001/* Point2D.java -- generic point in 2-D space 002 Copyright (C) 1999, 2000, 2002, 2004, 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.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 */ 051public 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