HoverWidget

VTKExamples/Cxx/Widgets/HoverWidget


Code

HoverWidget.cxx

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

class vtkHoverCallback : public vtkCommand
{
  public:
    static vtkHoverCallback *New()
    {
      return new vtkHoverCallback;
    }

    vtkHoverCallback() {}

    virtual void Execute(vtkObject*, unsigned long event, void *vtkNotUsed(calldata))
    {
      switch (event)
      {
        case vtkCommand::TimerEvent:
          std::cout << "TimerEvent -> the mouse stopped moving and the widget hovered" << std::endl;
          break;
        case vtkCommand::EndInteractionEvent:
          std::cout << "EndInteractionEvent -> the mouse started to move" << std::endl;
          break;
      }
    }
};

int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource =
      vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  // Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  // A renderer and render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderer->AddActor(actor);

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

  // Create the widget
  vtkSmartPointer<vtkHoverWidget> hoverWidget =
    vtkSmartPointer<vtkHoverWidget>::New();
  hoverWidget->SetInteractor(renderWindowInteractor);
  hoverWidget->SetTimerDuration(1000);

  // Create a callback to listen to the widget's two VTK events
  vtkSmartPointer<vtkHoverCallback> hoverCallback =
    vtkSmartPointer<vtkHoverCallback>::New();
  hoverWidget->AddObserver(vtkCommand::TimerEvent,hoverCallback);
  hoverWidget->AddObserver(vtkCommand::EndInteractionEvent,hoverCallback);

  renderWindow->Render();

  renderWindowInteractor->Initialize();
  renderWindow->Render();
  hoverWidget->On();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(HoverWidget)

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

Download and Build HoverWidget

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

cd HoverWidget/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:

./HoverWidget

WINDOWS USERS

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