J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-1998 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.awt.geom; |
| 27 | |
| 28 | import java.util.*; |
| 29 | |
| 30 | /** |
| 31 | * The <code>FlatteningPathIterator</code> class returns a flattened view of |
| 32 | * another {@link PathIterator} object. Other {@link java.awt.Shape Shape} |
| 33 | * classes can use this class to provide flattening behavior for their paths |
| 34 | * without having to perform the interpolation calculations themselves. |
| 35 | * |
| 36 | * @author Jim Graham |
| 37 | */ |
| 38 | public class FlatteningPathIterator implements PathIterator { |
| 39 | static final int GROW_SIZE = 24; // Multiple of cubic & quad curve size |
| 40 | |
| 41 | PathIterator src; // The source iterator |
| 42 | |
| 43 | double squareflat; // Square of the flatness parameter |
| 44 | // for testing against squared lengths |
| 45 | |
| 46 | int limit; // Maximum number of recursion levels |
| 47 | |
| 48 | double hold[] = new double[14]; // The cache of interpolated coords |
| 49 | // Note that this must be long enough |
| 50 | // to store a full cubic segment and |
| 51 | // a relative cubic segment to avoid |
| 52 | // aliasing when copying the coords |
| 53 | // of a curve to the end of the array. |
| 54 | // This is also serendipitously equal |
| 55 | // to the size of a full quad segment |
| 56 | // and 2 relative quad segments. |
| 57 | |
| 58 | double curx, cury; // The ending x,y of the last segment |
| 59 | |
| 60 | double movx, movy; // The x,y of the last move segment |
| 61 | |
| 62 | int holdType; // The type of the curve being held |
| 63 | // for interpolation |
| 64 | |
| 65 | int holdEnd; // The index of the last curve segment |
| 66 | // being held for interpolation |
| 67 | |
| 68 | int holdIndex; // The index of the curve segment |
| 69 | // that was last interpolated. This |
| 70 | // is the curve segment ready to be |
| 71 | // returned in the next call to |
| 72 | // currentSegment(). |
| 73 | |
| 74 | int levels[]; // The recursion level at which |
| 75 | // each curve being held in storage |
| 76 | // was generated. |
| 77 | |
| 78 | int levelIndex; // The index of the entry in the |
| 79 | // levels array of the curve segment |
| 80 | // at the holdIndex |
| 81 | |
| 82 | boolean done; // True when iteration is done |
| 83 | |
| 84 | /** |
| 85 | * Constructs a new <code>FlatteningPathIterator</code> object that |
| 86 | * flattens a path as it iterates over it. The iterator does not |
| 87 | * subdivide any curve read from the source iterator to more than |
| 88 | * 10 levels of subdivision which yields a maximum of 1024 line |
| 89 | * segments per curve. |
| 90 | * @param src the original unflattened path being iterated over |
| 91 | * @param flatness the maximum allowable distance between the |
| 92 | * control points and the flattened curve |
| 93 | */ |
| 94 | public FlatteningPathIterator(PathIterator src, double flatness) { |
| 95 | this(src, flatness, 10); |
| 96 | } |
| 97 | |
| 98 | /** |
| 99 | * Constructs a new <code>FlatteningPathIterator</code> object |
| 100 | * that flattens a path as it iterates over it. |
| 101 | * The <code>limit</code> parameter allows you to control the |
| 102 | * maximum number of recursive subdivisions that the iterator |
| 103 | * can make before it assumes that the curve is flat enough |
| 104 | * without measuring against the <code>flatness</code> parameter. |
| 105 | * The flattened iteration therefore never generates more than |
| 106 | * a maximum of <code>(2^limit)</code> line segments per curve. |
| 107 | * @param src the original unflattened path being iterated over |
| 108 | * @param flatness the maximum allowable distance between the |
| 109 | * control points and the flattened curve |
| 110 | * @param limit the maximum number of recursive subdivisions |
| 111 | * allowed for any curved segment |
| 112 | * @exception <code>IllegalArgumentException</code> if |
| 113 | * <code>flatness</code> or <code>limit</code> |
| 114 | * is less than zero |
| 115 | */ |
| 116 | public FlatteningPathIterator(PathIterator src, double flatness, |
| 117 | int limit) { |
| 118 | if (flatness < 0.0) { |
| 119 | throw new IllegalArgumentException("flatness must be >= 0"); |
| 120 | } |
| 121 | if (limit < 0) { |
| 122 | throw new IllegalArgumentException("limit must be >= 0"); |
| 123 | } |
| 124 | this.src = src; |
| 125 | this.squareflat = flatness * flatness; |
| 126 | this.limit = limit; |
| 127 | this.levels = new int[limit + 1]; |
| 128 | // prime the first path segment |
| 129 | next(false); |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Returns the flatness of this iterator. |
| 134 | * @return the flatness of this <code>FlatteningPathIterator</code>. |
| 135 | */ |
| 136 | public double getFlatness() { |
| 137 | return Math.sqrt(squareflat); |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Returns the recursion limit of this iterator. |
| 142 | * @return the recursion limit of this |
| 143 | * <code>FlatteningPathIterator</code>. |
| 144 | */ |
| 145 | public int getRecursionLimit() { |
| 146 | return limit; |
| 147 | } |
| 148 | |
| 149 | /** |
| 150 | * Returns the winding rule for determining the interior of the |
| 151 | * path. |
| 152 | * @return the winding rule of the original unflattened path being |
| 153 | * iterated over. |
| 154 | * @see PathIterator#WIND_EVEN_ODD |
| 155 | * @see PathIterator#WIND_NON_ZERO |
| 156 | */ |
| 157 | public int getWindingRule() { |
| 158 | return src.getWindingRule(); |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * Tests if the iteration is complete. |
| 163 | * @return <code>true</code> if all the segments have |
| 164 | * been read; <code>false</code> otherwise. |
| 165 | */ |
| 166 | public boolean isDone() { |
| 167 | return done; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Ensures that the hold array can hold up to (want) more values. |
| 172 | * It is currently holding (hold.length - holdIndex) values. |
| 173 | */ |
| 174 | void ensureHoldCapacity(int want) { |
| 175 | if (holdIndex - want < 0) { |
| 176 | int have = hold.length - holdIndex; |
| 177 | int newsize = hold.length + GROW_SIZE; |
| 178 | double newhold[] = new double[newsize]; |
| 179 | System.arraycopy(hold, holdIndex, |
| 180 | newhold, holdIndex + GROW_SIZE, |
| 181 | have); |
| 182 | hold = newhold; |
| 183 | holdIndex += GROW_SIZE; |
| 184 | holdEnd += GROW_SIZE; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /** |
| 189 | * Moves the iterator to the next segment of the path forwards |
| 190 | * along the primary direction of traversal as long as there are |
| 191 | * more points in that direction. |
| 192 | */ |
| 193 | public void next() { |
| 194 | next(true); |
| 195 | } |
| 196 | |
| 197 | private void next(boolean doNext) { |
| 198 | int level; |
| 199 | |
| 200 | if (holdIndex >= holdEnd) { |
| 201 | if (doNext) { |
| 202 | src.next(); |
| 203 | } |
| 204 | if (src.isDone()) { |
| 205 | done = true; |
| 206 | return; |
| 207 | } |
| 208 | holdType = src.currentSegment(hold); |
| 209 | levelIndex = 0; |
| 210 | levels[0] = 0; |
| 211 | } |
| 212 | |
| 213 | switch (holdType) { |
| 214 | case SEG_MOVETO: |
| 215 | case SEG_LINETO: |
| 216 | curx = hold[0]; |
| 217 | cury = hold[1]; |
| 218 | if (holdType == SEG_MOVETO) { |
| 219 | movx = curx; |
| 220 | movy = cury; |
| 221 | } |
| 222 | holdIndex = 0; |
| 223 | holdEnd = 0; |
| 224 | break; |
| 225 | case SEG_CLOSE: |
| 226 | curx = movx; |
| 227 | cury = movy; |
| 228 | holdIndex = 0; |
| 229 | holdEnd = 0; |
| 230 | break; |
| 231 | case SEG_QUADTO: |
| 232 | if (holdIndex >= holdEnd) { |
| 233 | // Move the coordinates to the end of the array. |
| 234 | holdIndex = hold.length - 6; |
| 235 | holdEnd = hold.length - 2; |
| 236 | hold[holdIndex + 0] = curx; |
| 237 | hold[holdIndex + 1] = cury; |
| 238 | hold[holdIndex + 2] = hold[0]; |
| 239 | hold[holdIndex + 3] = hold[1]; |
| 240 | hold[holdIndex + 4] = curx = hold[2]; |
| 241 | hold[holdIndex + 5] = cury = hold[3]; |
| 242 | } |
| 243 | |
| 244 | level = levels[levelIndex]; |
| 245 | while (level < limit) { |
| 246 | if (QuadCurve2D.getFlatnessSq(hold, holdIndex) < squareflat) { |
| 247 | break; |
| 248 | } |
| 249 | |
| 250 | ensureHoldCapacity(4); |
| 251 | QuadCurve2D.subdivide(hold, holdIndex, |
| 252 | hold, holdIndex - 4, |
| 253 | hold, holdIndex); |
| 254 | holdIndex -= 4; |
| 255 | |
| 256 | // Now that we have subdivided, we have constructed |
| 257 | // two curves of one depth lower than the original |
| 258 | // curve. One of those curves is in the place of |
| 259 | // the former curve and one of them is in the next |
| 260 | // set of held coordinate slots. We now set both |
| 261 | // curves level values to the next higher level. |
| 262 | level++; |
| 263 | levels[levelIndex] = level; |
| 264 | levelIndex++; |
| 265 | levels[levelIndex] = level; |
| 266 | } |
| 267 | |
| 268 | // This curve segment is flat enough, or it is too deep |
| 269 | // in recursion levels to try to flatten any more. The |
| 270 | // two coordinates at holdIndex+4 and holdIndex+5 now |
| 271 | // contain the endpoint of the curve which can be the |
| 272 | // endpoint of an approximating line segment. |
| 273 | holdIndex += 4; |
| 274 | levelIndex--; |
| 275 | break; |
| 276 | case SEG_CUBICTO: |
| 277 | if (holdIndex >= holdEnd) { |
| 278 | // Move the coordinates to the end of the array. |
| 279 | holdIndex = hold.length - 8; |
| 280 | holdEnd = hold.length - 2; |
| 281 | hold[holdIndex + 0] = curx; |
| 282 | hold[holdIndex + 1] = cury; |
| 283 | hold[holdIndex + 2] = hold[0]; |
| 284 | hold[holdIndex + 3] = hold[1]; |
| 285 | hold[holdIndex + 4] = hold[2]; |
| 286 | hold[holdIndex + 5] = hold[3]; |
| 287 | hold[holdIndex + 6] = curx = hold[4]; |
| 288 | hold[holdIndex + 7] = cury = hold[5]; |
| 289 | } |
| 290 | |
| 291 | level = levels[levelIndex]; |
| 292 | while (level < limit) { |
| 293 | if (CubicCurve2D.getFlatnessSq(hold, holdIndex) < squareflat) { |
| 294 | break; |
| 295 | } |
| 296 | |
| 297 | ensureHoldCapacity(6); |
| 298 | CubicCurve2D.subdivide(hold, holdIndex, |
| 299 | hold, holdIndex - 6, |
| 300 | hold, holdIndex); |
| 301 | holdIndex -= 6; |
| 302 | |
| 303 | // Now that we have subdivided, we have constructed |
| 304 | // two curves of one depth lower than the original |
| 305 | // curve. One of those curves is in the place of |
| 306 | // the former curve and one of them is in the next |
| 307 | // set of held coordinate slots. We now set both |
| 308 | // curves level values to the next higher level. |
| 309 | level++; |
| 310 | levels[levelIndex] = level; |
| 311 | levelIndex++; |
| 312 | levels[levelIndex] = level; |
| 313 | } |
| 314 | |
| 315 | // This curve segment is flat enough, or it is too deep |
| 316 | // in recursion levels to try to flatten any more. The |
| 317 | // two coordinates at holdIndex+6 and holdIndex+7 now |
| 318 | // contain the endpoint of the curve which can be the |
| 319 | // endpoint of an approximating line segment. |
| 320 | holdIndex += 6; |
| 321 | levelIndex--; |
| 322 | break; |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | /** |
| 327 | * Returns the coordinates and type of the current path segment in |
| 328 | * the iteration. |
| 329 | * The return value is the path segment type: |
| 330 | * SEG_MOVETO, SEG_LINETO, or SEG_CLOSE. |
| 331 | * A float array of length 6 must be passed in and can be used to |
| 332 | * store the coordinates of the point(s). |
| 333 | * Each point is stored as a pair of float x,y coordinates. |
| 334 | * SEG_MOVETO and SEG_LINETO types return one point, |
| 335 | * and SEG_CLOSE does not return any points. |
| 336 | * @param coords an array that holds the data returned from |
| 337 | * this method |
| 338 | * @return the path segment type of the current path segment. |
| 339 | * @exception <code>NoSuchElementException</code> if there |
| 340 | * are no more elements in the flattening path to be |
| 341 | * returned. |
| 342 | * @see PathIterator#SEG_MOVETO |
| 343 | * @see PathIterator#SEG_LINETO |
| 344 | * @see PathIterator#SEG_CLOSE |
| 345 | */ |
| 346 | public int currentSegment(float[] coords) { |
| 347 | if (isDone()) { |
| 348 | throw new NoSuchElementException("flattening iterator out of bounds"); |
| 349 | } |
| 350 | int type = holdType; |
| 351 | if (type != SEG_CLOSE) { |
| 352 | coords[0] = (float) hold[holdIndex + 0]; |
| 353 | coords[1] = (float) hold[holdIndex + 1]; |
| 354 | if (type != SEG_MOVETO) { |
| 355 | type = SEG_LINETO; |
| 356 | } |
| 357 | } |
| 358 | return type; |
| 359 | } |
| 360 | |
| 361 | /** |
| 362 | * Returns the coordinates and type of the current path segment in |
| 363 | * the iteration. |
| 364 | * The return value is the path segment type: |
| 365 | * SEG_MOVETO, SEG_LINETO, or SEG_CLOSE. |
| 366 | * A double array of length 6 must be passed in and can be used to |
| 367 | * store the coordinates of the point(s). |
| 368 | * Each point is stored as a pair of double x,y coordinates. |
| 369 | * SEG_MOVETO and SEG_LINETO types return one point, |
| 370 | * and SEG_CLOSE does not return any points. |
| 371 | * @param coords an array that holds the data returned from |
| 372 | * this method |
| 373 | * @return the path segment type of the current path segment. |
| 374 | * @exception <code>NoSuchElementException</code> if there |
| 375 | * are no more elements in the flattening path to be |
| 376 | * returned. |
| 377 | * @see PathIterator#SEG_MOVETO |
| 378 | * @see PathIterator#SEG_LINETO |
| 379 | * @see PathIterator#SEG_CLOSE |
| 380 | */ |
| 381 | public int currentSegment(double[] coords) { |
| 382 | if (isDone()) { |
| 383 | throw new NoSuchElementException("flattening iterator out of bounds"); |
| 384 | } |
| 385 | int type = holdType; |
| 386 | if (type != SEG_CLOSE) { |
| 387 | coords[0] = hold[holdIndex + 0]; |
| 388 | coords[1] = hold[holdIndex + 1]; |
| 389 | if (type != SEG_MOVETO) { |
| 390 | type = SEG_LINETO; |
| 391 | } |
| 392 | } |
| 393 | return type; |
| 394 | } |
| 395 | } |