Java tutorial
/* * 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 {@code 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 {@code 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; } }