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TreeView.BeforeLabelEdit (Evento)

Se produce antes de editarse el texto de la etiqueta del nodo de árbol.

Espacio de nombres: System.Windows.Forms
Ensamblado: System.Windows.Forms (en system.windows.forms.dll)

public event NodeLabelEditEventHandler BeforeLabelEdit
/** @event */
public void add_BeforeLabelEdit (NodeLabelEditEventHandler value)

/** @event */
public void remove_BeforeLabelEdit (NodeLabelEditEventHandler value)

En JScript, se pueden controlar los eventos que define una clase, pero no se pueden definir unos propios.
No aplicable.

Para obtener más información sobre la forma de controlar eventos, vea Utilizar eventos.

En el ejemplo de código siguiente se muestra cómo se utilizan los miembros BeforeLabelEditAfterSelect y TopNode. Para ejecutar este ejemplo, pegue el siguiente código en un formulario que contenga un control TreeView denominado TreeView1. Llame al método InitializeTreeView desde el constructor del formulario o el método Load.

	private void InitializeTreeView()
	{

		// Construct the TreeView object.
		this.TreeView1 = new System.Windows.Forms.TreeView();

		// Set dock, location, size name, and tab order
		// values for the TreeView object.
		TreeView1.Dock = System.Windows.Forms.DockStyle.Left;
		TreeView1.Location = new System.Drawing.Point(0, 0);
		TreeView1.Name = "TreeView1";
		TreeView1.Size = new System.Drawing.Size(152, 266);
		TreeView1.TabIndex = 1;
		
		// Associate the event-handling methods with the
		// BeforeLabeEdit and the AfterSelect events.
		TreeView1.BeforeLabelEdit += 
			new NodeLabelEditEventHandler(TreeView1_BeforeLabelEdit);
		TreeView1.AfterSelect += 
			new TreeViewEventHandler(TreeView1_AfterSelect);

		// Set the LabelEdit property to true to allow the 
		// user to edit the TreeNode text.
		this.TreeView1.LabelEdit = true;

		// Declare and create objects needed to populate 
		// the TreeView.
		string[] files = new string[]{"bigPresentation.ppt", 
			"myFinances.xls", "myResume.doc"};; 
		string filePath = "c:\\myFiles";
		System.Collections.ArrayList nodes = 
			new System.Collections.ArrayList();

		// Create a node for each file, setting the Text property to the 
		// file's name and the Tag property to file's fully-qualified name.
		foreach ( string file in files )
		{
			TreeNode node = new TreeNode(file);
			node.Tag = filePath+"\\"+file;
			nodes.Add(node);
		}

		TreeNode[] treeNodes = new TreeNode[nodes.Count];
		nodes.CopyTo(treeNodes);

		// Create a new node named topNode and add the ArrayList of 
		// nodes to topNode.
		TreeNode topNode = new TreeNode("myFiles",  treeNodes);
		topNode.Tag = filePath;

		// Add topNode to the TreeView.
		TreeView1.Nodes.Add(topNode);

		// Add the TreeView to the form.
		this.Controls.Add(TreeView1);
	}

	private void TreeView1_BeforeLabelEdit(object sender, 
		NodeLabelEditEventArgs e)
	{

		// Determine whether the user has selected the top node. If so,
		// change the LabelEdit property to false so the user cannot
		// edit this label.  
		if (e.Node == TreeView1.TopNode)

		{
			TreeView1.LabelEdit = false;
			MessageBox.Show("You are not allowed to edit the top node");
		}
		// Set the LabelEdit property to true again.
		TreeView1.LabelEdit = true;
	}
...

	// Handle the After_Select event.
	private void TreeView1_AfterSelect(System.Object sender, 
		System.Windows.Forms.TreeViewEventArgs e)
	{

		// Vary the response depending on which TreeViewAction
		// triggered the event. 
		switch((e.Action))
		{
			case TreeViewAction.ByKeyboard:
				MessageBox.Show("You like the keyboard!");
				break;
			case TreeViewAction.ByMouse:
				MessageBox.Show("You like the mouse!");
				break;
		}
	}

    private void InitializeTreeView()
    {
        // Construct the TreeView object.
        this.treeView1 = new System.Windows.Forms.TreeView();
        // Set dock, location, size name, and tab order
        // values for the TreeView object.
        treeView1.set_Dock(System.Windows.Forms.DockStyle.Left);
        treeView1.set_Location(new System.Drawing.Point(0, 0));
        treeView1.set_Name("TreeView1");
        treeView1.set_Size(new System.Drawing.Size(152, 266));
        treeView1.set_TabIndex(1);
        // Associate the event-handling methods with the
        // BeforeLabeEdit and the AfterSelect events.
        treeView1.add_BeforeLabelEdit(
            new NodeLabelEditEventHandler(treeView1_BeforeLabelEdit));
        treeView1.add_AfterSelect(new TreeViewEventHandler(
            treeView1_AfterSelect));
        // Set the LabelEdit property to true to allow the 
        // user to edit the TreeNode text.
        this.treeView1.set_LabelEdit(true);
        // Declare and create objects needed to populate 
        // the TreeView.
        String files[] = new String[] { "bigPresentation.ppt", "myFinances.xls",
            "myResume.doc" };
        String filePath = "c:\\myFiles";
        System.Collections.ArrayList nodes = new System.Collections.ArrayList();
        // Create a node for each file, setting the Text property to the 
        // file's name and the Tag property to file's fully-qualified name.
        for (int iCtr = 0; iCtr < files.length; iCtr++) {
            String file = files[iCtr];
            TreeNode node = new TreeNode(file);
            node.set_Tag(filePath + "\\" + file);
            nodes.Add(node);
        }

        TreeNode treeNodes[] = new TreeNode[nodes.get_Count()];
        nodes.CopyTo(treeNodes);
        // Create a new node named topNode and add the ArrayList of 
        // nodes to topNode.
        TreeNode topNode = new TreeNode("myFiles", treeNodes);
        topNode.set_Tag(filePath);
        // Add topNode to the TreeView.
        treeView1.get_Nodes().Add(topNode);
        // Add the TreeView to the form.
        this.get_Controls().Add(treeView1);
    } //InitializeTreeView

    private void treeView1_BeforeLabelEdit(Object sender,
        NodeLabelEditEventArgs e)
    {
        // Determine whether the user has selected the top node. If so,
        // change the LabelEdit property to false so the user cannot
        // edit this label.  
        if (e.get_Node().Equals(treeView1.get_TopNode())) {
            treeView1.set_LabelEdit(false);
            MessageBox.Show("You are not allowed to edit the top node");
        }
        // Set the LabelEdit property to true again.
        treeView1.set_LabelEdit(true);
    } //treeView1_BeforeLabelEdit
...

    // Handle the After_Select event.
    private void treeView1_AfterSelect(Object sender,
        System.Windows.Forms.TreeViewEventArgs e)
    {
        // Vary the response depending on which TreeViewAction
        // triggered the event. 
        switch (e.get_Action()) {
            case TreeViewAction.ByKeyboard:
                MessageBox.Show("You like the keyboard!");
                break;
            case TreeViewAction.ByMouse:
                MessageBox.Show("You like the mouse!");
                break;
        }
    } //treeView1_AfterSelect

Windows 98, Windows 2000 Service Pack 4, Windows CE, Windows Millennium, Windows Mobile para Pocket PC, Windows Mobile para Smartphone, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter

Microsoft .NET Framework 3.0 es compatible con Windows Vista, Microsoft Windows XP SP2 y Windows Server 2003 SP1.

.NET Framework

Compatible con: 3.0, 2.0, 1.1, 1.0
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