Move and delete files

Helpers/DataGridDropHandler.cs

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+using System.Collections.ObjectModel;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.VisualTree;
+using Avalonia.Xaml.Interactions.DragAndDrop;
+using ReceiptPDFBuilder.Models;
+using ReceiptPDFBuilder.ViewModels;
+
+namespace ReceiptPDFBuilder.Helpers;
+
+class DataGridDropHandler : BaseDataGridDropHandler<ReportFile>
+{
+    // https://wieslawsoltes.github.io/Xaml.Behaviors/articles/drag-and-drop-datagrid/datagrid-drag-and-drop-overview.html
+    // ...that page's code basically doesn't work in the way you'd expect. so just use the source code sample's code.
+    protected override bool Validate(DataGrid dg, DragEventArgs e, object? sourceContext, object? targetContext, bool execute)
+    {
+        if (sourceContext is not ReportFile sourceItem
+            || targetContext is not MainViewModel vm
+            || dg.GetVisualAt(e.GetPosition(dg)) is not Control targetControl
+            || targetControl.DataContext is not ReportFile targetItem)
+        {
+            return false;
+        }
+
+        var items = dg.ItemsSource as ObservableCollection<ReportFile>;
+        return RunDropAction(dg, e, execute, sourceItem, targetItem, items?? []);
+    }
+
+    protected override ReportFile MakeCopy(ObservableCollection<ReportFile> parentCollection, ReportFile item)
+    {
+        // Return a clone of the item if you support Copy operations
+        return new ReportFile { };
+    }
+}