001/* Point.java -- represents a point in 2-D space
002   Copyright (C) 1999, 2002, 2006 Free Software Foundation
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt;
040
041import java.awt.geom.Point2D;
042import 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 */
059public 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