练习：创建新命令 （.NET）

现在，您已经创建了一个项目并添加了必要的库引用，是时候创建一个命令了。该命令将在模型空间中创建新的多行文本 （MText） 对象。这些概念和其他概念将在后面的章节中深入讨论。

定义创建新 MText 对象的新命令

1. 在“解决方案资源管理器”中，根据您创建的项目类型双击“类 1.vb”或“类 1.cs”。

   将为 Class1 模块打开一个代码窗口，它应如下所示：

   VB.NET

   Public Class Class1
    
   End Class

   C#

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
    
   namespace MyFirstProject1
   {
     public class Class1
     {
     }
   }

2. 更改代码窗口中的代码以匹配以下内容：

   VB.NET

   Imports Autodesk.AutoCAD.Runtime
   Imports Autodesk.AutoCAD.ApplicationServices
   Imports Autodesk.AutoCAD.DatabaseServices
        
   Public Class Class1
     <CommandMethod("AdskGreeting")> _
     Public Sub AdskGreeting()
         '' Get the current document and database, and start a transaction
         Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
         Dim acCurDb As Database = acDoc.Database
    
         Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
             '' Open the Block table record for read
             Dim acBlkTbl As BlockTable
             acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, _
                                          OpenMode.ForRead)
    
             '' Open the Block table record Model space for write
             Dim acBlkTblRec As BlockTableRecord
             acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _
                                             OpenMode.ForWrite)
    
             '' Creates a new MText object and assigns it a location,
             '' text value and text style
             Using objText As MText = New MText
    
                 '' Specify the insertion point of the MText object
                 objText.Location = New Autodesk.AutoCAD.Geometry.Point3d(2, 2, 0)
    
                 '' Set the text string for the MText object
                 objText.Contents = "Greetings, Welcome to AutoCAD .NET"
    
                 '' Set the text style for the MText object
                 objText.TextStyleId = acCurDb.Textstyle
    
                 '' Appends the new MText object to model space
                 acBlkTblRec.AppendEntity(objText)
    
                 '' Appends to new MText object to the active transaction
                 acTrans.AddNewlyCreatedDBObject(objText, True)
             End Using
   
             '' Saves the changes to the database and closes the transaction
             acTrans.Commit()
         End Using
     End Sub
   End Class

   C#

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
    
   using Autodesk.AutoCAD.Runtime;
   using Autodesk.AutoCAD.ApplicationServices;
   using Autodesk.AutoCAD.DatabaseServices;
    
   [assembly: CommandClass(typeof(MyFirstProject1.Class1))]
    
   namespace MyFirstProject1
   {
     public class Class1
     {
         [CommandMethod("AdskGreeting")]
         public void AdskGreeting()
         {
             // Get the current document and database, and start a transaction
             Document acDoc = Application.DocumentManager.MdiActiveDocument;
             Database acCurDb = acDoc.Database;
    
             // Starts a new transaction with the Transaction Manager
             using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
             {
                 // Open the Block table record for read
                 BlockTable acBlkTbl;
                 acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                              OpenMode.ForRead) as BlockTable;
    
                 // Open the Block table record Model space for write
                 BlockTableRecord acBlkTblRec;
                 acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                                 OpenMode.ForWrite) as BlockTableRecord;
    
                 /* Creates a new MText object and assigns it a location,
                 text value and text style */
                 using (MText objText = new MText())
                 {
                     // Specify the insertion point of the MText object
                     objText.Location = new Autodesk.AutoCAD.Geometry.Point3d(2, 2, 0);
    
                     // Set the text string for the MText object
                     objText.Contents = "Greetings, Welcome to AutoCAD .NET";
    
                     // Set the text style for the MText object
                     objText.TextStyleId = acCurDb.Textstyle;
    
                     // Appends the new MText object to model space
                     acBlkTblRec.AppendEntity(objText);
    
                     // Appends to new MText object to the active transaction
                     acTrans.AddNewlyCreatedDBObject(objText, true);
                 }
   
                 // Saves the changes to the database and closes the transaction
                 acTrans.Commit();
             }
         }
     }
   }