页面视图新增缩略图模式

AIStudio.Wpf.DiagramDesigner/ViewModels/IDiagramViewModel.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Windows;
+using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
 using System.Xml.Serialization;
@@ -293,7 +294,7 @@ namespace AIStudio.Wpf.DiagramDesigner
         {
             get; set;
         }
-        string Thumbnail
+        Brush Thumbnail
         {
             get; set;
         }
@@ -341,6 +342,8 @@ namespace AIStudio.Wpf.DiagramDesigner
         void ClearSelectedItems();
 
         bool ExecuteShortcut(KeyEventArgs e);
+
+        void SaveThumbnail();
         #endregion
 
         #region 设置属性