TreeView::CheckBoxes Property


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Gets or sets a value indicating whether check boxes are displayed next to the tree nodes in the tree view control.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

property bool CheckBoxes {
	bool get();
	void set(bool value);

Property Value

Type: System::Boolean

true if a check box is displayed next to each tree node in the tree view control; otherwise, false. The default is false.

A check box is displayed to the left of both the tree node label and tree node Image, if any. Check boxes allow the user to select more than one tree node at a time.

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. 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. In this case, the state image at the indicated index position is shown. 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.


When setting the CheckBoxes property at run time, the TreeView handle is recreated (see Control::RecreateHandle) to update the control's appearance. This causes all tree nodes to be collapsed, with the exception of the selected TreeNode.

The following code example demonstrates how to change the collapse state of a TreeView so that all the checked nodes are visible. First, all the nodes are collapsed, and a handler is added for the BeforeExpand event. Next, all the nodes are expanded. The BeforeExpand event handler determines whether a given node has child nodes that are checked. If a node does not have checked children, the expansion is canceled for that node. In order to allow standard node expansion when the plus sign next to a node is clicked, the BeforeExpand event handler is then removed.

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
   TreeView^ treeView1;
   Button^ showCheckedNodesButton;
   TreeViewCancelEventHandler^ checkForCheckedChildren;

      treeView1 = gcnew TreeView;
      showCheckedNodesButton = gcnew Button;
      checkForCheckedChildren = gcnew TreeViewCancelEventHandler( this, &Form1::CheckForCheckedChildrenHandler );

      // 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 );

   void showCheckedNodesButton_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
      // Disable redrawing of treeView1 to prevent flickering 
      // while changes are made.

      // Collapse all nodes of treeView1.

      // 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.

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

      // Enable redrawing of treeView1.

   // 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 );

.NET Framework
Available since 1.1
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