Creating a table of AutoCAD blocks using .NET

This post – and the one to follow it – were inspired by a comment on this old post (which in many ways is quite similar to this one, just using an older syntax and starting with a static array of table data). We’re creating a table with information about the various blocks in the block table of the current drawing: in this post we create the basic table containing the table name and its thumbnail, while in the next post we’re going add some additional (and as-yet-to-be-determined) information. The basic point is to show how to manipulate an existing table by adding to it.

Here’s what gets created by our CBT command when run in the drawing seen recently in these two posts:

When we switch viewpoints, we can actually see the table contains 3D thumbnails. Pretty interesting, especially seeing how the various “thumbnails” have been scaled so their 2D extents fit the cell, leading to drastically differing sizes of 3D object.

Here’s the C# code defining our CBT command:

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.EditorInput;

using Autodesk.AutoCAD.Runtime;

 

namespace TableCreation

{

  public class Commands

  {

    const double rowHeight = 3.0, colWidth = 5.0;

    const double textHeight = rowHeight * 0.25;

 

    [CommandMethod("CBT")]

    static public void CreateBlockTable()

    {

      var doc = Application.DocumentManager.MdiActiveDocument;

      if (doc == null)

        return;

 

      var db = doc.Database;

      var ed = doc.Editor;

 

      var pr = ed.GetPoint("\nEnter table insertion point");

      if (pr.Status != PromptStatus.OK)

        return;

 

      using (var tr = doc.TransactionManager.StartTransaction())

      {

        var bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);

 

        // Create the table, set its style and default row/column size

 

        var tb = new Table();

        tb.TableStyle = db.Tablestyle;

        tb.SetRowHeight(rowHeight);

        tb.SetColumnWidth(colWidth);

        tb.Position = pr.Value;

 

        // Set the header cell

 

        var head = tb.Cells[0, 0];

        head.Value = "Blocks";

        head.Alignment = CellAlignment.MiddleCenter;

        head.TextHeight = textHeight;

 

        // Insert an additional column

 

        tb.InsertColumns(0, colWidth, 1);

 

        // Loop through the blocks in the drawing, creating rows

 

        foreach (var id in bt)

        {

          var btr = (BlockTableRecord)tr.GetObject(id, OpenMode.ForRead);

 

          // Only care about user-insertable blocks

 

          if (!btr.IsLayout && !btr.IsAnonymous)

          {

            // Add a row

 

            tb.InsertRows(tb.Rows.Count, rowHeight, 1);

 

            var rowIdx = tb.Rows.Count - 1;

 

            // The first cell will hold the block name

 

            var first = tb.Cells[rowIdx, 0];

            first.Value = btr.Name;

            first.Alignment = CellAlignment.MiddleCenter;

            first.TextHeight = textHeight;

 

            // The second will contain a thumbnail of the block

 

            var second = tb.Cells[rowIdx, 1];

            second.BlockTableRecordId = id;

          }

        }

 

        // Now we add the table to the current space

 

        var sp =

          (BlockTableRecord)tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);

        sp.AppendEntity(tb);

 

        // And to the transaction, which we then commit

 

        tr.AddNewlyCreatedDBObject(tb, true);

        tr.Commit();

      }

    }

  }

}