添加项目文件。

gong-wpf-dragdrop/src/Showcase/Models/ClonableItemModel.cs

@@ -0,0 +1,31 @@
+using System;
+
+namespace Showcase.WPF.DragDrop.Models
+{
+    public class ClonableItemModel : ItemModel, ICloneable
+    {
+        public ClonableItemModel()
+        {
+        }
+
+        public ClonableItemModel(int itemIndex)
+            : base(itemIndex)
+        {
+        }
+
+        public object Clone()
+        {
+            var clonableItemModel = new ClonableItemModel();
+            clonableItemModel.BindableDoubleValue = this.BindableDoubleValue;
+            clonableItemModel.SubItemCollection.Clear();
+            foreach (var subItem in this.SubItemCollection)
+            {
+                clonableItemModel.SubItemCollection.Add(subItem);
+            }
+            clonableItemModel.SelectedSubItem = this.SelectedSubItem;
+            clonableItemModel.Index = this.Index;
+            clonableItemModel.Caption = $"Cloned Item {this.Index}";
+            return clonableItemModel;
+        }
+    }
+}