Avalonia App hosting ASP.Net Core API

[dinonovak]

I am trying to add API support for exiting Avalonia APP.
So that APP would listen for REST API call's and update the GUI.
Below I have described the steps what I have done, but for some reason HTTP server is not listening to port 5000.
I tried running Visual Studio as admin to make sure that port can be created but no luck.

Help would be appreciated
Also how can I reference user controls activated in Avalonia app from API Controller?

I have done the following:

1. Referenced Microsoft.AspNetCore.Mvc nuget package

2. Referenced Microsoft.AspNetCore nuget package

3. Created a Startup.cs file in the root of the project, and copy the following code:

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace rpiScreenStation
{
    class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }
        public IConfiguration Configuration { get; }
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        }
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            //if (env.IsDevelopment())
            //{
                app.UseDeveloperExceptionPage();
            //}
            app.UseMvc();

        }
    }
}

4. Updated Program.cs:

added to Main()
CreateWebHostBuilder(args).Build().RunAsync();

created definition for web builder

         public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
             WebHost.CreateDefaultBuilder(args)
                 .UseStartup<Startup>();

As I have app that runs in Linux frame buffer I have the following Program.cs:

using System;
using System.Threading;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
//using Avalonia.Logging.Serilog;
using Avalonia.Dialogs;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;

namespace rpiScreenStation
{
    class Program
    {

        [STAThread]
        static int Main(string[] args)
        {
            if (args.Contains("--wait-for-attach"))
            {
                Console.WriteLine("Attach debugger and use 'Set next statement'");
                while (true)
                {
                    Thread.Sleep(100);
                    if (Debugger.IsAttached)
                        break;
                }
            }

            //Add API endpoint
            CreateWebHostBuilder(args).Build().RunAsync();

            //Avalonia app
            var builder = BuildAvaloniaApp();

            double GetScaling()
            {
                var idx = Array.IndexOf(args, "--scaling");
                if (idx != 0 && args.Length > idx + 1 &&
                    double.TryParse(args[idx + 1], NumberStyles.Any, CultureInfo.InvariantCulture, out var scaling))
                    return scaling;
                return 1;
            }
            if (args.Contains("--fbdev"))
            {
                Console.WriteLine(">> Run in Mode: Framebuffer");
                SilenceConsole();
                return builder.StartLinuxFbDev(args, scaling: GetScaling());
            }
            else if (args.Contains("--drm"))
            {
                SilenceConsole();
                return builder.StartLinuxDrm(args, scaling: GetScaling());
            }
            else
                return builder.StartWithClassicDesktopLifetime(args);
            //return builder.StartLinuxFbDev(args, scaling: GetScaling());


        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
            //.UseKestrel()
            .UseStartup<Startup>()
            .UseUrls("http://localhost:5000/");

        /// <summary>
        /// This method is needed for IDE previewer infrastructure
        /// </summary>
        public static AppBuilder BuildAvaloniaApp()
            => AppBuilder.Configure<App>()
                .UsePlatformDetect()
                .LogToDebug()
                .With(new X11PlatformOptions
                {
                    EnableMultiTouch = true,
                    UseDBusMenu = true
                })
                .With(new Win32PlatformOptions
                {
                    EnableMultitouch = true,
                    AllowEglInitialization = true
                })
                .UseSkia()
                .UseManagedSystemDialogs();

        static void SilenceConsole()
        {
            new Thread(() =>
            {
                Console.CursorVisible = false;
                while (true)
                    Console.ReadKey(true);
            })
            { IsBackground = true }.Start();
        }
    }
}

Added Controllers folder with ValuesController.cs file in it containing:

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.AspNetCore.Mvc;

namespace rpiScreenStation.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        [HttpGet]
        public ActionResult<string> Get()
        {
            string text = "This is some text";
            return text;
        }

    }
}

[dinonovak]

OK,
look like I found the root cause. One of the other nugets was dependant on Microsoft.Extensions.Logging.Abstractions and it required 5.0.0.0 minimal version while app is still .netcore3.1

and this was causing error in WebBuilder startup
Could not load type 'Microsoft.Extensions.Logging.Abstractions.Internal.NullScope' from assembly 'Microsoft.Extensions.Logging.Abstractions, Version=5.0.0.0,

[dinonovak]

referencing App.Current gives me instance of the current app.
But how can I gain access to currently opened window.
Also as I am supporting Windows / Linux frame buffer app is initialised as follows:

using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;
using rpiScreenStation.UserControls;
using rpiScreenStation.ViewModels;
using rpiScreenStation.Views;

namespace rpiScreenStation
{
    public class App : Application
    {
        public override void Initialize()
        {
            AvaloniaXamlLoader.Load(this);
        }

        public override void OnFrameworkInitializationCompleted()
        {
            if (ApplicationLifetime is ISingleViewApplicationLifetime single)
            {
                single.MainView = new RootControl();
            }
            else if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
            {
                desktop.MainWindow = new MainWindow();
            }

            base.OnFrameworkInitializationCompleted();
        }
    }
}

[dinonovak]

Ok, so look like it is not that hard to find things ...

 if (Avalonia.Application.Current.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
            {
                var mainWin = desktop.MainWindow;

                Dispatcher.UIThread.InvokeAsync(() =>
                {
                    RootControl xRootControl = (RootControl)mainWin.Content;
                   // now you can find controls .. 
                   var ctl = xRootControl.FindControl<UserControl>("MainUserControl");
                  // and play with them, change them ... 
                   ctl.Content = new UserControlOther();  
                });
            }