libjava/java/awt/Point.java

   1 /* Point.java -- represents a point in 2-D space
   2    Copyright (C) 1999, 2002 Free Software Foundation
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.awt;
  40
  41 import java.awt.geom.Point2D;
  42 import java.io.Serializable;
  43
  44 /**
  45  * This class represents a point on the screen using cartesian coordinates.
  46  * Remember that in screen coordinates, increasing x values go from left to
  47  * right, and increasing y values go from top to bottom.
  48  *
  49  * <p>There are some public fields; if you mess with them in an inconsistent
  50  * manner, it is your own fault when you get invalid results. Also, this
  51  * class is not threadsafe.
  52  *
  53  * @author Per Bothner <bothner@cygnus.com>
  54  * @author Aaron M. Renn <arenn@urbanophile.com>
  55  * @author Eric Blake <ebb9@email.byu.edu>
  56  * @since 1.0
  57  * @status updated to 1.4
  58  */
  59 public class Point extends Point2D implements Serializable
  60 {
  61   /**
  62    * Compatible with JDK 1.0+.
  63    */
  64   private static final long serialVersionUID = -5276940640259749850L;
  65
  66   /**
  67    * The x coordinate.
  68    *
  69    * @see #getLocation()
  70    * @see #move(int, int)
  71    * @serial the X coordinate of the point
  72    */
  73   public int x;
  74
  75   /**
  76    * The y coordinate.
  77    *
  78    * @see #getLocation()
  79    * @see #move(int, int)
  80    * @serial The Y coordinate of the point
  81    */
  82   public int y;
  83
  84   /**
  85    * Initializes a new instance of <code>Point</code> representing the
  86    * coordiates (0,0).
  87    *
  88    * @since 1.1
  89    */
  90   public Point()
  91   {
  92   }
  93
  94   /**
  95    * Initializes a new instance of <code>Point</code> with coordinates
  96    * identical to the coordinates of the specified points.
  97    *
  98    * @param point the point to copy the coordinates from
  99    * @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    * performs normal casting from double to int, so you may lose precision.
 182    *
 183    * @param x the new X coordinate
 184    * @param y the new Y coordinate
 185    */
 186   public void setLocation(double x, double y)
 187   {
 188     this.x = (int) x;
 189     this.y = (int) y;
 190   }
 191
 192   /**
 193    * Sets this object's coordinates to the specified values.  This method
 194    * is identical to the <code>setLocation(int, int)</code> method.
 195    *
 196    * @param x the new X coordinate
 197    * @param y the new Y coordinate
 198    */
 199   public void move(int x, int y)
 200   {
 201     this.x = x;
 202     this.y = y;
 203   }
 204
 205   /**
 206    * Changes the coordinates of this point such that the specified
 207    * <code>dx</code> parameter is added to the existing X coordinate and
 208    * <code>dy</code> is added to the existing Y coordinate.
 209    *
 210    * @param dx the amount to add to the X coordinate
 211    * @param dy the amount to add to the Y coordinate
 212    */
 213   public void translate(int dx, int dy)
 214   {
 215     x += dx;
 216     y += dy;
 217   }
 218
 219   /**
 220    * Tests whether or not this object is equal to the specified object.
 221    * This will be true if and only if the specified object is an instance
 222    * of Point2D and has the same X and Y coordinates.
 223    *
 224    * @param obj the object to test against for equality
 225    * @return true if the specified object is equal
 226   */
 227   public boolean equals(Object obj)
 228   {
 229     if (! (obj instanceof Point2D))
 230       return false;
 231     Point2D p = (Point2D) obj;
 232     return x == p.getX() && y == p.getY();
 233   }
 234
 235   /**
 236    * Returns a string representation of this object. The format is:
 237    * <code>getClass().getName() + "[x=" + x + ",y=" + y + ']'</code>.
 238    *
 239    * @return a string representation of this object
 240    */
 241   public String toString()
 242   {
 243     return getClass().getName() + "[x=" + x + ",y=" + y + ']';
 244   }
 245 } // class Point