Archive Browser

using System;
using System.Windows.Forms;

namespace CustomTreeViewLabelEdit
{
  internal partial class MainForm : Form
  {
    // Extending the LabelEdit functionality of a TreeView to include validation
    // http://cyotek.com/blog/extending-the-labeledit-functionality-of-a-treeview-to-include-validation

    #region Constructors

    public MainForm()
    {
      InitializeComponent();
    }

    #endregion

    #region Overridden Members

    protected override void OnLoad(EventArgs e)
    {
      base.OnLoad(e);

      this.FillTree(subclassedTreeView);
    }

    #endregion

    #region Members

    private void FillTree(TreeView treeView)
    {
      TreeNode root;
      Random random;

      random = new Random();

      treeView.BeginUpdate();

      root = new TreeNode
      {
        Name = "Alpha",
        Text = "Alpha",
      };

      foreach (string name in new[]
      {
        "Beta", "Gamma", "Delta", "Epsilon", "Zeta", "Eta", "Theta", "Iota", "Kappa", "Lambda", "Mu", "Nu", "Xi", "Omicron", "Pi", "Rho", "Sigma", "Tau", "Upsilon", "Phi", "Chi", "Psi", "Omega"
      })
      {
        string value;
        int imageIndex;

        imageIndex = random.Next(0, imageList.Images.Count);
        value = name.GetHashCode().ToString("X2");

        root.Nodes.Add(new TreeNode
        {
          Text = string.Format("{0}: {1}", name, value),
          Name = name,
          Tag = value,
          ImageIndex = imageIndex,
          SelectedImageIndex = imageIndex
        });
      }

      treeView.Nodes.Add(root);
      root.Expand();

      treeView.EndUpdate();
    }

    #endregion

    #region Event Handlers

    private void closeToolStripMenuItem_Click(object sender, EventArgs e)
    {
      this.Close();
    }

    private void renameToolStripMenuItem_Click(object sender, EventArgs e)
    {
      TreeView treeView;

      treeView = this.ActiveControl as TreeView;

      if (treeView != null && treeView.SelectedNode != null)
        treeView.SelectedNode.BeginEdit();
    }

    private void subclassedTreeView_RequestDisplayText(object sender, NodeRequestTextEventArgs e)
    {
      e.Node.Name = e.Label;
      e.Label = string.Format("{0}: {1}", e.Label, e.Node.Tag);
    }

    private void subclassedTreeView_RequestEditText(object sender, NodeRequestTextEventArgs e)
    {
      e.Label = e.Node.Name;
    }

    private void subclassedTreeView_ValidateLabelEdit(object sender, NodeLabelEditEventArgs e)
    {
      TreeNode[] matchingNodes;

      // Check to make sure the value the user enters isn't used by any other node than the current.
      // This code assumes that all names in the tree are unique, regardless of level
      matchingNodes = subclassedTreeView.Nodes.Find(e.Label, true);
      if (matchingNodes.Length != 0 && matchingNodes[0] != e.Node)
      {
        MessageBox.Show("You must enter a unique value.", "Validation Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        e.CancelEdit = true;
      }
    }

    #endregion
  }
}