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using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace CustomTreeViewLabelEdit
{
  internal class TreeViewEx : TreeView
  {
    // Specifying custom text when using the LabelEdit functionality of a TreeView
    // http://cyotek.com/blog/specifying-custom-text-when-using-the-labeledit-functionality-of-a-treeview

    #region Events

    [Category("Behavior")]
    public event EventHandler<NodeRequestTextEventArgs> RequestDisplayText;

    [Category("Behavior")]
    public event EventHandler<NodeRequestTextEventArgs> RequestEditText;

    #endregion

    #region Overridden Members

    protected override void OnAfterLabelEdit(NodeLabelEditEventArgs e)
    {
      if (e.Label != null) // if the user cancelled the edit this event is still raised, just with a null label
      {
        NodeRequestTextEventArgs displayTextArgs;

        displayTextArgs = new NodeRequestTextEventArgs(e.Node, e.Label);
        this.OnRequestDisplayText(displayTextArgs);

        e.CancelEdit = true; // cancel the built in operation so we can substitute our own

        if (!displayTextArgs.Cancel)
          e.Node.Text = displayTextArgs.Label;
      }

      base.OnAfterLabelEdit(e);
    }

    protected override void OnBeforeLabelEdit(NodeLabelEditEventArgs e)
    {
      NodeRequestTextEventArgs editTextArgs;

      // get the text to apply to the label
      editTextArgs = new NodeRequestTextEventArgs(e.Node, e.Node.Text);
      this.OnRequestEditText(editTextArgs);

      // cancel the edit if required
      if (editTextArgs.Cancel)
        e.CancelEdit = true;

      // apply the text to the EDIT control
      if (!e.CancelEdit)
      {
        IntPtr editHandle;

        editHandle = NativeMethods.SendMessage(this.Handle, NativeMethods.TVM_GETEDITCONTROL, IntPtr.Zero, IntPtr.Zero); // Get the handle of the EDIT control
        if (editHandle != IntPtr.Zero)
          NativeMethods.SendMessage(editHandle, NativeMethods.WM_SETTEXT, IntPtr.Zero, editTextArgs.Label); // And apply the text. Simples.
      }

      base.OnBeforeLabelEdit(e);
    }

    #endregion

    #region Members

    /// <summary>
    /// Raises the <see cref="RequestDisplayText" /> event.
    /// </summary>
    /// <param name="e">The <see cref="EventArgs" /> instance containing the event data.</param>
    protected virtual void OnRequestDisplayText(NodeRequestTextEventArgs e)
    {
      EventHandler<NodeRequestTextEventArgs> handler;

      handler = this.RequestDisplayText;

      if (handler != null)
        handler(this, e);
    }

    protected virtual void OnRequestEditText(NodeRequestTextEventArgs e)
    {
      EventHandler<NodeRequestTextEventArgs> handler;

      handler = this.RequestEditText;

      if (handler != null)
        handler(this, e);
    }

    #endregion
  }
}