/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkWarpImageFilter.h,v $
  Language:  C++
  Date:      $Date: 2006-04-04 13:13:51 $
  Version:   $Revision: 1.21 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkWarpImageFilter_h
#define __itkWarpImageFilter_h

#include "itkImageToImageFilter.h"
#include "itkInterpolateImageFunction.h"
#include "itkLinearInterpolateImageFunction.h"
#include "itkPoint.h"
#include "itkFixedArray.h"

namespace itk
{

/** \class WarpImageFilter
 * \brief Warps an image using an input deformation field.
 *
 * WarpImageFilter warps an existing image with respect to
 * a given deformation field.
 *
 * A deformation field is represented as a image whose pixel type is some
 * vector type with at least N elements, where N is the dimension of
 * the input image. The vector type must support element access via operator
 * [].
 *
 * The output image is produced by inverse mapping: the output pixels
 * are mapped back onto the input image. This scheme avoids the creation of
 * any holes and overlaps in the output image.
 *
 * Each vector in the deformation field represent the distance between
 * a geometric point in the input space and a point in the output space such 
 * that:
 *
 * \f[ p_{in} = p_{out} + d \f]
 *
 * Typically the mapped position does not correspond to an integer pixel 
 * position in the input image. Interpolation via an image function
 * is used to compute values at non-integer positions. The default 
 * interpolation typed used is the LinearInterpolateImageFunction.
 * The user can specify a particular interpolation function via
 * SetInterpolator(). Note that the input interpolator must derive
 * from base class InterpolateImageFunction.
 *
 * Position mapped to outside of the input image buffer are assigned
 * a edge padding value.
 *
 * The LargetPossibleRegion for the output is inherited from the 
 * input deformation field. The output image spacing and origin may be set 
 * via SetOutputSpacing, SetOutputOrigin. The default are respectively a 
 * vector of 1's and a vector of 0's.
 *
 * This class is templated over the type of the input image, the
 * type of the output image and the type of the deformation field.
 *
 * The input image is set via SetInput. The input deformation field
 * is set via SetDeformationField.
 *
 * This filter is implemented as a multithreaded filter.
 *
 * \warning This filter assumes that the input type, output type
 * and deformation field type all have the same number of dimensions.
 *
 * \ingroup GeometricTransforms MultiThreaded
 */
template <
  class TInputImage,
  class TOutputImage,
  class TDeformationField
  >
class ITK_EXPORT WarpImageFilter :
    public ImageToImageFilter<TInputImage, TOutputImage>
{
public:
  /** Standard class typedefs. */
  typedef WarpImageFilter      Self;
  typedef ImageToImageFilter<TInputImage,TOutputImage> Superclass;
  typedef SmartPointer<Self>         Pointer;
  typedef SmartPointer<const Self>   ConstPointer;

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

  /** Run-time type information (and related methods) */
  itkTypeMacro( WarpImageFilter, ImageToImageFilter );

  /** Typedef to describe the output image region type. */
  typedef typename TOutputImage::RegionType OutputImageRegionType;

  /** Inherit some types from the superclass. */
  typedef typename Superclass::InputImageType        InputImageType;
  typedef typename Superclass::InputImagePointer     InputImagePointer;
  typedef typename Superclass::OutputImageType       OutputImageType;
  typedef typename Superclass::OutputImagePointer    OutputImagePointer;
  typedef typename Superclass::InputImageConstPointer InputImageConstPointer;
  typedef typename OutputImageType::IndexType        IndexType;
  typedef typename OutputImageType::SizeType         SizeType;
  typedef typename OutputImageType::PixelType        PixelType;
  typedef typename OutputImageType::SpacingType      SpacingType;

  /** Determine the image dimension. */
  itkStaticConstMacro(ImageDimension, unsigned int,
                      TOutputImage::ImageDimension );
  itkStaticConstMacro(InputImageDimension, unsigned int,
                      TInputImage::ImageDimension );
  itkStaticConstMacro(DeformationFieldDimension, unsigned int,
                      TDeformationField::ImageDimension );

  /** Deformation field typedef support. */
  typedef TDeformationField    DeformationFieldType;
  typedef typename DeformationFieldType::Pointer  DeformationFieldPointer;
  typedef typename DeformationFieldType::PixelType DisplacementType;

  /** Interpolator typedef support. */
  typedef double CoordRepType;
  typedef InterpolateImageFunction<InputImageType,CoordRepType>   InterpolatorType;
  typedef typename InterpolatorType::Pointer   InterpolatorPointer;
  typedef LinearInterpolateImageFunction<InputImageType,CoordRepType>
  DefaultInterpolatorType;

  /** Point type */
  typedef Point<CoordRepType,itkGetStaticConstMacro(ImageDimension)> PointType;

  /** Set the deformation field. */
  void SetDeformationField( const DeformationFieldType * field );

  /** Get a pointer the deformation field. */
  DeformationFieldType * GetDeformationField(void);

  /** Set the interpolator function. */
  itkSetObjectMacro( Interpolator, InterpolatorType );

  /** Get a pointer to the interpolator function. */
  itkGetObjectMacro( Interpolator, InterpolatorType );

  /** Set the output image spacing. */
  itkSetMacro(OutputSpacing, SpacingType);
  virtual void SetOutputSpacing( const double* values);

  /** Get the output image spacing. */
  itkGetConstReferenceMacro(OutputSpacing, SpacingType);

  /** Set the output image origin. */
  itkSetMacro(OutputOrigin, PointType);
  virtual void SetOutputOrigin( const double* values);

  /** Get the output image origin. */
  itkGetConstReferenceMacro(OutputOrigin, PointType);

  /** Set the edge padding value */
  itkSetMacro( EdgePaddingValue, PixelType );

  /** Get the edge padding value */
  itkGetMacro( EdgePaddingValue, PixelType );

  /** WarpImageFilter produces an image which is a different
   * size than its input image. As such, it needs to provide an
   * implemenation for GenerateOutputInformation() which set
   * the output information according the OutputSpacing, OutputOrigin
   * and the deformation field's LargestPossibleRegion. */
  virtual void GenerateOutputInformation();

  /** It is difficult to compute in advance the input image region
   * required to compute the requested output region. Thus the safest
   * thing to do is to request for the whole input image.
   *
   * For the deformation field, the input requested region
   * set to be the same as that of the output requested region. */
  virtual void GenerateInputRequestedRegion();

  /** This method is used to set the state of the filter before 
   * multi-threading. */
  virtual void BeforeThreadedGenerateData();

  /** This method is used to set the state of the filter after 
   * multi-threading. */
  virtual void AfterThreadedGenerateData();

#ifdef ITK_USE_CONCEPT_CHECKING
  /** Begin concept checking */
  itkConceptMacro(SameDimensionCheck1,
    (Concept::SameDimension<ImageDimension, InputImageDimension>));
  itkConceptMacro(SameDimensionCheck2,
    (Concept::SameDimension<ImageDimension, DeformationFieldDimension>));
  itkConceptMacro(InputHasNumericTraitsCheck,
    (Concept::HasNumericTraits<typename TInputImage::PixelType>));
  itkConceptMacro(DeformationFieldHasNumericTraitsCheck,
    (Concept::HasNumericTraits<typename TDeformationField::PixelType::ValueType>));
  /** End concept checking */
#endif

protected:
  WarpImageFilter();
  ~WarpImageFilter() {};
  void PrintSelf(std::ostream& os, Indent indent) const;

  /** WarpImageFilter is implemented as a multi-threaded filter.
   * As such, it needs to provide and implementation for 
   * ThreadedGenerateData(). */
  void ThreadedGenerateData(const OutputImageRegionType& outputRegionForThread,
                            int threadId );

private:
  WarpImageFilter(const Self&); //purposely not implemented
  void operator=(const Self&); //purposely not implemented

  PixelType                  m_EdgePaddingValue;
  SpacingType                m_OutputSpacing;
  PointType                  m_OutputOrigin;

  InterpolatorPointer        m_Interpolator;
  
};

} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkWarpImageFilter.txx"
#endif

#endif