UserEvent

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

#include "vtkTestFilter.h"

namespace {

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

}

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

  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();

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

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

  // Create a renderer, render window, and interactor.
  vtkNew<vtkRenderer> renderer;
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("UserEvent");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  vtkNew<vtkTestFilter> filter;

  vtkNew<vtkCallbackCommand> callback;
  callback->SetCallback(CallbackFunction);
  filter->AddObserver(filter->RefreshEvent, callback);

  filter->Update();

  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {

void CallbackFunction(vtkObject* /* caller */, long unsigned int /* eventId */,
                      void* /* clientData */, void* /* callData */)
{
  std::cout << "CallbackFunction called." << std::endl;
}

} // namespace

#ifndef __vtkTestFilter_h
#define __vtkTestFilter_h

#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkPolyDataAlgorithm.h>

class vtkTestFilter : public vtkPolyDataAlgorithm
{
public:
  vtkTypeMacro(vtkTestFilter, vtkPolyDataAlgorithm);
  static vtkTestFilter* New();

  int RefreshEvent;

protected:
  vtkTestFilter();

  int RequestData(vtkInformation*, vtkInformationVector**,
                  vtkInformationVector*) override;

private:
  vtkTestFilter(const vtkTestFilter&);  // Not implemented.
  void operator=(const vtkTestFilter&); // Not implemented.
};

vtkStandardNewMacro(vtkTestFilter);

vtkTestFilter::vtkTestFilter()
{
  this->SetNumberOfInputPorts(0);

  this->RefreshEvent = vtkCommand::UserEvent + 1;
}

int vtkTestFilter::RequestData(vtkInformation* vtkNotUsed(request),
                               vtkInformationVector**, vtkInformationVector*)
{
  // Get the info object
  //  auto outInfo = outputVector->GetInformationObject(0);

  //  auto output = vtkPolyData::SafeDownCast(
  //      outInfo->Get(vtkDataObject::DATA_OBJECT()));
  this->InvokeEvent(this->RefreshEvent, nullptr);

  return 1;
}

#endif // __vtkTestFilter_h

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(UserEvent)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "UserEvent: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(UserEvent MACOSX_BUNDLE UserEvent.cxx )
  target_link_libraries(UserEvent PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS UserEvent
  MODULES ${VTK_LIBRARIES}
)

cd UserEvent/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./UserEvent