001 /* Point.java -- represents a point in 2-D space
002 Copyright (C) 1999, 2002, 2006 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import java.awt.geom.Point2D;
042 import java.io.Serializable;
043
044 /**
045 * This class represents a point on the screen using cartesian coordinates.
046 * Remember that in screen coordinates, increasing x values go from left to
047 * right, and increasing y values go from top to bottom.
048 *
049 * <p>There are some public fields; if you mess with them in an inconsistent
050 * manner, it is your own fault when you get invalid results. Also, this
051 * class is not threadsafe.
052 *
053 * @author Per Bothner (bothner@cygnus.com)
054 * @author Aaron M. Renn (arenn@urbanophile.com)
055 * @author Eric Blake (ebb9@email.byu.edu)
056 * @since 1.0
057 * @status updated to 1.4
058 */
059 public class Point extends Point2D implements Serializable
060 {
061 /**
062 * Compatible with JDK 1.0+.
063 */
064 private static final long serialVersionUID = -5276940640259749850L;
065
066 /**
067 * The x coordinate.
068 *
069 * @see #getLocation()
070 * @see #move(int, int)
071 * @serial the X coordinate of the point
072 */
073 public int x;
074
075 /**
076 * The y coordinate.
077 *
078 * @see #getLocation()
079 * @see #move(int, int)
080 * @serial The Y coordinate of the point
081 */
082 public int y;
083
084 /**
085 * Initializes a new instance of <code>Point</code> representing the
086 * coordinates (0, 0).
087 *
088 * @since 1.1
089 */
090 public Point()
091 {
092 }
093
094 /**
095 * Initializes a new instance of <code>Point</code> with coordinates
096 * identical to the coordinates of the specified point.
097 *
098 * @param p the point to copy the coordinates from
099 * @throws NullPointerException if p is null
100 */
101 public Point(Point p)
102 {
103 x = p.x;
104 y = p.y;
105 }
106
107 /**
108 * Initializes a new instance of <code>Point</code> with the specified
109 * coordinates.
110 *
111 * @param x the X coordinate
112 * @param y the Y coordinate
113 */
114 public Point(int x, int y)
115 {
116 this.x = x;
117 this.y = y;
118 }
119
120 /**
121 * Get the x coordinate.
122 *
123 * @return the value of x, as a double
124 */
125 public double getX()
126 {
127 return x;
128 }
129
130 /**
131 * Get the y coordinate.
132 *
133 * @return the value of y, as a double
134 */
135 public double getY()
136 {
137 return y;
138 }
139
140 /**
141 * Returns the location of this point. A pretty useless method, as this
142 * is already a point.
143 *
144 * @return a copy of this point
145 * @see #setLocation(Point)
146 * @since 1.1
147 */
148 public Point getLocation()
149 {
150 return new Point(x, y);
151 }
152
153 /**
154 * Sets this object's coordinates to match those of the specified point.
155 *
156 * @param p the point to copy the coordinates from
157 * @throws NullPointerException if p is null
158 * @since 1.1
159 */
160 public void setLocation(Point p)
161 {
162 x = p.x;
163 y = p.y;
164 }
165
166 /**
167 * Sets this object's coordinates to the specified values. This method
168 * is identical to the <code>move()</code> method.
169 *
170 * @param x the new X coordinate
171 * @param y the new Y coordinate
172 */
173 public void setLocation(int x, int y)
174 {
175 this.x = x;
176 this.y = y;
177 }
178
179 /**
180 * Sets this object's coordinates to the specified values. This method
181 * rounds to the nearest integer coordinates by adding 0.5 and calling
182 * {@link Math#floor(double)}.
183 *
184 * @param x the new X coordinate
185 * @param y the new Y coordinate
186 */
187 public void setLocation(double x, double y)
188 {
189 this.x = (int) Math.floor(x + 0.5);
190 this.y = (int) Math.floor(y + 0.5);
191 }
192
193 /**
194 * Sets this object's coordinates to the specified values. This method
195 * is identical to the <code>setLocation(int, int)</code> method.
196 *
197 * @param x the new X coordinate
198 * @param y the new Y coordinate
199 */
200 public void move(int x, int y)
201 {
202 this.x = x;
203 this.y = y;
204 }
205
206 /**
207 * Changes the coordinates of this point such that the specified
208 * <code>dx</code> parameter is added to the existing X coordinate and
209 * <code>dy</code> is added to the existing Y coordinate.
210 *
211 * @param dx the amount to add to the X coordinate
212 * @param dy the amount to add to the Y coordinate
213 */
214 public void translate(int dx, int dy)
215 {
216 x += dx;
217 y += dy;
218 }
219
220 /**
221 * Tests whether or not this object is equal to the specified object.
222 * This will be true if and only if the specified object is an instance
223 * of Point2D and has the same X and Y coordinates.
224 *
225 * @param obj the object to test against for equality
226 * @return true if the specified object is equal
227 */
228 public boolean equals(Object obj)
229 {
230 // NOTE: No special hashCode() method is required for this class,
231 // as this equals() implementation is functionally equivalent to
232 // super.equals(), which does define a proper hashCode().
233
234 if (! (obj instanceof Point2D))
235 return false;
236 Point2D p = (Point2D) obj;
237 return x == p.getX() && y == p.getY();
238 }
239
240 /**
241 * Returns a string representation of this object. The format is:
242 * <code>getClass().getName() + "[x=" + x + ",y=" + y + ']'</code>.
243 *
244 * @return a string representation of this object
245 */
246 public String toString()
247 {
248 return getClass().getName() + "[x=" + x + ",y=" + y + ']';
249 }
250 } // class Point