IP TextBox

namespace NullFX.Controls	{
    using System;
    using System.Net;
    using System.Windows.Forms;
    using System.Runtime.InteropServices;
    [StructLayout(LayoutKind.Sequential)]
    public struct Nmhdr	{
        public IntPtr HWndFrom;
        public int IdFrom;
        public int Code;
    }
    [StructLayout(LayoutKind.Sequential)]
    public struct NmIPAddress {
        public Nmhdr Hdr;
        public int Field;
        public int Value;
    }
    public enum	IPField	{OctetOne =	0,OctetTwo=1,OctetThree=2,OctetFour=3}
    public delegate	void TextChangedHandler(object sender, TextChangedEventArgs	e);
    public class TextChangedEventArgs :	EventArgs {
        private	int	_field,	_value;
        public int Field {
            get{return _field;}
        }
        public int Value {
            get{return _value;}
        }
        public TextChangedEventArgs(int	field, int value):base() {
            _field = field;
            _value = value;
        }
    }
    public class IPAddressControl : TextBox {
        private	const int WM_NOTIFY	= 0x004E,
            WM_USER	= 0x0400,
            WM_REFLECT = WM_USER + 0x1C00,
            IPM_SETRANGE = (WM_USER+103),
            IPM_GETADDRESS = (WM_USER+102),
            IPM_SETADDRESS = (WM_USER+101),
            IPM_CLEARADDRESS = (WM_USER+100),
            IPM_ISBLANK = (WM_USER+105);
        private	int[] values = new int[4];
        new	public event TextChangedHandler	TextChanged;
        public IPAddressControl() : base()	{
            for(int	i =	0; i < 4; i++)
                values[i] =	0;
        }
        protected virtual void OnTextChanged(TextChangedEventArgs e) {
            if(TextChanged != null)	TextChanged(this, e);
        }
        protected override CreateParams	CreateParams {
            get	{
                CreateParams cp	= base.CreateParams;
                cp.ClassName = "SysIPAddress32";
                cp.Height =	23;
                return cp;
            }
        }
        public bool	SetIPRange(IPField field, byte lowValue, byte highValue) {
            Message	m =	Message.Create(Handle, IPM_SETRANGE, (IntPtr)((int)field) ,	MakeRange(lowValue,	highValue));
            WndProc(ref	m);
            return m.Result.ToInt32() >	0;
        }
        public System.Net.IPAddress IPAddress {
            get{
                return IPAddress.Parse(base.Text);
            }
        }
        public bool IsBlank {
            get{
                Message m = Message.Create(Handle, IPM_ISBLANK, IntPtr.Zero, IntPtr.Zero);
                WndProc(ref m);
                return m.Result.ToInt32() > 0;
            }
        }
        new public void Clear() {
            Message m = Message.Create(Handle, IPM_CLEARADDRESS, IntPtr.Zero, IntPtr.Zero);
            WndProc(ref m); 
        }
        private System.Net.IPAddress GetIpAddress(IntPtr ip) {
            return new IPAddress(ip.ToInt64());
        }
        private	IntPtr MakeRange(byte low, byte	high) {
            return (IntPtr)((int)((high	<< 8) +	low));
        }
        protected override void	WndProc(ref	Message	m) {
            if(m.Msg ==	(WM_REFLECT	+ WM_NOTIFY)) {
                NmIPAddress	ipInfo =  (NmIPAddress)Marshal.PtrToStructure(m.LParam,	typeof(NmIPAddress));
                if(ipInfo.Hdr.Code == -860)	{
                    if(values[ipInfo.Field]	!= ipInfo.Value) {
                        values[ipInfo.Field] = ipInfo.Value;
                        OnTextChanged(new TextChangedEventArgs(ipInfo.Field, ipInfo.Value));
                    }
                }
            }
            base.WndProc (ref m);
        }
    }
}