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RectilinearWipeWidget

vtk-examples/Cxx/Widgets/RectilinearWipeWidget


Description

This example illustrates the Rectilinear Wipe widget. This widget is useful for comparing two images. There are 7 different image comparison modes. A rectilinear wipe is a 2x2 checkerboard pattern created by combining two separate images, where various combinations of the checker squares are possible. Using this widget, the user can adjust the layout of the checker pattern, such as moving the center point, moving the horizontal separator, or moving the vertical separator.

Pressing keys 0-6 select the various wipe modes.

For an alternative image comparison widget try the Checkerboard widget.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

RectilinearWipeWidget.cxx

#include <vtkCommand.h>
#include <vtkImageActor.h>
#include <vtkImageData.h>
#include <vtkImageMapper3D.h>
#include <vtkImageReader2.h>
#include <vtkImageReader2Factory.h>
#include <vtkImageRectilinearWipe.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkObjectFactory.h>
#include <vtkProperty.h>
#include <vtkProperty2D.h>
#include <vtkRectilinearWipeRepresentation.h>
#include <vtkRectilinearWipeWidget.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>

namespace {
// Define interaction style
class WipeInteractorStyle : public vtkInteractorStyleImage
{
public:
  static WipeInteractorStyle* New();
  vtkTypeMacro(WipeInteractorStyle, vtkInteractorStyleImage);

  virtual void OnChar()
  {
    if (this->Wipe)
    {
      vtkRenderWindowInteractor* rwi = this->Interactor;
      switch (rwi->GetKeyCode())
      {
      case '0':
        this->Wipe->SetWipe(0);
        break;
      case '1':
        this->Wipe->SetWipe(1);
        break;
      case '2':
        this->Wipe->SetWipe(2);
        break;
      case '3':
        this->Wipe->SetWipe(3);
        break;
      case '4':
        this->Wipe->SetWipe(4);
        break;
      case '5':
        this->Wipe->SetWipe(5);
        break;
      case '6':
        this->Wipe->SetWipe(6);
        break;
      default:
        this->Superclass::OnChar();
        break;
      }
    }
  }
  void SetWipe(vtkImageRectilinearWipe* wipe)
  {
    this->Wipe = wipe;
  }

protected:
  WipeInteractorStyle()
  {
    this->Wipe = NULL;
  }

private:
  vtkImageRectilinearWipe* Wipe;
};
vtkStandardNewMacro(WipeInteractorStyle);
} // namespace

int main(int argc, char* argv[])
{
  if (argc < 3)
  {
    std::cerr << "Usage: " << argv[0]
              << " Input1Filename Input2Filename e.g. Gourds2.jpg Ox.jpg"
              << std::endl;
    return EXIT_FAILURE;
  }

  vtkNew<vtkNamedColors> colors;

  int wipeMode = 0;
  if (argc > 3)
  {
    wipeMode = atoi(argv[3]);
  }
  // Read the images
  vtkNew<vtkImageReader2Factory> readerFactory;
  vtkSmartPointer<vtkImageReader2> reader1;
  reader1.TakeReference(readerFactory->CreateImageReader2(argv[1]));
  reader1->SetFileName(argv[1]);

  vtkSmartPointer<vtkImageReader2> reader2;
  reader2.TakeReference(readerFactory->CreateImageReader2(argv[2]));
  reader2->SetFileName(argv[2]);

  // Create a wipe pipeline
  vtkNew<vtkImageRectilinearWipe> wipe;
  wipe->SetInputConnection(0, reader1->GetOutputPort());
  wipe->SetInputConnection(1, reader2->GetOutputPort());
  wipe->SetPosition(256, 256);
  wipe->SetWipe(wipeMode);

  // Create the RenderWindow, Renderer and both Actors
  //
  vtkNew<vtkRenderer> ren1;
  ren1->SetBackground(colors->GetColor3d("Wheat").GetData());

  vtkNew<vtkRenderWindow> renWin;
  renWin->AddRenderer(ren1);
  renWin->SetWindowName("RectilinearWipeWidget");

  vtkNew<vtkRenderWindowInteractor> iren;
  iren->SetRenderWindow(renWin);

  vtkNew<WipeInteractorStyle> style;
  iren->SetInteractorStyle(style);
  style->SetWipe(wipe);

  vtkNew<vtkImageActor> wipeActor;
  wipeActor->GetMapper()->SetInputConnection(wipe->GetOutputPort());

  // VTK widgets consist of two parts: the widget part that handles
  // event processing; and the widget representation that defines how
  // the widget appears in the scene
  // (i.e., matters pertaining to geometry).
  vtkNew<vtkRectilinearWipeWidget> wipeWidget;
  wipeWidget->SetInteractor(iren);

  vtkRectilinearWipeRepresentation* wipeWidgetRep =
      static_cast<vtkRectilinearWipeRepresentation*>(
          wipeWidget->GetRepresentation());

  wipeWidgetRep->SetImageActor(wipeActor);
  wipeWidgetRep->SetRectilinearWipe(wipe);
  wipeWidgetRep->GetProperty()->SetLineWidth(2.0);
  wipeWidgetRep->GetProperty()->SetOpacity(0.75);

  // Add the actors to the renderer, set the background and size
  //
  ren1->AddActor(wipeActor);
  renWin->SetSize(300, 300);

  // render the image
  //
  renWin->Render();
  wipeWidget->On();
  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(RectilinearWipeWidget)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  IOImage
  ImagingHybrid
  InteractionStyle
  InteractionWidgets
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "RectilinearWipeWidget: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(RectilinearWipeWidget MACOSX_BUNDLE RectilinearWipeWidget.cxx )
  target_link_libraries(RectilinearWipeWidget PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS RectilinearWipeWidget
  MODULES ${VTK_LIBRARIES}
)

Download and Build RectilinearWipeWidget

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

cd RectilinearWipeWidget/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:

./RectilinearWipeWidget

WINDOWS USERS

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