Extend and Trim Objects

You can change the angle of arcs and you can change the length of lines, open polylines, elliptical arcs, and open splines. The results are similar to both extending and trimming objects.

You can extend or trim an object by editing its properties. For example, to lengthen a line, simply change the coordinates of the StartPoint or EndPoint properties. To change the angle of an arc, change the StartAngle or EndAngle property of the arc. Once you have altered an object's property or properties, you might need to regenerate the display to see the changes in the drawing window.

For more information about extending and trimming objects, see “Resize or Reshape Objects” in the AutoCAD User's Guide.

Lengthen a line

This example creates a line and then changes the endpoint of that line, resulting in a longer line.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

Imports Autodesk.AutoCAD.Geometry

<CommandMethod("ExtendObject")> _

Public Sub ExtendObject()

  '' Get the current document and database

  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument

  Dim acCurDb As Database = acDoc.Database

  '' Start a transaction

  Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

      '' Open the Block table 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)

      '' Create a line that starts at (4,4,0) and ends at (7,7,0)

      Dim acLine As Line = New Line(New Point3d(4, 4, 0), _

                                    New Point3d(7, 7, 0))

      '' Add the new object to the block table record and the transaction

      acBlkTblRec.AppendEntity(acLine)

      acTrans.AddNewlyCreatedDBObject(acLine, True)

      '' Update the display and diaplay a message box

      acDoc.Editor.Regen()

      Application.ShowAlertDialog("Before extend")

      '' Double the length of the line

      acLine.EndPoint = acLine.EndPoint + acLine.Delta

      '' Save the new object to the database

      acTrans.Commit()

  End Using

End Sub

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.Geometry;

[CommandMethod("ExtendObject")]

public static void ExtendObject()

  // Get the current document and database

  Document acDoc = Application.DocumentManager.MdiActiveDocument;

  Database acCurDb = acDoc.Database;

  // Start a transaction

  using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())

      // Open the Block table 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;

      // Create a line that starts at (4,4,0) and ends at (7,7,0)

      Line acLine = new Line(new Point3d(4, 4, 0),

                             new Point3d(7, 7, 0));

      // Add the new object to the block table record and the transaction

      acBlkTblRec.AppendEntity(acLine);

      acTrans.AddNewlyCreatedDBObject(acLine, true);

      // Update the display and diaplay a message box

      acDoc.Editor.Regen();

      Application.ShowAlertDialog("Before extend");

      // Double the length of the line

      acLine.EndPoint = acLine.EndPoint + acLine.Delta;

      // Save the new object to the database

      acTrans.Commit();

VBA/ActiveX Code Reference