Legend

VTKEx/Cxx/Visualization/Legend

Other languages

See (Java)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

Legend.cxx

#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkCubeSource.h>
#include <vtkSphereSource.h>
#include <vtkLegendBoxActor.h>
#include <vtkNamedColors.h>

#include <vtkSmartPointer.h>

int main (int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5000.0);
  sphereSource->Update();

  vtkPolyData* polydata = sphereSource->GetOutput();

  // Create a mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputData(polydata);

  // Create an actor
  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<vtkLegendBoxActor> legend = 
    vtkSmartPointer<vtkLegendBoxActor>::New();
  legend->SetNumberOfEntries(2);

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  double color[4];

  vtkSmartPointer<vtkCubeSource> legendBox = 
    vtkSmartPointer<vtkCubeSource>::New();
  legendBox->Update();
  colors->GetColor("tomato", color);
  legend->SetEntry(0, legendBox->GetOutput(), "Box", color);

  colors->GetColor("banana", color);
  legend->SetEntry(1, sphereSource->GetOutput(), "Ball", color);

  // place legend in lower right
  legend->GetPositionCoordinate()->SetCoordinateSystemToView();
  legend->GetPositionCoordinate()->SetValue(.5, -1.0);

  legend->GetPosition2Coordinate()->SetCoordinateSystemToView();
  legend->GetPosition2Coordinate()->SetValue(1.0, -0.5);

  legend->UseBackgroundOn();
  double background[4];
  colors->GetColor("warm_grey", background);
  legend->SetBackgroundColor(background);

  // Add the actors to the scene
  renderer->AddActor(actor);
  renderer->AddActor(legend);
  renderer->SetBackground(0,1,1); // Background color cyan

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

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Legend)

find_package(VTK COMPONENTS 
  vtkvtkCommonColor
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersSources
  vtkvtkInteractionStyle
  vtkvtkRenderingAnnotation
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Legend: ${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(Legend MACOSX_BUNDLE Legend.cxx )
  target_link_libraries(Legend PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Legend MACOSX_BUNDLE Legend.cxx )
  target_link_libraries(Legend PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Legend
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Legend

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

cd Legend/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:

./Legend

WINDOWS USERS

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