MLeader Class

Overview

The MLeader class represents a modern multi-leader annotation entity in AutoCAD (introduced in AutoCAD 2008). MLeaders are more flexible than legacy Leaders, supporting multiple leader lines, various content types (text, blocks, or none), and dedicated MLeader styles for consistent formatting.

Namespace

Autodesk.AutoCAD.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ Entity
              └─ MLeader

Key Properties

Property	Type	Description
`ContentType`	`ContentType`	Gets/sets content type (MText, Block, None)
`MText`	`MText`	Gets/sets the MText content
`BlockContentId`	`ObjectId`	Gets/sets the block content
`MLeaderStyle`	`ObjectId`	Gets/sets the MLeader style
`ArrowSymbolId`	`ObjectId`	Gets/sets the arrowhead block
`LeaderLineType`	`LeaderType`	Gets/sets leader line type (Straight, Spline)
`TextAttachmentType`	`TextAttachmentType`	Gets/sets how text attaches to leader
`DoglegLength`	`double`	Gets/sets the horizontal landing length
`EnableDogleg`	`bool`	Gets/sets whether dogleg is enabled
`EnableLanding`	`bool`	Gets/sets whether landing line is enabled

Key Methods

Method	Return Type	Description
`AddLeader()`	`int`	Adds a new leader line and returns its index
`RemoveLeader(int)`	`void`	Removes the leader at the specified index
`AddLeaderLine(int)`	`int`	Adds a leader line to an existing leader
`RemoveLeaderLine(int, int)`	`void`	Removes a leader line
`SetFirstVertex(int, Point3d)`	`void`	Sets the first vertex of a leader line
`SetLastVertex(int, Point3d)`	`void`	Sets the last vertex of a leader line
`GetLeaderIndex(int)`	`int`	Gets the leader index for a leader line
`GetLeaderLineIndexes(int)`	`IntegerCollection`	Gets all leader line indexes for a leader

Code Examples

Example 1: Creating a Simple MLeader with Text

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    
    // Create MLeader
    MLeader mleader = new MLeader();
    mleader.SetDatabaseDefaults();
    
    // Set content type to MText
    mleader.ContentType = ContentType.MTextContent;
    
    // Set text content
    MText mtext = new MText();
    mtext.Contents = "This is an MLeader note";
    mleader.MText = mtext;
    
    // Add leader line
    int leaderIndex = mleader.AddLeader();
    int lineIndex = mleader.AddLeaderLine(leaderIndex);
    
    // Set vertices (from text to feature)
    mleader.SetFirstVertex(lineIndex, new Point3d(10, 10, 0));
    mleader.SetLastVertex(lineIndex, new Point3d(0, 0, 0));
    
    // Add to drawing
    btr.AppendEntity(mleader);
    tr.AddNewlyCreatedDBObject(mleader, true);
    
    tr.Commit();
}

Example 2: Creating MLeader with Multiple Leader Lines

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    
    MLeader mleader = new MLeader();
    mleader.SetDatabaseDefaults();
    mleader.ContentType = ContentType.MTextContent;
    
    MText mtext = new MText();
    mtext.Contents = "Multiple Leaders";
    mleader.MText = mtext;
    
    // Add first leader
    int leader1 = mleader.AddLeader();
    int line1 = mleader.AddLeaderLine(leader1);
    mleader.SetFirstVertex(line1, new Point3d(10, 10, 0));
    mleader.SetLastVertex(line1, new Point3d(0, 0, 0));
    
    // Add second leader
    int leader2 = mleader.AddLeader();
    int line2 = mleader.AddLeaderLine(leader2);
    mleader.SetFirstVertex(line2, new Point3d(10, 10, 0));
    mleader.SetLastVertex(line2, new Point3d(5, -5, 0));
    
    // Add third leader
    int leader3 = mleader.AddLeader();
    int line3 = mleader.AddLeaderLine(leader3);
    mleader.SetFirstVertex(line3, new Point3d(10, 10, 0));
    mleader.SetLastVertex(line3, new Point3d(-5, 5, 0));
    
    btr.AppendEntity(mleader);
    tr.AddNewlyCreatedDBObject(mleader, true);
    
    tr.Commit();
}

Example 3: Creating MLeader with Block Content

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTable bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) as BlockTable;
    BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    
    MLeader mleader = new MLeader();
    mleader.SetDatabaseDefaults();
    
    // Set content type to Block
    mleader.ContentType = ContentType.BlockContent;
    
    // Set block content (assuming "DetailTag" block exists)
    if (bt.Has("DetailTag"))
    {
        mleader.BlockContentId = bt["DetailTag"];
    }
    
    // Add leader
    int leaderIndex = mleader.AddLeader();
    int lineIndex = mleader.AddLeaderLine(leaderIndex);
    mleader.SetFirstVertex(lineIndex, new Point3d(10, 10, 0));
    mleader.SetLastVertex(lineIndex, new Point3d(0, 0, 0));
    
    btr.AppendEntity(mleader);
    tr.AddNewlyCreatedDBObject(mleader, true);
    
    tr.Commit();
}

Example 4: Setting MLeader Properties

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    MLeader mleader = tr.GetObject(mleaderId, OpenMode.ForWrite) as MLeader;
    
    // Set leader line type
    mleader.LeaderLineType = LeaderType.SplineLeader;
    
    // Enable and set dogleg
    mleader.EnableDogleg = true;
    mleader.DoglegLength = 5.0;
    
    // Enable landing
    mleader.EnableLanding = true;
    
    // Set text attachment
    mleader.TextAttachmentType = TextAttachmentType.AttachmentMiddle;
    
    // Set color
    mleader.ColorIndex = 3; // Green
    
    tr.Commit();
}

Example 5: Reading MLeader Information

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    MLeader mleader = tr.GetObject(mleaderId, OpenMode.ForRead) as MLeader;
    
    ed.WriteMessage("\n=== MLeader Information ===");
    ed.WriteMessage($"\nContent Type: {mleader.ContentType}");
    ed.WriteMessage($"\nLeader Line Type: {mleader.LeaderLineType}");
    ed.WriteMessage($"\nDogleg Enabled: {mleader.EnableDogleg}");
    ed.WriteMessage($"\nDogleg Length: {mleader.DoglegLength:F2}");
    ed.WriteMessage($"\nLanding Enabled: {mleader.EnableLanding}");
    
    if (mleader.ContentType == ContentType.MTextContent)
    {
        ed.WriteMessage($"\nText Content: {mleader.MText.Contents}");
    }
    
    // Count leaders
    int leaderCount = 0;
    for (int i = 0; i < 100; i++) // Arbitrary upper limit
    {
        try
        {
            IntegerCollection lines = mleader.GetLeaderLineIndexes(i);
            if (lines != null && lines.Count > 0)
                leaderCount++;
            else
                break;
        }
        catch
        {
            break;
        }
    }
    
    ed.WriteMessage($"\nNumber of Leaders: {leaderCount}");
    
    tr.Commit();
}

Example 6: Applying MLeader Style

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    MLeader mleader = tr.GetObject(mleaderId, OpenMode.ForWrite) as MLeader;
    
    // Get MLeader style dictionary
    DBDictionary mleaderDict = tr.GetObject(db.MLeaderStyleDictionaryId, OpenMode.ForRead) as DBDictionary;
    
    if (mleaderDict.Contains("Annotative"))
    {
        mleader.MLeaderStyle = mleaderDict.GetAt("Annotative");
        ed.WriteMessage("\nApplied 'Annotative' MLeader style");
    }
    
    tr.Commit();
}

Example 7: Creating MLeader with No Content

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    BlockTableRecord btr = tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
    
    // Create MLeader with no content (just leader lines)
    MLeader mleader = new MLeader();
    mleader.SetDatabaseDefaults();
    mleader.ContentType = ContentType.NoneContent;
    
    // Add leader
    int leaderIndex = mleader.AddLeader();
    int lineIndex = mleader.AddLeaderLine(leaderIndex);
    mleader.SetFirstVertex(lineIndex, new Point3d(10, 0, 0));
    mleader.SetLastVertex(lineIndex, new Point3d(0, 0, 0));
    
    mleader.ColorIndex = 1; // Red
    
    btr.AppendEntity(mleader);
    tr.AddNewlyCreatedDBObject(mleader, true);
    
    tr.Commit();
}

Example 8: Modifying MLeader Text

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    MLeader mleader = tr.GetObject(mleaderId, OpenMode.ForWrite) as MLeader;
    
    if (mleader.ContentType == ContentType.MTextContent)
    {
        MText mtext = mleader.MText;
        mtext.Contents = "Updated text content\\PWith multiple lines";
        mtext.TextHeight = 3.0;
        mleader.MText = mtext;
        
        ed.WriteMessage("\nUpdated MLeader text");
    }
    
    tr.Commit();
}

Content Types

Type	Description
`MTextContent`	Multi-line text annotation
`BlockContent`	Block reference annotation
`NoneContent`	No content (leader lines only)

Leader Types

Type	Description
`StraightLeader`	Straight line segments
`SplineLeader`	Smooth spline curve

Text Attachment Types

Type	Description
`AttachmentTop`	Attach to top of text
`AttachmentMiddle`	Attach to middle of text
`AttachmentBottom`	Attach to bottom of text

MLeader vs Leader

Feature	Leader (Legacy)	MLeader (Modern)
Introduction	R13	2008
Multiple Leaders	No	Yes
Content Types	Limited	Text, Block, None
Styles	Dimension Style	MLeader Style
Flexibility	Basic	Advanced
Recommended	Legacy only	All new work

Best Practices

Use MLeader Styles: Create and use MLeader styles for consistency
Content Type: Choose appropriate content type for your needs
Multiple Leaders: Use for pointing to multiple features
Dogleg: Enable for horizontal landing line
Spline Leaders: Use for organic, curved appearance
Text Formatting: Use MText formatting codes for rich text
Block Content: Use for standardized callouts and tags
Layer Management: Place MLeaders on appropriate annotation layers

Common Use Cases

Callouts: Multi-point feature identification
Notes: Explanatory annotations
Detail Tags: Standardized detail references
Part Labels: Component identification
Revision Clouds: Revision annotations
Weld Symbols: Welding annotations

Related Objects

Leader - Legacy leader annotation
Dimension - Dimension annotation base class
Entity - Base class for all entities
MText - Text content for MLeaders
BlockReference - Block content for MLeaders
MLeaderStyle - Style definition for MLeaders

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MLeader Class

Overview

Namespace

Inheritance Hierarchy

Key Properties

Key Methods

Code Examples

Example 1: Creating a Simple MLeader with Text

Example 2: Creating MLeader with Multiple Leader Lines

Example 3: Creating MLeader with Block Content

Example 4: Setting MLeader Properties

Example 5: Reading MLeader Information

Example 6: Applying MLeader Style

Example 7: Creating MLeader with No Content

Example 8: Modifying MLeader Text

Content Types

Leader Types

Text Attachment Types

MLeader vs Leader

Best Practices

Common Use Cases

Related Objects

References

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MLeader.md

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MLeader.md

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MLeader Class

Overview

Namespace

Inheritance Hierarchy

Key Properties

Key Methods

Code Examples

Example 1: Creating a Simple MLeader with Text

Example 2: Creating MLeader with Multiple Leader Lines

Example 3: Creating MLeader with Block Content

Example 4: Setting MLeader Properties

Example 5: Reading MLeader Information

Example 6: Applying MLeader Style

Example 7: Creating MLeader with No Content

Example 8: Modifying MLeader Text

Content Types

Leader Types

Text Attachment Types

MLeader vs Leader

Best Practices

Common Use Cases

Related Objects

References