/*=========================================================================
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkSignedMaurerDistanceMapImageFilter_h
#define itkSignedMaurerDistanceMapImageFilter_h

#include "itkImageToImageFilter.h"

namespace itk
{
/** \class SignedMaurerDistanceMapImageFilter
 *
 *  \brief This filter calculates the Euclidean distance transform
 *  of a binary image in linear time for arbitrary dimensions.
 *
 *  \par Inputs and Outputs
 *  This is an image-to-image filter. The dimensionality is arbitrary. The
 *  only dimensionality constraint is that the input and output images be of
 *  the same dimensions and size. To maintain integer arithmetic within the
 *  filter, the default output is the signed squared distance. This implies
 *  that the input image should be of type "unsigned int" or "int" whereas the
 *  output image is of type "int".  Obviously, if the user wishes to utilize
 *  the image spacing or to have a filter with the Euclidean distance (as
 *  opposed to the squared distance), output image types of float or double
 *  should be used.
 *
 *  The inside is considered as having negative distances. Outside is
 *  treated as having positive distances. To change the convention, use the
 *  InsideIsPositive(bool) function.
 *
 *  \par Parameters
 *  Set/GetBackgroundValue specifies the background of the value of the
 *  input binary image. Normally this is zero and, as such, zero is the
 *  default value.  Other than that, the usage is completely analogous to
 *  the itk::DanielssonDistanceImageFilter class except it does not return
 *  the Voronoi map.
 *
 *  Reference:
 *  C. R. Maurer, Jr., R. Qi, and V. Raghavan, "A Linear Time Algorithm
 *  for Computing Exact Euclidean Distance Transforms of Binary Images in
 *  Arbitrary Dimensions", IEEE - Transactions on Pattern Analysis and
 *  Machine Intelligence, 25(2): 265-270, 2003.
 *
 * \ingroup ImageFeatureExtraction
 * \ingroup ITKDistanceMap
 */
template< typename TInputImage, typename TOutputImage >
class SignedMaurerDistanceMapImageFilter:
  public ImageToImageFilter< TInputImage, TOutputImage >
{
public:

  /** Extract dimension from input and output image. */
  itkStaticConstMacro(InputImageDimension, unsigned int,
                      TInputImage::ImageDimension);
  itkStaticConstMacro(OutputImageDimension, unsigned int,
                      TOutputImage::ImageDimension);
  itkStaticConstMacro(ImageDimension, unsigned int,
                      TOutputImage::ImageDimension);

  /** Convenient typedefs for simplifying declarations. */
  typedef TInputImage                           InputImageType;
  typedef typename InputImageType::ConstPointer InputImageConstPointer;

  typedef TOutputImage                          OutputImageType;
  typedef typename OutputImageType::Pointer     OutputImagePointer;

  /** Standard class typedefs. */
  typedef SignedMaurerDistanceMapImageFilter  Self;
  typedef ImageToImageFilter<
    InputImageType,
    OutputImageType >                         Superclass;

  typedef SmartPointer< Self >                Pointer;
  typedef SmartPointer< const Self >          ConstPointer;

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** Runtime information support. */
  itkTypeMacro(SignedMaurerDistanceMapImageFilter,
               ImageToImageFilter);

  typedef typename InputImageType::RegionType   InputRegionType;
  typedef typename OutputImageType::RegionType  OutputRegionType;

  /** Image typedef support. */
  typedef typename InputImageType::PixelType  InputPixelType;
  typedef typename OutputImageType::PixelType OutputPixelType;

  typedef typename InputImageType::SizeType       InputSizeType;
  typedef typename InputImageType::SizeValueType  InputSizeValueType;
  typedef typename OutputImageType::SizeType      OutputSizeType;
  typedef typename OutputImageType::SizeValueType OutputSizeValueType;

  typedef typename InputImageType::IndexType        InputIndexType;
  typedef typename InputImageType::IndexValueType   InputIndexValueType;
  typedef typename OutputImageType::IndexType       OutputIndexType;
  typedef typename OutputImageType::IndexValueType  OutputIndexValueType;

  typedef typename InputImageType::SpacingType  InputSpacingType;
  typedef typename OutputImageType::SpacingType OutputSpacingType;
  typedef typename OutputImageType::RegionType  OutputImageRegionType;

  /** Set if the distance should be squared. */
  itkSetMacro(SquaredDistance, bool);

  /** Get the distance squared. */
  itkGetConstReferenceMacro(SquaredDistance, bool);

  /** Set On/Off if the distance is squared. */
  itkBooleanMacro(SquaredDistance);

  /** Set if the inside represents positive values in the signed distance
   *  map. By convention ON pixels are treated as inside pixels.*/
  itkSetMacro(InsideIsPositive, bool);

  /** Get if the inside represents positive values in the signed distance
   * map. \see GetInsideIsPositive()  */
  itkGetConstReferenceMacro(InsideIsPositive, bool);

  /** Set if the inside represents positive values in the signed distance
   * map. By convention ON pixels are treated as inside pixels. Default is
   * true.                             */
  itkBooleanMacro(InsideIsPositive);

  /** Set if image spacing should be used in computing distances. */
  itkSetMacro(UseImageSpacing, bool);

  /** Get whether spacing is used. */
  itkGetConstReferenceMacro(UseImageSpacing, bool);

  /** Set On/Off whether spacing is used. */
  itkBooleanMacro(UseImageSpacing);

  /**
   * Set the background value which defines the object.  Usually this
   * value is = 0.
   */
  itkSetMacro(BackgroundValue, InputPixelType);
  itkGetConstReferenceMacro(BackgroundValue, InputPixelType);

protected:
  SignedMaurerDistanceMapImageFilter();
  virtual ~SignedMaurerDistanceMapImageFilter();

  virtual void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;

  virtual void GenerateData() ITK_OVERRIDE;

  virtual unsigned int SplitRequestedRegion(unsigned int i, unsigned int num,
    OutputImageRegionType & splitRegion) ITK_OVERRIDE;

  virtual void ThreadedGenerateData(const OutputImageRegionType & outputRegionForThread,
                            ThreadIdType threadId) ITK_OVERRIDE;

private:
  SignedMaurerDistanceMapImageFilter(const Self &) ITK_DELETE_FUNCTION;
  void operator=(const Self &) ITK_DELETE_FUNCTION;

  void Voronoi(unsigned int, OutputIndexType idx, OutputImageType *output );
  bool Remove(OutputPixelType, OutputPixelType, OutputPixelType,
              OutputPixelType, OutputPixelType, OutputPixelType);

  InputPixelType   m_BackgroundValue;
  InputSpacingType m_Spacing;

  unsigned int m_CurrentDimension;

  bool m_InsideIsPositive;
  bool m_UseImageSpacing;
  bool m_SquaredDistance;

  const InputImageType *m_InputCache;
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkSignedMaurerDistanceMapImageFilter.hxx"
#endif

#endif
