casacore::LCPolygon Class Reference

Define a 2-dimensional region by a polygon. More...

#include <LCPolygon.h>

Inheritance diagram for casacore::LCPolygon:

Public Member Functions
	LCPolygon ()
	LCPolygon (const Vector< Float > &x, const Vector< Float > &y, const IPosition &latticeShape)
	Construct from the given x and y values.
	LCPolygon (const Vector< Double > &x, const Vector< Double > &y, const IPosition &latticeShape)
	LCPolygon (const LCPolygon &other)
	Copy constructor (reference semantics).
virtual	~LCPolygon ()
LCPolygon &	operator= (const LCPolygon &other)
	Assignment (copy semantics).
virtual Bool	operator== (const LCRegion &other) const
	Comparison.
virtual LCRegion *	cloneRegion () const
	Make a copy of the derived object.
const Vector< Float > &	x () const
	Get the X-values.
const Vector< Float > &	y () const
	Get the Y-values.
virtual String	type () const
	Get the region type.
virtual TableRecord	toRecord (const String &tableName) const
	Convert the (derived) object to a record.
Static Public Member Functions
static String	className ()
	Get the class name (to store in the record).
static LCPolygon *	fromRecord (const TableRecord &, const String &tablename)
	Convert correct object from a record.
Protected Member Functions
virtual LCRegion *	doTranslate (const Vector< Float > &translateVector, const IPosition &newLatticeShape) const
	Construct another LCPolygon (for e.g.
Private Member Functions
void	defineBox ()
	Make the bounding box.
void	defineMask ()
	Define the mask to indicate which elements are inside the polygon.
void	fillMask (Bool mask, Int nx, Int ny, Int blcx, Int blcy, const Float ptrX, const Float *ptrY, uInt nrline)
	Fill the mask from the given points.
Int	truncateStart (Float v)
	Truncate a start value to a pixel point.
Int	truncateEnd (Float v, Int maxEnd)
	Truncate an end value to a pixel point.
Private Attributes
Vector< Float >	itsX
Vector< Float >	itsY

Detailed Description

Define a 2-dimensional region by a polygon.

Intended use:

Public interface

Prerequisite

LCRegion

Synopsis

The LCPolygon class is a specialization of class LCRegion . 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.

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.

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.
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.

Example

 // 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));

Definition at line 109 of file LCPolygon.h.

Constructor & Destructor Documentation

casacore::LCPolygon::LCPolygon ( )

casacore::LCPolygon::LCPolygon	(	const Vector< Float > &	x,
		const Vector< Float > &	y,
		const IPosition &	latticeShape
	)

Construct from the given x and y values.

The latticeShape must define a 2-dimensional lattice.
LCPolygon can be used for an N-dimensional lattice by making another lattice representing any 2 axes from the original lattice.

casacore::LCPolygon::LCPolygon	(	const Vector< Double > &	x,
		const Vector< Double > &	y,
		const IPosition &	latticeShape
	)

casacore::LCPolygon::LCPolygon ( const LCPolygon & other )

Copy constructor (reference semantics).

virtual casacore::LCPolygon::~LCPolygon ( ) [virtual]

Member Function Documentation

static String casacore::LCPolygon::className ( ) [static]

Get the class name (to store in the record).

virtual LCRegion* casacore::LCPolygon::cloneRegion ( ) const [virtual]

Make a copy of the derived object.

Implements casacore::LCRegion.

void casacore::LCPolygon::defineBox ( ) [private]

Make the bounding box.

void casacore::LCPolygon::defineMask ( ) [private]

Define the mask to indicate which elements are inside the polygon.

virtual LCRegion* casacore::LCPolygon::doTranslate	(	const Vector< Float > &	translateVector,
		const IPosition &	newLatticeShape
	)			const `[protected, virtual]`