在运行时添加 TreeView 时，如何将 AfterCheck 事件处理程序添加到 TreeNode

Question

我正在尝试为 TreeNode AfterCheck 事件创建事件处理程序。我想在检查父母时检查所有孩子。唯一的问题是我不确定在运行时创建 TreeView 时如何执行此操作。此代码假定表单上已有一个名为 treeView1 的 TreeView。我需要做什么才能将 treeView1 替换为尚不存在的 TreeView？

' Updates all child tree nodes recursively. 
    Private Sub CheckAllChildNodes(treeNode As TreeNode, nodeChecked As Boolean)
        Dim node As TreeNode
        For Each node In treeNode.Nodes
            node.Checked = nodeChecked
            If node.Nodes.Count > 0 Then
                ' If the current node has child nodes, call the CheckAllChildsNodes method recursively. 
                Me.CheckAllChildNodes(node, nodeChecked)
            End If
        Next node
    End Sub

    ' NOTE   This code can be added to the BeforeCheck event handler instead of the AfterCheck event. 
    ' After a tree node's Checked property is changed, all its child nodes are updated to the same value. 
    Private Sub node_AfterCheck(sender As Object, e As TreeViewEventArgs) Handles treeView1.AfterCheck
        ' The code only executes if the user caused the checked state to change. 
        If e.Action <> TreeViewAction.Unknown Then
            If e.Node.Nodes.Count > 0 Then
                ' Calls the CheckAllChildNodes method, passing in the current  
                ' Checked value of the TreeNode whose checked state changed.  
                Me.CheckAllChildNodes(e.Node, e.Node.Checked)
            End If
        End If
    End Sub

---

正确的代码

在我添加树视图的地方，我添加了

AddHandler newTree.AfterCheck, AddressOf node_AfterCheck

然后我对上面的代码所做的就是删除它所说的地方

Handles treeView1.AfterCheck

在事件处理程序声明中。

我还能够添加另一个事件处理程序以将光标更改为 Cursors。如果您将鼠标悬停在子节点上，则为否；如果您将鼠标悬停在父节点上，则为手。这是在与后检查处理程序相同的位置添加的。

AddHandler newTree.NodeMouseHover, AddressOf node_MouseOver

这是实际的事件处理程序

' Event handler for node mouse over
    Private Sub node_MouseOver(sender As Object, e As TreeNodeMouseHoverEventArgs)

        If e.Node.Tag > 99999999 Then
            sender.Cursor = Cursors.Hand
        Else
            sender.Cursor = Cursors.No
        End If

    End Sub

Answer 1

可以指示添加到程序其他位置的新 TreeNode 对象使用相同的 AfterCheck 方法，例如通过写

Dim myTreeView As New TreeView 'create a new tree view
AddHandler myTreeView.AfterCheck, AddressOf node_AfterCheck 'add this speficic AfterCheck callback to the new TreeView.
'Add myTreeView to the GUI..