How to embed unity (exe) in maui windows?

Question

hi

I used this method to embed Unity into MAUI but it doesn't work properly

I want it to be placed inside a view and resize when the page is resized

It works fine in Winforms

using System.Diagnostics;
using System.Formats.Tar;
using System.Runtime.InteropServices;

namespace Momentum
{
    public partial class MainPage : ContentPage
    {
        [DllImport("User32.dll")]
        static extern bool MoveWindow(IntPtr handle, int x, int y, int width, int height, bool redraw);

        internal delegate int WindowEnumProc(IntPtr hwnd, IntPtr lparam);
        [DllImport("user32.dll")]
        internal static extern bool EnumChildWindows(IntPtr hwnd, WindowEnumProc func, IntPtr lParam);

        [DllImport("user32.dll")]
        static extern int SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

        private Process process;
        private IntPtr unityHWND = IntPtr.Zero;

        private const int WM_ACTIVATE = 0x0006;
        private readonly IntPtr WA_ACTIVE = new IntPtr(1);
        private readonly IntPtr WA_INACTIVE = new IntPtr(0);

        public MainPage()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();

            // Delay handler access
            Task.Delay(2000).ContinueWith(_ =>
            {
                StartUnityProcess();
            });
        }

        private void StartUnityProcess()
        {
            try
            {
                if (File.Exists("C:\\Users\\AMIN\\Desktop\\unity\\unity.exe"))
                {
                    process = new Process
                    {
                        StartInfo =
                    {
                        FileName = "C:\\Users\\AMIN\\Desktop\\unity\\unity.exe", // Path to Unity app
                        Arguments = $"-parentHWND {GetNativePanelHandle()} {Environment.CommandLine}",
                        UseShellExecute = true,
                        CreateNoWindow = true
                    }
                    };

                    process.Start();
                    process.WaitForInputIdle();

                    IntPtr hwnd = GetNativePanelHandle();
                    if (hwnd == IntPtr.Zero)
                    {
                        Debug.WriteLine("Failed to retrieve valid HWND.");
                        return;
                    }
                    Task.Delay(2000).Wait();
                    bool result =  EnumChildWindows(hwnd, WindowEnum, IntPtr.Zero);

                    if (!result)
                    {
                        Debug.WriteLine("EnumChildWindows failed.");
                    }
                    else
                    {
                        Debug.WriteLine("EnumChildWindows succeeded.");
                    }

                }
                else
                {
                    DisplayAlert("Error", "file not exist", "OK");
                }

            }
            catch (Exception ex)
            {
                DisplayAlert("Error", $"{ex.Message}. Check if Container.exe is placed next to Child.exe.", "OK");
            }
        }

        private IntPtr GetNativePanelHandle()
        {
#if WINDOWS
            // Retrieve the window handle for the native panel
            var windowHandle = (IntPtr)(UnityContainer.Window.Handler.PlatformView as MauiWinUIWindow).WindowHandle;
            if (windowHandle == IntPtr.Zero)
            {
                Debug.WriteLine("Failed to retrieve window handle.");
            }

            Debug.WriteLine($"windowHandle type: {windowHandle}");
            return windowHandle;
#else
        throw new PlatformNotSupportedException("Unity embedding only supported on Windows.");
#endif
        }

        private int WindowEnum(IntPtr hwnd, IntPtr lparam)
        {
            unityHWND = hwnd;
            Debug.WriteLine($"Unity window handle: {unityHWND}");
            ActivateUnityWindow();
            return 1;
        }

        private void ActivateUnityWindow()
        {
            SendMessage(unityHWND, WM_ACTIVATE, WA_ACTIVE, IntPtr.Zero);
        }


        private void DeactivateUnityWindow()
        {
            SendMessage(unityHWND, WM_ACTIVATE, WA_INACTIVE, IntPtr.Zero);
        }

        private void OnResize(object sender, EventArgs e)
        {
#if WINDOWS
            var rect = UnityContainer.Bounds;
            MoveWindow(unityHWND, (int)rect.X, (int)rect.Y, (int)rect.Width, (int)rect.Height, true);
            ActivateUnityWindow();
#endif
        }

        protected override void OnDisappearing()
        {
            base.OnDisappearing();
            try
            {
                process.CloseMainWindow();
                Thread.Sleep(1000);

                if (!process.HasExited)
                    process.Kill();
            }
            catch (Exception) { }
        }


    }

}

Answer 1

Hello,

On the Windows platform, Maui uses WinUI3 technology, which is different from WPF technology. Currently WinUI3 does not support displaying Unity programs in controls. There is a feature request submitted in the github.

Please continue to follow Proposal: Support embedding another executable inside a UserControl with WinUI 3 desktop (win32). #4501 to avoid missing updates from the development team.

Best Regards,

Alec Liu.

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