Char Validation Text Box with error tooltip

using System;

using System.Collections.Generic;

using System.Text;

using System.Windows.Forms;

///

/// Show tooltip and prevent user input invalid characters defined in char[]

/// Need to hookup Container.OnMove, [MouseEnter] to HideTooltip

///

public class CharValidationTextBox : TextBox

{

private char[] INVALID_CHARS = new char[] { '\\', '/', ':', '*', '?', '\"', '<', '>', '|' };

private string WARNING = "A prefix cannot contain any of the following characters:\r\n\t";

private ToolTip _tooltip = new ToolTip();

private bool _first = true;

public CharValidationTextBox()

{

SetTooltip();

}

public CharValidationTextBox(string invalid_chars)

{

INVALID_CHARS = invalid_chars.ToCharArray();

SetTooltip();

}

private void SetTooltip()

{

WARNING += charsToString(INVALID_CHARS);

_tooltip.IsBalloon = true;

KeyDown += new KeyEventHandler(CharValidationTextBox_KeyDown);

KeyPress += new KeyPressEventHandler(CharValidationTextBox_KeyPress);

LostFocus += new EventHandler(CharValidationTextBox_LostFocus);

}

private void FixArrowAlign()

{

_tooltip.Active = false;

_tooltip.SetToolTip(this, WARNING);

_tooltip.Active = true;

_tooltip.SetToolTip(this, string.Empty);

}

public static string charsToString(char[] chars)

{

StringBuilder builder = new StringBuilder(chars.Length);

foreach (char ch in chars)

{

builder.Append(ch);

builder.Append(' ');

}

return builder.ToString();

}

public void HideToolTip()

{

_tooltip.Hide(this);

}

public void ShowToolTip()

{

if (_first)

{

FixArrowAlign();

_first = false;

}

_tooltip.Show(WARNING, this, Width / 2, Height / 2, _tooltip.AutoPopDelay);

}

void CharValidationTextBox_KeyPress(object sender, KeyPressEventArgs e)

{

foreach (char ch in INVALID_CHARS)

{

if (ch == e.KeyChar)

{

ShowToolTip();

e.Handled = true;

break;

}

}

}

void CharValidationTextBox_KeyDown(object sender, KeyEventArgs e)

{

if (e.Control && e.KeyCode == Keys.V)

{

string text = Clipboard.GetText();

if (text.IndexOfAny(INVALID_CHARS) >= 0)

{

ShowToolTip();

e.SuppressKeyPress = true;

}

}

}

void CharValidationTextBox_LostFocus(object sender, EventArgs e)

{

HideToolTip();

}

}