Java/.NET Integration as Simple as Possible

using System;
using System.ComponentModel;
using System.Drawing;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace CSharpInJava
{
    public class CreateParams
    {
        private string caption;
        private string className;
        private int classStyle;
        private int exStyle;
        private int height;
        
        private IntPtr parent;
        private int width;
        private int x;
        private int y;

        public CreateParams(){}

        public string Caption
        {
            get { return caption; }
            set { caption = value; }
        }
        public string ClassName
        {
            get { return className; }
            set { className = value; }
        }

        public int ClassStyle
        {
            get { return classStyle; }
            set { classStyle = value; }
        }

        public int ExStyle
        {
            get { return exStyle; }
            set { exStyle = value; }
        }

        public int Height
        {
            get { return height; }
            set { height = value; }
        }

        public IntPtr Parent
        {
            get { return parent; }
            set { parent = value; }
        }

        public int Width
        {
            get { return width; }
            set { width = value; }
        }

        public int X
        {
            get { return x; }
            set { x = value; }
        }

        public int Y
        {
            get { return y; }
            set { y = value; }
        }
    }

	public class FrameWindow : Control, IWin32Window
	{
        [DllImport("kernel32.dll", EntryPoint="GetModuleHandleW", SetLastError=true)]
        internal static extern IntPtr GetModuleHandle(string lpszModule);
        [DllImport("kernel32.dll")]
        public static extern int GetWindowLong(IntPtr hWnd, int nItem);
        [DllImport("kernel32.dll")]
        public static extern void SetWindowLong(IntPtr hWnd, int GetWindowLongParam, int nValue);
        [DllImport("kernel32.dll")]
        public static extern IntPtr GetCapture();
        [DllImport("user32.dll", EntryPoint="CreateWindowExW", SetLastError=true)]
        public static extern IntPtr CreateWindowEx(
            int dwExStyle, 
            string lpClassName, 
            string lpWindowName, 
            int dwStyle, 
            int x, 
            int y, 
            int nWidth, 
            int nHeight, 
            IntPtr hWndParent, 
            IntPtr hMenu, 
            IntPtr hInstance, 
            IntPtr lpParam 
            ); 
        [DllImport("kernel32.dll")]
        public static extern bool SetFocus(IntPtr hWnd);
        [DllImport("kernel32.dll")]
        public extern static int SetWindowPos (
            IntPtr hWnd, int pos,
            int X, int Y, int cx, int cy, int uFlags);
        [DllImport("kernel32.dll")] 
        public static extern IntPtr DestroyWindow(IntPtr hWnd);

        private string m_name = String.Empty;
        private IntPtr m_hwnd = IntPtr.Zero;
        private IntPtr m_parenthwnd = IntPtr.Zero;
        private IntPtr m_childhwnd = IntPtr.Zero;
        private IntPtr m_instance;
        private object m_tag;
        private CreateParams m_createParams;
        private BorderStyle m_border = BorderStyle.None;

        public static void UpdateWindowStyle(IntPtr hwnd, int RemoveStyle, int AddStyle) 
        {
            int style = GetWindowLong(hwnd, -16);
            style &= ~RemoveStyle;
            style |= AddStyle;
            SetWindowLong(hwnd, -16, style);
            SetWindowPos(hwnd, 0, 0, 0, 0, 0, 0x0037);
        }

		public FrameWindow(IntPtr parenthwnd)
		{
            m_parenthwnd = parenthwnd;
            m_instance = GetModuleHandle(null);
            m_createParams = new CreateParams();
            m_createParams.ClassStyle = (int)0x10000000;
		}

        public BorderStyle BorderStyle
        {
            get { return m_border; }
            set {
                m_border = value;
                if(value==BorderStyle.None)
                {
                    UpdateWindowStyle(Handle, (int)0x00800000, 0);
                }
                else
                {
                    UpdateWindowStyle(Handle, 0,(int)0x00800000);
                }
            }
        }
        protected internal IntPtr ChildHandle
        {
            get { return m_childhwnd; }
        }	
        public new bool Created
        {
            get { return (m_childhwnd != IntPtr.Zero); }
        }
        protected new CreateParams CreateParams 
        {
            get { return m_createParams; }
        }
        public new IntPtr Handle
        {
            get {
                if(m_hwnd==IntPtr.Zero)
                {
                    this.Capture = true;
                    m_hwnd = GetCapture();
                    this.Capture = false;
                }
                return m_hwnd;
            }
        }
        protected IntPtr Instance
        {
            get { return m_instance; }
        }
        public new string Name
        {
            get {
                if(m_name == string.Empty)
                {
                    m_name = GetName(this);
                }
                return m_name;
            }
        }
        public static string GetName(Control control)
        {
            FieldInfo[] fi = control.Parent.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance |
                BindingFlags.Public | BindingFlags.IgnoreCase);

            foreach(FieldInfo f in fi)
            {
                if(f.GetValue(control.Parent).Equals(control))
                    return f.Name;
            }

            return string.Empty;
        }
        public new object Tag
        {
            get { return m_tag; }
            set { m_tag = value; }
        }
        public new void CreateControl()
        {
            if(m_childhwnd != IntPtr.Zero)
            {
                DestroyWindow(m_childhwnd);
            }
            CreateParams.Width = this.Width;
            CreateParams.Height = this.Height;
			String err;
			try
			{
				m_childhwnd = CreateWindowEx(m_createParams.ExStyle, m_createParams.ClassName, m_createParams.Caption, (int)m_createParams.ClassStyle, m_createParams.X, m_createParams.Y, m_createParams.Width, m_createParams.Height, (IntPtr)m_parenthwnd/*m_createParams.Parent*/, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
			}
			catch(Exception e)
			{
				err = e.Message;
			}
        }
        protected override void OnGotFocus(EventArgs e)
        {
            if(ChildHandle != IntPtr.Zero)
            {
                SetFocus(ChildHandle);
            }
        }
        protected override void OnParentChanged(EventArgs e)
        {
            CreateControl();
            base.OnParentChanged (e);
        }
        protected override void OnResize(EventArgs e)
        {
            if(ChildHandle != IntPtr.Zero)
            {
                SetWindowPos(ChildHandle, 0, 0, 0, this.Width, this.Height, 0);
            }
            base.OnResize (e);
        }
        public new void SetBounds(int x, int y, int width, int height)
        {
            this.Bounds = new Rectangle(x, y, width, height);
        }
        protected override void Dispose(bool disposing)
        {
            if(m_childhwnd != IntPtr.Zero)
            {
                DestroyWindow(m_childhwnd);
                m_childhwnd = IntPtr.Zero;
            }
            base.Dispose (disposing);
        }
        public static IntPtr GetHandle(Control c)
        {
            c.Capture = true;
            IntPtr handle = GetCapture();
            c.Capture = false;
            return handle;
        }
        public static Control GetControlByName(Control parent, string name)
        {
            FieldInfo info = parent.GetType().GetField(name,
                BindingFlags.NonPublic | BindingFlags.Instance |
                BindingFlags.Public | BindingFlags.IgnoreCase);
            if(info == null) return null;
            object o = info.GetValue(parent);
            return (Control)o;
        }
    }
}