//# VectorKernel.h: generate Vector kernels
//# Copyright (C) 1996,1997,1998,1999,2000,2001
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//#        Internet email: casa-feedback@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA

#ifndef SCIMATH_VECTORKERNEL_H
#define SCIMATH_VECTORKERNEL_H


//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Vector.h>

namespace casacore { //# NAMESPACE CASACORE - BEGIN

//# Forward Declarations
class Regex;
class String;

// <summary>
// Make a Vector smoothing kernel from a kernel specification
// </summary>

// <use visibility=export>

// <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
// </reviewed>

// <prerequisite>
//   <li> <linkto class="Vector">Vector</linkto>
// </prerequisite>

// <etymology>
// Returns a vector from a smoothing kernel specification.
// </etymology>

// <synopsis>
// This class takes a smoothing kernel type and a width, and
// generates  a Vector holding that kernel.  It can be used
// in conjunction with the separable image convolver,
// SepImageConvolver
//
// The kernels can be normalized so that the peak of the
// kernel is 1, or 1/area under the kernel. The latter ensures
// conservation of integrated pixel value (the usual jargon
// is conservation of flux for images) and is the default.
// </synopsis>

// <example>
// <srcBlock>
// </srcBlock>
// </example>

// <motivation>
// </motivation>

// <todo asof="1990/03/31">
//   <li> 
// </todo>
 

class VectorKernel
{
public:

enum KernelTypes {

// Box-car smoothing kernel
   BOXCAR,

// Gaussian smoothing kernel
   GAUSSIAN,

// Hanning smoothing kernel
   HANNING,

   NKERNELS};

// Create kernel vector for width in pixels.  For Gaussian, width is FWHM,
// for Boxcar, width is full width.  For Hanning width is ignored.
// If useShapeExactly is True, the provided shape is used exactly. 
// If useShapeExactly is False,
// the kernel length will be the max of the provided shape and an
// autoestimate (e.g. from +/- 5sigma limits for a Gaussian).  
// <group>   
   static Vector<Double> make(KernelTypes kernelType, Double width, 
                              uInt shape, Bool useShapeExactly, Bool peakIsUnity=False);
   static Vector<Float> make(KernelTypes kernelType, Float width, 
                             uInt shape, Bool useShapeExactly, Bool peakIsUnity=False);
// </group>   


// Helper function to convert a string containing a list of desired smoothed kernel types
// to the correct <src>Vector<Int></src> required for the <src>setSmooth</src> function.
// This may be usful if your user interface involves strings rather than integers.
// A new value is added to the output vector (which is resized appropriately) if any of the 
// substrings "boxcar", "gaussian" or "hanning" (actually "box", "gauss", and "hann"
// will do) is present.
   static Vector<Int> toKernelTypes (const String& kernels,
                                     const std::regex& delimiter);
   static Vector<Int> toKernelTypes (const Vector<String>& kernels);
   static VectorKernel::KernelTypes toKernelType (const String& kernel);
   static String fromKernelType (KernelTypes kernelType);
};


} //# NAMESPACE CASACORE - END

#endif

