Integrate font management for Linux demo (#822)

* feat: integrate font management by adding Semi.Avalonia.Demo.Fonts project.

* chore: test on ubuntu.

* feat: add linux options.

* feat: update theme settings and adjust window decorations.

* feat: add font to DRM project.

* misc: net8.0->net10.0

demo/Semi.Avalonia.Demo/App.axaml

@@ -5,6 +5,7 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:semi="https://irihi.tech/semi"
     xmlns:vm="clr-namespace:Semi.Avalonia.Demo.ViewModels"
+    RequestedThemeVariant="Default"
     x:DataType="vm:ApplicationViewModel">
     <Application.Styles>
         <semi:SemiTheme Locale="zh-CN" />

demo/Semi.Avalonia.Demo/App.axaml.cs

@@ -1,6 +1,6 @@
+using System;
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
-using Avalonia.Data.Core.Plugins;
 using Avalonia.Markup.Xaml;
 using Semi.Avalonia.Demo.ViewModels;
 using Semi.Avalonia.Demo.Views;
@@ -15,25 +15,29 @@ public partial class App : Application
 #if DEBUG
         this.AttachDeveloperTools();
 #endif
-        this.DataContext = new ApplicationViewModel();
+        DataContext = new ApplicationViewModel();
+        if (OperatingSystem.IsLinux())
+        {
+            Resources.Add("DefaultFontFamily", null);
+        }
     }
 
     public override void OnFrameworkInitializationCompleted()
     {
-        switch (ApplicationLifetime)
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
-            case IClassicDesktopStyleApplicationLifetime desktop:
-                // Line below is needed to remove Avalonia data validation.
-                // Without this line you will get duplicate validations from both Avalonia and CT
-                // BindingPlugins.DataValidators.RemoveAt(0);
-                desktop.MainWindow = new MainWindow();
-                break;
-            case ISingleViewApplicationLifetime singleView:
-                singleView.MainView = new MainView();
-                break;
+            desktop.MainWindow = new MainWindow { DataContext = new MainViewModel() };
+        }
+        else if (ApplicationLifetime is IActivityApplicationLifetime applicationLifetime)
+        {
+            applicationLifetime.MainViewFactory = () => new MainView { DataContext = new MainViewModel() };
+        }
+        else if (ApplicationLifetime is ISingleViewApplicationLifetime singleViewPlatform)
+        {
+            singleViewPlatform.MainView = new MainView { DataContext = new MainViewModel() };
         }
 
         this.RegisterFollowSystemTheme();
         base.OnFrameworkInitializationCompleted();
     }
-}
+}

demo/Semi.Avalonia.Demo/Semi.Avalonia.Demo.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net10.0</TargetFramework>
         <Nullable>enable</Nullable>
         <LangVersion>latest</LangVersion>
     </PropertyGroup>