TreeView.CheckBoxes TreeView.CheckBoxes TreeView.CheckBoxes TreeView.CheckBoxes Property

定義

取得或設定值,指出樹狀檢視控制項的樹狀節點旁是否顯示核取方塊。Gets or sets a value indicating whether check boxes are displayed next to the tree nodes in the tree view control.

public:
 property bool CheckBoxes { bool get(); void set(bool value); };
public bool CheckBoxes { get; set; }
member this.CheckBoxes : bool with get, set
Public Property CheckBoxes As Boolean

屬性值

如果樹狀檢視控制項的每個樹狀節點旁都顯示核取方塊,則為 true,否則為 falsetrue if a check box is displayed next to each tree node in the tree view control; otherwise, false. 預設為 falseThe default is false.

範例

下列程式碼範例示範如何變更的折迭狀態TreeView ,讓所有已檢查的節點都可以看到。The following code example demonstrates how to change the collapse state of a TreeView so that all the checked nodes are visible. 首先,會折迭所有節點,並為BeforeExpand事件新增處理常式。First, all the nodes are collapsed, and a handler is added for the BeforeExpand event. 接下來,所有節點都會展開。Next, all the nodes are expanded. BeforeExpand事件處理常式會判斷指定的節點是否有已核取的子節點。The BeforeExpand event handler determines whether a given node has child nodes that are checked. 如果節點沒有已核取的子系,則會取消該節點的展開。If a node does not have checked children, the expansion is canceled for that node. 若要在按一下節點旁邊的加號時允許標準節點展開, BeforeExpand則會移除事件處理常式。In order to allow standard node expansion when the plus sign next to a node is clicked, the BeforeExpand event handler is then removed.

此行為也可以藉由處理BeforeCollapse事件來執行,如該主題的範例所示。This behavior can also be implemented by handling the BeforeCollapse event, as illustrated in the example for that topic.

#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 );
}
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;
    }

}
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

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

    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

    ' 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

    ' 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 

備註

樹狀節點標籤和樹狀節點Image的左邊都會顯示一個核取方塊(如果有的話)。A check box is displayed to the left of both the tree node label and tree node Image, if any. 核取方塊可讓使用者一次選取一個以上的樹狀節點。Check boxes allow the user to select more than one tree node at a time.

TreeView true TreeView TreeNode StateImageList當的CheckBoxes屬性設定為,且屬性已設定時,包含在中的每個都會顯示中的第一個和第二StateImageList個影像,表示未檢查或已檢查的狀態。When the CheckBoxes property of a TreeView is set to true, and the StateImageList property is set, each TreeNode that is contained in the TreeView displays the first and second images from the StateImageList to indicate an unchecked or checked state, respectively. 不過,如果發生下列情況,顯示的影像可能會不同:如果節點SelectedImageIndex的設定為0或1以外的值, CheckBoxes而且父系TreeView的屬性設定為falseSelectedImageIndex則不會自動重設為-1,表示未設定。However, the displayed images may be different if the following situation occurs: If the SelectedImageIndex of the node is set to a value other than 0 or 1, and the CheckBoxes property of the parent TreeView is set to false, the SelectedImageIndex will not automatically reset to -1 to indicate it is not set. 在此情況下,會顯示位於指定索引位置的狀態影像。In this case, the state image at the indicated index position is shown. 如果CheckBoxes再次設定為trueStateImageList會顯示的第一個和第二個影像,分別表示已檢查或未核取的狀態。If CheckBoxes is set to true again, the first and second images of the StateImageList are shown to indicate a checked or unchecked state, respectively.

注意

在執行時間CheckBoxes設定屬性時TreeView ,會重新建立控制碼(請Control.RecreateHandle參閱)以更新控制項的外觀。When setting the CheckBoxes property at run time, the TreeView handle is recreated (see Control.RecreateHandle) to update the control's appearance. 這會使所有樹狀節點都折迭,但選取TreeNode了例外狀況。This causes all tree nodes to be collapsed, with the exception of the selected TreeNode.

適用於

另請參閱