text: /*=========================================================================
   *
   *  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 <iostream>
  #include "itkFrameDifferenceVideoFilter.h"
  #include "itkVideoFileReader.h"
  #include "itkVideoFileWriter.h"
  #include "itkFileListVideoIOFactory.h"
  
  
  // Set up type alias for test
  constexpr unsigned int Dimension = 2;
  using InputPixelType = unsigned char;
  using InputFrameType = itk::Image<InputPixelType, Dimension>;
  using InputVideoType = itk::VideoStream<InputFrameType>;
  using OutputPixelType = unsigned char;
  using OutputFrameType = itk::Image<OutputPixelType, Dimension>;
  using OutputVideoType = itk::VideoStream<OutputFrameType>;
  using SizeValueType = itk::SizeValueType;
  
  
  /**
   * Helper function
   */
  namespace itk
  {
  namespace FrameDifferenceVideoFilterTest
  {
  
  /**
   * Create a new frame and fill it with the indicated value
   */
  InputFrameType::Pointer
  CreateInputFrame(InputPixelType val)
  {
    auto out = InputFrameType::New();
  
    InputFrameType::RegionType largestRegion;
    InputFrameType::SizeType   sizeLR;
    InputFrameType::IndexType  startLR;
    startLR.Fill(0);
    sizeLR[0] = 50;
    sizeLR[1] = 40;
    largestRegion.SetSize(sizeLR);
    largestRegion.SetIndex(startLR);
    out->SetRegions(largestRegion);
  
    out->Allocate();
  
    // Fill with the desired value
    itk::ImageRegionIterator<InputFrameType> iter(out, largestRegion);
    while (!iter.IsAtEnd())
    {
      iter.Set(val);
      ++iter;
    }
  
    return out;
  }
  
  } // end namespace FrameDifferenceVideoFilterTest
  } // end namespace itk
  
  
  /**
   * Main test
   */
  int
  itkFrameDifferenceVideoFilterTest(int itkNotUsed(argc), char * itkNotUsed(argv)[])
  {
    // Instantiate the filter
    using FilterType = itk::FrameDifferenceVideoFilter<InputVideoType, OutputVideoType>;
    auto filter = FilterType::New();
  
  
    // Set up an input VideoStream
    auto          inputVideo = InputVideoType::New();
    SizeValueType numInputFrames = 50;
    inputVideo->SetNumberOfBuffers(numInputFrames);
    itk::TemporalRegion inputTempRegion;
    inputTempRegion.SetFrameStart(0);
    inputTempRegion.SetFrameDuration(numInputFrames);
    inputVideo->SetLargestPossibleTemporalRegion(inputTempRegion);
    inputVideo->SetRequestedTemporalRegion(inputTempRegion);
    inputVideo->SetBufferedTemporalRegion(inputTempRegion);
    for (SizeValueType i = 0; i < numInputFrames; ++i)
    {
      inputVideo->SetFrame(i, itk::FrameDifferenceVideoFilterTest::CreateInputFrame(i));
    }
    filter->SetInput(inputVideo);
  
  
    //////
    // Test filter with difference of adjacent frames (the default)
    //////
  
    filter->UpdateOutputInformation();
  
    // Make sure output largest possible temporal region is correct
    itk::TemporalRegion outputLargestTempRegion = filter->GetOutput()->GetLargestPossibleTemporalRegion();
    SizeValueType       outputStart = outputLargestTempRegion.GetFrameStart();
    SizeValueType       outputDuration = outputLargestTempRegion.GetFrameDuration();
    if (outputStart != 0)
    {
      std::cerr << "output's LargestPossibleTemporalRegion incorrect start. Got: " << outputStart << " Expected: 0"
                << std::endl;
      return EXIT_FAILURE;
    }
    if (outputDuration != numInputFrames - 1)
    {
      std::cerr << "output's LargestPossibleTemporalRegion incorrect duration. Got: " << outputDuration
                << " Expected: " << numInputFrames - 1 << std::endl;
      return EXIT_FAILURE;
    }
  
    // Go one frame at a time and check results
    OutputFrameType::IndexType checkPx;
    checkPx[0] = inputVideo->GetFrame(0)->GetLargestPossibleRegion().GetSize()[0] - 1;
    checkPx[1] = inputVideo->GetFrame(0)->GetLargestPossibleRegion().GetSize()[1] - 1;
    for (unsigned int i = outputStart; i < outputStart + outputDuration; ++i)
    {
      itk::TemporalRegion reqTempRegion;
      reqTempRegion.SetFrameStart(i);
      reqTempRegion.SetFrameDuration(1);
      filter->GetOutput()->SetRequestedTemporalRegion(reqTempRegion);
      filter->Update();
  
      // Check the results
      OutputPixelType expectedVal = 1;
      OutputPixelType actualVal = filter->GetOutput()->GetFrame(i)->GetPixel(checkPx);
      if (expectedVal != actualVal)
      {
        std::cerr << "Filter failed to compute frame " << i << " correctly for adjacent frames." << std::endl;
        std::cerr << "Expected Pixel Val: " << expectedVal << std::endl;
        std::cerr << "Actual Pixel Val: " << actualVal << std::endl;
        return EXIT_FAILURE;
      }
    }
  
    //////
    // Test filter with offset of 2
    //////
  
    // Reset the filter
    filter = FilterType::New();
    filter->SetInput(inputVideo);
    filter->SetFrameOffset(2);
    filter->UpdateOutputInformation();
  
    // Make sure output largest possible temporal region is correct
    outputLargestTempRegion = filter->GetOutput()->GetLargestPossibleTemporalRegion();
    outputStart = outputLargestTempRegion.GetFrameStart();
    outputDuration = outputLargestTempRegion.GetFrameDuration();
    if (outputStart != 0)
    {
      std::cerr << "output's LargestPossibleTemporalRegion incorrect start. Got: " << outputStart << " Expected: 0"
                << std::endl;
      return EXIT_FAILURE;
    }
    if (outputDuration != numInputFrames - 2)
    {
      std::cerr << "output's LargestPossibleTemporalRegion incorrect duration. Got: " << outputDuration
                << " Expected: " << numInputFrames - 2 << std::endl;
      return EXIT_FAILURE;
    }
  
    // Get all the frames at once and check results
    filter->Update();
    for (unsigned int i = outputStart; i < outputStart + outputDuration; ++i)
    {
      OutputPixelType expectedVal = 4; // Difference of 2 squared
      OutputPixelType actualVal = filter->GetOutput()->GetFrame(i)->GetPixel(checkPx);
      if (expectedVal != actualVal)
      {
        std::cerr << "Filter failed to compute frame " << i << " correctly with offset of 2." << std::endl;
        std::cerr << "Expected Pixel Val: " << expectedVal << std::endl;
        std::cerr << "Actual Pixel Val: " << actualVal << std::endl;
        return EXIT_FAILURE;
      }
    }
  
    //////
    // Return successfully
    //////
    return EXIT_SUCCESS;
  }
  