Reading the Block Table of a Dynamic Block

csharp

Reading the Block Table of a Dynamic BlockBy Augusto Goncalves
For a dynamic block we can create a Block Properties Table, which defines and controls values for parameters and properties. This is available when BEDIT’ing a dynamic block, as shown below.

From the API perspective, this data is stored under a DBDictionary called ACAD_ENHANCEDBLOCK. To access it, we need to use some ‘Internal’ APIs, which means that there is no documentation and it may change.
The following code sample show how to access it for a given selected BlockReference object. Minimal error check were done for simplicity.

[CommandMethod("readBlockTable"

static public void CmdReadBlockTable()

{

  Editor ed = Application.DocumentManager.

    MdiActiveDocument.Editor;

  // select a block reference

  PromptEntityOptions peo = new PromptEntityOptions(

    "Select a dynamic block reference: ");

  peo.SetRejectMessage("Only block reference");

  peo.AddAllowedClass(typeof(BlockReference), false);

  PromptEntityResult per = ed.GetEntity(peo);

  if (per.Status != PromptStatus.OK) return;

  ObjectId blockRefId = per.ObjectId;

  // get the database and start a transaction

  Database db = Application.DocumentManager.

    MdiActiveDocument.Database;

  using (Transaction trans = db.

    TransactionManager.StartTransaction())

  {

    // open the dynamic block reference

    BlockReference blockRef = trans.GetObject(

      blockRefId, OpenMode.ForRead) as BlockReference;

    if (!blockRef.IsDynamicBlock) return;

    // get the dynamic block table definition

    BlockTableRecord blockDef = trans.GetObject(

      blockRef.DynamicBlockTableRecord,

      OpenMode.ForRead) as BlockTableRecord;

    // open the extension dictionary

    if (blockDef.ExtensionDictionary.IsNull) return;

    DBDictionary extDic = trans.GetObject(

      blockDef.ExtensionDictionary, OpenMode.ForRead)

      as DBDictionary;

    // open the ENHANCEDBLOCK dictionary

    Autodesk.AutoCAD.Internal.DatabaseServices.EvalGraph graph =

      trans.GetObject(extDic.GetAt("ACAD_ENHANCEDBLOCK"),

      OpenMode.ForRead) as EvalGraph;

    int[] nodeIds = graph.GetAllNodes();

    foreach (uint nodeId in nodeIds)

    {

      // open the node ID

      DBObject node = graph.GetNode(nodeId,

        OpenMode.ForRead, trans);

      // check is if the correct type

      if (!(node is BlockPropertiesTable)) continue;

      // convert the object

      BlockPropertiesTable table =

        node as BlockPropertiesTable;

      // ok, we have the data, let's show it...

      // get the number of columns

      int columns = table.Columns.Count;

      int currentRow = 0;

      foreach (

        BlockPropertiesTableRow row

        in table.Rows)

      {

        ed.WriteMessage("\n[{0}]:\t", currentRow);

        for (

          int currentColumn = 0;

          currentColumn < columns;

          currentColumn++)

        {

          // get the colum value for the

          // current row. May be more multiple

          TypedValue[] columnValue =

            row[currentColumn].AsArray();

          foreach (TypedValue tpVal in columnValue)

          {

            ed.WriteMessage("{0}; ", tpVal.Value);

          }

          ed.WriteMessage("|");

        }

        currentRow++;

      }

    }

  }

}

csharp

1. How to get the name of an anonymous block?


blockreference = (BlockReference)transition.GetObject(objectid, OpenMode.ForRead);
if (blockreference.IsDynamicBlock)
blockname = ((BlockTableRecord)transition.GetObject(blockreference.DynamicBlockTableRecord, OpenMode.ForRead)).Name;
else
blockname = ((BlockTableRecord)transition.GetObject(blockreference.BlockTableRecord, OpenMode.ForRead)).Name;

( blockreference.DynamicBlockTableRecord return nothing/null )

2. How to list all references of a block definition by the name if the block are dynamic?


BlockTable blocktable = (BlockTable)transaction.GetObject(database.BlockTableId, OpenMode.ForRead); if (blocktable.Has(blockname))
{
BlockTableRecord blocktablerecord = (BlockTableRecord)transaction.GetObject(blocktable[blockname], OpenMode.ForRead, false, false);

ObjectIdCollection allblockreferences = blocktablerecord.GetBlockReferenceIds(true, true);

foreach (ObjectId auxreferenceid in allblockreferences)
blocksreferencesbyname.Add(auxReferenceId); //add to a list of objects ids

if (blocktablerecord.IsDynamicBlock)
{
//ObjectIdCollection blockanonymousreferences = blocktablerecord.GetAnonymousBlockIds();


//foreach (ObjectId anonyreferenceid in blockanonymousreferences)
//{
// blocktablerecord = (BlockTableRecord)transaction.GetObject(anonyreferenceid, OpenMode.ForRead, false, false);


// blockreferences = blocktablerecord.GetBlockReferenceIds(true, true);

// foreach (ObjectId auxreferenceid in blockreferences)
// if (!BlocksReferencesByName.Contains(auxreferenceid))
// BlocksReferencesByName.Add(auxreferenceid);
//}
}
}