VTK/Examples/Cxx/Images/CenterAnImage

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VTK Examples Baseline Images TestCenterAnImage.png

This moves (0,0) from the bottom left corner of the image to the center of the image.

CenterAnImage.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
 
#include <vtkActor.h>
#include <vtkBorderRepresentation.h>
#include <vtkBorderWidget.h>
#include <vtkCommand.h>
#include <vtkImageActor.h>
#include <vtkImageMapper3D.h>
#include <vtkImageChangeInformation.h>
#include <vtkImageClip.h>
#include <vtkImageData.h>
#include <vtkInteractorStyleImage.h>
#include <vtkJPEGReader.h>
#include <vtkMath.h>
#include <vtkProperty2D.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkXMLPolyDataReader.h>
 
class vtkBorderCallback : public vtkCommand
{
public:
  vtkBorderCallback(){}
 
  static vtkBorderCallback *New()
    {
    return new vtkBorderCallback;
    }
 
  virtual void Execute(vtkObject *caller, unsigned long, void*);
 
  void SetRenderer(vtkSmartPointer<vtkRenderer> renderer)
    {
    this->Renderer = renderer;
    }
  void SetImageActor(vtkSmartPointer<vtkImageActor> actor)
    {
    this->ImageActor = actor;
    }
 
private:
  vtkSmartPointer<vtkRenderer>   Renderer;
  vtkSmartPointer<vtkImageActor> ImageActor;
};
 
int main(int argc, char* argv[])
{
  if ( argc != 2 )
    {
    std::cerr << "Usage: " << argv[0]
              << " Required parameters: Filename" << std::endl;
    return EXIT_FAILURE;
    }
 
  std::string inputFilename = argv[1];
 
  // Read the image
  vtkSmartPointer<vtkJPEGReader> jPEGReader = 
    vtkSmartPointer<vtkJPEGReader>::New();
 
  if( !jPEGReader->CanReadFile( inputFilename.c_str() ) )
    {
    cout << "Error: cannot read " << inputFilename.c_str() << std::endl;
    return EXIT_FAILURE;
    }
 
  jPEGReader->SetFileName ( inputFilename.c_str() );
  jPEGReader->Update();
 
  // Shift the image center to (0,0)
  int dims[3];
  jPEGReader->GetOutput()->GetDimensions(dims);
 
  vtkSmartPointer<vtkImageChangeInformation> changeInformation = 
    vtkSmartPointer<vtkImageChangeInformation>::New();
  changeInformation->SetInputConnection(jPEGReader->GetOutputPort());
  changeInformation->CenterImageOn();
  changeInformation->Update();
 
  vtkSmartPointer<vtkImageData> image =
    changeInformation->GetOutput();
 
  vtkSmartPointer<vtkImageActor> imageActor = 
    vtkSmartPointer<vtkImageActor>::New();
#if VTK_MAJOR_VERSION <= 5
  imageActor->SetInput(image);
#else
  imageActor->GetMapper()->SetInputData(image);
#endif
 
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
 
  vtkSmartPointer<vtkRenderWindowInteractor> interactor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
 
  vtkSmartPointer<vtkInteractorStyleImage> style = 
    vtkSmartPointer<vtkInteractorStyleImage>::New();
  interactor->SetInteractorStyle( style );  
 
  vtkSmartPointer<vtkBorderWidget> borderWidget = 
    vtkSmartPointer<vtkBorderWidget>::New();
  borderWidget->SetInteractor(interactor);
  static_cast<vtkBorderRepresentation*>(borderWidget->GetRepresentation())->GetBorderProperty()->SetColor(0,1,0);
  borderWidget->SelectableOff();
 
  interactor->SetRenderWindow(renderWindow);
 
  // Setup both renderers
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  renderer->SetBackground(1,0,0);
  renderWindow->AddRenderer(renderer);
 
  renderer->AddActor(imageActor);
 
  renderer->ResetCamera();
 
  vtkSmartPointer<vtkBorderCallback> borderCallback = 
    vtkSmartPointer<vtkBorderCallback>::New();
  borderCallback->SetRenderer(renderer);
  borderCallback->SetImageActor(imageActor);
 
  borderWidget->AddObserver(vtkCommand::InteractionEvent,borderCallback);
  borderWidget->On();
  renderWindow->Render();
  interactor->Start();
 
  return EXIT_SUCCESS;
}
 
void vtkBorderCallback::Execute(vtkObject *caller, unsigned long, void*)
{
 
  vtkBorderWidget *borderWidget = 
    reinterpret_cast<vtkBorderWidget*>(caller);
 
  // Get the world coordinates of the two corners of the box
  vtkCoordinate* lowerLeftCoordinate =
    static_cast<vtkBorderRepresentation*>(
      borderWidget->GetRepresentation())->GetPositionCoordinate();
  double* lowerLeft =
    lowerLeftCoordinate->GetComputedWorldValue(this->Renderer);
  std::cout << "Lower left coordinate: "
            << lowerLeft[0] << ", "
            << lowerLeft[1] << ", "
            << lowerLeft[2] << std::endl;
 
  vtkCoordinate* upperRightCoordinate =
    static_cast<vtkBorderRepresentation*>(
      borderWidget->GetRepresentation())->GetPosition2Coordinate();
  double* upperRight =
    upperRightCoordinate->GetComputedWorldValue(this->Renderer);
  std::cout << "Upper right coordinate: "
            << upperRight[0] << ", "
            << upperRight[1] << ", "
            << upperRight[2] << std::endl;
 
  double* bounds = this->ImageActor->GetBounds();
  double xmin = bounds[0];
  double xmax = bounds[1];
  double ymin = bounds[2];
  double ymax = bounds[3];
 
  if( (lowerLeft[0] > xmin) &&
      (upperRight[0] < xmax) &&
      (lowerLeft[1] > ymin) &&
      (upperRight[1] < ymax) )
    {
    //std::cout << "box is inside image" << std::endl;
    //std::cout << "xmin: " << xmin << " xmax: " << xmax << " ymin: " << ymin << " ymax: " << ymax << std::endl;
    }
  else
    {
    std::cout << "box is NOT inside image" << std::endl;
    }
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
 
PROJECT(CenterAnImage)
 
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
 
add_executable(CenterAnImage MACOSX_BUNDLE CenterAnImage.cxx)
 
if(VTK_LIBRARIES)
  target_link_libraries(CenterAnImage ${VTK_LIBRARIES})
else()
  target_link_libraries(CenterAnImage vtkHybrid vtkWidgets)
endif()

Download and Build CenterAnImage

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

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

cd CenterAnImage/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:

./CenterAnImage

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.