Windows hook

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;

//author ibennz

namespace wnprocsharp
{
    public partial class Form1 : Form
    {
        //http://www.pinvoke.net/default.aspx/user32/GetWindowLongPtr.html
        [DllImport("user32.dll", EntryPoint = "GetWindowLongW")]
        private static extern int GetWindowLongPtr32(IntPtr hWnd, int nIndex);

        [DllImport("user32.dll", EntryPoint = "GetWindowLongPtrW")]
        private static extern IntPtr GetWindowLongPtr64(IntPtr hWnd, int nIndex);

        public static IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex)
        {
            if (IntPtr.Size == 8)
                return GetWindowLongPtr64(hWnd, nIndex);
            else
                return new IntPtr(GetWindowLongPtr32(hWnd, nIndex));
        }

        [DllImport("user32.dll")]
        public static extern IntPtr DefWindowProc(IntPtr hWnd, uint uMsg, IntPtr wParam, IntPtr lParam);
        [DllImport("user32.dll")]
        public static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        //http://pinvoke.net/default.aspx/user32/SetWindowLongPtr.html
        public static IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong)
        {
            if (IntPtr.Size == 8)
                return SetWindowLongPtr64(hWnd, nIndex, dwNewLong);
            else
                return new IntPtr(SetWindowLong32(hWnd, nIndex, dwNewLong.ToInt32()));
        }

        [DllImport("user32.dll", EntryPoint = "SetWindowLongW")]
        private static extern int SetWindowLong32(IntPtr hWnd, int nIndex, int dwNewLong);

        [DllImport("user32.dll", EntryPoint = "SetWindowLongPtrW")]
        private static extern IntPtr SetWindowLongPtr64(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool IsWindow(IntPtr hWnd);
        public delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
        public static WndProcDelegate m_CtrlWndProcDelegate;
        public static WndProcDelegate m_DefWndProcDelegate;
        public static Dictionary<IntPtr, IntPtr> m_WndProc = new Dictionary<IntPtr, IntPtr>(); //List<IntPtr> mList = new List<IntPtr>();  m_WndProc

        public static IntPtr CtrlWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
        {
            if (!m_WndProc.Keys.Contains (hWnd))
                return m_DefWndProcDelegate(hWnd, msg, wParam, lParam);


            IntPtr nRet = CallWindowProc(m_WndProc[hWnd], hWnd, msg, wParam, lParam);

            switch (msg)
            {
                case WindowsMessage.WM_SIZE:
                    // do your stuff here
                    break;
                case WindowsMessage.WM_PAINT:
                case WindowsMessage.WM_CTLCOLOREDIT:
                case WindowsMessage.WM_CTLCOLORBTN:
                case WindowsMessage.WM_CTLCOLORSTATIC:
                case WindowsMessage.WM_CTLCOLORMSGBOX:
                case WindowsMessage.WM_CTLCOLORDLG:
                case WindowsMessage.WM_CTLCOLORLISTBOX:
                case WindowsMessage.WM_CTLCOLORSCROLLBAR:
                case WindowsMessage.WM_CAPTURECHANGED:

                    break;

                default:
                    break;
            }

            return nRet;
        }

        struct WindowsMessage
        {
            public const Int32 WM_SIZE = 0x0005;
            public const Int32 WM_LBUTTONDOWN = 0x0201;
            public const Int32 WM_NCLBUTTONDOWN = 0x00A1;
            public const Int32 WM_SYSCOMMAND = 0x112;
            public const Int32 WM_PAINT = 0x000F;
            public const Int32 WM_MOVE = 0x0003;
            public const Int32 WM_CTLCOLORMSGBOX = 0x0132;
            public const Int32 WM_CTLCOLOREDIT = 0x0133;
            public const Int32 WM_CTLCOLORLISTBOX = 0x0134;
            public const Int32 WM_CTLCOLORBTN = 0x0135;
            public const Int32 WM_CTLCOLORDLG = 0x0136;
            public const Int32 WM_CTLCOLORSCROLLBAR = 0x0137;
            public const Int32 WM_CTLCOLORSTATIC = 0x0138;
            public const Int32 WM_CAPTURECHANGED = 0x0215;
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            m_DefWndProcDelegate = new WndProcDelegate(DefWindowProc);
            m_CtrlWndProcDelegate = new WndProcDelegate(CtrlWndProc);


        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (IsWindow(this.Handle))
            {
                m_WndProc[this.Handle] = GetWindowLongPtr(this.Handle, -4);
                SetWindowLongPtr(this.Handle
                    , -4
                    , Marshal.GetFunctionPointerForDelegate(m_CtrlWndProcDelegate)
                    );
            }
        }

    }
}