Autocad Block Net Info

Creating a block definition involves creating a new BlockTableRecord and adding it to the BlockTable.

Scenario: Create a simple block named "MySquare" consisting of a square polyline.

public void CreateBlockDefinition()
Document doc = Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;

using (Transaction tr = db.TransactionManager.StartTransaction())
// 1. Open the Block Table for writing
    BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForWrite);
// 2. Check if "MySquare" already exists to prevent duplicates
    if (!bt.Has("MySquare"))
// 3. Create a new BlockTableRecord
        BlockTableRecord btr = new BlockTableRecord();
        btr.Name = "MySquare";
// 4. Create geometry (a simple square)
        Polyline pl = new Polyline();
        pl.AddVertexAt(0, new Point2d(0, 0), 0, 0, 0);
        pl.AddVertexAt(1, new Point2d(10, 0), 0, 0, 0);
        pl.AddVertexAt(2, new Point2d(10, 10), 0, 0, 0);
        pl.AddVertexAt(3, new Point2d(0, 10), 0, 0, 0);
        pl.Closed = true;
// 5. Add geometry to the BTR
        // AppendEntity returns the ObjectId of the entity inside the block
        btr.AppendEntity(pl);
// 6. Add the BTR to the BlockTable and Transaction
        bt.Add(btr);
        tr.AddNewlyCreatedDBObject(btr, true);
        tr.AddNewlyCreatedDBObject(pl, true);
tr.Commit();

In the AutoCAD environment, the term "Block" refers to a collection of objects combined into a single, reusable entity. For developers working with the AutoCAD .NET API, managing blocks is one of the most fundamental tasks. Unlike AutoLISP or VBA, the .NET API provides strong typing, event handling, and seamless integration with the Windows UI, allowing for the creation of powerful plugins that can manipulate block definitions and references with high efficiency. autocad block net

This guide explores the architecture, objects, and coding techniques required to master Block development in .NET (C#).

Before writing code, ensure your C# project references the standard AutoCAD assemblies: Creating a block definition involves creating a new

Note: In modern AutoCAD versions (2013+), these are split by .NET version (e.g., netDXX).

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