SphereWidgetEvents

VTKEx/Cxx/Widgets/SphereWidgetEvents

Description

This example shows how to subclass a widget so that events can be further customized.

Contributed by: Alex Malyushytskyy.

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

SphereWidgetEvents.cxx

#include <vtkCallbackCommand.h>
#include <vtkCommand.h>
#include <vtkObjectFactory.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkSphereWidget.h>
#include <vtkSphereRepresentation.h>

class MySphereWidget : public vtkSphereWidget
{
 public:
  static MySphereWidget* New();
  vtkTypeMacro(MySphereWidget, vtkSphereWidget);

  // Handles the events
  static void ProcessEvents(vtkObject* object,
                            unsigned long event,
                            void* clientdata,
                            void* calldata);

protected:
  MySphereWidget();

  // Create a new callback command rather than using the one defined in
  // vtkSphereWidget. This prevents problems with unexpected behavior due
  // to the AbortFlag being manipulated.
  vtkSmartPointer<vtkCallbackCommand> MyEventCallbackCommand;

};


MySphereWidget::MySphereWidget()
{

  this->MyEventCallbackCommand = vtkSmartPointer<vtkCallbackCommand>::New();

  // Connect our own callback command to our own ProcessEvents function.
  // This way we do not have to deal with side effects of SphereWidget::ProcessEvents
  this->MyEventCallbackCommand->SetCallback( MySphereWidget::ProcessEvents );

  // Connect our callback function to a few events.
  this->AddObserver(vtkCommand::StartInteractionEvent,
                    this->MyEventCallbackCommand);

  this->AddObserver(vtkCommand::InteractionEvent,
                    this->MyEventCallbackCommand);

  this->AddObserver(vtkCommand::EndInteractionEvent,
                    this->MyEventCallbackCommand);

}

void MySphereWidget::ProcessEvents( vtkObject *vtkNotUsed(object),
                                    unsigned long event,
                                    void *vtkNotUsed(clientdata),
                                    void *vtkNotUsed(calldata) )
{
  switch(event)
  {
    case vtkCommand::StartInteractionEvent:
      std::cout << "StartInteractionEvent" << std::endl;
      break;
    case vtkCommand::EndInteractionEvent:
      std::cout << "EndInteractionEvent" << std::endl;
      break;
    case vtkCommand::InteractionEvent:
      std::cout << "InteractionEvent" << std::endl;
      break;
  }
}

vtkStandardNewMacro(MySphereWidget);

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

  // Create an interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  vtkSmartPointer<MySphereWidget> sphereWidget =
    vtkSmartPointer<MySphereWidget>::New();
  sphereWidget->SetInteractor(renderWindowInteractor);
  sphereWidget->SetRepresentationToSurface();
  sphereWidget->HandleVisibilityOn();

  renderWindow->Render();
  renderWindowInteractor->Initialize();
  renderWindow->Render();
  sphereWidget->On();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(SphereWidgetEvents)

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

Download and Build SphereWidgetEvents

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

cd SphereWidgetEvents/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:

./SphereWidgetEvents

WINDOWS USERS

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