自定义控件之DataGridView列（下拉列表树）

最新推荐文章于 2024-09-20 09:13:36 发布

wzuomin

最新推荐文章于 2024-09-20 09:13:36 发布

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文章标签： dropdown integer class object function string

本文链接：https://blog.youkuaiyun.com/wzuomin/article/details/1653619

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本文介绍了一个自定义控件的实现，该控件将DataGridView列转化为下拉列表树的形式。通过创建`DataGridViewTreeViewColumn`、`ComboBoxTreeView`和`DataGridViewTreeViewCell`类，实现了在单元格中显示可展开的树形结构。用户在单元格内双击或点击时会展示下拉列表树，选择节点后，单元格显示所选节点文本。测试代码展示了如何填充树形结构的数据。

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效果图如下：

代码如下：
Public Class DataGridViewTreeViewColumn
    Inherits DataGridViewColumn

    Public Sub New()
        MyBase.New(New DataGridViewTreeViewCell)
    End Sub

    Public Overrides Property CellTemplate() As System.Windows.Forms.DataGridViewCell
        Get
            Return MyBase.CellTemplate
        End Get
        Set(ByVal value As System.Windows.Forms.DataGridViewCell)
            If value IsNot Nothing And Not value.GetType.IsAssignableFrom(GetType(DataGridViewTreeViewCell)) Then
                Throw New InvalidCastException("不是DataGridViewTreeViewCell")
            End If
            MyBase.CellTemplate = value
        End Set
    End Property
End Class

Public Class ComboBoxTreeView
    Inherits ComboBox

    Private Const WN_LBUTTONDOWN = &H201
    Private Const WM_LBUTTONDBLCLK = &H203
    Private treeViewHost As ToolStripControlHost
    Private Shadows dropDown As ToolStripDropDown

    Public Sub New()
        Dim treeView As TreeView = New TreeView
        AddHandler treeView.AfterSelect, AddressOf Me.treeView_AfterSelect

        treeViewHost = New ToolStripControlHost(treeView)
        dropDown = New ToolStripDropDown
        dropDown.Width = Me.Width
        dropDown.Items.Add(treeViewHost)
    End Sub

    Private Sub treeView_AfterSelect(ByVal sender As Object, ByVal e As TreeViewEventArgs)
        Me.Text = TreeView.SelectedNode.text
        dropDown.Close()
    End Sub

    Public ReadOnly Property TreeView() As TreeView
        Get
            Return CType(treeViewHo

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