TreeViewCancelEventHandler 대리자

아티클
08/21/2007

TreeView의 BeforeCheck, BeforeCollapse, BeforeExpand 또는 BeforeSelect 이벤트를 처리할 메서드를 나타냅니다.

네임스페이스: System.Windows.Forms
어셈블리: System.Windows.Forms(system.windows.forms.dll)

구문

‘선언
Public Delegate Sub TreeViewCancelEventHandler ( _
    sender As Object, _
    e As TreeViewCancelEventArgs _
)
‘사용 방법
Dim instance As New TreeViewCancelEventHandler(AddressOf HandlerMethod)

public delegate void TreeViewCancelEventHandler (
    Object sender,
    TreeViewCancelEventArgs e
)

public delegate void TreeViewCancelEventHandler (
    Object^ sender, 
    TreeViewCancelEventArgs^ e
)

/** @delegate */
public delegate void TreeViewCancelEventHandler (
    Object sender, 
    TreeViewCancelEventArgs e
)

JScript에서는 대리자를 사용할 수 있지만 새로 선언할 수는 없습니다.

매개 변수

sender
이벤트 소스입니다.

e
이벤트 데이터가 들어 있는 TreeViewCancelEventArgs입니다.

설명

TreeViewCancelEventArgs 대리자를 만드는 경우 이벤트를 처리할 메서드를 결정합니다. 이벤트를 이벤트 처리기와 연결하려면 대리자의 인스턴스를 해당 이벤트에 추가합니다. 대리자를 제거하지 않는 경우 이벤트가 발생할 때마다 이벤트 처리기가 호출됩니다. 이벤트 처리기 대리자에 대한 자세한 내용은 이벤트 및 대리자를 참조하십시오.

예제

다음 예제에서는 선택된 노드가 모두 표시되도록 TreeView의 축소 상태를 변경하는 방법을 보여 줍니다. 먼저 모든 노드가 축소되고 TreeView.BeforeExpand 이벤트에 대한 처리기가 추가됩니다. 다음에는 모든 노드가 확장됩니다. TreeView.BeforeExpand 이벤트 처리기는 특정 노드에 선택된 자식 노드가 있는지 여부를 확인합니다. 노드에 선택된 자식 노드가 없으면 해당 노드에 대한 확장이 취소됩니다. 그런 다음 노드 옆의 더하기 기호를 클릭할 때 일반적인 노드 확장 작업을 허용하기 위해 TreeView.BeforeExpand 이벤트 처리기가 제거됩니다.

이 동작은 해당 항목에 대한 예제에서 보여 준 것처럼 TreeView.BeforeCollapse 이벤트를 처리하여 구현할 수도 있습니다.

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Public Class Form1
    Inherits Form
    Private treeView1 As TreeView
    Private showCheckedNodesButton As Button

    Public Sub New()
        treeView1 = New TreeView
        showCheckedNodesButton = New Button

        Me.SuspendLayout()

        ' Initialize treeView1.
        treeView1.Location = New Point(0, 25)
        treeView1.Size = New Size(292, 248)
        treeView1.Anchor = AnchorStyles.Top Or AnchorStyles.Left Or AnchorStyles.Bottom Or AnchorStyles.Right
        treeView1.CheckBoxes = True

        ' Add nodes to treeView1.
        Dim node As TreeNode
        Dim x As Integer
        For x = 0 To 3
            ' Add a root node.
            node = treeView1.Nodes.Add(String.Format("Node{0}", x * 4))
            Dim y As Integer
            For y = 1 To 4
                ' Add a node as a child of the previously added node.
                node = node.Nodes.Add(String.Format("Node{0}", x * 4 + y))
            Next y
        Next x

        ' Set the checked state of one of the nodes to
        ' demonstrate the showCheckedNodesButton button behavior.
        treeView1.Nodes(1).Nodes(0).Nodes(0).Checked = True

        ' Initialize showCheckedNodesButton.
        showCheckedNodesButton.Size = New Size(144, 24)
        showCheckedNodesButton.Text = "Show Checked Nodes"
        AddHandler showCheckedNodesButton.Click, AddressOf showCheckedNodesButton_Click

        ' Initialize the form.
        Me.ClientSize = New Size(292, 273)
        Me.Controls.AddRange(New Control() {showCheckedNodesButton, treeView1})

        Me.ResumeLayout(False)
    End Sub 'New

    <STAThreadAttribute()> _
    Shared Sub Main()
        Application.Run(New Form1)
    End Sub 'Main

    Private Sub showCheckedNodesButton_Click(ByVal sender As Object, ByVal e As EventArgs)
        ' Disable redrawing of treeView1 to prevent flickering 
        ' while changes are made.
        treeView1.BeginUpdate()

        ' Collapse all nodes of treeView1.
        treeView1.CollapseAll()

        ' Add the CheckForCheckedChildren event handler to the BeforeExpand event.
        AddHandler treeView1.BeforeExpand, AddressOf CheckForCheckedChildren

        ' Expand all nodes of treeView1. Nodes without checked children are 
        ' prevented from expanding by the checkForCheckedChildren event handler.
        treeView1.ExpandAll()

        ' Remove the checkForCheckedChildren event handler from the BeforeExpand 
        ' event so manual node expansion will work correctly.
        RemoveHandler treeView1.BeforeExpand, AddressOf CheckForCheckedChildren

        ' Enable redrawing of treeView1.
        treeView1.EndUpdate()
    End Sub 'showCheckedNodesButton_Click

    ' Prevent expansion of a node that does not have any checked child nodes.
    Private Sub CheckForCheckedChildren(ByVal sender As Object, ByVal e As TreeViewCancelEventArgs)
        If Not HasCheckedChildNodes(e.Node) Then
            e.Cancel = True
        End If
    End Sub 'CheckForCheckedChildren

    ' Returns a value indicating whether the specified 
    ' TreeNode has checked child nodes.
    Private Function HasCheckedChildNodes(ByVal node As TreeNode) As Boolean
        If node.Nodes.Count = 0 Then
            Return False
        End If
        Dim childNode As TreeNode
        For Each childNode In node.Nodes
            If childNode.Checked Then
                Return True
            End If
            ' Recursively check the children of the current child node.
            If HasCheckedChildNodes(childNode) Then
                Return True
            End If
        Next childNode
        Return False
    End Function 'HasCheckedChildNodes

End Class 'Form1

using System;
using System.Drawing;
using System.Windows.Forms;

public class Form1 : Form
{
    private TreeView treeView1;
    private Button showCheckedNodesButton;
    private TreeViewCancelEventHandler checkForCheckedChildren;

    public Form1()
    {
        treeView1 = new TreeView();
        showCheckedNodesButton = new Button();
        checkForCheckedChildren = 
            new TreeViewCancelEventHandler(CheckForCheckedChildrenHandler);

        this.SuspendLayout();

        // Initialize treeView1.
        treeView1.Location = new Point(0, 25);
        treeView1.Size = new Size(292, 248);
        treeView1.Anchor = AnchorStyles.Top | AnchorStyles.Left | 
            AnchorStyles.Bottom | AnchorStyles.Right;
        treeView1.CheckBoxes = true;

        // Add nodes to treeView1.
        TreeNode node;
        for (int x = 0; x < 3; ++x)
        {
            // Add a root node.
            node = treeView1.Nodes.Add(String.Format("Node{0}", x*4));
            for (int y = 1; y < 4; ++y)
            {
                // Add a node as a child of the previously added node.
                node = node.Nodes.Add(String.Format("Node{0}", x*4 + y));
            }
        }

        // Set the checked state of one of the nodes to
        // demonstrate the showCheckedNodesButton button behavior.
        treeView1.Nodes[1].Nodes[0].Nodes[0].Checked = true;

        // Initialize showCheckedNodesButton.
        showCheckedNodesButton.Size = new Size(144, 24);
        showCheckedNodesButton.Text = "Show Checked Nodes";
        showCheckedNodesButton.Click += 
            new EventHandler(showCheckedNodesButton_Click);

        // Initialize the form.
        this.ClientSize = new Size(292, 273);
        this.Controls.AddRange(new Control[] 
            { showCheckedNodesButton, treeView1 } );

        this.ResumeLayout(false);
    }

    [STAThreadAttribute()]
    static void Main() 
    {
        Application.Run(new Form1());
    }

    private void showCheckedNodesButton_Click(object sender, EventArgs e)
    {
        // Disable redrawing of treeView1 to prevent flickering 
        // while changes are made.
        treeView1.BeginUpdate();

        // Collapse all nodes of treeView1.
        treeView1.CollapseAll();

        // Add the checkForCheckedChildren event handler to the BeforeExpand event.
        treeView1.BeforeExpand += checkForCheckedChildren;

        // Expand all nodes of treeView1. Nodes without checked children are 
        // prevented from expanding by the checkForCheckedChildren event handler.
        treeView1.ExpandAll();

        // Remove the checkForCheckedChildren event handler from the BeforeExpand 
        // event so manual node expansion will work correctly.
        treeView1.BeforeExpand -= checkForCheckedChildren;

        // Enable redrawing of treeView1.
        treeView1.EndUpdate();
    }

    // Prevent expansion of a node that does not have any checked child nodes.
    private void CheckForCheckedChildrenHandler(object sender, 
        TreeViewCancelEventArgs e)
    {
        if (!HasCheckedChildNodes(e.Node)) e.Cancel = true;
    }

    // Returns a value indicating whether the specified 
    // TreeNode has checked child nodes.
    private bool HasCheckedChildNodes(TreeNode node)
    {
        if (node.Nodes.Count == 0) return false;
        foreach (TreeNode childNode in node.Nodes)
        {
            if (childNode.Checked) return true;
            // Recursively check the children of the current child node.
            if (HasCheckedChildNodes(childNode)) return true;
        }
        return false;
    }

}

#using <System.dll>
#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
public ref class Form1: public Form
{
private:
   TreeView^ treeView1;
   Button^ showCheckedNodesButton;
   TreeViewCancelEventHandler^ checkForCheckedChildren;

public:
   Form1()
   {
      treeView1 = gcnew TreeView;
      showCheckedNodesButton = gcnew Button;
      checkForCheckedChildren = gcnew TreeViewCancelEventHandler( this, &Form1::CheckForCheckedChildrenHandler );
      this->SuspendLayout();
      
      // Initialize treeView1.
      treeView1->Location = Point(0,25);
      treeView1->Size = System::Drawing::Size( 292, 248 );
      treeView1->Anchor = static_cast<AnchorStyles>(AnchorStyles::Top | AnchorStyles::Left | AnchorStyles::Bottom | AnchorStyles::Right);
      treeView1->CheckBoxes = true;
      
      // Add nodes to treeView1.
      TreeNode^ node;
      for ( int x = 0; x < 3; ++x )
      {
         
         // Add a root node.
         node = treeView1->Nodes->Add( String::Format( "Node{0}", x * 4 ) );
         for ( int y = 1; y < 4; ++y )
         {
            
            // Add a node as a child of the previously added node.
            node = node->Nodes->Add( String::Format( "Node{0}", x * 4 + y ) );

         }
      }
      
      // Set the checked state of one of the nodes to
      // demonstrate the showCheckedNodesButton button behavior.
      treeView1->Nodes[ 1 ]->Nodes[ 0 ]->Nodes[ 0 ]->Checked = true;
      
      // Initialize showCheckedNodesButton.
      showCheckedNodesButton->Size = System::Drawing::Size( 144, 24 );
      showCheckedNodesButton->Text = "Show Checked Nodes";
      showCheckedNodesButton->Click += gcnew EventHandler( this, &Form1::showCheckedNodesButton_Click );
      
      // Initialize the form.
      this->ClientSize = System::Drawing::Size( 292, 273 );
      array<Control^>^temp0 = {showCheckedNodesButton,treeView1};
      this->Controls->AddRange( temp0 );
      this->ResumeLayout( false );
   }

private:
   void showCheckedNodesButton_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      // Disable redrawing of treeView1 to prevent flickering 
      // while changes are made.
      treeView1->BeginUpdate();
      
      // Collapse all nodes of treeView1.
      treeView1->CollapseAll();
      
      // Add the checkForCheckedChildren event handler to the BeforeExpand event.
      treeView1->BeforeExpand += checkForCheckedChildren;
      
      // Expand all nodes of treeView1. Nodes without checked children are 
      // prevented from expanding by the checkForCheckedChildren event handler.
      treeView1->ExpandAll();
      
      // Remove the checkForCheckedChildren event handler from the BeforeExpand 
      // event so manual node expansion will work correctly.
      treeView1->BeforeExpand -= checkForCheckedChildren;
      
      // Enable redrawing of treeView1.
      treeView1->EndUpdate();
   }

   // Prevent expansion of a node that does not have any checked child nodes.
   void CheckForCheckedChildrenHandler( Object^ /*sender*/, TreeViewCancelEventArgs^ e )
   {
      if (  !HasCheckedChildNodes( e->Node ) )
            e->Cancel = true;
   }


   // Returns a value indicating whether the specified 
   // TreeNode has checked child nodes.
   bool HasCheckedChildNodes( TreeNode^ node )
   {
      if ( node->Nodes->Count == 0 )
            return false;

      System::Collections::IEnumerator^ myEnum = node->Nodes->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         TreeNode^ childNode = safe_cast<TreeNode^>(myEnum->Current);
         if ( childNode->Checked )
                  return true;

         // Recursively check the children of the current child node.
         if ( HasCheckedChildNodes( childNode ) )
                  return true;
      }

      return false;
   }
};

int main()
{
   Application::Run( gcnew Form1 );
}

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;

public class Form1 extends Form
{
    private TreeView treeView1;
    private Button showCheckedNodesButton;
    private TreeViewCancelEventHandler checkForCheckedChildren;

    public Form1()
    {
        treeView1 = new TreeView();
        showCheckedNodesButton = new Button();
        checkForCheckedChildren =
            new TreeViewCancelEventHandler(CheckForCheckedChildrenHandler);

        this.SuspendLayout();
        // Initialize treeView1.
        treeView1.set_Location(new Point(0, 25));
        treeView1.set_Size(new Size(292, 248));
        treeView1.set_Anchor(AnchorStyles.Top | AnchorStyles.Left
            | AnchorStyles.Bottom | AnchorStyles.Right);
        treeView1.set_CheckBoxes(true);
        // Add nodes to treeView1.
        TreeNode node;
        for (int x = 0; x < 3; ++x) {
            // Add a root node.
            node = treeView1.get_Nodes().Add(String.Format
                ("Node{0}", (Int32)(x * 4)));
            for (int y = 1; y < 4; ++y) {
                // Add a node as a child of the previously added node.
                node = node.get_Nodes().Add(String.Format
                    ("Node{0}", (Int32)(x * 4 + y)));
            }
        }
        // Set the checked state of one of the nodes to
        // demonstrate the showCheckedNodesButton button behavior.
        treeView1.get_Nodes().get_Item(1).get_Nodes().get_Item(0).
            get_Nodes().get_Item(0).set_Checked(true);
        // Initialize showCheckedNodesButton.
        showCheckedNodesButton.set_Size(new Size(144, 24));
        showCheckedNodesButton.set_Text("Show Checked Nodes");
        showCheckedNodesButton.add_Click(
            new EventHandler(showCheckedNodesButton_Click));
        // Initialize the form.
        this.set_ClientSize(new Size(292, 273));
        this.get_Controls().AddRange(new Control[]
            { showCheckedNodesButton, treeView1 });

        this.ResumeLayout(false);
    } //Form1

    public static void main(String[] args)
    {
        Application.Run(new Form1());
    } //main

    private void showCheckedNodesButton_Click(Object sender, EventArgs e)
    {
        // Disable redrawing of treeView1 to prevent flickering 
        // while changes are made.
        treeView1.BeginUpdate();
        // Collapse all nodes of treeView1.
        treeView1.CollapseAll();
        // Add the checkForCheckedChildren event handler to the
        // BeforeExpand event.
        treeView1.add_BeforeExpand(checkForCheckedChildren);
        // Expand all nodes of treeView1. Nodes without checked children are 
        // prevented from expanding by the checkForCheckedChildren event handler.
        treeView1.ExpandAll();
        // Remove the checkForCheckedChildren event handler from
        // the BeforeExpand 
        // event so manual node expansion will work correctly.
        treeView1.remove_BeforeExpand(checkForCheckedChildren);
        // Enable redrawing of treeView1.
        treeView1.EndUpdate();
    } //showCheckedNodesButton_Click

    // Prevent expansion of a node that does not have any checked child nodes.
    private void CheckForCheckedChildrenHandler(Object sender,
        TreeViewCancelEventArgs e)
    {
        if (!(HasCheckedChildNodes(e.get_Node()))) {
            e.set_Cancel(true);
        }
    } //CheckForCheckedChildrenHandler

    // Returns a value indicating whether the specified 
    // TreeNode has checked child nodes.
    private boolean HasCheckedChildNodes(TreeNode node)
    {
        if (node.get_Nodes().get_Count() == 0) {
            return false;
        }
        for (int iCtr = 0; iCtr < node.get_Nodes().get_Count(); iCtr++) {
            TreeNode childNode = node.get_Nodes().get_Item(iCtr);
            if (childNode.get_Checked()) {
                return true;
            }
            // Recursively check the children of the current child node.
            if (HasCheckedChildNodes(childNode)) {
                return true;
            }
        }
        return false;
    } //HasCheckedChildNodes
} //Form1

플랫폼

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework에서 모든 플래폼의 모든 버전을 지원하지는 않습니다. 지원되는 버전의 목록은 시스템 요구 사항을 참조하십시오.

버전 정보

.NET Framework

2.0, 1.1, 1.0에서 지원

.NET Compact Framework

2.0, 1.0에서 지원

참고 항목

참조

System.Windows.Forms 네임스페이스
TreeViewCancelEventArgs 클래스
TreeView 클래스

다음을 통해 공유