Selection Set Keywords (.NET)

Applications may use keywords to prompt users for selection preferences before actually creating the selection set.

Keywords can be assigned to an object selection operation by creating and instance of a PromptSelectionOptions object. After a PromptSelectionOptions object is created, the SetKeywords method is used to assign each individual keyword that the user can enter at the Command prompt. Once the keywords have been assigned to the PromptSelectionOptions object, the PromptSelectionOptions object must then be passed to the GetSelection method of the editor.

The implementation of the keywords that a user can enter at the Select objects: prompt is handled with a PromptSelectionOptions.KeywordInput event handler. When the user enters a keyword at the resulting prompt, the KeywordInput event is raised and the application's handler is called.

A KeywordInput handler receives a SelectionTextInputEventArgs argument that serves as both an input and output parameter. The Input property of the SelectionTextInputEventArgs argument indicates the keyword chosen. A typical handler compares this keyword to those in the application's keyword list and calls an appropriate selection method. If entities are returned by the selection method, the application adds these to the SelectionTextInputEventArgs argument with the SelectionTextInputEventArgs.AddObjects method. When the original GetSelection call returns, it provides the selected entities to the method that set the keyword list.

The following example defines five keywords and adds a handler to support the keyword chosen by the user.

C# Example

private static void SelectionKeywordInputHandler(object sender, SelectionTextInputEventArgs eSelectionInput)
{
			 // Gets the current document editor and define other variables for the current scope
			 Editor acDocEd = Application.DocumentManager.MdiActiveDocument.Editor;
    PromptSelectionResult acSSPrompt = null;
    SelectionSet acSSet = null;
    ObjectId[] acObjIds = null;

	   // See if the user choose the myFence keyword
	   switch (eSelectionInput.Input) {
        case "myFence":
			         // Uses the four points to define a fence selection
            Point3dCollection ptsFence = new Point3dCollection();
            ptsFence.Add(new Point3d(5.0, 5.0, 0.0));
            ptsFence.Add(new Point3d(13.0, 15.0, 0.0));
            ptsFence.Add(new Point3d(12.0, 9.0, 0.0));
            ptsFence.Add(new Point3d(5.0, 5.0, 0.0));

            acSSPrompt = acDocEd.SelectFence(ptsFence);
			         break;
        case "myWindow":
			         // Defines a rectangular window selection
            acSSPrompt = acDocEd.SelectWindow(new Point3d(1.0, 1.0, 0.0), new Point3d(30.0, 20.0, 0.0));
			         break;
        case "myWPoly":
			         // Uses the four points to define a polygon window selection
            Point3dCollection ptsPolygon = new Point3dCollection();
            ptsPolygon.Add(new Point3d(5.0, 5.0, 0.0));
            ptsPolygon.Add(new Point3d(13.0, 15.0, 0.0));
            ptsPolygon.Add(new Point3d(12.0, 9.0, 0.0));
            ptsPolygon.Add(new Point3d(5.0, 5.0, 0.0));

            acSSPrompt = acDocEd.SelectWindowPolygon(ptsPolygon);
			         break;
		      case "myLastSel":
			        // Gets the last object created
			        acSSPrompt = acDocEd.SelectLast();
			        break;
		      case "myPrevSel":
			        // Gets the previous object selection set
			        acSSPrompt = acDocEd.SelectPrevious();
			        break;
	   }

    // If the prompt status is OK, objects were selected and return
    if (acSSPrompt != null)
    {
        if (acSSPrompt.Status == PromptStatus.OK)
        {
            // Objects were selected, so add them to the current selection
            acSSet = acSSPrompt.Value;
            acObjIds = acSSet.GetObjectIds();
            eSelectionInput.AddObjects(acObjIds);
        }
    }
}

[CommandMethod("SelectionKeywordInput")]
public static void SelectionKeywordInput()
{
    // Gets the current document editor
    Editor acDocEd = Application.DocumentManager.MdiActiveDocument.Editor;

    // Setups the keyword options
    PromptSelectionOptions acKeywordOpts = new PromptSelectionOptions();
    acKeywordOpts.Keywords.Add("myFence");
    acKeywordOpts.Keywords.Add("myWindow");
    acKeywordOpts.Keywords.Add("myWPoly");
    acKeywordOpts.Keywords.Add("myLastSel");
    acKeywordOpts.Keywords.Add("myPrevSel");

    // Adds the event handler for keyword input
    acKeywordOpts.KeywordInput += new SelectionTextInputEventHandler(SelectionKeywordInputHandler);

    // Prompts the user for a selection set
    PromptSelectionResult acSSPrompt = acDocEd.GetSelection(acKeywordOpts);

    // If the prompt status is OK, objects were selected
    if (acSSPrompt.Status == PromptStatus.OK)
    {
        // Gets the selection set
        SelectionSet acSSet = acSSPrompt.Value;

        // Gets the objects from the selection set
        ObjectId[] acObjIds = acSSet.GetObjectIds();
        Database acCurDb = Application.DocumentManager.MdiActiveDocument.Database;

        // Starts a transaction
        using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
        {
            try
            {
                // Gets information about each object
                foreach (ObjectId acObjId in acObjIds)
                {
                    Entity acEnt = (Entity)acTrans.GetObject(acObjId, OpenMode.ForWrite, true);
                    acDocEd.WriteMessage("\nObject selected: " + acEnt.GetType().FullName);

                }
            }
            finally
            {
                acTrans.Dispose();
            }
        }
    }

    // Removes the event handler for keyword input
    acKeywordOpts.KeywordInput -= new SelectionTextInputEventHandler(SelectionKeywordInputHandler);
}