treeview中check复选事件

最新推荐文章于 2018-11-19 16:32:34 发布

原创最新推荐文章于 2018-11-19 16:32:34 发布 · 703 阅读

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CC 4.0 BY-SA版权

文章标签：

#tree #object #each #user

本文介绍如何在TreeView控件中实现节点全选和反选功能。通过`BeforeCheck`或`AfterCheck`事件，当父节点状态改变时，递归更新所有子节点的检查状态，确保父子节点状态同步。

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注必须把treeview中的一个父节点设置为treenode，但他的状态改变时会自动调用这个函数。达到全选的目的。

' 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