1/* 2 * Copyright (c) 1996, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package java.awt; 27 28import java.awt.geom.AffineTransform; 29import java.awt.geom.PathIterator; 30import java.awt.geom.Point2D; 31import java.awt.geom.Rectangle2D; 32 33/** 34 * The {@code Shape} interface provides definitions for objects 35 * that represent some form of geometric shape. The {@code Shape} 36 * is described by a {@link PathIterator} object, which can express the 37 * outline of the {@code Shape} as well as a rule for determining 38 * how the outline divides the 2D plane into interior and exterior 39 * points. Each {@code Shape} object provides callbacks to get the 40 * bounding box of the geometry, determine whether points or 41 * rectangles lie partly or entirely within the interior 42 * of the {@code Shape}, and retrieve a {@code PathIterator} 43 * object that describes the trajectory path of the {@code Shape} 44 * outline. 45 * <p> 46 * <a id="def_insideness"><b>Definition of insideness:</b></a> 47 * A point is considered to lie inside a 48 * {@code Shape} if and only if: 49 * <ul> 50 * <li> it lies completely 51 * inside the {@code Shape} boundary <i>or</i> 52 * <li> 53 * it lies exactly on the {@code Shape} boundary <i>and</i> the 54 * space immediately adjacent to the 55 * point in the increasing {@code X} direction is 56 * entirely inside the boundary <i>or</i> 57 * <li> 58 * it lies exactly on a horizontal boundary segment <b>and</b> the 59 * space immediately adjacent to the point in the 60 * increasing {@code Y} direction is inside the boundary. 61 * </ul> 62 * <p>The {@code contains} and {@code intersects} methods 63 * consider the interior of a {@code Shape} to be the area it 64 * encloses as if it were filled. This means that these methods 65 * consider 66 * unclosed shapes to be implicitly closed for the purpose of 67 * determining if a shape contains or intersects a rectangle or if a 68 * shape contains a point. 69 * 70 * @see java.awt.geom.PathIterator 71 * @see java.awt.geom.AffineTransform 72 * @see java.awt.geom.FlatteningPathIterator 73 * @see java.awt.geom.GeneralPath 74 * 75 * @author Jim Graham 76 * @since 1.2 77 */ 78public interface Shape { 79 /** 80 * Returns an integer {@link Rectangle} that completely encloses the 81 * {@code Shape}. Note that there is no guarantee that the 82 * returned {@code Rectangle} is the smallest bounding box that 83 * encloses the {@code Shape}, only that the {@code Shape} 84 * lies entirely within the indicated {@code Rectangle}. The 85 * returned {@code Rectangle} might also fail to completely 86 * enclose the {@code Shape} if the {@code Shape} overflows 87 * the limited range of the integer data type. The 88 * {@code getBounds2D} method generally returns a 89 * tighter bounding box due to its greater flexibility in 90 * representation. 91 * 92 * <p> 93 * Note that the <a href="{@docRoot}/java/awt/Shape.html#def_insideness"> 94 * definition of insideness</a> can lead to situations where points 95 * on the defining outline of the {@code shape} may not be considered 96 * contained in the returned {@code bounds} object, but only in cases 97 * where those points are also not considered contained in the original 98 * {@code shape}. 99 * </p> 100 * <p> 101 * If a {@code point} is inside the {@code shape} according to the 102 * {@link #contains(double x, double y) contains(point)} method, then 103 * it must be inside the returned {@code Rectangle} bounds object 104 * according to the {@link #contains(double x, double y) contains(point)} 105 * method of the {@code bounds}. Specifically: 106 * </p> 107 * <p> 108 * {@code shape.contains(x,y)} requires {@code bounds.contains(x,y)} 109 * </p> 110 * <p> 111 * If a {@code point} is not inside the {@code shape}, then it might 112 * still be contained in the {@code bounds} object: 113 * </p> 114 * <p> 115 * {@code bounds.contains(x,y)} does not imply {@code shape.contains(x,y)} 116 * </p> 117 * @return an integer {@code Rectangle} that completely encloses 118 * the {@code Shape}. 119 * @see #getBounds2D 120 * @since 1.2 121 */ 122 public Rectangle getBounds(); 123 124 /** 125 * Returns a high precision and more accurate bounding box of 126 * the {@code Shape} than the {@code getBounds} method. 127 * Note that there is no guarantee that the returned 128 * {@link Rectangle2D} is the smallest bounding box that encloses 129 * the {@code Shape}, only that the {@code Shape} lies 130 * entirely within the indicated {@code Rectangle2D}. The 131 * bounding box returned by this method is usually tighter than that 132 * returned by the {@code getBounds} method and never fails due 133 * to overflow problems since the return value can be an instance of 134 * the {@code Rectangle2D} that uses double precision values to 135 * store the dimensions. 136 * 137 * <p> 138 * Note that the <a href="{@docRoot}/java/awt/Shape.html#def_insideness"> 139 * definition of insideness</a> can lead to situations where points 140 * on the defining outline of the {@code shape} may not be considered 141 * contained in the returned {@code bounds} object, but only in cases 142 * where those points are also not considered contained in the original 143 * {@code shape}. 144 * </p> 145 * <p> 146 * If a {@code point} is inside the {@code shape} according to the 147 * {@link #contains(Point2D p) contains(point)} method, then it must 148 * be inside the returned {@code Rectangle2D} bounds object according 149 * to the {@link #contains(Point2D p) contains(point)} method of the 150 * {@code bounds}. Specifically: 151 * </p> 152 * <p> 153 * {@code shape.contains(p)} requires {@code bounds.contains(p)} 154 * </p> 155 * <p> 156 * If a {@code point} is not inside the {@code shape}, then it might 157 * still be contained in the {@code bounds} object: 158 * </p> 159 * <p> 160 * {@code bounds.contains(p)} does not imply {@code shape.contains(p)} 161 * </p> 162 * @return an instance of {@code Rectangle2D} that is a 163 * high-precision bounding box of the {@code Shape}. 164 * @see #getBounds 165 * @since 1.2 166 */ 167 public Rectangle2D getBounds2D(); 168 169 /** 170 * Tests if the specified coordinates are inside the boundary of the 171 * {@code Shape}, as described by the 172 * <a href="{@docRoot}/java/awt/Shape.html#def_insideness"> 173 * definition of insideness</a>. 174 * @param x the specified X coordinate to be tested 175 * @param y the specified Y coordinate to be tested 176 * @return {@code true} if the specified coordinates are inside 177 * the {@code Shape} boundary; {@code false} 178 * otherwise. 179 * @since 1.2 180 */ 181 public boolean contains(double x, double y); 182 183 /** 184 * Tests if a specified {@link Point2D} is inside the boundary 185 * of the {@code Shape}, as described by the 186 * <a href="{@docRoot}/java/awt/Shape.html#def_insideness"> 187 * definition of insideness</a>. 188 * @param p the specified {@code Point2D} to be tested 189 * @return {@code true} if the specified {@code Point2D} is 190 * inside the boundary of the {@code Shape}; 191 * {@code false} otherwise. 192 * @since 1.2 193 */ 194 public boolean contains(Point2D p); 195 196 /** 197 * Tests if the interior of the {@code Shape} intersects the 198 * interior of a specified rectangular area. 199 * The rectangular area is considered to intersect the {@code Shape} 200 * if any point is contained in both the interior of the 201 * {@code Shape} and the specified rectangular area. 202 * <p> 203 * The {@code Shape.intersects()} method allows a {@code Shape} 204 * implementation to conservatively return {@code true} when: 205 * <ul> 206 * <li> 207 * there is a high probability that the rectangular area and the 208 * {@code Shape} intersect, but 209 * <li> 210 * the calculations to accurately determine this intersection 211 * are prohibitively expensive. 212 * </ul> 213 * This means that for some {@code Shapes} this method might 214 * return {@code true} even though the rectangular area does not 215 * intersect the {@code Shape}. 216 * The {@link java.awt.geom.Area Area} class performs 217 * more accurate computations of geometric intersection than most 218 * {@code Shape} objects and therefore can be used if a more precise 219 * answer is required. 220 * 221 * @param x the X coordinate of the upper-left corner 222 * of the specified rectangular area 223 * @param y the Y coordinate of the upper-left corner 224 * of the specified rectangular area 225 * @param w the width of the specified rectangular area 226 * @param h the height of the specified rectangular area 227 * @return {@code true} if the interior of the {@code Shape} and 228 * the interior of the rectangular area intersect, or are 229 * both highly likely to intersect and intersection calculations 230 * would be too expensive to perform; {@code false} otherwise. 231 * @see java.awt.geom.Area 232 * @since 1.2 233 */ 234 public boolean intersects(double x, double y, double w, double h); 235 236 /** 237 * Tests if the interior of the {@code Shape} intersects the 238 * interior of a specified {@code Rectangle2D}. 239 * The {@code Shape.intersects()} method allows a {@code Shape} 240 * implementation to conservatively return {@code true} when: 241 * <ul> 242 * <li> 243 * there is a high probability that the {@code Rectangle2D} and the 244 * {@code Shape} intersect, but 245 * <li> 246 * the calculations to accurately determine this intersection 247 * are prohibitively expensive. 248 * </ul> 249 * This means that for some {@code Shapes} this method might 250 * return {@code true} even though the {@code Rectangle2D} does not 251 * intersect the {@code Shape}. 252 * The {@link java.awt.geom.Area Area} class performs 253 * more accurate computations of geometric intersection than most 254 * {@code Shape} objects and therefore can be used if a more precise 255 * answer is required. 256 * 257 * @param r the specified {@code Rectangle2D} 258 * @return {@code true} if the interior of the {@code Shape} and 259 * the interior of the specified {@code Rectangle2D} 260 * intersect, or are both highly likely to intersect and intersection 261 * calculations would be too expensive to perform; {@code false} 262 * otherwise. 263 * @see #intersects(double, double, double, double) 264 * @since 1.2 265 */ 266 public boolean intersects(Rectangle2D r); 267 268 /** 269 * Tests if the interior of the {@code Shape} entirely contains 270 * the specified rectangular area. All coordinates that lie inside 271 * the rectangular area must lie within the {@code Shape} for the 272 * entire rectangular area to be considered contained within the 273 * {@code Shape}. 274 * <p> 275 * The {@code Shape.contains()} method allows a {@code Shape} 276 * implementation to conservatively return {@code false} when: 277 * <ul> 278 * <li> 279 * the {@code intersect} method returns {@code true} and 280 * <li> 281 * the calculations to determine whether or not the 282 * {@code Shape} entirely contains the rectangular area are 283 * prohibitively expensive. 284 * </ul> 285 * This means that for some {@code Shapes} this method might 286 * return {@code false} even though the {@code Shape} contains 287 * the rectangular area. 288 * The {@link java.awt.geom.Area Area} class performs 289 * more accurate geometric computations than most 290 * {@code Shape} objects and therefore can be used if a more precise 291 * answer is required. 292 * 293 * @param x the X coordinate of the upper-left corner 294 * of the specified rectangular area 295 * @param y the Y coordinate of the upper-left corner 296 * of the specified rectangular area 297 * @param w the width of the specified rectangular area 298 * @param h the height of the specified rectangular area 299 * @return {@code true} if the interior of the {@code Shape} 300 * entirely contains the specified rectangular area; 301 * {@code false} otherwise or, if the {@code Shape} 302 * contains the rectangular area and the 303 * {@code intersects} method returns {@code true} 304 * and the containment calculations would be too expensive to 305 * perform. 306 * @see java.awt.geom.Area 307 * @see #intersects 308 * @since 1.2 309 */ 310 public boolean contains(double x, double y, double w, double h); 311 312 /** 313 * Tests if the interior of the {@code Shape} entirely contains the 314 * specified {@code Rectangle2D}. 315 * The {@code Shape.contains()} method allows a {@code Shape} 316 * implementation to conservatively return {@code false} when: 317 * <ul> 318 * <li> 319 * the {@code intersect} method returns {@code true} and 320 * <li> 321 * the calculations to determine whether or not the 322 * {@code Shape} entirely contains the {@code Rectangle2D} 323 * are prohibitively expensive. 324 * </ul> 325 * This means that for some {@code Shapes} this method might 326 * return {@code false} even though the {@code Shape} contains 327 * the {@code Rectangle2D}. 328 * The {@link java.awt.geom.Area Area} class performs 329 * more accurate geometric computations than most 330 * {@code Shape} objects and therefore can be used if a more precise 331 * answer is required. 332 * 333 * @param r The specified {@code Rectangle2D} 334 * @return {@code true} if the interior of the {@code Shape} 335 * entirely contains the {@code Rectangle2D}; 336 * {@code false} otherwise or, if the {@code Shape} 337 * contains the {@code Rectangle2D} and the 338 * {@code intersects} method returns {@code true} 339 * and the containment calculations would be too expensive to 340 * perform. 341 * @see #contains(double, double, double, double) 342 * @since 1.2 343 */ 344 public boolean contains(Rectangle2D r); 345 346 /** 347 * Returns an iterator object that iterates along the 348 * {@code Shape} boundary and provides access to the geometry of the 349 * {@code Shape} outline. If an optional {@link AffineTransform} 350 * is specified, the coordinates returned in the iteration are 351 * transformed accordingly. 352 * <p> 353 * Each call to this method returns a fresh {@code PathIterator} 354 * object that traverses the geometry of the {@code Shape} object 355 * independently from any other {@code PathIterator} objects in use 356 * at the same time. 357 * <p> 358 * It is recommended, but not guaranteed, that objects 359 * implementing the {@code Shape} interface isolate iterations 360 * that are in process from any changes that might occur to the original 361 * object's geometry during such iterations. 362 * 363 * @param at an optional {@code AffineTransform} to be applied to the 364 * coordinates as they are returned in the iteration, or 365 * {@code null} if untransformed coordinates are desired 366 * @return a new {@code PathIterator} object, which independently 367 * traverses the geometry of the {@code Shape}. 368 * @since 1.2 369 */ 370 public PathIterator getPathIterator(AffineTransform at); 371 372 /** 373 * Returns an iterator object that iterates along the {@code Shape} 374 * boundary and provides access to a flattened view of the 375 * {@code Shape} outline geometry. 376 * <p> 377 * Only SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point types are 378 * returned by the iterator. 379 * <p> 380 * If an optional {@code AffineTransform} is specified, 381 * the coordinates returned in the iteration are transformed 382 * accordingly. 383 * <p> 384 * The amount of subdivision of the curved segments is controlled 385 * by the {@code flatness} parameter, which specifies the 386 * maximum distance that any point on the unflattened transformed 387 * curve can deviate from the returned flattened path segments. 388 * Note that a limit on the accuracy of the flattened path might be 389 * silently imposed, causing very small flattening parameters to be 390 * treated as larger values. This limit, if there is one, is 391 * defined by the particular implementation that is used. 392 * <p> 393 * Each call to this method returns a fresh {@code PathIterator} 394 * object that traverses the {@code Shape} object geometry 395 * independently from any other {@code PathIterator} objects in use at 396 * the same time. 397 * <p> 398 * It is recommended, but not guaranteed, that objects 399 * implementing the {@code Shape} interface isolate iterations 400 * that are in process from any changes that might occur to the original 401 * object's geometry during such iterations. 402 * 403 * @param at an optional {@code AffineTransform} to be applied to the 404 * coordinates as they are returned in the iteration, or 405 * {@code null} if untransformed coordinates are desired 406 * @param flatness the maximum distance that the line segments used to 407 * approximate the curved segments are allowed to deviate 408 * from any point on the original curve 409 * @return a new {@code PathIterator} that independently traverses 410 * a flattened view of the geometry of the {@code Shape}. 411 * @since 1.2 412 */ 413 public PathIterator getPathIterator(AffineTransform at, double flatness); 414} 415