Use Selection Filters to Define Selection Set Rules (.NET)

Selection filters are composed of pairs of arguments in the form of TypedValues. The first argument of a TypedValue identifies the type of filter (for example, an object), and the second argument specifies the value you are filtering on (for example, circles). The filter type is a DXF group code that specifies which filter to use. A few of the most common filter types are listed here.

DXF codes for common filters
DXF code	Filter type
0 (or DxfCode.Start)	Object Type (String) Such as “Line,” “Circle,” “Arc,” and so forth.
2 (or DxfCode.BlockName)	Block Name (String) The block name of an insert reference.
8 or (DxfCode.LayerName)	Layer Name (String) Such as “Layer 0.”
60 (DxfCode.Visibility)	Object Visibility (Integer) Use 0 = visible, 1 = invisible.
62 (or DxfCode.Color)	Color Number (Integer) Numeric index values ranging from 0 to 256. Zero indicates BYBLOCK. 256 indicates BYLAYER. A negative value indicates that the layer is turned off.
67	Model/paper space indicator (Integer) Use 0 or omitted = model space, 1 = paper space.

Specify a single selection criterion for a selection set

The following example prompts users to select objects to be included in a selection set, and filters out all objects except for circles.

C# Example

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
 
[CommandMethod("FilterSelectionSet")]
public static void FilterSelectionSet()
{
    // Get the current document editor
    Editor acDocEd = Application.DocumentManager.MdiActiveDocument.Editor;

    // Create a TypedValue array to define the filter criteria
    TypedValue[] acTypValAr = new TypedValue[1];
    acTypValAr.SetValue(new TypedValue((int)DxfCode.Start, "CIRCLE"), 0);

    // Assign the filter criteria to a SelectionFilter object
    SelectionFilter acSelFtr = new SelectionFilter(acTypValAr);

    // Request for objects to be selected in the drawing area
    PromptSelectionResult acSSPrompt;
    acSSPrompt = acDocEd.GetSelection(acSelFtr);

    // 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");
    }
}