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ImageMapper

vtk-examples/Cxx/Images/ImageMapper


Description

This example demonstrates how to display an image in 2D. The size and position are in screen coordinates.

Question

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

Code

ImageMapper.cxx

#include <vtkActor2D.h>
#include <vtkImageData.h>
#include <vtkImageMapper.h>
#include <vtkImageSlice.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <array>

namespace {
void CreateColorImage(vtkImageData*);
}

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkImageData> colorImage;
  CreateColorImage(colorImage);

  vtkNew<vtkImageMapper> imageMapper;
  imageMapper->SetInputData(colorImage);
  imageMapper->SetColorWindow(255);
  imageMapper->SetColorLevel(127.5);

  vtkNew<vtkActor2D> imageActor;
  imageActor->SetMapper(imageMapper);
  imageActor->SetPosition(20, 20);

  // Setup renderers
  vtkNew<vtkRenderer> renderer;

  // Setup render window
  vtkNew<vtkRenderWindow> renderWindow;

  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("ImageMapper");

  // Setup render window interactor
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;

  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);

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

  // renderer->AddViewProp(imageActor);
  renderer->AddActor2D(imageActor);
  renderer->SetBackground(colors->GetColor3d("DarkSlateGray").GetData());

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

  return EXIT_SUCCESS;
}

namespace {
void CreateColorImage(vtkImageData* image)
{
  vtkNew<vtkNamedColors> colors;

  std::array<unsigned char, 3> drawColor1{0, 0, 0};
  std::array<unsigned char, 3> drawColor2{0, 0, 0};
  auto color1 = colors->GetColor3ub("HotPink").GetData();
  auto color2 = colors->GetColor3ub("Chartreuse").GetData();
  for (auto i = 0; i < 3; ++i)
  {
    drawColor1[i] = color1[i];
    drawColor2[i] = color2[i];
  }

  unsigned int dim = 20;

  image->SetDimensions(dim, dim, 1);
  image->AllocateScalars(VTK_UNSIGNED_CHAR, 3);

  for (unsigned int x = 0; x < dim; x++)
  {
    for (unsigned int y = 0; y < dim; y++)
    {
      auto pixel =
          static_cast<unsigned char*>(image->GetScalarPointer(x, y, 0));
      if (x < dim / 2)
      {
        for (auto i = 0; i < 3; ++i)
        {
          pixel[i] = drawColor1[i];
        }
      }
      else
      {
        for (auto i = 0; i < 3; ++i)
        {
          pixel[i] = drawColor2[i];
        }
      }
    }
  }

  image->Modified();
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageMapper)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping ImageMapper: ${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(ImageMapper MACOSX_BUNDLE ImageMapper.cxx )
  target_link_libraries(ImageMapper PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ImageMapper MACOSX_BUNDLE ImageMapper.cxx )
  target_link_libraries(ImageMapper PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ImageMapper
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build ImageMapper

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

cd ImageMapper/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:

./ImageMapper

WINDOWS USERS

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