SphinxExamples/src/Core/Common/ImportPixelBufferIntoAnImage/Code.cxx

/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/

#include "itkImage.h"
#include "itkImportImageFilter.h"
#include "itkImageFileWriter.h"

int main( int argc, char* argv[] )
{
  if( argc != 2 )
    {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << "  outputImageFile" << std::endl;
    return EXIT_FAILURE;
    }

  // We select the data type used to represent the image pixels. We
  // assume that the external block of memory uses the same data type to
  // represent the pixels.
  using PixelType = unsigned char;
  constexpr unsigned int Dimension = 2;

  using ImageType = itk::Image< PixelType, Dimension >;
  using ImportFilterType = itk::ImportImageFilter< PixelType, Dimension >;
  ImportFilterType::Pointer importFilter = ImportFilterType::New();
  // This filter requires the user to specify the size of the image to be
  // produced as output.  The `SetRegion()` method is used to this end.
  // The image size should exactly match the number of pixels available in the
  // locally allocated buffer.
  ImportFilterType::SizeType  size;

  size[0]  = 200;  // size along X
  size[1]  = 200;  // size along Y

  ImportFilterType::IndexType start;
  start.Fill( 0 );

  ImportFilterType::RegionType region;
  region.SetIndex( start );
  region.SetSize(  size  );

  importFilter->SetRegion( region );

  const itk::SpacePrecisionType origin[ Dimension ] = { 0.0, 0.0};
  importFilter->SetOrigin( origin );
  const itk::SpacePrecisionType  spacing[ Dimension ] =  { 1.0, 1.0};
  importFilter->SetSpacing( spacing );
  // Next we allocate the memory block containing the pixel data to be
  // passed to the `ImportImageFilter`. Note that we use exactly the
  // same size that was specified with the `SetRegion()` method. In a
  // practical application, you may get this buffer from some other library
  // using a different data structure to represent the images.
  const unsigned int numberOfPixels =  size[0] * size[1];
  auto * localBuffer = new PixelType[ numberOfPixels ];
  constexpr double radius = 80.0;
  // Here we fill up the buffer with a binary sphere.
  const double radius2 = radius * radius;
  PixelType * it = localBuffer;

  for(unsigned int y=0; y < size[1]; y++)
    {
    const double dy = static_cast<double>( y )
      - static_cast<double>(size[1])/2.0;
    for(unsigned int x=0; x < size[0]; x++)
      {
      const double dx = static_cast<double>( x )
        - static_cast<double>(size[0])/2.0;
      const double d2 = dx*dx + dy*dy;
      *it++ = ( d2 < radius2 ) ? 255 : 0;
      }
    }
  // The buffer is passed to the ImportImageFilter with the
  // `SetImportPointer()` method. Note that the last argument of this method
  // specifies who will be responsible for deleting the memory block once it
  // is no longer in use. A `true` value, will allow the
  // filter to delete the memory block upon destruction of the import filter.
  //
  // For the `ImportImageFilter` to appropriately delete the
  // memory block, the memory must be allocated with the C++
  // `new()` operator. Memory allocated with other memory
  // allocation mechanisms, such as C `malloc` or `calloc`, will not
  // be deleted properly by the `ImportImageFilter`. In
  // other words, it is the application programmer's responsibility
  // to ensure that `ImportImageFilter` is only given
  // permission to delete the C++ `new` operator-allocated memory.
  const bool importImageFilterWillOwnTheBuffer = true;
  importFilter->SetImportPointer( localBuffer, numberOfPixels,
                                  importImageFilterWillOwnTheBuffer );
  // Finally, we can connect the output of this filter to a pipeline.
  // For simplicity we just use a writer here, but it could be any other filter.
  using WriterType = itk::ImageFileWriter< ImageType >;
  WriterType::Pointer writer = WriterType::New();

  writer->SetFileName( argv[1] );
  writer->SetInput(  importFilter->GetOutput()  );
  try
    {
    writer->Update();
    }
  catch( itk::ExceptionObject & exp )
    {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr << exp << std::endl;
    return EXIT_FAILURE;
    }

  // Note that we do not call `delete` on the buffer since we pass
  // `true` as the last argument of `SetImportPointer()`. Now the
  // buffer is owned by the `ImportImageFilter`.

  return EXIT_SUCCESS;
}