Select Objects in the Drawing Area

You can select objects through by having the user interactively select objects, or you can simulate many of the various object selection options through the .NET API. If your routine performs multiple selection sets, you will need to either track each selection set returned or create an ObjectIdCollection object to keep track of all the selected objects. The following functions allow you to select objects from the drawing:

GetSelection: Prompts the user to pick objects from the screen.
SelectAll: Selects all objects in the current space in which are not locked or frozen.
SelectCrossingPolygon: Selects objects within and crossing a polygon defined by specifying points. The polygon can be any shape but cannot cross or touch itself.
SelectCrossingWindow: Selects objects within and crossing an area defined by two points.
SelectFence: Selects all objects crossing a selection fence. Fence selection is similar to crossing polygon selection except that the fence is not closed, and a fence can cross itself.
SelectLast: Selects the last object created in the current space.
SelectPrevious: Selects all objects selected during the previous Select objects: prompt.
SelectWindow: Selects all objects completely inside a rectangle defined by two points.
SelectWindowPolygon: Selects objects completely inside a polygon defined by points. The polygon can be any shape but cannot cross or touch itself.
SelectAtPoint: Selects objects passing through a given point and places them into the active selection set.
SelectByPolygon: Selects objects within a fence and adds them to the active selection set.

Prompt for objects on screen and iterate the selection set

This example prompts the user to select objects, then changes the color of each object selected to Green or the AutoCAD Color Index of 3.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

Imports Autodesk.AutoCAD.EditorInput

<CommandMethod("SelectObjectsOnscreen")> _

Public Sub SelectObjectsOnscreen()

  '' Get the current document and database

  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument

  Dim acCurDb As Database = acDoc.Database

  '' Start a transaction

  Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

      '' Request for objects to be selected in the drawing area

      Dim acSSPrompt As PromptSelectionResult = acDoc.Editor.GetSelection()

      '' If the prompt status is OK, objects were selected

      If acSSPrompt.Status = PromptStatus.OK Then

          Dim acSSet As SelectionSet = acSSPrompt.Value

          '' Step through the objects in the selection set

          For Each acSSObj As SelectedObject In acSSet

              '' Check to make sure a valid SelectedObject object was returned

              If Not IsDBNull(acSSObj) Then

                  '' Open the selected object for write

                  Dim acEnt As Entity = acTrans.GetObject(acSSObj.ObjectId, _

                                                          OpenMode.ForWrite)

                  If Not IsDBNull(acEnt) Then

                      '' Change the object's color to Green

                      acEnt.ColorIndex = 3

                  End If

              End If

          Next

          '' Save the new object to the database

          acTrans.Commit()

      End If

      '' Dispose of the transaction

  End Using

End Sub

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.EditorInput;

[CommandMethod("SelectObjectsOnscreen")]

public static void SelectObjectsOnscreen()

  // Get the current document and database

  Document acDoc = Application.DocumentManager.MdiActiveDocument;

  Database acCurDb = acDoc.Database;

  // Start a transaction

  using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())

      // Request for objects to be selected in the drawing area

      PromptSelectionResult acSSPrompt = acDoc.Editor.GetSelection();

      // If the prompt status is OK, objects were selected

      if (acSSPrompt.Status == PromptStatus.OK)

          SelectionSet acSSet = acSSPrompt.Value;

          // Step through the objects in the selection set

          foreach (SelectedObject acSSObj in acSSet)

              // Check to make sure a valid SelectedObject object was returned

              if (acSSObj != null)

                  // Open the selected object for write

                  Entity acEnt = acTrans.GetObject(acSSObj.ObjectId,

                                                   OpenMode.ForWrite) as Entity;

                  if (acEnt != null)

                      // Change the object's color to Green

                      acEnt.ColorIndex = 3;

          // Save the new object to the database

          acTrans.Commit();

      // Dispose of the transaction

VBA/ActiveX Code Reference

Select objects with crossing window

This example selects the objects within and that intersect a crossing window.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

Imports Autodesk.AutoCAD.Geometry

Imports Autodesk.AutoCAD.EditorInput

<CommandMethod("SelectObjectsByCrossingWindow")> _

Public Sub SelectObjectsByCrossingWindow()

  '' Get the current document editor

  Dim acDocEd As Editor = Application.DocumentManager.MdiActiveDocument.Editor

  '' Create a crossing window from (2,2,0) to (10,8,0)

  Dim acSSPrompt As PromptSelectionResult

  acSSPrompt = acDocEd.SelectCrossingWindow(New Point3d(2, 2, 0), _

                                            New Point3d(10, 8, 0))

  '' If the prompt status is OK, objects were selected

  If acSSPrompt.Status = PromptStatus.OK Then

      Dim acSSet As SelectionSet = acSSPrompt.Value

      Application.ShowAlertDialog("Number of objects selected: " & _

                                  acSSet.Count.ToString())

  Else

      Application.ShowAlertDialog("Number of objects selected: 0")

  End If

End Sub

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.Geometry;

using Autodesk.AutoCAD.EditorInput;

[CommandMethod("SelectObjectsByCrossingWindow")]

public static void SelectObjectsByCrossingWindow()

  // Get the current document editor

  Editor acDocEd = Application.DocumentManager.MdiActiveDocument.Editor;

  // Create a crossing window from (2,2,0) to (10,8,0)

  PromptSelectionResult acSSPrompt;

  acSSPrompt = acDocEd.SelectCrossingWindow(new Point3d(2, 2, 0),

                                            new Point3d(10, 8, 0));

  // If the prompt status is OK, objects were selected

  if (acSSPrompt.Status == PromptStatus.OK)

      SelectionSet acSSet = acSSPrompt.Value;

      Application.ShowAlertDialog("Number of objects selected: " +

                                  acSSet.Count.ToString());

  else

      Application.ShowAlertDialog("Number of objects selected: 0");

VBA/ActiveX Code Reference