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