block 可以拖拽到内部，还有少量问题待解决

Extensions/AIStudio.Wpf.Block/ViewModels/VariableModules/VariableBlockItemViewModel.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using AIStudio.Wpf.Block.Models;
+using AIStudio.Wpf.DiagramDesigner;
+using AIStudio.Wpf.DiagramDesigner.Models;
+
+namespace AIStudio.Wpf.Block.ViewModels.VariableModules
+{
+    public class VariableBlockItemViewModel : BlockDesignerItemViewModel
+    {
+        public VariableBlockItemViewModel()
+        {
+        }
+
+        public VariableBlockItemViewModel(IDiagramViewModel root) : base(root)
+        {
+        }
+
+        public VariableBlockItemViewModel(IDiagramViewModel root, SelectableItemBase designer) : base(root, designer)
+        {
+        }
+
+        public VariableBlockItemViewModel(IDiagramViewModel root, SerializableItem serializableItem, string serializableType) : base(root, serializableItem, serializableType)
+        {
+        }
+
+        protected override void InitNew()
+        {
+            ItemWidth = double.NaN;
+            ItemHeight = double.NaN;
+            Value = new VarParameter();
+        }
+
+        private IParameter _value;
+        public IParameter Value
+        {
+            get
+            {
+                return _value;
+            }
+            set
+            {
+                SetProperty(ref _value, value);
+            }
+        }
+    }
+}