VTK/Examples/Cxx/Interaction/RubberBand2DObserver

#include <vtkSmartPointer.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkInteractorStyleRubberBand2D.h>
#include <vtkCallbackCommand.h>
 
void SelectionChangedCallbackFunction( vtkObject* caller, 
  long unsigned int eventId, void* clientData, void* callData );
 
int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();
 
  // Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());
 
  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
 
  // A renderer and render window
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
 
  // An interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  // Add the actors to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(1,1,1); // Background color white
  renderWindow->Render();
 
  vtkSmartPointer<vtkCallbackCommand> selectionChangedCallback = 
    vtkSmartPointer<vtkCallbackCommand>::New();
  selectionChangedCallback->SetCallback ( SelectionChangedCallbackFunction );
 
  vtkSmartPointer<vtkInteractorStyleRubberBand2D> style = 
    vtkSmartPointer<vtkInteractorStyleRubberBand2D>::New();
  style->AddObserver ( vtkCommand::SelectionChangedEvent, selectionChangedCallback );
  renderWindowInteractor->SetInteractorStyle( style );
 
  // Begin mouse interaction
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}
 
 
void SelectionChangedCallbackFunction ( vtkObject* vtkNotUsed(caller), 
  long unsigned int vtkNotUsed(eventId), void* vtkNotUsed(clientData), void* callData )
{
  std::cout << "SelectionChanged callback" << std::endl;
 
  unsigned int* rect = reinterpret_cast<unsigned int*> ( callData );
  unsigned int pos1X = rect[0];
  unsigned int pos1Y = rect[1];
  unsigned int pos2X = rect[2];
  unsigned int pos2Y = rect[3];
 
  std::cout << "Start x: " << pos1X << " Start y: " << pos1Y 
            << " End x: " << pos2X << " End y: " << pos2Y << std::endl;
}