画板基础基本完成

AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/DesignerItemViewModelBase.cs

@@ -523,6 +523,32 @@ namespace AIStudio.Wpf.DiagramDesigner
             }
         }
 
+        private double _minItemWidth;
+        public double MinItemWidth
+        {
+            get
+            {
+                return _minItemWidth;
+            }
+            set
+            {
+                SetProperty(ref _minItemWidth, value);
+            }
+        }
+
+        private double _minItemHeight;
+        public double MinItemHeight
+        {
+            get
+            {
+                return _minItemHeight;
+            }
+            set
+            {
+                SetProperty(ref _minItemHeight, value);
+            }
+        }
+
         /// <summary>
         /// 连接点是否可以按偏移自定义
         /// </summary>