UserEvent

VTKEx/Cxx/Interaction/UserEvent

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

UserEvent.cxx

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

#include "vtkTestFilter.h"

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

int main(int, char *[])
{
  // Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  vtkSmartPointer<vtkTestFilter> filter =
    vtkSmartPointer<vtkTestFilter>::New();

  vtkSmartPointer<vtkCallbackCommand> callback =
    vtkSmartPointer<vtkCallbackCommand>::New();
  callback->SetCallback(CallbackFunction );
  filter->AddObserver(filter->RefreshEvent, callback);

  filter->Update();

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

  return EXIT_SUCCESS;
}

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

vtkTestFilter.h

#ifndef __vtkTestFilter_h
#define __vtkTestFilter_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.

};

#endif

#include <vtkObjectFactory.h>
#include <vtkCommand.h>
#include <vtkStreamingDemandDrivenPipeline.h>
#include <vtkInformationVector.h>
#include <vtkInformation.h>
#include <vtkDataObject.h>
#include <vtkSmartPointer.h>
#include <vtkAppendPolyData.h>
#include <vtkSphereSource.h>

vtkStandardNewMacro(vtkTestFilter);

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

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

}

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

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

  return 1;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(UserEvent)

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

Download and Build UserEvent

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

cd UserEvent/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:

./UserEvent

WINDOWS USERS

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