feat: add basic IconDemo.

demo/Semi.Avalonia.Demo/Pages/IconDemo.axaml

@@ -0,0 +1,10 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="Semi.Avalonia.Demo.Pages.IconDemo">
+    <ScrollViewer>
+        <StackPanel x:Name="IconsPanel" Orientation="Vertical" Spacing="10" Margin="10" />
+    </ScrollViewer>
+</UserControl>

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

@@ -0,0 +1,45 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Shapes;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media;
+using Avalonia.Threading;
+
+namespace Semi.Avalonia.Demo.Pages;
+
+public partial class IconDemo : UserControl
+{
+    public IconDemo()
+    {
+        InitializeComponent();
+    }
+
+    protected override async void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+        await Dispatcher.UIThread.InvokeAsync(LoadIcons);
+    }
+
+    private void LoadIcons()
+    {
+        IResourceDictionary? resources =
+            AvaloniaXamlLoader.Load(new Uri("avares://Semi.Avalonia/Themes/Shared/Icon.axaml")) as ResourceDictionary;
+        if (resources is null) return;
+
+        var stackPanel = this.FindControl<StackPanel>("IconsPanel");
+        foreach (var key in resources.Keys)
+        {
+            if (resources[key] is not Geometry geometry) continue;
+            var iconControl = new Path
+            {
+                Data = geometry,
+                Fill = Brushes.Black,
+                Width = 48,
+                Height = 48
+            };
+
+            stackPanel?.Children.Add(iconControl);
+        }
+    }
+}

demo/Semi.Avalonia.Demo/Views/MainView.axaml

@@ -104,6 +104,9 @@
             <TabItem Header="Palette">
                 <pages:PaletteDemo />
             </TabItem>
+            <TabItem Header="Icon">
+                <pages:IconDemo />
+            </TabItem>
             <TabItem Header="AutoCompleteBox">
                 <pages:AutoCompleteBoxDemo />
             </TabItem>