Identifying the boundary through API

By Virupaksha Aithal

AutoCAD 2011 introduced a new API to identify the boundary objects for a provided point. Below code shows the use of the same API in .NET. The equivalent ObjectARX API is “acedTraceBoundary”.

Note, only visible entities are considered while identifying the boundary objects.

[CommandMethod("BoundaryTest")]
public static void BoundaryTest()
{
 Document doc = Application.DocumentManager.MdiActiveDocument;
 Database db = doc.Database;
 Editor ed = doc.Editor;
 
 PromptPointOptions ptOptions = 
                     new PromptPointOptions("Select point ");
 ptOptions.AllowNone = false;
 PromptPointResult ptResult = ed.GetPoint(ptOptions);
 
 if (ptResult.Status != PromptStatus.OK)
     return;
 
 DBObjectCollection collection = 
                ed.TraceBoundary(ptResult.Value, true);
 
 using (Transaction Tx =
           db.TransactionManager.StartTransaction())
 {
     ObjectId ModelSpaceId = 
            SymbolUtilityServices.GetBlockModelSpaceId(db);
 
      BlockTableRecord model = Tx.GetObject(ModelSpaceId,
                     OpenMode.ForWrite) as BlockTableRecord;
 
     foreach (DBObject obj in collection)
     {
         Entity ent = obj as Entity;
 
         if (ent != null)
         {
             //make the color as red.
             ent.ColorIndex = 1;
  
             model.AppendEntity(ent);
             Tx.AddNewlyCreatedDBObject(ent, true);
 
         }
     }
 
     Tx.Commit();
 }
}