Feature: Add drag-and-drop folder support in MainWindow.

Author: deanthecoder

CodeIngest.Desktop/Views/MainWindow.axaml.cs

@@ -0,0 +1,37 @@
+// Code authored by Dean Edis (DeanTheCoder).
+// Anyone is free to copy, modify, use, compile, or distribute this software,
+// either in source code form or as a compiled binary, for any non-commercial
+// purpose.
+//
+// If you modify the code, please retain this copyright header,
+// and consider contributing back to the repository or letting us know
+// about your modifications. Your contributions are valued!
+//
+// THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND.
+using System.Linq;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Platform.Storage;
+using CSharp.Core.Extensions;
+using CSharp.Core.UI;
+
+namespace CodeIngest.Desktop.Views;
+
+public partial class MainWindow : Window
+{
+    public MainWindow()
+    {
+        InitializeComponent();
+
+        AddHandler(DragDrop.DropEvent, OnDrop);
+    }
+
+    private void OnDrop(object sender, DragEventArgs e)
+    {
+        if (e.Data.GetFiles()?.FirstOrDefault() is not IStorageFolder folder)
+            return;
+        if (DataContext == null)
+            return;
+        ((MainViewModel)DataContext).Root = new FolderTreeRoot(folder.ToDirectoryInfo());
+    }
+}