Java example source code file (Ellipse2D.java)

This example Java source code file (Ellipse2D.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

double, ellipse2d, ellipseiterator, float, pathiterator, rectangle2d, rectangularshape, serializable

The Ellipse2D.java Java example source code

/*
 * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.awt.geom;

import java.io.Serializable;

/**
 * The <code>Ellipse2D class describes an ellipse that is defined
 * by a framing rectangle.
 * <p>
 * This class is only the abstract superclass for all objects which
 * store a 2D ellipse.
 * The actual storage representation of the coordinates is left to
 * the subclass.
 *
 * @author      Jim Graham
 * @since 1.2
 */
public abstract class Ellipse2D extends RectangularShape {

    /**
     * The <code>Float class defines an ellipse specified
     * in <code>float precision.
     * @since 1.2
     */
    public static class Float extends Ellipse2D implements Serializable {
        /**
         * The X coordinate of the upper-left corner of the
         * framing rectangle of this {@code Ellipse2D}.
         * @since 1.2
         * @serial
         */
        public float x;

        /**
         * The Y coordinate of the upper-left corner of the
         * framing rectangle of this {@code Ellipse2D}.
         * @since 1.2
         * @serial
         */
        public float y;

        /**
         * The overall width of this <code>Ellipse2D.
         * @since 1.2
         * @serial
         */
        public float width;

        /**
         * The overall height of this <code>Ellipse2D.
         * @since 1.2
         * @serial
         */
        public float height;

        /**
         * Constructs a new <code>Ellipse2D, initialized to
         * location (0, 0) and size (0, 0).
         * @since 1.2
         */
        public Float() {
        }

        /**
         * Constructs and initializes an <code>Ellipse2D from the
         * specified coordinates.
         *
         * @param x the X coordinate of the upper-left corner
         *          of the framing rectangle
         * @param y the Y coordinate of the upper-left corner
         *          of the framing rectangle
         * @param w the width of the framing rectangle
         * @param h the height of the framing rectangle
         * @since 1.2
         */
        public Float(float x, float y, float w, float h) {
            setFrame(x, y, w, h);
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getX() {
            return (double) x;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getY() {
            return (double) y;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getWidth() {
            return (double) width;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getHeight() {
            return (double) height;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public boolean isEmpty() {
            return (width <= 0.0 || height <= 0.0);
        }

        /**
         * Sets the location and size of the framing rectangle of this
         * <code>Shape to the specified rectangular values.
         *
         * @param x the X coordinate of the upper-left corner of the
         *              specified rectangular shape
         * @param y the Y coordinate of the upper-left corner of the
         *              specified rectangular shape
         * @param w the width of the specified rectangular shape
         * @param h the height of the specified rectangular shape
         * @since 1.2
         */
        public void setFrame(float x, float y, float w, float h) {
            this.x = x;
            this.y = y;
            this.width = w;
            this.height = h;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public void setFrame(double x, double y, double w, double h) {
            this.x = (float) x;
            this.y = (float) y;
            this.width = (float) w;
            this.height = (float) h;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public Rectangle2D getBounds2D() {
            return new Rectangle2D.Float(x, y, width, height);
        }

        /*
         * JDK 1.6 serialVersionUID
         */
        private static final long serialVersionUID = -6633761252372475977L;
    }

    /**
     * The <code>Double class defines an ellipse specified
     * in <code>double precision.
     * @since 1.2
     */
    public static class Double extends Ellipse2D implements Serializable {
        /**
         * The X coordinate of the upper-left corner of the
         * framing rectangle of this {@code Ellipse2D}.
         * @since 1.2
         * @serial
         */
        public double x;

        /**
         * The Y coordinate of the upper-left corner of the
         * framing rectangle of this {@code Ellipse2D}.
         * @since 1.2
         * @serial
         */
        public double y;

        /**
         * The overall width of this <code>Ellipse2D.
         * @since 1.2
         * @serial
         */
        public double width;

        /**
         * The overall height of the <code>Ellipse2D.
         * @since 1.2
         * @serial
         */
        public double height;

        /**
         * Constructs a new <code>Ellipse2D, initialized to
         * location (0, 0) and size (0, 0).
         * @since 1.2
         */
        public Double() {
        }

        /**
         * Constructs and initializes an <code>Ellipse2D from the
         * specified coordinates.
         *
         * @param x the X coordinate of the upper-left corner
         *        of the framing rectangle
         * @param y the Y coordinate of the upper-left corner
         *        of the framing rectangle
         * @param w the width of the framing rectangle
         * @param h the height of the framing rectangle
         * @since 1.2
         */
        public Double(double x, double y, double w, double h) {
            setFrame(x, y, w, h);
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getX() {
            return x;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getY() {
            return y;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getWidth() {
            return width;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public double getHeight() {
            return height;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public boolean isEmpty() {
            return (width <= 0.0 || height <= 0.0);
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public void setFrame(double x, double y, double w, double h) {
            this.x = x;
            this.y = y;
            this.width = w;
            this.height = h;
        }

        /**
         * {@inheritDoc}
         * @since 1.2
         */
        public Rectangle2D getBounds2D() {
            return new Rectangle2D.Double(x, y, width, height);
        }

        /*
         * JDK 1.6 serialVersionUID
         */
        private static final long serialVersionUID = 5555464816372320683L;
    }

    /**
     * This is an abstract class that cannot be instantiated directly.
     * Type-specific implementation subclasses are available for
     * instantiation and provide a number of formats for storing
     * the information necessary to satisfy the various accessor
     * methods below.
     *
     * @see java.awt.geom.Ellipse2D.Float
     * @see java.awt.geom.Ellipse2D.Double
     * @since 1.2
     */
    protected Ellipse2D() {
    }

    /**
     * {@inheritDoc}
     * @since 1.2
     */
    public boolean contains(double x, double y) {
        // Normalize the coordinates compared to the ellipse
        // having a center at 0,0 and a radius of 0.5.
        double ellw = getWidth();
        if (ellw <= 0.0) {
            return false;
        }
        double normx = (x - getX()) / ellw - 0.5;
        double ellh = getHeight();
        if (ellh <= 0.0) {
            return false;
        }
        double normy = (y - getY()) / ellh - 0.5;
        return (normx * normx + normy * normy) < 0.25;
    }

    /**
     * {@inheritDoc}
     * @since 1.2
     */
    public boolean intersects(double x, double y, double w, double h) {
        if (w <= 0.0 || h <= 0.0) {
            return false;
        }
        // Normalize the rectangular coordinates compared to the ellipse
        // having a center at 0,0 and a radius of 0.5.
        double ellw = getWidth();
        if (ellw <= 0.0) {
            return false;
        }
        double normx0 = (x - getX()) / ellw - 0.5;
        double normx1 = normx0 + w / ellw;
        double ellh = getHeight();
        if (ellh <= 0.0) {
            return false;
        }
        double normy0 = (y - getY()) / ellh - 0.5;
        double normy1 = normy0 + h / ellh;
        // find nearest x (left edge, right edge, 0.0)
        // find nearest y (top edge, bottom edge, 0.0)
        // if nearest x,y is inside circle of radius 0.5, then intersects
        double nearx, neary;
        if (normx0 > 0.0) {
            // center to left of X extents
            nearx = normx0;
        } else if (normx1 < 0.0) {
            // center to right of X extents
            nearx = normx1;
        } else {
            nearx = 0.0;
        }
        if (normy0 > 0.0) {
            // center above Y extents
            neary = normy0;
        } else if (normy1 < 0.0) {
            // center below Y extents
            neary = normy1;
        } else {
            neary = 0.0;
        }
        return (nearx * nearx + neary * neary) < 0.25;
    }

    /**
     * {@inheritDoc}
     * @since 1.2
     */
    public boolean contains(double x, double y, double w, double h) {
        return (contains(x, y) &&
                contains(x + w, y) &&
                contains(x, y + h) &&
                contains(x + w, y + h));
    }

    /**
     * Returns an iteration object that defines the boundary of this
     * <code>Ellipse2D.
     * The iterator for this class is multi-threaded safe, which means
     * that this <code>Ellipse2D class guarantees that
     * modifications to the geometry of this <code>Ellipse2D
     * object do not affect any iterations of that geometry that
     * are already in process.
     * @param at an optional <code>AffineTransform to be applied to
     * the coordinates as they are returned in the iteration, or
     * <code>null if untransformed coordinates are desired
     * @return    the <code>PathIterator object that returns the
     *          geometry of the outline of this <code>Ellipse2D,
     *          one segment at a time.
     * @since 1.2
     */
    public PathIterator getPathIterator(AffineTransform at) {
        return new EllipseIterator(this, at);
    }

    /**
     * Returns the hashcode for this <code>Ellipse2D.
     * @return the hashcode for this <code>Ellipse2D.
     * @since 1.6
     */
    public int hashCode() {
        long bits = java.lang.Double.doubleToLongBits(getX());
        bits += java.lang.Double.doubleToLongBits(getY()) * 37;
        bits += java.lang.Double.doubleToLongBits(getWidth()) * 43;
        bits += java.lang.Double.doubleToLongBits(getHeight()) * 47;
        return (((int) bits) ^ ((int) (bits >> 32)));
    }

    /**
     * Determines whether or not the specified <code>Object is
     * equal to this <code>Ellipse2D.  The specified
     * <code>Object is equal to this Ellipse2D
     * if it is an instance of <code>Ellipse2D and if its
     * location and size are the same as this <code>Ellipse2D.
     * @param obj  an <code>Object to be compared with this
     *             <code>Ellipse2D.
     * @return  <code>true if obj is an instance
     *          of <code>Ellipse2D and has the same values;
     *          <code>false otherwise.
     * @since 1.6
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj instanceof Ellipse2D) {
            Ellipse2D e2d = (Ellipse2D) obj;
            return ((getX() == e2d.getX()) &&
                    (getY() == e2d.getY()) &&
                    (getWidth() == e2d.getWidth()) &&
                    (getHeight() == e2d.getHeight()));
        }
        return false;
    }
}