# ImageTranslateExtent

VTKExamples/Cxx/ImageData/ImageTranslateExtent

### Description

If you are looking to change the extent to change the "origin" of the image from the corner to the center, see vtkImageChangeInformation (http://www.vtk.org/Wiki/VTK/Examples/Cxx/Images/CenterAnImage).

Currently this method changes the extent (shown by the terminal output in the example), but does not change where the corner of the image is displayed relative to the sphere at (0,0,0).

### Code

ImageTranslateExtent.cxx

    #include <vtkImageData.h>
    #include <vtkSmartPointer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkInteractorStyleImage.h>
    #include <vtkRenderer.h>
    #include <vtkImageMapper.h>
    #include <vtkImageSliceMapper.h>
    #include <vtkImageSlice.h>
    #include <vtkSphereSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkImageTranslateExtent.h>

    static void CreateColorImage(vtkImageData* const);

    int main(int, char *[])
    {
      vtkSmartPointer<vtkImageData> colorImage = vtkSmartPointer<vtkImageData>::New();
      CreateColorImage(colorImage); // This image has (0,0) at the bottom left corner

      int extent[6];
      colorImage->GetExtent(extent);
      std::cout << "Old extent: " << extent[0] << " " << extent[1] << " " << extent[2] << " " << extent[3] << " " << extent[4] << " " << extent[5] << std::endl;

      // This moves the (0,0) position in the image to the center of the image
    //  int extent[6];
    //  colorImage->GetExtent(extent);
    //  colorImage->SetExtent(extent[0] - (extent[1] - extent[0])/2, extent[0] + (extent[1] - extent[0])/2,
    //                        extent[2] - (extent[3] - extent[2])/2, extent[2] + (extent[3] - extent[2])/2,
    //                        extent[4] - (extent[5] - extent[4])/2, extent[4] + (extent[5] - extent[4])/2);

      int dimensions[3];
      colorImage->GetDimensions(dimensions);

      vtkSmartPointer<vtkImageTranslateExtent> translateExtent =
        vtkSmartPointer<vtkImageTranslateExtent>::New();
      translateExtent->SetTranslation(-dimensions[0]/2,-dimensions[1]/2,0);
      translateExtent->SetInputData(colorImage);
      translateExtent->Update();
      colorImage->DeepCopy(translateExtent->GetOutput());

      colorImage->GetExtent(extent);
      std::cout << "New extent: " << extent[0] << " " << extent[1] << " " << extent[2] << " " << extent[3] << " " << extent[4] << " " << extent[5] << std::endl;

      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(0.0, 0.0, 0.0);
      sphereSource->SetRadius(1.0);
      sphereSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      sphereMapper->SetInputConnection(sphereSource->GetOutputPort());

      vtkSmartPointer<vtkActor> sphereActor =
        vtkSmartPointer<vtkActor>::New();
      sphereActor->SetMapper(sphereMapper);

      vtkSmartPointer<vtkImageSliceMapper> imageSliceMapper = vtkSmartPointer<vtkImageSliceMapper>::New();
      imageSliceMapper->SetInputData(colorImage);

      vtkSmartPointer<vtkImageSlice> imageSlice = vtkSmartPointer<vtkImageSlice>::New();
      imageSlice->SetMapper(imageSliceMapper);
      imageSlice->SetPosition(0,0,0);

      // Setup renderers
      vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
      renderer->AddViewProp(imageSlice);
      renderer->AddViewProp(sphereActor);
      renderer->ResetCamera();

      // Setup render window
      vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(300, 300);
      renderWindow->AddRenderer(renderer);

      // Setup render window interactor
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();

      vtkSmartPointer<vtkInteractorStyleImage> style =
        vtkSmartPointer<vtkInteractorStyleImage>::New();

      renderWindowInteractor->SetInteractorStyle(style);

      // Render and start interaction
      renderWindow->Render();
      renderWindowInteractor->SetRenderWindow(renderWindow);
      renderWindowInteractor->Initialize();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

    void CreateColorImage(vtkImageData* const image)
    {
      image->SetDimensions(10, 10, 1);
      image->AllocateScalars(VTK_UNSIGNED_CHAR,3);

      for(unsigned int x = 0; x < 10; x++)
      {
        for(unsigned int y = 0; y < 10; y++)
        {
          unsigned char* pixel = static_cast<unsigned char*>(image->GetScalarPointer(x,y,0));
          pixel[0] = 255;
          pixel[1] = 0;
          pixel[2] = 255;
        }
      }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ImageTranslateExtent)

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

### Download and Build ImageTranslateExtent

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

    cd ImageTranslateExtent/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:

    ./ImageTranslateExtent

WINDOWS USERS

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