001 /* Point2D.java -- generic point in 2-D space
002 Copyright (C) 1999, 2000, 2002, 2004, 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.geom;
040
041 /**
042 * This class implements a generic point in 2D Cartesian space. The storage
043 * representation is left up to the subclass. Point includes two useful
044 * nested classes, for float and double storage respectively.
045 *
046 * @author Per Bothner (bothner@cygnus.com)
047 * @author Eric Blake (ebb9@email.byu.edu)
048 * @since 1.2
049 * @status updated to 1.4
050 */
051 public abstract class Point2D implements Cloneable
052 {
053 /**
054 * The default constructor.
055 *
056 * @see java.awt.Point
057 * @see Point2D.Float
058 * @see Point2D.Double
059 */
060 protected Point2D()
061 {
062 }
063
064 /**
065 * Get the X coordinate, in double precision.
066 *
067 * @return the x coordinate
068 */
069 public abstract double getX();
070
071 /**
072 * Get the Y coordinate, in double precision.
073 *
074 * @return the y coordinate
075 */
076 public abstract double getY();
077
078 /**
079 * Set the location of this point to the new coordinates. There may be a
080 * loss of precision.
081 *
082 * @param x the new x coordinate
083 * @param y the new y coordinate
084 */
085 public abstract void setLocation(double x, double y);
086
087 /**
088 * Set the location of this point to the new coordinates. There may be a
089 * loss of precision.
090 *
091 * @param p the point to copy
092 * @throws NullPointerException if p is null
093 */
094 public void setLocation(Point2D p)
095 {
096 setLocation(p.getX(), p.getY());
097 }
098
099 /**
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
268 public double getX()
269 {
270 return x;
271 }
272
273 /**
274 * Return the y coordinate.
275 *
276 * @return the y coordinate
277 */
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 */
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 */
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 */
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 */
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 */
346 public double getX()
347 {
348 return x;
349 }
350
351 /**
352 * Return the y coordinate.
353 *
354 * @return the y coordinate
355 */
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 */
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 */
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 */
391 public String toString()
392 {
393 return "Point2D.Float[" + x + ", " + y + ']';
394 }
395 } // class Float
396 } // class Point2D