眾多的問題，最後還是決定自己實作MDI子視窗清單的功能，好在實作這樣的功能並不困難，只要處理MenuItem的DropDownOpening與DropDownClosed事件即可，這邊簡單的紀錄一下：

        Dim separators() As ToolStripItem = WindowsMenu.DropDownItems.Find("MdiWindowListSeperator", False)
        If separators.Count = 0 Then
            Return
        End If
        Dim spIdx As Integer = WindowsMenu.DropDownItems.IndexOf(separators(0))
        For idx As Integer = WindowsMenu.DropDownItems.Count - 1 To spIdx Step -1
            WindowsMenu.DropDownItems.RemoveAt(idx)
        Next
    End Sub

    Private Sub WindowsMenu_DropDownOpening(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles WindowsMenu.DropDownOpening
        If ActiveMdiChild Is Nothing Then
            Return
        End If
        Dim sp As New ToolStripSeparator
        sp.Name = "MdiWindowListSeperator"
        WindowsMenu.DropDownItems.Add(sp)
        For Each f As Form In MdiChildren
            If Not f.Visible Then
                Continue For
            End If
            WindowsMenu.DropDownItems.Add(New ToolStripMenuItem(f.Text, Nothing, AddressOf MDIChildren_Click) With {.Checked = ActiveMdiChild Is f, .Tag = f})
        Next
    End Sub

    Private Sub MDIChildren_Click(ByVal sender As Object, ByVal e As EventArgs)
        DirectCast(DirectCast(sender, ToolStripMenuItem).Tag, Form).Activate()
    End Sub

也可以只處理MenuItem的DropDownOpening事件：

        Const seperatorKey As String = "MdiWindowListSeperator" 
        Dim dropDownItems As ToolStripItemCollection = _ideForm.WindowToolStripMenuItem.DropDownItems 
        If dropDownItems.ContainsKey(seperatorKey) Then 
            Dim spIdx As Integer = dropDownItems.IndexOf(dropDownItems.Find(seperatorKey, False)(0)) 
            For idx As Integer = dropDownItems.Count - 1 To spIdx Step -1 
                dropDownItems.RemoveAt(idx) 
            Next 
        End If 

        Dim linq = From f In _ideForm.MdiChildren Where f.Visible Select f 
        If linq.Count = 0 Then 
            Return 
        End If 
        Dim sp As New ToolStripSeparator 
        sp.Name = seperatorKey 
        dropDownItems.Add(sp) 
        For Each f As Form In linq 
            dropDownItems.Add(New ToolStripMenuItem(f.Text, Nothing, AddressOf MDIChildren_Click) With {.Checked = _ideForm.ActiveMdiChild Is f, .Tag = f}) 
        Next 
    End Sub

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