Several classes are involved to represent SelectionSets, these are:

• SavedItem
  • The abstract base class of all the following section set related classes
• FolderItem
  • A folder, containing a collection of SavedItem
  • Derived from GroupItem which is in turn derived from SavedItem
• SelectionSet

  • A selection set. This can be an explicit collection of ModelItems in the Document or a dynamic result of a specific Search.

To access the SelectionSets in a Document there is the property SelectionSets which is an instance of DocumentSelectionSets. This is a Autodesk.Navisworks.Api.DocumentParts and so follows the normal structure.

DocumentSelectionSets..::..Value provides the entry point to the selection sets structure and DocumentSelectionSets..::..RootItem provides a convenient read-only equivelent of a parent FolderItem of the same selection sets. This FolderItem however cannot be removed as it is just a placeholder to access the entries in DocumentSelectionSets..::..Value.

In the following example we use recursion to iterate through the selection sets contained in the currectly active Document.

CopyWriting out the selection sets structure

using System.Text;

using Autodesk.Navisworks.Api.Controls;

      static public string WriteSelectionSetContent(SavedItem item, string label, string lineText)
      {
         //set the output
         string output = lineText + "+ " + label + "\n";

         //See if this SavedItem is a GroupItem
         if (item.IsGroup)
         {
            //Indent the lines below this item
            lineText += "   ";

            //iterate the children and output
            foreach (SavedItem childItem in ((GroupItem)item).Children)
            {
               output += WriteSelectionSetContent(childItem, childItem.DisplayName, lineText);
            }
         }

         //return the node information
         return output;
      }

      /// <summary>
      /// Outputs to a message box the structure of the selection sets
      /// </summary>
      static public void ListSelectionSets()
      {
         //build output string for display
         string output =
            WriteSelectionSetContent(
            Autodesk.Navisworks.Api.Application.ActiveDocument.SelectionSets.RootItem,
            Autodesk.Navisworks.Api.Application.ActiveDocument.Title,
            "");

         //output in a message box
         MessageBox.Show(output);
      }

Selection Sets can be removed from the list of sets by calling one the methods of Remove.

Similarly they can be created using one of the various SelectionSet constructors or CopyFrom methods.

Reference