Class Ellipse

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public class Ellipse
extends Region

Java interface to the AST Ellipse class - an elliptical region within a 2-dimensional Frame. The Ellipse class implements a Region which represents a ellipse within a 2-dimensional Frame.


This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public Licence as published by the Free Software Foundation; either version 2 of the Licence, or (at your option) any later version.

This program 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 General Public Licence for more details.

You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA

See Also:
AST Ellipse

Nested Class Summary
Nested classes/interfaces inherited from class
Mapping.Interpolator, Mapping.Spreader
Field Summary
Fields inherited from class
Fields inherited from class
Fields inherited from class
AST__BAD, AST__TUNULL, pointer
Constructor Summary
Ellipse(Frame frame, int form, double[] centre, double[] point1, double[] point2, Region unc)
          Create a Ellipse.
Method Summary
Methods inherited from class
getAdaptive, getBounded, getClosed, getFillFactor, getMeshSize, getNegated, getRegionBounds, getRegionFrame, getRegionPoints, getUnc, mapRegion, mask, maskB, maskD, maskF, maskI, maskL, maskS, negate, overlap, setAdaptive, setClosed, setFillFactor, setMeshSize, setNegated, setUnc, showMesh
Methods inherited from class
angle, axAngle, axDistance, axOffset, convert, distance, findFrame, format, getActiveUnit, getAlignSystem, getBottom, getDigits, getDigits, getDirection, getDomain, getDut1, getEpoch, getFormat, getLabel, getMatchEnd, getMaxAxes, getMinAxes, getNaxes, getNormUnit, getObsLat, getObsLon, getPermute, getPreserveAxes, getSymbol, getSystem, getTitle, getTop, getUnit, intersect, norm, offset, offset2, permAxes, pickAxes, resolve, setActiveUnit, setAlignSystem, setBottom, setDigits, setDigits, setDirection, setDomain, setDut1, setEpoch, setEpoch, setFormat, setLabel, setMatchEnd, setMaxAxes, setMinAxes, setObsLat, setObsLon, setPermute, setPreserveAxes, setSymbol, setSystem, setTitle, setTop, setUnit, unformat
Methods inherited from class
decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP
Methods inherited from class
annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune
Methods inherited from class java.lang.Object
clone, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public Ellipse(Frame frame,
               int form,
               double[] centre,
               double[] point1,
               double[] point2,
               Region unc)
Create a Ellipse. This function creates a new Ellipse and optionally initialises its attributes.

A Ellipse is a Region which represents a elliptical area within the supplied 2-dimensional Frame.


- A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

frame - A pointer to the Frame in which the region is defined. It must have exactly 2 axes. A deep copy is taken of the supplied Frame. This means that any subsequent changes made to the Frame using the supplied pointer will have no effect the Region.
form - Indicates how the ellipse is described by the remaining parameters. A value of zero indicates that the ellipse is specified by a centre position and two positions on the circumference. A value of one indicates that the ellipse is specified by its centre position, the half-lengths of its two axes, and the orientation of its first axis.
centre - An array of 2 doubles, containing the coordinates at the centre of the ellipse.
point1 - An array of 2 doubles. If "form" is zero, this array should contain the coordinates of one of the four points where an axis of the ellipse crosses the circumference of the ellipse. If "form" is one, it should contain the lengths of semi-major and semi-minor axes of the ellipse, given as geodesic distances within the Frame.
point2 - An array of 2 doubles. If "form" is zero, this array should containing the coordinates at some other point on the circumference of the ellipse, distinct from "point1". If "form" is one, the first element of this array should hold the angle between the second axis of the Frame and the first ellipse axis (i.e. the ellipse axis which is specified first in the "point1" array), and the second element will be ignored. The angle should be given in radians, measured positive in the same sense as rotation from the positive direction of the second Frame axis to the positive direction of the first Frame axis.
unc - An optional pointer to an existing Region which specifies the uncertainties associated with the boundary of the Box being created. The uncertainty in any point on the boundary of the Box is found by shifting the supplied "uncertainty" Region so that it is centred at the boundary point being considered. The area covered by the shifted uncertainty Region then represents the uncertainty in the boundary position. The uncertainty is assumed to be the same for all points.

If supplied, the uncertainty Region must be of a class for which all instances are centro-symetric (e.g. Box, Circle, Ellipse, etc.) or be a Prism containing centro-symetric component Regions. A deep copy of the supplied Region will be taken, so subsequent changes to the uncertainty Region using the supplied pointer will have no effect on the created Box. Alternatively, a NULL Object pointer may be supplied, in which case a default uncertainty is used equivalent to a box 1.0E-6 of the size of the Box being created.

The uncertainty Region has two uses: 1) when the astOverlap function compares two Regions for equality the uncertainty Region is used to determine the tolerance on the comparison, and 2) when a Region is mapped into a different coordinate system and subsequently simplified (using astSimplify), the uncertainties are used to determine if the transformed boundary can be accurately represented by a specific shape of Region.

AstException - if an error occurred in the AST library

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