414 lines
11 KiB
Java
414 lines
11 KiB
Java
/* Ellipse2D.java -- represents an ellipse in 2-D space
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Copyright (C) 2000, 2002, 2004 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt.geom;
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/**
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* Ellipse2D is the shape of an ellipse.
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* <BR>
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* <img src="doc-files/Ellipse-1.png" width="347" height="221"
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* alt="A drawing of an ellipse" /><BR>
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* The ellipse is defined by it's bounding box (shown in red),
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* and is defined by the implicit curve:<BR>
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* <blockquote>(<i>x</i>/<i>a</i>)<sup>2</sup> +
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* (<i>y</i>/<i>b</i>)<sup>2</sup> = 1<BR><BR></blockquote>
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*
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* @author Tom Tromey (tromey@cygnus.com)
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* @author Eric Blake (ebb9@email.byu.edu)
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*
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* @since 1.2
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*/
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public abstract class Ellipse2D extends RectangularShape
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{
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/**
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* Ellipse2D is defined as abstract.
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* Implementing classes are Ellipse2D.Float and Ellipse2D.Double.
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*/
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protected Ellipse2D()
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{
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}
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/**
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* Determines if a point is contained within the ellipse. <P>
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* @param x - x coordinate of the point.
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* @param y - y coordinate of the point.
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* @return true if the point is within the ellipse, false otherwise.
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*/
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public boolean contains(double x, double y)
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{
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double rx = getWidth() / 2;
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double ry = getHeight() / 2;
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double tx = (x - (getX() + rx)) / rx;
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double ty = (y - (getY() + ry)) / ry;
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return tx * tx + ty * ty < 1.0;
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}
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/**
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* Determines if a rectangle is completely contained within the
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* ellipse. <P>
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* @param x - x coordinate of the upper-left corner of the rectangle
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* @param y - y coordinate of the upper-left corner of the rectangle
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* @param w - width of the rectangle
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* @param h - height of the rectangle
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* @return true if the rectangle is completely contained, false otherwise.
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*/
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public boolean contains(double x, double y, double w, double h)
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{
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double x2 = x + w;
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double y2 = y + h;
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return (contains(x, y) && contains(x, y2) && contains(x2, y)
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&& contains(x2, y2));
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}
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/**
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* Returns a PathIterator object corresponding to the ellipse.<P>
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*
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* Note: An ellipse cannot be represented exactly in PathIterator
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* segments, the outline is thefore approximated with cubic
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* Bezier segments.
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*
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* @param at an optional transform.
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* @return A path iterator.
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*/
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public PathIterator getPathIterator(AffineTransform at)
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{
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// An ellipse is just a complete arc.
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return new Arc2D.ArcIterator(this, at);
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}
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/**
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* Determines if a rectangle intersects any part of the ellipse.<P>
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* @param x - x coordinate of the upper-left corner of the rectangle
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* @param y - y coordinate of the upper-left corner of the rectangle
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* @param w - width of the rectangle
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* @param h - height of the rectangle
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* @return true if the rectangle intersects the ellipse, false otherwise.
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*/
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public boolean intersects(double x, double y, double w, double h)
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{
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Rectangle2D r = new Rectangle2D.Double(x, y, w, h);
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if (! r.intersects(getX(), getY(), getWidth(), getHeight()))
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return false;
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if (contains(x, y) || contains(x, y + h) || contains(x + w, y)
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|| contains(x + w, y + h))
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return true;
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Line2D l1 = new Line2D.Double(getX(), getY() + (getHeight() / 2),
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getX() + getWidth(),
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getY() + (getHeight() / 2));
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Line2D l2 = new Line2D.Double(getX() + (getWidth() / 2), getY(),
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getX() + (getWidth() / 2),
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getY() + getHeight());
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if (l1.intersects(r) || l2.intersects(r))
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return true;
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return false;
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}
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/**
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* An {@link Ellipse2D} that stores its coordinates using <code>double</code>
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* primitives.
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*/
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public static class Double extends Ellipse2D
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{
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/**
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* The height of the ellipse.
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*/
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public double height;
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/**
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* The width of the ellipse.
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*/
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public double width;
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/**
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* The upper-left x coordinate of the bounding-box
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*/
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public double x;
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/**
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* The upper-left y coordinate of the bounding-box
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*/
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public double y;
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/**
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* Creates a new Ellipse2D with an upper-left coordinate of (0,0)
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* and a zero size.
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*/
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public Double()
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{
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}
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/**
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* Creates a new Ellipse2D within a given rectangle
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* using double-precision coordinates.<P>
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* @param x - x coordinate of the upper-left of the bounding rectangle
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* @param y - y coordinate of the upper-left of the bounding rectangle
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* @param w - width of the ellipse
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* @param h - height of the ellipse
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*/
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public Double(double x, double y, double w, double h)
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{
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this.x = x;
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this.y = y;
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height = h;
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width = w;
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}
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/**
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* Returns the bounding-box of the ellipse.
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* @return The bounding box.
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*/
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public Rectangle2D getBounds2D()
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{
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return new Rectangle2D.Double(x, y, width, height);
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}
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/**
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* Returns the height of the ellipse.
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* @return The height of the ellipse.
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*/
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public double getHeight()
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{
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return height;
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}
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/**
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* Returns the width of the ellipse.
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* @return The width of the ellipse.
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*/
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public double getWidth()
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{
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return width;
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}
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/**
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* Returns x coordinate of the upper-left corner of
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* the ellipse's bounding-box.
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* @return The x coordinate.
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*/
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public double getX()
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{
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return x;
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}
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/**
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* Returns y coordinate of the upper-left corner of
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* the ellipse's bounding-box.
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* @return The y coordinate.
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*/
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public double getY()
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{
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return y;
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}
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/**
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* Returns <code>true</code> if the ellipse encloses no area, and
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* <code>false</code> otherwise.
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*
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* @return A boolean.
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*/
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public boolean isEmpty()
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{
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return height <= 0 || width <= 0;
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}
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/**
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* Sets the geometry of the ellipse's bounding box.<P>
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*
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* @param x - x coordinate of the upper-left of the bounding rectangle
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* @param y - y coordinate of the upper-left of the bounding rectangle
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* @param w - width of the ellipse
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* @param h - height of the ellipse
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*/
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public void setFrame(double x, double y, double w, double h)
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{
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this.x = x;
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this.y = y;
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height = h;
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width = w;
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}
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} // class Double
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/**
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* An {@link Ellipse2D} that stores its coordinates using <code>float</code>
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* primitives.
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*/
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public static class Float extends Ellipse2D
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{
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/**
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* The height of the ellipse.
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*/
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public float height;
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/**
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* The width of the ellipse.
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*/
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public float width;
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/**
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* The upper-left x coordinate of the bounding-box
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*/
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public float x;
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/**
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* The upper-left y coordinate of the bounding-box
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*/
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public float y;
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/**
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* Creates a new Ellipse2D with an upper-left coordinate of (0,0)
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* and a zero size.
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*/
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public Float()
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{
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}
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/**
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* Creates a new Ellipse2D within a given rectangle
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* using floating-point precision.<P>
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* @param x - x coordinate of the upper-left of the bounding rectangle
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* @param y - y coordinate of the upper-left of the bounding rectangle
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* @param w - width of the ellipse
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* @param h - height of the ellipse
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*
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*/
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public Float(float x, float y, float w, float h)
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{
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this.x = x;
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this.y = y;
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this.height = h;
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this.width = w;
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}
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/**
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* Returns the bounding-box of the ellipse.
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* @return The bounding box.
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*/
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public Rectangle2D getBounds2D()
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{
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return new Rectangle2D.Float(x, y, width, height);
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}
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/**
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* Returns the height of the ellipse.
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* @return The height of the ellipse.
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*/
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public double getHeight()
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{
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return height;
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}
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/**
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* Returns the width of the ellipse.
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* @return The width of the ellipse.
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*/
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public double getWidth()
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{
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return width;
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}
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/**
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* Returns x coordinate of the upper-left corner of
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* the ellipse's bounding-box.
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* @return The x coordinate.
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*/
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public double getX()
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{
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return x;
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}
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/**
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* Returns y coordinate of the upper-left corner of
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* the ellipse's bounding-box.
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* @return The y coordinate.
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*/
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public double getY()
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{
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return y;
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}
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/**
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* Returns <code>true</code> if the ellipse encloses no area, and
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* <code>false</code> otherwise.
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*
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* @return A boolean.
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*/
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public boolean isEmpty()
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{
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return height <= 0 || width <= 0;
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}
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/**
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* Sets the geometry of the ellipse's bounding box.<P>
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*
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* @param x - x coordinate of the upper-left of the bounding rectangle
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* @param y - y coordinate of the upper-left of the bounding rectangle
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* @param w - width of the ellipse
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* @param h - height of the ellipse
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*/
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public void setFrame(float x, float y, float w, float h)
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{
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this.x = x;
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this.y = y;
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height = h;
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width = w;
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}
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/**
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* Sets the geometry of the ellipse's bounding box.
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*
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* Note: This leads to a loss of precision.<P>
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*
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* @param x - x coordinate of the upper-left of the bounding rectangle
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* @param y - y coordinate of the upper-left of the bounding rectangle
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* @param w - width of the ellipse
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* @param h - height of the ellipse
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*/
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public void setFrame(double x, double y, double w, double h)
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{
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this.x = (float) x;
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this.y = (float) y;
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height = (float) h;
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width = (float) w;
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}
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} // class Float
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} // class Ellipse2D
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