feat: add aboutus page.

demo/Semi.Avalonia.Demo/Pages/AboutUs.axaml.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using System.Windows.Input;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
+using Avalonia.Platform.Storage;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+
+namespace Semi.Avalonia.Demo.Pages;
+
+public partial class AboutUs : UserControl
+{
+    public AboutUs()
+    {
+        InitializeComponent();
+        this.DataContext = new AboutUsViewModel();
+    }
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+        if (this.DataContext is AboutUsViewModel vm)
+        {
+            var launcher = TopLevel.GetTopLevel(this)?.Launcher;
+            vm.Launcher = launcher;
+        }
+    }
+}
+
+public partial class AboutUsViewModel: ObservableObject
+{
+    public ICommand NavigateCommand { get; set; }
+    
+    internal ILauncher? Launcher { get; set; }
+
+    public AboutUsViewModel()
+    {
+        NavigateCommand = new AsyncRelayCommand<string>(OnNavigateAsync);
+    }
+
+    private static readonly IReadOnlyDictionary<string, string> _keyToUrlMapping = new Dictionary<string, string>()
+    {
+        ["semi"] = "https://github.com/irihitech/Semi.Avalonia",
+    };
+
+    private async Task OnNavigateAsync(string? arg)
+    {
+        if (Launcher is not null && arg is not null && _keyToUrlMapping.TryGetValue(arg.ToLower(), out var uri))
+        {
+            await Launcher.LaunchUriAsync(new Uri(uri));
+        }
+        
+    }
+}