Select Objects in the Drawing Area (.NET)

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 AutoCAD .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 the objects in the drawing.

Note: Objects in all layouts and spaces are selected, and objects that are 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.

C# Example

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
    }
}

Select objects with crossing window

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

C# Example

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");
    }
}