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KeypressObserver

vtk-examples/Cxx/Interaction/KeypressObserver


Question

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Code

KeypressObserver.cxx

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

namespace {

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

}

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Create a sphere
  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  // Create an actor
  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());

  // A renderer and render window
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);

  // An interactor
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindow->SetWindowName("KeypressObserver");

  vtkNew<vtkCallbackCommand> keypressCallback;
  keypressCallback->SetCallback(KeypressCallbackFunction);
  renderWindowInteractor->AddObserver(vtkCommand::KeyPressEvent,
                                      keypressCallback);

  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {

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;
}

} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(KeypressObserver)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  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.