# 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 <vtkVersion.h>
    #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);
    #if VTK_MAJOR_VERSION <= 5
      translateExtent->SetInput(colorImage);
    #else
      translateExtent->SetInputData(colorImage);
    #endif
      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();
    #if VTK_MAJOR_VERSION <= 5
      imageSliceMapper->SetInput(colorImage);
    #else
      imageSliceMapper->SetInputData(colorImage);
    #endif
      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
      renderWindowInteractor->SetRenderWindow(renderWindow);
      renderWindowInteractor->Initialize();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

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

    #if VTK_MAJOR_VERSION <= 5
      image->SetNumberOfScalarComponents(3);
      image->SetScalarTypeToUnsignedChar();
      image->AllocateScalars();
    #else
      image->AllocateScalars(VTK_UNSIGNED_CHAR,3);
    #endif

      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 2.8)

    PROJECT(ImageTranslateExtent)

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

    add_executable(ImageTranslateExtent MACOSX_BUNDLE ImageTranslateExtent.cxx)

    target_link_libraries(ImageTranslateExtent ${VTK_LIBRARIES})

### Download and Build ImageTranslateExtent

Danger

The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.

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