# SeedWidgetWithCustomCallback

VTKExamples/Cxx/Widgets/SeedWidgetWithCustomCallback

### Description

This example demonstrates how to place seed points in the scene. The seed points can be used for operations like connectivity, segmentation, and region growing.

### Code

SeedWidgetWithCustomCallback.cxx

    #include <vtkActor.h>
    #include <vtkCommand.h>
    #include <vtkPointHandleRepresentation2D.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty2D.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSeedRepresentation.h>
    #include <vtkSeedWidget.h>
    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>

    class vtkSeedCallback : public vtkCommand
    {
      public:
        static vtkSeedCallback *New()
        {
          return new vtkSeedCallback;
        }

        vtkSeedCallback() {}

        virtual void Execute(vtkObject*, unsigned long event, void *calldata)
        {
          if(event == vtkCommand::PlacePointEvent)
          {
            std::cout << "Point placed, total of: "
                << this->SeedRepresentation->GetNumberOfSeeds() << std::endl;
          }
          if(event == vtkCommand::InteractionEvent)
          {
            if(calldata)
            {
              std::cout << "Interacting with seed : "
                  << *(static_cast< int * >(calldata)) << std::endl;
            }
          }

          std::cout << "List of seeds (Display coordinates):" << std::endl;
          for(vtkIdType i = 0; i < this->SeedRepresentation->GetNumberOfSeeds(); i++)
          {
            double pos[3];
            this->SeedRepresentation->GetSeedDisplayPosition(i, pos);
            std::cout << "(" << pos[0] << " " << pos[1] << " " << pos[2] << ")" << std::endl;
          }

        }

        void SetRepresentation(vtkSmartPointer<vtkSeedRepresentation> rep) {this->SeedRepresentation = rep;}
      private:
        vtkSmartPointer<vtkSeedRepresentation> SeedRepresentation;
    };

    int main(int, char *[])
    {
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      // 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);
      renderer->AddActor(actor);

      // An interactor
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Create the representation
      vtkSmartPointer<vtkPointHandleRepresentation2D> handle =
        vtkSmartPointer<vtkPointHandleRepresentation2D>::New();
      handle->GetProperty()->SetColor(1,0,0);
      vtkSmartPointer<vtkSeedRepresentation> rep =
        vtkSmartPointer<vtkSeedRepresentation>::New();
      rep->SetHandleRepresentation(handle);

      // Seed widget
      vtkSmartPointer<vtkSeedWidget> seedWidget =
        vtkSmartPointer<vtkSeedWidget>::New();
      seedWidget->SetInteractor(renderWindowInteractor);
      seedWidget->SetRepresentation(rep);

      vtkSmartPointer<vtkSeedCallback> seedCallback =
        vtkSmartPointer<vtkSeedCallback>::New();
      seedCallback->SetRepresentation(rep);
      seedWidget->AddObserver(vtkCommand::PlacePointEvent,seedCallback);
      seedWidget->AddObserver(vtkCommand::InteractionEvent,seedCallback);

      renderWindow->Render();

      renderWindowInteractor->Initialize();
      renderWindow->Render();
      seedWidget->On();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(SeedWidgetWithCustomCallback)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(SeedWidgetWithCustomCallback MACOSX_BUNDLE SeedWidgetWithCustomCallback.cxx )

    target_link_libraries(SeedWidgetWithCustomCallback ${VTK_LIBRARIES})

### Download and Build SeedWidgetWithCustomCallback

Click here to download SeedWidgetWithCustomCallback and its CMakeLists.txt file. Once the tarball SeedWidgetWithCustomCallback.tar has been downloaded and extracted,

    cd SeedWidgetWithCustomCallback/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./SeedWidgetWithCustomCallback

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.