.Net Maui Windows & WinUI3 System/Global Hotkey

MauiProgram.cs

using MauiApp1.Data;
using Microsoft.Extensions.Logging;
using Microsoft.Maui.LifecycleEvents;
using Microsoft.Maui.Platform;
using System.Runtime.InteropServices;
using MauiApp1.Shared;

namespace MauiApp1
{
    public static class MauiProgram
    {
        //private const uint WM_HOTKEY = 0x0312;
        //private Windows.Win32.UI.WindowsAndMessaging.WNDPROC origPrc;
        //private Windows.Win32.UI.WindowsAndMessaging.WNDPROC hotKeyPrc;
        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

        [DllImport("user32.dll")]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);


        [DllImport("user32.dll")]
        static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

        [DllImport("user32.dll")]
        static extern bool SetForegroundWindow(IntPtr hWnd);

        [DllImport("user32.dll")]
        static extern IntPtr SetFocus(IntPtr hWnd);

        [DllImport("user32.dll")]
        static extern IntPtr SetActiveWindow(IntPtr hWnd);


        public static MauiApp CreateMauiApp()
        {


            var builder = MauiApp.CreateBuilder();
            builder
                .UseMauiApp<App>()
                .ConfigureLifecycleEvents(events =>
                {
#if WINDOWS
                    events.AddWindows(windows => windows
                           .OnClosed((window, args) =>
                           {
                               // unregister hot key
                               var h = window.GetWindowHandle();
                               UnregisterHotKey(h, 1);
                               LogEvent(nameof(WindowsLifecycle.OnClosed));
                           })
                           .OnWindowCreated((window) => 
                           {
                               // register hot key ctrl+win+.
                               var h = window.GetWindowHandle();
                               var success = RegisterHotKey(h, 1, 0x0008 | 0x0002, 0xBE);
                               LogEvent(nameof(WindowsLifecycle.OnWindowCreated));
                           })
                           .OnPlatformMessage((window, args) =>
                           {
                               // on hotkey received from os
                               if (args.MessageId == 0x0312 && args.WParam.ToInt32() == 1)
                               {
                                   // toggle app window visibility
                                   var h = window.GetWindowHandle();
                                   if(window.Visible)
                                   {
                                       ShowWindow(h, 6);
                                   }
                                   else
                                   {
                                       SetActiveWindow(h);
                                       ShowWindow(h, 9);
                                       //window.GetAppWindow().Title = "oh no";
                                       //SetForegroundWindow(h);
                                       //SetFocus(h);
                                       //SetActiveWindow(h);
                                   }
                               }
                           }));
#endif
                    static bool LogEvent(string eventName, string type = null)
                    {
                        System.Diagnostics.Debug.WriteLine($"Lifecycle event: {eventName}{(type == null ? string.Empty : $" ({type})")}");
                        return true;
                    }
                })
                .ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                });

            builder.Services.AddMauiBlazorWebView();

#if DEBUG
		builder.Services.AddBlazorWebViewDeveloperTools();
		builder.Logging.AddDebug();
#endif

            builder.Services.AddSingleton<WeatherForecastService>();

            return builder.Build();
        }
    }
}

learned quite a bit from this blog post then found a way to not directly have to create a new window procedure to handle the os messaging.