LCPolygon.h

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// # LCPolygon.h: Define a 2-dimensional region by a polygon
// # Copyright (C) 1998,2000
// # 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_LCPOLYGON_H
#define LATTICES_LCPOLYGON_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/lattices/LRegions/LCRegionFixed.h>
#include <casacore/casa/Arrays/Vector.h>
#include <casacore/casa/Arrays/ArrayFwd.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Define a 2-dimensional region by a polygon.
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="" tests="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class=LCRegion>LCRegion</linkto>
// </prerequisite>
 
// <synopsis>
// The LCPolygon class is a specialization of class
// <linkto class=LCRegion>LCRegion</linkto>.
// It makes it possible to define a 2-dimensional region by means
// an ordered collection of points with straight lines connecting
// adjacent points. The last point can be equal to the first one.
// If not, an extra point gets added to form the closing line.
// <p>
// The polygon can be as complex as one likes. E.g. it is possible to
// have a rectangle with an inner rectangle to exclude interior points.
// <p>
// The points defining the polygon do not need to coincide with pixel points.
// Points may be outside the lattice meaning that only part of the
// polygon surface is actually used. However, at least some part of the
// polygon surface has to intersect with the lattice.
// <br>A lattice pixel is part of the polygon surface if the center of
// the pixel is on or inside the polygon. Note that 0 is the beginning ond
// 1 is the end of the first pixel. Thus 0.5 is its center.
// </synopsis>
 
// <example>
// <srcblock>
//    // A simple (tilted) square.
//    Vector<Float> x(4), y(4);
//    x(0)=3; y(0)=3;
//    x(1)=6; y(1)=6;
//    x(2)=3; y(2)=9;
//    x(3)=0; y(3)=6;
//    LCPolygon region(x, y, IPosition(2,128,128));
//
//    // A rectangle with an inner region to exclude interior points.
//    // Note that the last point is equal to the first point, thus
//    // the last line is given explicitly.
//    Vector<Float> x(11), y(11);
//    x(0)=3; y(0)=3;
//    x(1)=9; y(1)=3;
//    x(2)=9; y(2)=8;
//    x(3)=3; y(3)=8;
//    x(4)=3; y(4)=3;
//    x(5)=5; y(5)=5;
//    x(6)=8; y(6)=4;
//    x(7)=7; y(7)=7;
//    x(8)=5; y(8)=7;
//    x(9)=5; y(9)=5;
//    x(10)=3; y(10)=3;
//    LCPolygon region(x, y, IPosition(2,128,128));
// </srcblock>
// </example>
 
// # <todo asof="1997/11/11">
// # <li>
// # </todo>
 
class LCPolygon : public LCRegionFixed {
 public:
  LCPolygon();
 
  // Construct from the given x and y values.
  // The latticeShape must define a 2-dimensional lattice.
  // <br>LCPolygon can be used for an N-dimensional lattice by making
  // another lattice representing any 2 axes from the original lattice.
  // <group>
  LCPolygon(const Vector<Float>& x, const Vector<Float>& y, const IPosition& latticeShape);
  LCPolygon(const Vector<Double>& x, const Vector<Double>& y, const IPosition& latticeShape);
  // </group>
 
  // Copy constructor (reference semantics).
  LCPolygon(const LCPolygon& other);
 
  virtual ~LCPolygon();
 
  // Assignment (copy semantics).
  LCPolygon& operator=(const LCPolygon& other);
 
  // Make a copy of the derived object.
  LCRegion* cloneRegion() const override;
 
  // Get the X-values.
  const Vector<Float>& x() const;
 
  // Get the Y-values.
  const Vector<Float>& y() const;
 
  // Get the class name (to store in the record).
  static String className();
 
  // Get the region type.  Returns className()
  String type() const override;
 
  // Convert the (derived) object to a record.
  TableRecord toRecord(const String& tableName) const override;
 
  // Convert correct object from a record.
  static LCPolygon* fromRecord(const TableRecord&, const String& tablename);
 
 protected:
  // Comparison
  Bool equals(const LCRegion& other) const override;
 
  // Construct another LCPolygon (for e.g. another lattice) by moving
  // this one. It recalculates the bounding box.
  // A positive translation value indicates "to right".
  LCRegion* doTranslate(const Vector<Float>& translateVector,
                        const IPosition& newLatticeShape) const override;
 
 private:
  // Make the bounding box.
  void defineBox();
 
  // Define the mask to indicate which elements are inside the polygon.
  void defineMask();
 
  // Fill the mask from the given points.
  void fillMask(Bool* mask, Int nx, Int ny, Int blcx, Int blcy, const Float* ptrX,
                const Float* ptrY, uInt nrline);
 
  // Truncate a start value to a pixel point.
  // A pixel point is taken if near the value, otherwise floor(value+1).
  // The returned value is never < 0.
  Int truncateStart(Float v);
 
  // Truncate an end value to a pixel point.
  // A pixel point is taken if near the value, otherwise floor(value).
  // The returned value is never > maxEnd.
  Int truncateEnd(Float v, Int maxEnd);
 
  // takes into account when one value is zero and the other is absolutely (as
  // opposed to relatively) near zero.
  static Bool _isNear(Float val1, Float val2);
 
  Vector<Float> itsX;
  Vector<Float> itsY;
};
 
inline const Vector<Float>& LCPolygon::x() const { return itsX; }
inline const Vector<Float>& LCPolygon::y() const { return itsY; }
 
}  // namespace casacore
 
#endif