MouseEventsObserver

VTKExamples/Cxx/Interaction/MouseEventsObserver


Description

This example shows how to add an event observer to an existing style class.

See MouseEvents for a different approach that subclasses an existin interactor style to implement custom behaviors.

Other Languages

See (Python)

Question

If you have a simple question about this example contact us at VTKExamplesProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

MouseEventsObserver.cxx

#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkCommand.h>
#include <vtkActor.h>
#include <vtkCallbackCommand.h>
#include <vtkSmartPointer.h>
#include <vtkPointPicker.h>
#include <vtkCamera.h>
#include <vtkNamedColors.h>

namespace
{
void ClickCallbackFunction ( vtkObject* caller, long unsigned int eventId, void* clientData, void* callData );
}

int main(int, char *[])
{

  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());

  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  renderer->SetBackground(colors->GetColor3d("Slate_grey").GetData());
  renderer->AddActor(actor);

  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow ( renderWindow );

  vtkSmartPointer<vtkCallbackCommand> clickCallback = 
    vtkSmartPointer<vtkCallbackCommand>::New();
  clickCallback->SetCallback ( ClickCallbackFunction );

  renderWindowInteractor->AddObserver ( vtkCommand::LeftButtonPressEvent, clickCallback );
  renderWindowInteractor->AddObserver ( vtkCommand::RightButtonPressEvent, clickCallback );
  renderWindowInteractor->AddObserver ( vtkCommand::KeyPressEvent, clickCallback );

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

  return EXIT_SUCCESS;
}

namespace
{
void ClickCallbackFunction (
  vtkObject* vtkNotUsed(caller),
  long unsigned int eventId,
  void* vtkNotUsed(clientData),
  void* vtkNotUsed(callData) )
{
  std::cout << "Click callback" << std::endl;
  std::cout << "Event: " << vtkCommand::GetStringFromEventId(eventId) << std::endl;

  // Get the interactor like this:
  // vtkRenderWindowInteractor *iren = 
  //  static_cast<vtkRenderWindowInteractor*>(caller);

}
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(MouseEventsObserver)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping MouseEventsObserver: ${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(MouseEventsObserver MACOSX_BUNDLE MouseEventsObserver.cxx )
  target_link_libraries(MouseEventsObserver PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(MouseEventsObserver MACOSX_BUNDLE MouseEventsObserver.cxx )
  target_link_libraries(MouseEventsObserver PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS MouseEventsObserver
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build MouseEventsObserver

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

cd MouseEventsObserver/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:

./MouseEventsObserver

WINDOWS USERS

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