TiledCollapser.h

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// # TiledCollapser.h: Abstract base class to collapse chunks for LatticeApply
// # Copyright (C) 1996,1997,1998
// # 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 LATTICES_TILEDCOLLAPSER_H
#define LATTICES_TILEDCOLLAPSER_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/ArrayFwd.h>
#include <casacore/scimath/Mathematics/NumericTraits.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class IPosition;
 
// <summary>
// Abstract base class to collapse chunks for LatticeApply
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class=LatticeApply>LatticeApply</linkto>
// </prerequisite>
 
// <etymology>
// </etymology>
 
// <synopsis>
// This is an abstract base class for the collapsing of chunks to
// be used in function <src>tiledApply</src>
// in class <linkto class=LatticeApply>LatticeApply</linkto>.
// It is meant for cases where an entire line or plane is not needed
// (e.g. calculation of maximum). If that is needed (e.g. to calculate moment),
// it is better to use function <src>LatticeApply::lineApply</src>
// with class <linkto class=LineCollapser>LineCollapser</linkto>.
// <p>
// The user has to derive a concrete class from this base class
// and implement the (pure) virtual functions.
// <br> The main function is <src>process</src>, which needs to do the
// calculation.
// <br> Other functions make it possible to perform an initial check.
// <p>
// The class is Doubly templated.  Ths first template type
// is for the data type you are processing.  The second type is
// for what type you want the results of the processing assigned to.
// For example, if you are computing sums of squares for statistical
// purposes, you might use higher precision (FLoat->Double) for this.
// No check is made that the template types are self-consistent.
// </synopsis>
 
// <example>
// <srcblock>
// </srcblock>
// </example>
 
// <motivation>
// </motivation>
 
// <todo asof="1997/08/01">
//   <li>
// </todo>
 
template <class T, class U = T>
class TiledCollapser {
 public:
  // Destructor
  virtual ~TiledCollapser();
 
  // The init function for a derived class.
  // It can be used to check if <src>nOutPixelsPerCollapse</src>
  // corresponds with the number of pixels produced per collapsed chunk.
  // <br><src>processAxis</src> is the axis of the line being passed
  // to the <src>process</src> function.
  virtual void init(uInt nOutPixelsPerCollapse) = 0;
 
  // Can the process function in the derived class handle a null mask pointer?
  // If not, LatticeApply ensures that it'll always pass a mask block,
  // even if the lattice does not have a mask (in that case that mask block
  // contains all True values).
  // <br>The default implementation returns False.
  // <br>The function is there to make optimization possible when no masks
  // are involved. On the other side, it allows the casual user to ignore
  // optimization.
  virtual Bool canHandleNullMask() const;
 
  // Create and initialize the accumulator.
  // The accumulator can be a cube with shape [n1,n2,n3],
  // where <src>n2</src> is equal to <src>nOutPixelsPerCollapse</src>.
  // However, one can also use several matrices as accumulator.
  // <br> The data type of the accumulator can be any. E.g. when
  // accumulating Float lattices, the accumulator could be of
  // type Double to have enough precision.
  // <br>In the <src>endAccumulator</src> function the accumulator
  // data has to be copied into an Array object with the correct
  // shape and data type.
  virtual void initAccumulator(uInt64 n1, uInt64 n3) = 0;
 
  // Collapse the given input data containing (<src>nrval</src> values
  // with an increment of <src>inDataIncr</src> elements).
  // <src>inMask</src> is a Bool block representing a mask with the
  // same nr of values and increment as the input data. If a mask
  // value is False, the corresponding input value is masked off.
  // <br>When function <src>canHandleNullMask</src> returned True,
  // it is possible that <src>inMask</src> is a null pointer indicating
  // that the input has no mask, thus all values are valid.
  // <br>
  // The result(s) have to be stored in the accumulator at the given indices.
  // <br><src>startPos</src> gives the lattice position of the first value.
  // The position of other values can be calculated from index and shape
  // using function <src>toPositionInArray</src> in class
  // <linkto class=IPosition>IPosition</linkto>.
  virtual void process(uInt accumIndex1, uInt accumIndex3, const T* inData, const Bool* inMask,
                       uInt inDataIncr, uInt inMaskIncr, uInt nrval, const IPosition& startPos,
                       const IPosition& shape) = 0;
 
  // End the accumulator. It should return the accumulator as an
  // Array of datatype U (e.g. double the precision of type T)
  // with the given shape. The accumulator should thereafter be deleted when needed.
  virtual void endAccumulator(Array<U>& result, Array<Bool>& resultMask,
                              const IPosition& shape) = 0;
};
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/lattices/LatticeMath/TiledCollapser.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif