如何把定制的信息保存到DWG中

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How can I store my custom information in a dwg file?          By Marat Mirgaleev
  Q: I need to store some information in a dwg file, which would describe this drawing and let to integrate it with another software system. Can I write such custom information into a drawing and read it later? Can it be done without opening the drawing in AutoCAD?
     
A: You may use so called Named Object Dictionary (NOD) to store custom data in a drawing. NOD is an essential part of an AutoCAD drawing database and it is created automatically when the drawing is created.     

  As always with database operations, your program may open a dwg file invisibly to the user via Database.ReadDwgFile() method, i.e. it does not have to be the drawing in the active AutoCAD window.   

  Here is an example:

1. // Write some data to the NOD
   
2. //============================
   
3. [CommandMethod("WNOD")]
   
4. public void WriteToNOD()
   
5. {
   
6.   Database db = new Database();
   
7.   try
   
8.   {
   
9.     // We will write to C:\Temp\Test.dwg. Make sure it exists!
   
10.     // Load it into AutoCAD
    
11.     db.ReadDwgFile(@"C:\Temp\Test.dwg",
    
12.                     System.IO.FileShare.ReadWrite, false, null);
    
13.     using( Transaction trans =
    
14.                       db.TransactionManager.StartTransaction() )
    
15.     {
    
16.       // Find the NOD in the database
    
17.       DBDictionary nod = (DBDictionary)trans.GetObject(
    
18.                   db.NamedObjectsDictionaryId, OpenMode.ForWrite);
    
19.       // We use Xrecord class to store data in Dictionaries
    
20.       Xrecord myXrecord = new Xrecord();
    
21.       myXrecord.Data = new ResultBuffer(
    
22.               new TypedValue((int)DxfCode.Int16, 1234),
    
23.               new TypedValue((int)DxfCode.Text,
    
24.                               "This drawing has been processed"));
    
25.       // Create the entry in the Named Object Dictionary
    
26.       nod.SetAt("MyData", myXrecord);
    
27.       trans.AddNewlyCreatedDBObject(myXrecord, true);
    
28.       // Now let's read the data back and print them out
    
29.       //  to the Visual Studio's Output window
    
30.       ObjectId myDataId = nod.GetAt("MyData");
    
31.       Xrecord readBack = (Xrecord)trans.GetObject(
    
32.                                     myDataId, OpenMode.ForRead);
    
33.       foreach (TypedValue value in readBack.Data)
    
34.         System.Diagnostics.Debug.Print(
    
35.                   "===== OUR DATA: " + value.TypeCode.ToString()
    
36.                   + ". " + value.Value.ToString());
    
37.       trans.Commit();
    
38.     } // using
    
39.     db.SaveAs(@"C:\Temp\Test.dwg", DwgVersion.Current);
    
40.   }
    
41.   catch( Exception e )
    
42.   {
    
43.     System.Diagnostics.Debug.Print(e.ToString());
    
44.   }
    
45.   finally
    
46.   {
    
47.     db.Dispose();
    
48.   }
    
49. } // End of WriteToNOD()

// Write some data to the NOD<br /> //============================<br /> [CommandMethod("WNOD")]<br /> public void WriteToNOD()<br /> {<br />   Database db = new Database();<br />   try<br />   {<br />     // We will write to C:\Temp\Test.dwg. Make sure it exists!<br />     // Load it into AutoCAD<br />     db.ReadDwgFile(@"C:\Temp\Test.dwg",<br />                     System.IO.FileShare.ReadWrite, false, null);<br />     using( Transaction trans =<br />                       db.TransactionManager.StartTransaction() )<br />     {<br />       // Find the NOD in the database<br />       DBDictionary nod = (DBDictionary)trans.GetObject(<br />                   db.NamedObjectsDictionaryId, OpenMode.ForWrite); <br />       // We use Xrecord class to store data in Dictionaries<br />       Xrecord myXrecord = new Xrecord();<br />       myXrecord.Data = new ResultBuffer(<br />               new TypedValue((int)DxfCode.Int16, 1234),<br />               new TypedValue((int)DxfCode.Text,<br />                               "This drawing has been processed")); <br />       // Create the entry in the Named Object Dictionary<br />       nod.SetAt("MyData", myXrecord);<br />       trans.AddNewlyCreatedDBObject(myXrecord, true); <br />       // Now let's read the data back and print them out<br />       //  to the Visual Studio's Output window<br />       ObjectId myDataId = nod.GetAt("MyData");<br />       Xrecord readBack = (Xrecord)trans.GetObject(<br />                                     myDataId, OpenMode.ForRead);<br />       foreach (TypedValue value in readBack.Data)<br />         System.Diagnostics.Debug.Print(<br />                   "===== OUR DATA: " + value.TypeCode.ToString()<br />                   + ". " + value.Value.ToString());<br />       trans.Commit();<br />     } // using<br />     db.SaveAs(@"C:\Temp\Test.dwg", DwgVersion.Current);<br />   }<br />   catch( Exception e )<br />   {<br />     System.Diagnostics.Debug.Print(e.ToString());<br />   }<br />   finally<br />   {<br />     db.Dispose();<br />   }<br /> } // End of WriteToNOD()

You can treat the NOD as a place to keep "document-level" data.   

  If you need to store some data related to particular objects in the drawing, consider using their Extension Dictionaries.