Draw graphic on screen without requiring a double click to finish sketch

Question

I am trying to get the user to draw a line(only 2 vertices) on the screen(just like the georeferencing link/spatial adjustment link). I got the below snippet from ESRI website which does give me a polyline but it requires the user to double click to finish the sketch.

public IPolyline GetPolylineFromMouseClicks(IActiveView activeView)
        {

          IScreenDisplay screenDisplay = activeView.ScreenDisplay;

          IRubberBand rubberBand = new RubberLineClass();
          IGeometry geometry = rubberBand.TrackNew(screenDisplay, null);

          IPolyline polyline = (IPolyline)geometry;

          return polyline;

        }

I would like the tool to finish the drawing as soon as two points are clicked, thus avoiding a double click. Can somebody help me on this? I seem to be making a mess of a simple situation!

Answer 1

I don't think you can use the IRubberBand interface. Once you start the TrackNew method you lose control of your calling tool because it requires a double-click to finish it's process.

Here is a solution using a custom tool:

    private bool _isFirstClick;
    private ESRI.ArcGIS.Display.INewLineFeedback _lineFeedback;
    private IActiveView _focusMap;
    private IApplication _application;
    private IMxDocument _mxDoc;

    public override void OnCreate(object hook)
    {
        _application = hook as IApplication;

        //Disable if it is not ArcMap
        if (hook is IMxApplication)
            base.m_enabled = true;
        else
            base.m_enabled = false;
    }

    public override void OnMouseDown(int Button, int Shift, int X, int Y)
    {
        _mxDoc = (IMxDocument) _application.Document;
        _focusMap = mxDoc.FocusMap as IActiveView;

        IPoint point = _focusMap.ScreenDisplay.DisplayTransformation.ToMapPoint(X, Y) as IPoint;

        if (_lineFeedback == null)
        {
            _lineFeedback = new ESRI.ArcGIS.Display.NewLineFeedback();
            _lineFeedback.Display = _focusMap.ScreenDisplay;
            _lineFeedback.Start(point);
            _isFirstClick = true;
        }
        else
        {
            _lineFeedback.AddPoint(point);
            _isFirstClick = false;
        }

    }
    public override void OnMouseUp(int Button, int Shift, int X, int Y)
    {

        if (_isFirstClick) return;

        IPolyline polyline = _lineFeedback.Stop();

        //Do something with the polyline here

        _lineFeedback = null;
    }

After the second click you will have a reference to your two-point polyline. You then need to create a function to draw it on the map, create a feature from it, or whatever you are trying to do.

I tested this in ArcGIS 10, not 9.3.1 so let me know if it doesn't work for you.