1 /* Point2D.java -- generic point in 2-D space
2    Copyright (C) 1999, 2000, 2002, 2004, 2006,  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., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 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.geom;
40 
41 /**
42  * This class implements a generic point in 2D Cartesian space. The storage
43  * representation is left up to the subclass. Point includes two useful
44  * nested classes, for float and double storage respectively.
45  *
46  * @author Per Bothner (bothner@cygnus.com)
47  * @author Eric Blake (ebb9@email.byu.edu)
48  * @since 1.2
49  * @status updated to 1.4
50  */
51 public abstract class Point2D implements Cloneable
52 {
53   /**
54    * The default constructor.
55    *
56    * @see java.awt.Point
57    * @see Point2D.Float
58    * @see Point2D.Double
59    */
Point2D()60   protected Point2D()
61   {
62   }
63 
64   /**
65    * Get the X coordinate, in double precision.
66    *
67    * @return the x coordinate
68    */
getX()69   public abstract double getX();
70 
71   /**
72    * Get the Y coordinate, in double precision.
73    *
74    * @return the y coordinate
75    */
getY()76   public abstract double getY();
77 
78   /**
79    * Set the location of this point to the new coordinates. There may be a
80    * loss of precision.
81    *
82    * @param x the new x coordinate
83    * @param y the new y coordinate
84    */
setLocation(double x, double y)85   public abstract void setLocation(double x, double y);
86 
87   /**
88    * Set the location of this point to the new coordinates. There may be a
89    * loss of precision.
90    *
91    * @param p the point to copy
92    * @throws NullPointerException if p is null
93    */
setLocation(Point2D p)94   public void setLocation(Point2D p)
95   {
96     setLocation(p.getX(), p.getY());
97   }
98 
99   /**
100    * Return the square of the distance between two points.
101    *
102    * @param x1 the x coordinate of point 1
103    * @param y1 the y coordinate of point 1
104    * @param x2 the x coordinate of point 2
105    * @param y2 the y coordinate of point 2
106    * @return (x2 - x1)^2 + (y2 - y1)^2
107    */
distanceSq(double x1, double y1, double x2, double y2)108   public static double distanceSq(double x1, double y1, double x2, double y2)
109   {
110     x2 -= x1;
111     y2 -= y1;
112     return x2 * x2 + y2 * y2;
113   }
114 
115   /**
116    * Return the distance between two points.
117    *
118    * @param x1 the x coordinate of point 1
119    * @param y1 the y coordinate of point 1
120    * @param x2 the x coordinate of point 2
121    * @param y2 the y coordinate of point 2
122    * @return the distance from (x1,y1) to (x2,y2)
123    */
distance(double x1, double y1, double x2, double y2)124   public static double distance(double x1, double y1, double x2, double y2)
125   {
126     return Math.sqrt(distanceSq(x1, y1, x2, y2));
127   }
128 
129   /**
130    * Return the square of the distance from this point to the given one.
131    *
132    * @param x the x coordinate of the other point
133    * @param y the y coordinate of the other point
134    * @return the square of the distance
135    */
distanceSq(double x, double y)136   public double distanceSq(double x, double y)
137   {
138     return distanceSq(getX(), getY(), x, y);
139   }
140 
141   /**
142    * Return the square of the distance from this point to the given one.
143    *
144    * @param p the other point
145    * @return the square of the distance
146    * @throws NullPointerException if p is null
147    */
distanceSq(Point2D p)148   public double distanceSq(Point2D p)
149   {
150     return distanceSq(getX(), getY(), p.getX(), p.getY());
151   }
152 
153   /**
154    * Return the distance from this point to the given one.
155    *
156    * @param x the x coordinate of the other point
157    * @param y the y coordinate of the other point
158    * @return the distance
159    */
distance(double x, double y)160   public double distance(double x, double y)
161   {
162     return distance(getX(), getY(), x, y);
163   }
164 
165   /**
166    * Return the distance from this point to the given one.
167    *
168    * @param p the other point
169    * @return the distance
170    * @throws NullPointerException if p is null
171    */
distance(Point2D p)172   public double distance(Point2D p)
173   {
174     return distance(getX(), getY(), p.getX(), p.getY());
175   }
176 
177   /**
178    * Create a new point of the same run-time type with the same contents as
179    * this one.
180    *
181    * @return the clone
182    */
clone()183   public Object clone()
184   {
185     try
186       {
187         return super.clone();
188       }
189     catch (CloneNotSupportedException e)
190       {
191         throw (Error) new InternalError().initCause(e); // Impossible
192       }
193   }
194 
195   /**
196    * Return the hashcode for this point. The formula is not documented, but
197    * appears to be the same as:
198    * <pre>
199    * long l = Double.doubleToLongBits(getY());
200    * l = l * 31 ^ Double.doubleToLongBits(getX());
201    * return (int) ((l >> 32) ^ l);
202    * </pre>
203    *
204    * @return the hashcode
205    */
hashCode()206   public int hashCode()
207   {
208     // Talk about a fun time reverse engineering this one!
209     long l = java.lang.Double.doubleToLongBits(getY());
210     l = l * 31 ^ java.lang.Double.doubleToLongBits(getX());
211     return (int) ((l >> 32) ^ l);
212   }
213 
214   /**
215    * Compares two points for equality. This returns true if they have the
216    * same coordinates.
217    *
218    * @param o the point to compare
219    * @return true if it is equal
220    */
equals(Object o)221   public boolean equals(Object o)
222   {
223     if (! (o instanceof Point2D))
224       return false;
225     Point2D p = (Point2D) o;
226     return getX() == p.getX() && getY() == p.getY();
227   }
228 
229   /**
230    * This class defines a point in <code>double</code> precision.
231    *
232    * @author Eric Blake (ebb9@email.byu.edu)
233    * @since 1.2
234    * @status updated to 1.4
235    */
236   public static class Double extends Point2D
237   {
238     /** The X coordinate. */
239     public double x;
240 
241     /** The Y coordinate. */
242     public double y;
243 
244     /**
245      * Create a new point at (0,0).
246      */
Double()247     public Double()
248     {
249     }
250 
251     /**
252      * Create a new point at (x,y).
253      *
254      * @param x the x coordinate
255      * @param y the y coordinate
256      */
Double(double x, double y)257     public Double(double x, double y)
258     {
259       this.x = x;
260       this.y = y;
261     }
262 
263     /**
264      * Return the x coordinate.
265      *
266      * @return the x coordinate
267      */
getX()268     public double getX()
269     {
270       return x;
271     }
272 
273     /**
274      * Return the y coordinate.
275      *
276      * @return the y coordinate
277      */
getY()278     public double getY()
279     {
280       return y;
281     }
282 
283     /**
284      * Sets the location of this point.
285      *
286      * @param x the new x coordinate
287      * @param y the new y coordinate
288      */
setLocation(double x, double y)289     public void setLocation(double x, double y)
290     {
291       this.x = x;
292       this.y = y;
293     }
294 
295     /**
296      * Returns a string representation of this object. The format is:
297      * <code>"Point2D.Double[" + x + ", " + y + ']'</code>.
298      *
299      * @return a string representation of this object
300      */
toString()301     public String toString()
302     {
303       return "Point2D.Double[" + x + ", " + y + ']';
304     }
305   } // class Double
306 
307   /**
308    * This class defines a point in <code>float</code> precision.
309    *
310    * @author Eric Blake (ebb9@email.byu.edu)
311    * @since 1.2
312    * @status updated to 1.4
313    */
314   public static class Float extends Point2D
315   {
316     /** The X coordinate. */
317     public float x;
318 
319     /** The Y coordinate. */
320     public float y;
321 
322     /**
323      * Create a new point at (0,0).
324      */
Float()325     public Float()
326     {
327     }
328 
329     /**
330      * Create a new point at (x,y).
331      *
332      * @param x the x coordinate
333      * @param y the y coordinate
334      */
Float(float x, float y)335     public Float(float x, float y)
336     {
337       this.x = x;
338       this.y = y;
339     }
340 
341     /**
342      * Return the x coordinate.
343      *
344      * @return the x coordinate
345      */
getX()346     public double getX()
347     {
348       return x;
349     }
350 
351     /**
352      * Return the y coordinate.
353      *
354      * @return the y coordinate
355      */
getY()356     public double getY()
357     {
358       return y;
359     }
360 
361     /**
362      * Sets the location of this point.
363      *
364      * @param x the new x coordinate
365      * @param y the new y coordinate
366      */
setLocation(double x, double y)367     public void setLocation(double x, double y)
368     {
369       this.x = (float) x;
370       this.y = (float) y;
371     }
372 
373     /**
374      * Sets the location of this point.
375      *
376      * @param x the new x coordinate
377      * @param y the new y coordinate
378      */
setLocation(float x, float y)379     public void setLocation(float x, float y)
380     {
381       this.x = x;
382       this.y = y;
383     }
384 
385     /**
386      * Returns a string representation of this object. The format is:
387      * <code>"Point2D.Float[" + x + ", " + y + ']'</code>.
388      *
389      * @return a string representation of this object
390      */
toString()391     public String toString()
392     {
393       return "Point2D.Float[" + x + ", " + y + ']';
394     }
395   } // class Float
396 } // class Point2D
397