KeypressObserver

VTKEx/Cxx/Interaction/KeypressObserver

Question

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Code

KeypressObserver.cxx

#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkCallbackCommand.h>
#include <vtkCommand.h>

void KeypressCallbackFunction (
  vtkObject* caller,
  long unsigned int eventId,
  void* clientData,
  void* callData );

int main(int, char *[])
{
  // Create a sphere
  vtkSmartPointer<vtkSphereSource> sphereSource = 
      vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();

  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  // 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<vtkCallbackCommand> keypressCallback = 
    vtkSmartPointer<vtkCallbackCommand>::New();
  keypressCallback->SetCallback ( KeypressCallbackFunction );
  renderWindowInteractor->AddObserver ( vtkCommand::KeyPressEvent, keypressCallback );

  renderer->AddActor(actor);
  renderer->SetBackground(1,1,1); // Background color white
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

void KeypressCallbackFunction ( vtkObject* caller, long unsigned int vtkNotUsed(eventId), void* vtkNotUsed(clientData), void* vtkNotUsed(callData) )
{
  std::cout << "Keypress callback" << std::endl;

  vtkRenderWindowInteractor *iren = 
    static_cast<vtkRenderWindowInteractor*>(caller);

  std::cout << "Pressed: " << iren->GetKeySym() << std::endl;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(KeypressObserver)

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

Download and Build KeypressObserver

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

cd KeypressObserver/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:

./KeypressObserver

WINDOWS USERS

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