ENH: Add ImageBufferAndIndexRange example

Using `ImageBufferRange` and `IndexRange`, which were introduced with ITK 5.0.

Author: N-Dekker

src/Core/Common/CMakeLists.txt

@@ -22,6 +22,7 @@ add_example(AddOffsetToIndex)
 add_example(GetNameOfClass)
 add_example(CreateAnImageRegion)
 add_example(IsPixelInsideRegion)
+add_example(ImageBufferAndIndexRange)
 add_example(ImageRegionIntersection)
 
 add_example(ImageRegionOverlap)

src/Core/Common/ImageBufferAndIndexRange/CMakeLists.txt

@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.16.3)
+
+project(ImageBufferAndIndexRange)
+
+find_package(ITK REQUIRED)
+include(${ITK_USE_FILE})
+
+add_executable(${PROJECT_NAME} Code.cxx)
+target_link_libraries(${PROJECT_NAME} ${ITK_LIBRARIES})
+
+install(TARGETS ${PROJECT_NAME}
+  DESTINATION bin/ITKSphinxExamples/Core/Common
+  COMPONENT Runtime
+)
+
+install(FILES Code.cxx CMakeLists.txt
+  DESTINATION share/ITKSphinxExamples/Code/Core/Common/${PROJECT_NAME}
+  COMPONENT Code
+)
+
+enable_testing()
+add_test(NAME ${PROJECT_NAME}Test
+  COMMAND ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME})

src/Core/Common/ImageBufferAndIndexRange/Code.cxx

@@ -0,0 +1,87 @@
+/*=========================================================================
+ *
+ *  Copyright NumFOCUS
+ *
+ *  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 "itkImageBufferRange.h"
+#include "itkIndexRange.h"
+#include "itkNumericTraits.h"
+
+#include <cassert>
+#include <numeric> // For iota
+
+namespace
+{
+// Creates an image with sequentially increasing pixel values (0, 1, 2, ...).
+template <typename TImage>
+typename TImage::Pointer
+CreateImageWithSequentiallyIncreasingPixelValues(const typename TImage::RegionType & region)
+{
+  using PixelType = typename TImage::PixelType;
+
+  const auto image = TImage::New();
+  image->SetRegions(region);
+  image->Allocate();
+
+  const itk::ImageBufferRange<TImage> imageBufferRange(*image);
+  std::iota(imageBufferRange.begin(), imageBufferRange.end(), PixelType{ 0 });
+
+  return image;
+}
+
+
+// Prints all pixel values with their N-dimensional indices.
+template <typename TImage>
+void
+PrintPixelValues(const TImage & image)
+{
+  constexpr unsigned int                      Dimension{ TImage::ImageDimension };
+  const itk::ImageRegion<Dimension>           region = image.GetBufferedRegion();
+  const itk::ImageRegionIndexRange<Dimension> indexRange(region);
+  const itk::ImageBufferRange<const TImage>   imageBufferRange(image);
+
+  using PixelType = typename TImage::PixelType;
+  using PrintType = typename itk::NumericTraits<PixelType>::PrintType;
+
+  std::cout << "Region index: " << region.GetIndex() << "; Region size: " << region.GetSize() << "\n\n";
+
+  auto indexIterator = indexRange.cbegin();
+
+  for (const PixelType pixel : imageBufferRange)
+  {
+    const itk::Index<Dimension> index = *indexIterator;
+    std::cout << "Pixel index: " << index << "; Pixel value: " << PrintType{ pixel } << '\n';
+    ++indexIterator;
+  }
+
+  assert(indexIterator == indexRange.cend());
+}
+
+} // namespace
+
+
+int
+main()
+{
+  using PixelType = unsigned char;
+  using ImageType = itk::Image<PixelType>;
+  using RegionType = ImageType::RegionType;
+
+  const RegionType              region(itk::MakeIndex(100, 200), itk::MakeSize(4, 5));
+  const ImageType::ConstPointer image = CreateImageWithSequentiallyIncreasingPixelValues<ImageType>(region);
+  PrintPixelValues(*image);
+}

src/Core/Common/ImageBufferAndIndexRange/Documentation.rst

@@ -0,0 +1,59 @@
+:name: ImageBufferAndIndexRange
+
+Image Buffer and Index Range
+============================
+
+.. index::
+   single: ImageBufferRange
+
+Synopsis
+--------
+
+
+This example demonstrates how to iterate over all pixels of the buffered region
+of an image, using either an iterator-based algorithm from the C++ Standard
+Library, or a range-based for loop.
+
+
+Results
+-------
+
+Output::
+
+  Region index: [100, 200]; Region size: [4, 5]
+
+  Pixel index: [100, 200]; Pixel value: 0
+  Pixel index: [101, 200]; Pixel value: 1
+  Pixel index: [102, 200]; Pixel value: 2
+  Pixel index: [103, 200]; Pixel value: 3
+  Pixel index: [100, 201]; Pixel value: 4
+  Pixel index: [101, 201]; Pixel value: 5
+  Pixel index: [102, 201]; Pixel value: 6
+  Pixel index: [103, 201]; Pixel value: 7
+  Pixel index: [100, 202]; Pixel value: 8
+  Pixel index: [101, 202]; Pixel value: 9
+  Pixel index: [102, 202]; Pixel value: 10
+  Pixel index: [103, 202]; Pixel value: 11
+  Pixel index: [100, 203]; Pixel value: 12
+  Pixel index: [101, 203]; Pixel value: 13
+  Pixel index: [102, 203]; Pixel value: 14
+  Pixel index: [103, 203]; Pixel value: 15
+  Pixel index: [100, 204]; Pixel value: 16
+  Pixel index: [101, 204]; Pixel value: 17
+  Pixel index: [102, 204]; Pixel value: 18
+  Pixel index: [103, 204]; Pixel value: 19
+
+Code
+----
+
+C++
+...
+
+.. literalinclude:: Code.cxx
+   :lines: 18-
+
+
+Classes demonstrated
+--------------------
+
+.. breathelink:: itk::ImageBufferRange itk::IndexRange

src/Core/Common/index.rst

@@ -58,6 +58,7 @@ Common
   GetNameOfClass/Documentation.rst
   GetOrSetMemberVariableOfITKClass/Documentation.rst
   GetTypeBasicInformation/Documentation.rst
+  ImageBufferAndIndexRange/Documentation.rst
   ImageRegionIntersection/Documentation.rst
   ImageRegionOverlap/Documentation.rst
   ImportPixelBufferIntoAnImage/Documentation.rst