# BorderWidget

VTKExamples/Cxx/Widgets/BorderWidget

### Description

This example draws a border around a region selected with the mouse. Note that the default border color is white - so if you have a white background you will not see anything!

### Code

BorderWidget.cxx

    #include <vtkSmartPointer.h>
    #include <vtkWidgetCallbackMapper.h>
    #include <vtkCommand.h>
    #include <vtkWidgetEvent.h>
    #include <vtkObjectFactory.h>
    #include <vtkActor.h>
    #include <vtkBorderRepresentation.h>
    #include <vtkBorderWidget.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSphereSource.h>

    class vtkCustomBorderWidget : public vtkBorderWidget
    {
    public:
      static vtkCustomBorderWidget *New();
      vtkTypeMacro(vtkCustomBorderWidget, vtkBorderWidget);

      static void EndSelectAction(vtkAbstractWidget *w);

      vtkCustomBorderWidget();

    };

    vtkStandardNewMacro(vtkCustomBorderWidget);

    vtkCustomBorderWidget::vtkCustomBorderWidget()
    {
      this->CallbackMapper->SetCallbackMethod(vtkCommand::MiddleButtonReleaseEvent,
                                            vtkWidgetEvent::EndSelect,
                                            this, vtkCustomBorderWidget::EndSelectAction);
    }

    void vtkCustomBorderWidget::EndSelectAction(vtkAbstractWidget *w)
    {
      vtkBorderWidget *borderWidget =
        vtkBorderWidget::SafeDownCast(w);

      // Get the actual box coordinates/planes
      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();

      // Get the bottom left corner
      double* lowerLeft;
      lowerLeft = static_cast<vtkBorderRepresentation*>(borderWidget->GetRepresentation())->GetPosition();
      std::cout << "Lower left: " << lowerLeft[0] << " "
                << lowerLeft[1] << std::endl;

      double* upperRight;
      upperRight = static_cast<vtkBorderRepresentation*>(borderWidget->GetRepresentation())->GetPosition2();
      std::cout << "Upper right: " << upperRight[0] << " "
                << upperRight[1] << std::endl;

      vtkBorderWidget::EndSelectAction(w);
    }

    int main(int, char *[])
    {
      // Sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetRadius(4.0);
      sphereSource->Update();

      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);

      vtkSmartPointer<vtkCustomBorderWidget> borderWidget =
        vtkSmartPointer<vtkCustomBorderWidget>::New();
      borderWidget->SetInteractor(renderWindowInteractor);
      borderWidget->CreateDefaultRepresentation();
      borderWidget->SelectableOff();

      // Add the actors to the scene
      renderer->AddActor(actor);

      // Render an image (lights and cameras are created automatically)
      renderWindowInteractor->Initialize();
      renderWindow->Render();
      borderWidget->On();

      // Begin mouse interaction
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(BorderWidget)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersSources
      vtkInteractionStyle
      vtkInteractionWidgets
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping BorderWidget: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(BorderWidget MACOSX_BUNDLE BorderWidget.cxx )
      target_link_libraries(BorderWidget PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(BorderWidget MACOSX_BUNDLE BorderWidget.cxx )
      target_link_libraries(BorderWidget PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS BorderWidget
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build BorderWidget

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

    cd BorderWidget/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:

    ./BorderWidget

WINDOWS USERS

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