[vtkusers] Pass value from vtkInteractorStyle to local variable?

[DVigneault]

All--

I'd like to understand the best practice for passing a variable obtained in
an interactor to a local variable, such that it can be used after the render
window is closed (in my case: open a window, obtain pixel coordinates from
mouse click, close window, then use the pixel coordinates later on in the
program).  I can get the functionality I want by creating a InteractorStyle
class (inheriting from vtkInteractorStyleImage, pasted at the bottom of this
e-mail) that saves the pixel coordinates to a global variable pointPosition
OnLeftButtonUp, then closes the window OnRightButtonUp.  However, I'm
nervous that coding a global variable name into a class is not very
maintainable, and thought there was likely a better way to do it.  What is
the best practice in this case?

Sorry if this is more of a c++ question and less of a VTK question--I've
been learning c++/vtk/itk in tandem with one another, and am sometimes
unclear when one ends and the other begins.

Best, and thanks,

--Davis

// Create a class inheriting from vtkInteractorStyleImage
class dvInteractorStyleSelectPoint : public vtkInteractorStyleImage
{
	public:
		static dvInteractorStyleSelectPoint* New();
		vtkTypeMacro(dvInteractorStyleSelectPoint, vtkInteractorStyleImage);
		
                // OnLeftButtonUp, save the pixel coordinates to the global
variable pointPosition
		virtual void OnLeftButtonUp() {
    		std::cout << "Picking pixel: " <<
this->Interactor->GetEventPosition()[0] << " " <<
this->Interactor->GetEventPosition()[1] << std::endl;
    	
this->Interactor->GetPicker()->Pick(this->Interactor->GetEventPosition()[0], 
                         						this->Interactor->GetEventPosition()[1], 
                         						0,  // always zero.
                         					
this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());
			this->Interactor->GetPicker()->GetPickPosition(pointPosition);
      		std::cout << "Picked value: " << pointPosition[0] << " " <<
pointPosition[1] << std::endl;
			vtkInteractorStyleImage::OnLeftButtonUp();
		}
		
                // OnRightButtonUp, close the window
		virtual void OnRightButtonUp() {
			this->GetInteractor()->GetRenderWindow()->Finalize();
			std::cout << "Closing window..." << std::endl;
			vtkInteractorStyleImage::OnRightButtonUp();
		}
 
};



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