Add drag-to-reorder photo ordering in New Listing tab

Photos can now be dragged to any position — cursor changes to a move
cursor to signal draggability, the drop target dims to show the
insertion point, and the list rebuilds immediately after the drop.

First photo gets a 'Cover' badge since eBay uses it as the gallery
hero image. All add/remove/clear operations now go through
RebuildPhotoThumbnails() so the panel always reflects the true order
in PhotoPaths.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

EbayListingTool/Views/SingleItemView.xaml.cs

@@ -20,6 +20,10 @@ public partial class SingleItemView : UserControl
     private System.Threading.CancellationTokenSource? _categoryCts;
     private string _suggestedPriceValue = "";
 
+    // Photo drag-reorder
+    private Point _dragStartPoint;
+    private bool  _isDragging;
+
     public SingleItemView()
     {
         InitializeComponent();
@@ -329,25 +333,35 @@ public partial class SingleItemView : UserControl
             if (!imageExts.Contains(Path.GetExtension(path))) continue;
             if (_draft.PhotoPaths.Count >= 12) break;
             if (_draft.PhotoPaths.Contains(path)) continue;
-
             _draft.PhotoPaths.Add(path);
-            AddPhotoThumbnail(path);
         }
 
+        RebuildPhotoThumbnails();
+    }
+
+    /// <summary>
+    /// Clears and recreates all photo thumbnails from <see cref="ListingDraft.PhotoPaths"/>.
+    /// Called after any add, remove, or reorder operation so the panel always matches the list.
+    /// </summary>
+    private void RebuildPhotoThumbnails()
+    {
+        PhotosPanel.Children.Clear();
+        for (int i = 0; i < _draft.PhotoPaths.Count; i++)
+            AddPhotoThumbnail(_draft.PhotoPaths[i], i);
         UpdatePhotoPanel();
     }
 
-    private void AddPhotoThumbnail(string path)
+    private void AddPhotoThumbnail(string path, int index)
     {
         try
         {
             var bmp = new BitmapImage();
             bmp.BeginInit();
-            bmp.UriSource        = new Uri(path, UriKind.Absolute); // W1
+            bmp.UriSource        = new Uri(path, UriKind.Absolute);
             bmp.DecodePixelWidth = 128;
             bmp.CacheOption      = BitmapCacheOption.OnLoad;
             bmp.EndInit();
-            bmp.Freeze(); // M2
+            bmp.Freeze();
 
             var img = new System.Windows.Controls.Image
             {
@@ -356,12 +370,9 @@ public partial class SingleItemView : UserControl
                 Source = bmp,
                 ToolTip = Path.GetFileName(path)
             };
+            img.Clip = new System.Windows.Media.RectangleGeometry(new Rect(0, 0, 72, 72), 4, 4);
 
-            // Rounded clip on the image
+            // Remove button
-            img.Clip = new System.Windows.Media.RectangleGeometry(
-                new Rect(0, 0, 72, 72), 4, 4);
-
-            // Remove button — shown on hover via opacity triggers
             var removeBtn = new Button
             {
                 Width = 18, Height = 18,
@@ -375,38 +386,116 @@ public partial class SingleItemView : UserControl
                     System.Windows.Media.Color.FromArgb(200, 30, 30, 30)),
                 Foreground = System.Windows.Media.Brushes.White,
                 BorderThickness = new Thickness(0),
-                FontSize = 11,
+                FontSize = 11, FontWeight = FontWeights.Bold,
-                FontWeight = FontWeights.Bold,
                 Content = "✕",
                 Opacity = 0
             };
+            removeBtn.Click += (s, e) =>
+            {
+                e.Handled = true; // don't bubble and trigger drag
+                _draft.PhotoPaths.Remove(path);
+                RebuildPhotoThumbnails();
+            };
+
+            // "Cover" badge on the first photo — it becomes the eBay gallery hero image
+            Border? coverBadge = null;
+            if (index == 0)
+            {
+                coverBadge = new Border
+                {
+                    CornerRadius = new CornerRadius(3),
+                    Background = new System.Windows.Media.SolidColorBrush(
+                        System.Windows.Media.Color.FromArgb(210, 60, 90, 200)),
+                    Padding = new Thickness(3, 1, 3, 1),
+                    Margin = new Thickness(2, 2, 0, 0),
+                    HorizontalAlignment = HorizontalAlignment.Left,
+                    VerticalAlignment   = VerticalAlignment.Top,
+                    IsHitTestVisible    = false, // don't block drag
+                    Child = new TextBlock
+                    {
+                        Text = "Cover",
+                        FontSize = 8,
+                        FontWeight = FontWeights.SemiBold,
+                        Foreground = System.Windows.Media.Brushes.White
+                    }
+                };
+            }
 
-            // Container grid — shows remove button on mouse over
             var container = new Grid
             {
                 Width = 72, Height = 72,
                 Margin = new Thickness(4),
-                Cursor = Cursors.Hand
+                Cursor = Cursors.SizeAll, // signal draggability
+                AllowDrop = true,
+                Tag = path  // stable identifier used by drop handler
             };
             container.Children.Add(img);
+            if (coverBadge != null) container.Children.Add(coverBadge);
             container.Children.Add(removeBtn);
 
+            // Hover: reveal remove button
             container.MouseEnter += (s, e) => removeBtn.Opacity = 1;
             container.MouseLeave += (s, e) => removeBtn.Opacity = 0;
-            removeBtn.Click += (s, e) => RemovePhoto(path, container);
+
+            // Drag initiation
+            container.MouseLeftButtonDown += (s, e) =>
+            {
+                _dragStartPoint = e.GetPosition(null);
+            };
+            container.MouseMove += (s, e) =>
+            {
+                if (e.LeftButton != MouseButtonState.Pressed || _isDragging) return;
+                var pos = e.GetPosition(null);
+                if (Math.Abs(pos.X - _dragStartPoint.X) > SystemParameters.MinimumHorizontalDragDistance ||
+                    Math.Abs(pos.Y - _dragStartPoint.Y) > SystemParameters.MinimumVerticalDragDistance)
+                {
+                    _isDragging = true;
+                    DragDrop.DoDragDrop(container, path, DragDropEffects.Move);
+                    _isDragging = false;
+                }
+            };
+
+            // Drop target
+            container.DragOver += (s, e) =>
+            {
+                if (e.Data.GetDataPresent(typeof(string)) &&
+                    (string)e.Data.GetData(typeof(string)) != path)
+                {
+                    e.Effects = DragDropEffects.Move;
+                    container.Opacity = 0.45; // dim to signal insertion point
+                }
+                else
+                {
+                    e.Effects = DragDropEffects.None;
+                }
+                e.Handled = true;
+            };
+            container.DragLeave += (s, e) => container.Opacity = 1.0;
+            container.Drop += (s, e) =>
+            {
+                container.Opacity = 1.0;
+                if (!e.Data.GetDataPresent(typeof(string))) return;
+
+                var sourcePath = (string)e.Data.GetData(typeof(string));
+                var targetPath = (string)container.Tag;
+                if (sourcePath == targetPath) return;
+
+                var sourceIdx = _draft.PhotoPaths.IndexOf(sourcePath);
+                var targetIdx = _draft.PhotoPaths.IndexOf(targetPath);
+                if (sourceIdx < 0 || targetIdx < 0) return;
+
+                _draft.PhotoPaths.RemoveAt(sourceIdx);
+                _draft.PhotoPaths.Insert(targetIdx, sourcePath);
+
+                RebuildPhotoThumbnails();
+                e.Handled = true;
+            };
 
             PhotosPanel.Children.Add(container);
         }
         catch { /* skip unreadable files */ }
     }
 
-    private void RemovePhoto(string path, UIElement thumb)
-    {
-        _draft.PhotoPaths.Remove(path);
-        PhotosPanel.Children.Remove(thumb);
-        UpdatePhotoPanel();
-    }
-
     private void UpdatePhotoPanel()
     {
         var count = _draft.PhotoPaths.Count;
@@ -421,8 +510,7 @@ public partial class SingleItemView : UserControl
     private void ClearPhotos_Click(object sender, RoutedEventArgs e)
     {
         _draft.PhotoPaths.Clear();
-        PhotosPanel.Children.Clear();
+        RebuildPhotoThumbnails();
-        UpdatePhotoPanel();
     }
 
     // ---- Post / Save ----