# CaptionActor2D

VTKExamples/Cxx/Visualization/CaptionActor2D

### Code

CaptionActor2D.cxx

    #include <vtkAbstractPicker.h>
    #include <vtkActor.h>
    #include <vtkActor2D.h>
    #include <vtkCaptionActor2D.h>
    #include <vtkCoordinate.h>
    #include <vtkFollower.h>
    #include <vtkImageActor.h>
    #include <vtkImageMapper3D.h>
    #include <vtkImageCanvasSource2D.h>
    #include <vtkCoordinate.h>
    #include <vtkTransform.h>
    #include <vtkTransformPolyDataFilter.h>
    #include <vtkPolyDataMapper2D.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkMath.h>
    #include <vtkObjectFactory.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkProperty2D.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRendererCollection.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSphereSource.h>
    #include <vtkSmartPointer.h>
    #include <vtkTextActor.h>
    #include <vtkTextProperty.h>
    #include <vtkVectorText.h>

    #include <sstream>

    class MyStyle : public vtkInteractorStyleImage
    {
      public:
        static MyStyle* New();
        vtkTypeMacro(MyStyle, vtkInteractorStyleImage);

        std::vector<vtkActor2D*> Numbers;

        void OnLeftButtonDown()
        {
          //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->CurrentRenderer );
          double picked[3];
          this->Interactor->GetPicker()->GetPickPosition(picked);
          //std::cout << "Picked point with coordinate: " << picked[0] << " " << picked[1] << " " << picked[2] << std::endl;

          this->AddNumber(picked);

          // Forward events
          vtkInteractorStyleImage::OnLeftButtonDown();

          //this->Interactor->GetRenderWindow()->Render();
          this->Interactor->Render();
        }

        void AddNumber(double p[3])
        {
          std::cout << "Adding marker at " << p[0] << " " << p[1] ;//<< std::endl;

          // normally, with an image you would do
          // double* s = image->GetSpacing();
          // double* o = image->GetOrigin();
          // p[0] = static_cast<int>( (p[0] - o[0]) / s[0] + 0.5 );
          p[0] = static_cast<int>( p[0] + 0.5 );
          p[1] = static_cast<int>( p[1] + 0.5 );

          std::cout << " -> " << p[0] << " " << p[1] << std::endl;

          // Convert the current number to a string
          std::stringstream ss;
          ss << Numbers.size();
          std::cout << "Adding number: " << ss.str() << std::endl;

          // Create an actor for the text
          vtkSmartPointer<vtkCaptionActor2D> captionActor = vtkSmartPointer<vtkCaptionActor2D>::New();
          captionActor->SetCaption( ss.str().c_str() );
          captionActor->SetAttachmentPoint(p);
          captionActor->BorderOff();
          captionActor->GetCaptionTextProperty()->BoldOff();
          captionActor->GetCaptionTextProperty()->ItalicOff();
          captionActor->GetCaptionTextProperty()->ShadowOff();
          captionActor->ThreeDimensionalLeaderOff();

          this->CurrentRenderer->AddViewProp( captionActor );

          this->Numbers.push_back(captionActor);
        }
    };

    vtkStandardNewMacro(MyStyle);

    int main (int, char *[])
    {
      // Create a blank, black image
      vtkSmartPointer<vtkImageCanvasSource2D> drawing = vtkSmartPointer<vtkImageCanvasSource2D>::New();
      drawing->SetScalarTypeToUnsignedChar();
      drawing->SetNumberOfScalarComponents(3);
      drawing->SetExtent(0, 20, 0, 50, 0, 0);
      drawing->FillBox(0,20,0,50);

      // Draw a red circle of radius 5 centered at (9,10)
      drawing->SetDrawColor(255, 0, 0, 0);
      drawing->DrawCircle(9, 10, 5);
      drawing->Update();

      vtkSmartPointer<vtkImageActor> actor = vtkSmartPointer<vtkImageActor>::New();
      actor->GetMapper()->SetInputConnection(drawing->GetOutputPort());
      actor->InterpolateOff();

      vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);

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

      renderer->AddActor(actor);
      renderer->SetBackground(1,1,1); // Background color white

      renderer->GradientBackgroundOn();
      renderer->SetBackground2(0,0,1); // Background 2 color blue

      renderWindow->Render();

      vtkSmartPointer<MyStyle> style = vtkSmartPointer<MyStyle>::New();

      renderWindowInteractor->SetInteractorStyle( style );
      style->SetDefaultRenderer( renderer );
      style->SetCurrentRenderer( renderer );
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(CaptionActor2D)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkCommonTransforms
      vtkFiltersGeneral
      vtkFiltersSources
      vtkImagingSources
      vtkInteractionStyle
      vtkRenderingAnnotation
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping CaptionActor2D: ${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(CaptionActor2D MACOSX_BUNDLE CaptionActor2D.cxx )
      target_link_libraries(CaptionActor2D PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(CaptionActor2D MACOSX_BUNDLE CaptionActor2D.cxx )
      target_link_libraries(CaptionActor2D PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS CaptionActor2D
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build CaptionActor2D

Click here to download CaptionActor2D and its CMakeLists.txt file. Once the tarball CaptionActor2D.tar has been downloaded and extracted,

    cd CaptionActor2D/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:

    ./CaptionActor2D

WINDOWS USERS

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