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: */ 60: protected Point2D() 61: { 62: } 63: 64: /** 65: * Get the X coordinate, in double precision. 66: * 67: * @return the x coordinate 68: */ 69: public abstract double getX(); 70: 71: /** 72: * Get the Y coordinate, in double precision. 73: * 74: * @return the y coordinate 75: */ 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: */ 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: */ 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: */ 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