Add DeferredContent class to improve startup performance

Author: CodingOctocat

IPConfig/Controls/DeferredContent.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace IPConfig.Controls;
+
+/// <summary>
+/// <see href="https://stackoverflow.com/a/26543731/4380178">Deferred loading of XAML</see>
+/// </summary>
+public class DeferredContent : ContentPresenter
+{
+    public static readonly DependencyProperty DeferredContentTemplateProperty =
+        DependencyProperty.Register("DeferredContentTemplate",
+        typeof(DataTemplate), typeof(DeferredContent), null);
+
+    public DataTemplate DeferredContentTemplate
+    {
+        get => (DataTemplate)GetValue(DeferredContentTemplateProperty);
+        set => SetValue(DeferredContentTemplateProperty, value);
+    }
+
+    public event EventHandler<RoutedEventArgs>? DeferredContentLoaded;
+
+    public DeferredContent()
+    {
+        Loaded += HandleLoaded;
+    }
+
+    public void ShowDeferredContent()
+    {
+        if (DeferredContentTemplate is not null)
+        {
+            Content = DeferredContentTemplate.LoadContent();
+            RaiseDeferredContentLoaded();
+        }
+    }
+
+    private void HandleLoaded(object sender, RoutedEventArgs e)
+    {
+        Loaded -= HandleLoaded;
+        Dispatcher.BeginInvoke(ShowDeferredContent);
+    }
+
+    private void RaiseDeferredContentLoaded()
+    {
+        DeferredContentLoaded?.Invoke(this, new RoutedEventArgs());
+    }
+}

IPConfig/Views/MainWindow.xaml

@@ -7,6 +7,7 @@
            xmlns:hcd="clr-namespace:HandyControl.Data;assembly=HandyControl"
            xmlns:app="clr-namespace:IPConfig"
            xmlns:b="clr-namespace:IPConfig.Behaviors"
+           xmlns:c="clr-namespace:IPConfig.Controls"
            xmlns:conv="clr-namespace:IPConfig.Converters"
            xmlns:lang="clr-namespace:IPConfig.Languages"
            xmlns:m="clr-namespace:IPConfig.Models"
@@ -408,9 +409,15 @@
                     </hc:ToggleBlock.UnCheckedContent>
 
                     <hc:ToggleBlock.CheckedContent>
-                        <hc:TransitioningContentControl TransitionMode="Right2Left">
-                            <v:NicConfigDetailView />
-                        </hc:TransitioningContentControl>
+                        <c:DeferredContent>
+                            <c:DeferredContent.DeferredContentTemplate>
+                                <DataTemplate>
+                                    <hc:TransitioningContentControl TransitionMode="Right2Left">
+                                        <v:NicConfigDetailView />
+                                    </hc:TransitioningContentControl>
+                                </DataTemplate>
+                            </c:DeferredContent.DeferredContentTemplate>
+                        </c:DeferredContent>
                     </hc:ToggleBlock.CheckedContent>
                 </hc:ToggleBlock>
             </Grid>