Leader Associativity (.NET)

Leaders are associated with their annotation so that when the annotation moves, the endpoint of the leader moves with it. As you move text and feature control frame annotation, the final leader line segment alternates between attaching to the left side and to the right side of the annotation according to the relation of the annotation to the penultimate (second to last) point of the leader. If the midpoint of the annotation is to the right of the penultimate leader point, then the leader attaches to the right; otherwise, it attaches to the left.

Removing either object from the drawing using either the Erase, Add (to add a block), or WBlock method will break associativity. If the leader and its annotation are copied together in a single operation, the new copy is associative. If they are copied separately, they will non-associative. If associativity is broken for any reason, for example, by copying only the Leader object or by erasing the annotation, the hook line will be removed from the leader.

Associate a leader to the annotation

This example creates an MText object. A leader line is then created using the MText object as its annotation.

VB.NET

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
 
<CommandMethod("AddLeaderAnnotation")> _
Public Sub AddLeaderAnnotation()
    '' Get the current 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 the MText annotation
        Using acMText As MText = New MText()
            acMText.Contents = "Hello, World."
            acMText.Location = New Point3d(5, 5, 0)
            acMText.Width = 2

            '' Add the new object to Model space and the transaction
            acBlkTblRec.AppendEntity(acMText)
            acTrans.AddNewlyCreatedDBObject(acMText, True)

            '' Create the leader with annotation
            Using acLdr As Leader = New Leader()
                acLdr.AppendVertex(New Point3d(0, 0, 0))
                acLdr.AppendVertex(New Point3d(4, 4, 0))
                acLdr.AppendVertex(New Point3d(4, 5, 0))
                acLdr.HasArrowHead = True

                '' Add the new object to Model space and the transaction
                acBlkTblRec.AppendEntity(acLdr)
                acTrans.AddNewlyCreatedDBObject(acLdr, True)

                '' Attach the annotation after the leader object is added
                acLdr.Annotation = acMText.ObjectId
                acLdr.EvaluateLeader()
            End Using
        End Using

        '' Commit the changes and dispose of the transaction
        acTrans.Commit()
    End Using
End Sub

C#

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
[CommandMethod("AddLeaderAnnotation")]
public static void AddLeaderAnnotation()
{
    // Get the current 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 the MText annotation
        using (MText acMText = new MText())
        {
            acMText.Contents = "Hello, World.";
            acMText.Location = new Point3d(5, 5, 0);
            acMText.Width = 2;

            // Add the new object to Model space and the transaction
            acBlkTblRec.AppendEntity(acMText);
            acTrans.AddNewlyCreatedDBObject(acMText, true);

            // Create the leader with annotation
            using (Leader acLdr = new Leader())
            {
                acLdr.AppendVertex(new Point3d(0, 0, 0));
                acLdr.AppendVertex(new Point3d(4, 4, 0));
                acLdr.AppendVertex(new Point3d(4, 5, 0));
                acLdr.HasArrowHead = true;

                // Add the new object to Model space and the transaction
                acBlkTblRec.AppendEntity(acLdr);
                acTrans.AddNewlyCreatedDBObject(acLdr, true);

                // Attach the annotation after the leader object is added
                acLdr.Annotation = acMText.ObjectId;
                acLdr.EvaluateLeader();
            }
        }

        // Commit the changes and dispose of the transaction
        acTrans.Commit();
    }
}

VBA/ActiveX Code Reference

Sub AddLeaderAnnotation()
    Dim leaderObj As AcadLeader
    Dim mtextObj As AcadMText
    Dim points(0 To 8) As Double
    Dim insertionPoint(0 To 2) As Double
    Dim width As Double
    Dim leaderType As Integer
    Dim annotationObject As Object
    Dim textString As String, msg As String
 
    ' Create the MText object in model space
    textString = "Hello, World."
    insertionPoint(0) = 5
    insertionPoint(1) = 5
    insertionPoint(2) = 0
    width = 2
    Set mtextObj = ThisDrawing.ModelSpace. _
                       AddMText(insertionPoint, width, textString)
 
    ' Data for Leader
    points(0) = 0: points(1) = 0: points(2) = 0
    points(3) = 4: points(4) = 4: points(5) = 0
    points(6) = 4: points(7) = 5: points(8) = 0
    leaderType = acLineWithArrow
 
    ' Create the Leader object in model space and associate
    ' the MText object with the leader
    Set annotationObject = mtextObj
    Set leaderObj = ThisDrawing.ModelSpace. _
                        AddLeader(points, annotationObject, leaderType)
 
    ZoomAll
End Sub