About Using the Dynamic Language Runtime (.NET)

The AutoCAD Managed .NET API allows you to utilize the Dynamic Language Runtime (DLR) that was introduced with .NET 4.0.

Using DLR allows you to access objects directly without having to:

• Open an object for read or write, and then close the object once you are done.
• Utilize transactions to commit the changes made.

You can access the properties and methods of an object directly once you have obtained its ObjectId when using DLR. After you have obtained an ObjectId, you can assign the ObjectId to a variable of the data type:

• Object in VB.NET
• dynamic in C#

Obtaining an ObjectId varies by how the object is saved to the database. For objects stored in a table or dictionary, you can access its ObjectId by:

• Using the Item method of an ObjectId to access an element in the collection.
• Creating a reference to the ObjectId of the table or dictionary and assigning it to a variable, and then accessing the element of the array.

The following example shows both options for accessing an object that is stored in a table or dictionary with DLR:

C# Example

// Item method
dynamic acCurDb = HostApplicationServices.WorkingDatabase;
dynamic acMSpace = acCurDb.BlockTableId.Item(BlockTableRecord.ModelSpace);

// Reference an element directly from a collection
dynamic acCurDb = HostApplicationServices.WorkingDatabase;
dynamic acBlkTbl = acCurDb.BlockTableId;
dynamic acMSpace = acBlkTbl[BlockTableRecord.ModelSpace];

Important: When working with DLR and C#, you will need to reference the Microsoft.CSharp library.

Working with the GetEnumerator Method

When using the GetEnumerator method with DLR, you need to explicitly dispose of the enumerator object once you are done working with it. The following sample demonstrates how to dispose of the enumerator when you are done with it.

C# Example

dynamic acCurDb = HostApplicationServices.WorkingDatabase;
var acLtypeTbl = acCurDb.LinetypeTableId;
var acTblEnum = acLtypeTbl.GetEnumerator();
...
acTblEnum.Dispose();

Using LINQ Queries

You can utilize LINQ queries to query the contents of a table or dictionary in a drawing with DLR. The following example demonstrates the use of LINQ queries to query which layers have certain states assigned to them in the current drawing.

C# Example

[CommandMethod("LINQ")]
public static void LINQExample()
{
    dynamic db = HostApplicationServices.WorkingDatabase;
    dynamic doc = Application.DocumentManager.MdiActiveDocument;

    var layers = db.LayerTableId;
    for (int i = 0; i < 2; i++)
    {
        var newrec = layers.Add(new LayerTableRecord());
        newrec.Name = "Layer" + i.ToString();
        if (i == 0)
            newrec.IsFrozen = true;
        if (i == 1)
            newrec.IsOff = true;
    }

    var OffLayers = from l in (IEnumerable<dynamic>)layers
                    where l.IsOff
                    select l;

    doc.Editor.WriteMessage("\nLayers Turned Off:");

    foreach (dynamic rec in OffLayers)
        doc.Editor.WriteMessage("\n - " + rec.Name);

    var frozenOrOffNames = from l in (IEnumerable<dynamic>)layers
                            where l.IsFrozen == true || l.IsOff == true
                            select l;

    doc.Editor.WriteMessage("\nLayers Frozen or Turned Off:");

    foreach (dynamic rec in frozenOrOffNames)
        doc.Editor.WriteMessage("\n - " + rec.Name);
}

Sample Code

The sample code on this page uses the following name spaces:

Autodesk.AutoCAD.Runtime
Autodesk.AutoCAD.ApplicationServices
Autodesk.AutoCAD.DatabaseServices
Autodesk.AutoCAD.Colors
Autodesk.AutoCAD.Geometry

The following example demonstrates how to add a Line to the current space without DLR.

C# Example

[CommandMethod("ADDLINE")]
public static void AddLine()
{
    // Get the current database
    Database acCurDb = HostApplicationServices.WorkingDatabase;

    // 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 5,5 and ends at 12,3
        using (Line acLine = new Line(new Point3d(5, 5, 0),
                                      new Point3d(12, 3, 0)))
        {
            // Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acLine);
            acTrans.AddNewlyCreatedDBObject(acLine, true);
        }

        // Save the new object to the database
        acTrans.Commit();
    }
}

The following example demonstrates how to add a Line to the current space with DLR.

C# Example

[CommandMethod("ADDLINE")]
public static void AddLine()
{
    // Get the current database
    dynamic acCurDb = HostApplicationServices.WorkingDatabase;

    // Create a dynamic reference to model or paper space
    dynamic acSpace = acCurDb.CurrentSpaceId;

    // Create a line that starts at 5,5 and ends at 12,3
    dynamic acLine = new Line(new Point3d(5, 5, 0),
                              new Point3d(12, 3, 0));

    // Add the new object to the current space
    acSpace.AppendEntity(acLine);
}

The following example demonstrates how to add a Layer to the current database without DLR.

C# Example

[CommandMethod("ADDLAYER")]
public static void AddLayer()
{
    // Get the current database
    Database acCurDb = HostApplicationServices.WorkingDatabase;

    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Returns the layer table for the current database
        LayerTable acLyrTbl;
        acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
                                     OpenMode.ForRead) as LayerTable;

        // Check to see if MyLayer exists in the Layer table
        if (acLyrTbl.Has("MyLayer") != true)
        {
            // Open the Layer Table for write
            acTrans.GetObject(acCurDb.LayerTableId, OpenMode.ForWrite);

            // Create a new layer named "MyLayer"
            using (LayerTableRecord acLyrTblRec = new LayerTableRecord())
            {
                acLyrTblRec.Name = "MyLayer";

                // Assign the ACI color 3 to the new layer
                Color acClr = Color.FromColorIndex(ColorMethod.ByAci, 3);
                acLyrTblRec.Color = acClr;

                // Add the new layer table record to the layer table and the transaction
                acLyrTbl.Add(acLyrTblRec);
                acTrans.AddNewlyCreatedDBObject(acLyrTblRec, true);
            }

            // Commit the changes
            acTrans.Commit();
        }

        // Dispose of the transaction
    }
}

The following example demonstrates how to add a Layer to the current database with DLR.

C# Example

[CommandMethod("ADDLAYER")]
public static void AddLayer()
{
    // Get the current database
    dynamic acCurDb = HostApplicationServices.WorkingDatabase;

    dynamic acLyrTbl = acCurDb.LayerTableId;

    // Check to see if MyLayer exists in the Layer table
    if (acLyrTbl.Has("MyLayer") != true)
    {
        // Create a new layer named "MyLayer"
        dynamic acLyrTblRec = new LayerTableRecord();
        acLyrTblRec.Name = "MyLayer";

        // Assign the ACI color 3 to the new layer
        dynamic acClr = Color.FromColorIndex(ColorMethod.ByAci, 3);
        acLyrTblRec.Color = acClr;

        // Add the new layer table record to the layer table
        acLyrTbl.Add(acLyrTblRec);
    }
}

The following example demonstrates how to step through and list all the objects in the current space without DLR.

C# Example

[CommandMethod("LISTOBJECTS")]
public static void ListObjects()
{
    // Get the current document and database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = HostApplicationServices.WorkingDatabase;

    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table record Model space for write
        BlockTableRecord acSpace;
        acSpace = acTrans.GetObject(acCurDb.CurrentSpaceId,
                                    OpenMode.ForRead) as BlockTableRecord;

        // Step through the current space
        foreach (ObjectId objId in acSpace)
        {
            // Display the class and current layer of the object
            Entity acEnt = (Entity)acTrans.GetObject(objId, OpenMode.ForRead);
            acDoc.Editor.WriteMessage("\nObject Class: " + acEnt.GetRXClass().Name +
                                      "\nCurrent Layer: " + acEnt.Layer + 
                                       "\n");
        }
        acTrans.Commit();
    }
}

The following example demonstrates how to step through and list all the objects in the current space with DLR.

C# Example

[CommandMethod("LISTOBJECTS")]
public static void ListObjects()
{
    // Get the current document and database
    dynamic acDoc = Application.DocumentManager.MdiActiveDocument;
    dynamic acCurDb = HostApplicationServices.WorkingDatabase;

    // Create a dynamic reference to model or paper space
    dynamic acSpace = acCurDb.CurrentSpaceId;

    // Step through the current space
    foreach (dynamic acEnt in acSpace)
    {
        // Display the class and current layer of the object
        acDoc.Editor.WriteMessage("\nObject Class: " + acEnt.GetRXClass().Name +
                                  "\nCurrent Layer: " + acEnt.Layer +
                                  "\n");
    }
}