VTK/Examples/Cxx/Interaction/KeypressEvents

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VTK Examples Baseline Interaction TestHandleKeypress.png

This example shows how to catch keypress events. For example, do something if the user presses the 's' key.

KeypressEvents.cxx

#include <vtkPolyDataMapper.h>
#include <vtkObjectFactory.h>
#include <vtkActor.h>
#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkInteractorStyleTrackballCamera.h>

// Define interaction style
class KeyPressInteractorStyle : public vtkInteractorStyleTrackballCamera
{
  public:
    static KeyPressInteractorStyle* New();
    vtkTypeMacro(KeyPressInteractorStyle, vtkInteractorStyleTrackballCamera);

    virtual void OnKeyPress() 
    {
      // Get the keypress
      vtkRenderWindowInteractor *rwi = this->Interactor;
      std::string key = rwi->GetKeySym();
      
      // Output the key that was pressed
      std::cout << "Pressed " << key << std::endl;
      
      // Handle an arrow key
      if(key == "Up")
        {
        std::cout << "The up arrow was pressed." << std::endl;
        }
      
      // Handle a "normal" key
      if(key == "a")
        {
        std::cout << "The a key was pressed." << std::endl;
        }
      
      // Forward events
      vtkInteractorStyleTrackballCamera::OnKeyPress();
    }
  
};
vtkStandardNewMacro(KeyPressInteractorStyle);

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());

  // Create an actor
  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);

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

  vtkSmartPointer<KeyPressInteractorStyle> style = 
    vtkSmartPointer<KeyPressInteractorStyle>::New();
  renderWindowInteractor->SetInteractorStyle(style);
  style->SetCurrentRenderer(renderer);

  renderer->AddActor(actor);
  renderer->SetBackground(1,1,1); // Background color white

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

  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(KeypressEvents)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(KeypressEvents MACOSX_BUNDLE KeypressEvents.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(KeypressEvents ${VTK_LIBRARIES})
else()
  target_link_libraries(KeypressEvents vtkHybrid vtkWidgets)
endif()

Download and Build KeypressEvents

Click here to download KeypressEvents. and its CMakeLists.txt file.

Once the tarball KeypressEvents.tar has been downloaded and extracted,

cd KeypressEvents/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:

./KeypressEvents

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

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