TheXamlGuy.TaskbarGroup/TheXamlGuy.TaskbarGroup.Core/WndProcMonitor.cs

using Windows.Win32;
using Windows.Win32.Foundation;
using Windows.Win32.Graphics.Gdi;
using Windows.Win32.UI.WindowsAndMessaging;

namespace TheXamlGuy.TaskbarGroup.Core
{
    public class WndProcMonitor : IWndProcMonitor
    {
        private WNDPROC? handler;
        private readonly IMessenger messenger;

        public WndProcMonitor(IMessenger messenger)
        {
            this.messenger = messenger;
        }

        public IntPtr Handle { get; private set; }

        public void Dispose()
        {
            PInvoke.DestroyWindow((HWND)Handle);
        }

        private unsafe void InitializeWndProc()
        {
            var windowName = Guid.NewGuid().ToString();
            handler = Wndproc;

            WNDCLASSW wndProcWindow;

            wndProcWindow.style = 0;
            wndProcWindow.lpfnWndProc = handler;
            wndProcWindow.cbClsExtra = 0;
            wndProcWindow.cbWndExtra = 0;
            wndProcWindow.hInstance = new HINSTANCE();
            wndProcWindow.hIcon = new HICON();
            wndProcWindow.hCursor = new HCURSOR();
            wndProcWindow.hbrBackground = new HBRUSH();

            fixed (char* menuName = "")
            {
                wndProcWindow.lpszMenuName = new PCWSTR(menuName);
            }

            fixed (char* className = windowName)
            {
                wndProcWindow.lpszClassName = new PCWSTR(className);
            }

            PInvoke.RegisterClass(wndProcWindow);
            Handle = PInvoke.CreateWindowEx(0, wndProcWindow.lpszClassName, new PCWSTR(), 0, 0, 0, 0, 0, new HWND(),
                new HMENU(),
                new HINSTANCE());
        }

        private LRESULT Wndproc(HWND param0, uint param1, WPARAM param2, LPARAM param3)
        {
            messenger.Send(new WndProc(param1, (uint)param2.Value, (uint)param3.Value));
            return PInvoke.DefWindowProc(param0, param1, param2, param3);
        }

        public void Initialize()
        {
            InitializeWndProc();
        }
    }
}