[vtkusers] vtkSeedWidget GetSeedDisplayPosition Question

[Ken Urish]

Ive been struggling with vtkSeedWidget and I would apprecaite if
anyone can point me in the right direction. Any example code on how to
get seed position off 2d image would be just as good.

I can easily place seeds on a 2d image using vtkSeedWidget. I am
having difficulty getting their location. I setup a callback that
monitors mouse position and pointPlaceEvents. It correctly tells me
how many seeds I have.
I am trying to then have it give me the seed location by calling:
this->SeedRepresentation->GetSeedDisplayPosition (seedNumber, point);
		
I get the error message: vtkSeedRepresentation (029B6D28): Trying to
access non-existent handle. I am stuck. I put the call back below for
any help.

Thanks
--Ken--



// This callback is responsible for setting the seed label.
class vtkSeedCallback : public vtkCommand
{
public:
  static vtkSeedCallback *New()
    { return new vtkSeedCallback; }
  virtual void Execute(vtkObject*, unsigned long eid, void*)
    {
      if ( eid == vtkCommand::CursorChangedEvent )
        cout << "cursor changed\n";
      else
        {
		int seedNumber;
		  double point[3];
		  double ptMapped[3];

        cout << "point placed\n";
		cout << "Total number of seeds: "
			 << this->SeedRepresentation->GetNumberOfSeeds () << "\n";
		seedNumber = this->SeedRepresentation->GetNumberOfSeeds ();
                this->SeedRepresentation->GetSeedDisplayPosition
(seedNumber, point);
		}
		
    }
	vtkSeedCallback() : SeedRepresentation(0) {}
	vtkSeedRepresentation *SeedRepresentation;
};



//Below is the setup in main program for the callback

  vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
  iren->SetRenderWindow(renWin);
  renWin->Render();

  // Say hello to my big widget
  // Create the widget and its representation
  vtkPointHandleRepresentation2D *handle =
vtkPointHandleRepresentation2D::New();
  handle->GetProperty()->SetColor(1,0,0);
  vtkSeedRepresentation *rep = vtkSeedRepresentation::New();
  rep->SetHandleRepresentation(handle);

  vtkSeedWidget *widget = vtkSeedWidget::New();
  widget->SetInteractor(iren);
  widget->SetRepresentation(rep);

  vtkSeedCallback *mcbk = vtkSeedCallback::New();
  mcbk->SeedRepresentation = rep;
  widget->AddObserver(vtkCommand::PlacePointEvent,mcbk);
  widget->AddObserver(vtkCommand::CursorChangedEvent,mcbk);

  // render the image
  iren->Initialize();
  renWin->Render();
  widget->On();
  iren->Start();