Source for java.awt.BasicStroke

   1: /* BasicStroke.java --
   2:    Copyright (C) 2002, 2003, 2004, 2005, 2006  Free Software Foundation, Inc.
   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;
  40: 
  41: import gnu.java.awt.java2d.CubicSegment;
  42: import gnu.java.awt.java2d.LineSegment;
  43: import gnu.java.awt.java2d.QuadSegment;
  44: import gnu.java.awt.java2d.Segment;
  45: 
  46: import java.awt.geom.FlatteningPathIterator;
  47: import java.awt.geom.GeneralPath;
  48: import java.awt.geom.PathIterator;
  49: import java.awt.geom.Point2D;
  50: import java.util.Arrays;
  51: 
  52: /**
  53:  * A general purpose {@link Stroke} implementation that can represent a wide
  54:  * variety of line styles for use with subclasses of {@link Graphics2D}.
  55:  * <p>
  56:  * The line cap and join styles can be set using the options illustrated
  57:  * here:
  58:  * <p>
  59:  * <img src="doc-files/capjoin.png" width="350" height="180"
  60:  * alt="Illustration of line cap and join styles" />
  61:  * <p>
  62:  * A dash array can be used to specify lines with alternating opaque and
  63:  * transparent sections.
  64:  */
  65: public class BasicStroke implements Stroke
  66: {
  67:   /**
  68:    * Indicates a mitered line join style. See the class overview for an
  69:    * illustration.
  70:    */
  71:   public static final int JOIN_MITER = 0;
  72: 
  73:   /**
  74:    * Indicates a rounded line join style. See the class overview for an
  75:    * illustration.
  76:    */
  77:   public static final int JOIN_ROUND = 1;
  78: 
  79:   /**
  80:    * Indicates a bevelled line join style. See the class overview for an
  81:    * illustration.
  82:    */
  83:   public static final int JOIN_BEVEL = 2;
  84: 
  85:   /**
  86:    * Indicates a flat line cap style. See the class overview for an
  87:    * illustration.
  88:    */
  89:   public static final int CAP_BUTT = 0;
  90: 
  91:   /**
  92:    * Indicates a rounded line cap style. See the class overview for an
  93:    * illustration.
  94:    */
  95:   public static final int CAP_ROUND = 1;
  96: 
  97:   /**
  98:    * Indicates a square line cap style. See the class overview for an
  99:    * illustration.
 100:    */
 101:   public static final int CAP_SQUARE = 2;
 102: 
 103:   /** The stroke width. */
 104:   private final float width;
 105: 
 106:   /** The line cap style. */
 107:   private final int cap;
 108: 
 109:   /** The line join style. */
 110:   private final int join;
 111: 
 112:   /** The miter limit. */
 113:   private final float limit;
 114: 
 115:   /** The dash array. */
 116:   private final float[] dash;
 117: 
 118:   /** The dash phase. */
 119:   private final float phase;
 120: 
 121:   // The inner and outer paths of the stroke
 122:   private Segment start, end;
 123: 
 124:   /**
 125:    * Creates a new <code>BasicStroke</code> instance with the given attributes.
 126:    *
 127:    * @param width  the line width (>= 0.0f).
 128:    * @param cap  the line cap style (one of {@link #CAP_BUTT},
 129:    *             {@link #CAP_ROUND} or {@link #CAP_SQUARE}).
 130:    * @param join  the line join style (one of {@link #JOIN_ROUND},
 131:    *              {@link #JOIN_BEVEL}, or {@link #JOIN_MITER}).
 132:    * @param miterlimit  the limit to trim the miter join. The miterlimit must be
 133:    * greater than or equal to 1.0f.
 134:    * @param dash The array representing the dashing pattern. There must be at
 135:    * least one non-zero entry.
 136:    * @param dashPhase is negative and dash is not null.
 137:    *
 138:    * @throws IllegalArgumentException If one input parameter doesn't meet
 139:    * its needs.
 140:    */
 141:   public BasicStroke(float width, int cap, int join, float miterlimit,
 142:                      float[] dash, float dashPhase)
 143:   {
 144:     if (width < 0.0f )
 145:       throw new IllegalArgumentException("width " + width + " < 0");
 146:     else if (cap < CAP_BUTT || cap > CAP_SQUARE)
 147:       throw new IllegalArgumentException("cap " + cap + " out of range ["
 148:                                          + CAP_BUTT + ".." + CAP_SQUARE + "]");
 149:     else if (miterlimit < 1.0f && join == JOIN_MITER)
 150:       throw new IllegalArgumentException("miterlimit " + miterlimit
 151:                                          + " < 1.0f while join == JOIN_MITER");
 152:     else if (join < JOIN_MITER || join > JOIN_BEVEL)
 153:       throw new IllegalArgumentException("join " + join + " out of range ["
 154:                                          + JOIN_MITER + ".." + JOIN_BEVEL
 155:                                          + "]");
 156:     else if (dashPhase < 0.0f && dash != null)
 157:       throw new IllegalArgumentException("dashPhase " + dashPhase
 158:                                          + " < 0.0f while dash != null");
 159:     else if (dash != null)
 160:       if (dash.length == 0)
 161:         throw new IllegalArgumentException("dash.length is 0");
 162:       else
 163:         {
 164:           boolean allZero = true;
 165: 
 166:           for ( int i = 0; i < dash.length; ++i)
 167:             {
 168:               if (dash[i] != 0.0f)
 169:                 {
 170:                   allZero = false;
 171:                   break;
 172:                 }
 173:             }
 174: 
 175:           if (allZero)
 176:             throw new IllegalArgumentException("all dashes are 0.0f");
 177:         }
 178: 
 179:     this.width = width;
 180:     this.cap = cap;
 181:     this.join = join;
 182:     limit = miterlimit;
 183:     this.dash = dash == null ? null : (float[]) dash.clone();
 184:     phase = dashPhase;
 185:   }
 186: 
 187:   /**
 188:    * Creates a new <code>BasicStroke</code> instance with the given attributes.
 189:    *
 190:    * @param width  the line width (>= 0.0f).
 191:    * @param cap  the line cap style (one of {@link #CAP_BUTT},
 192:    *             {@link #CAP_ROUND} or {@link #CAP_SQUARE}).
 193:    * @param join  the line join style (one of {@link #JOIN_ROUND},
 194:    *              {@link #JOIN_BEVEL}, or {@link #JOIN_MITER}).
 195:    * @param miterlimit the limit to trim the miter join. The miterlimit must be
 196:    * greater than or equal to 1.0f.
 197:    *
 198:    * @throws IllegalArgumentException If one input parameter doesn't meet
 199:    * its needs.
 200:    */
 201:   public BasicStroke(float width, int cap, int join, float miterlimit)
 202:   {
 203:     this(width, cap, join, miterlimit, null, 0);
 204:   }
 205: 
 206:   /**
 207:    * Creates a new <code>BasicStroke</code> instance with the given attributes.
 208:    * The miter limit defaults to <code>10.0</code>.
 209:    *
 210:    * @param width  the line width (>= 0.0f).
 211:    * @param cap  the line cap style (one of {@link #CAP_BUTT},
 212:    *             {@link #CAP_ROUND} or {@link #CAP_SQUARE}).
 213:    * @param join  the line join style (one of {@link #JOIN_ROUND},
 214:    *              {@link #JOIN_BEVEL}, or {@link #JOIN_MITER}).
 215:    *
 216:    * @throws IllegalArgumentException If one input parameter doesn't meet
 217:    * its needs.
 218:    */
 219:   public BasicStroke(float width, int cap, int join)
 220:   {
 221:     this(width, cap, join, 10, null, 0);
 222:   }
 223: 
 224:   /**
 225:    * Creates a new <code>BasicStroke</code> instance with the given line
 226:    * width.  The default values are:
 227:    * <ul>
 228:    * <li>line cap style: {@link #CAP_SQUARE};</li>
 229:    * <li>line join style: {@link #JOIN_MITER};</li>
 230:    * <li>miter limit: <code>10.0f</code>.
 231:    * </ul>
 232:    *
 233:    * @param width  the line width (>= 0.0f).
 234:    *
 235:    * @throws IllegalArgumentException If <code>width</code> is negative.
 236:    */
 237:   public BasicStroke(float width)
 238:   {
 239:     this(width, CAP_SQUARE, JOIN_MITER, 10, null, 0);
 240:   }
 241: 
 242:   /**
 243:    * Creates a new <code>BasicStroke</code> instance.  The default values are:
 244:    * <ul>
 245:    * <li>line width: <code>1.0f</code>;</li>
 246:    * <li>line cap style: {@link #CAP_SQUARE};</li>
 247:    * <li>line join style: {@link #JOIN_MITER};</li>
 248:    * <li>miter limit: <code>10.0f</code>.
 249:    * </ul>
 250:    */
 251:   public BasicStroke()
 252:   {
 253:     this(1, CAP_SQUARE, JOIN_MITER, 10, null, 0);
 254:   }
 255: 
 256:   /**
 257:    * Creates a shape representing the stroked outline of the given shape.
 258:    * THIS METHOD IS NOT YET IMPLEMENTED.
 259:    *
 260:    * @param s  the shape.
 261:    */
 262:   public Shape createStrokedShape(Shape s)
 263:   {
 264:     PathIterator pi = s.getPathIterator(null);
 265: 
 266:     if( dash == null )
 267:       return solidStroke( pi );
 268: 
 269:     return dashedStroke( pi );
 270:   }
 271: 
 272:   /**
 273:    * Returns the line width.
 274:    *
 275:    * @return The line width.
 276:    */
 277:   public float getLineWidth()
 278:   {
 279:     return width;
 280:   }
 281: 
 282:   /**
 283:    * Returns a code indicating the line cap style (one of {@link #CAP_BUTT},
 284:    * {@link #CAP_ROUND}, {@link #CAP_SQUARE}).
 285:    *
 286:    * @return A code indicating the line cap style.
 287:    */
 288:   public int getEndCap()
 289:   {
 290:     return cap;
 291:   }
 292: 
 293:   /**
 294:    * Returns a code indicating the line join style (one of {@link #JOIN_BEVEL},
 295:    * {@link #JOIN_MITER} or {@link #JOIN_ROUND}).
 296:    *
 297:    * @return A code indicating the line join style.
 298:    */
 299:   public int getLineJoin()
 300:   {
 301:     return join;
 302:   }
 303: 
 304:   /**
 305:    * Returns the miter limit.
 306:    *
 307:    * @return The miter limit.
 308:    */
 309:   public float getMiterLimit()
 310:   {
 311:     return limit;
 312:   }
 313: 
 314:   /**
 315:    * Returns the dash array, which defines the length of alternate opaque and
 316:    * transparent sections in lines drawn with this stroke.  If
 317:    * <code>null</code>, a continuous line will be drawn.
 318:    *
 319:    * @return The dash array (possibly <code>null</code>).
 320:    */
 321:   public float[] getDashArray()
 322:   {
 323:     return dash;
 324:   }
 325: 
 326:   /**
 327:    * Returns the dash phase for the stroke.  This is the offset from the start
 328:    * of a path at which the pattern defined by {@link #getDashArray()} is
 329:    * rendered.
 330:    *
 331:    * @return The dash phase.
 332:    */
 333:   public float getDashPhase()
 334:   {
 335:     return phase;
 336:   }
 337: 
 338:   /**
 339:    * Returns the hash code for this object. The hash is calculated by
 340:    * xoring the hash, cap, join, limit, dash array and phase values
 341:    * (converted to <code>int</code> first with
 342:    * <code>Float.floatToIntBits()</code> if the value is a
 343:    * <code>float</code>).
 344:    *
 345:    * @return The hash code.
 346:    */
 347:   public int hashCode()
 348:   {
 349:     int hash = Float.floatToIntBits(width);
 350:     hash ^= cap;
 351:     hash ^= join;
 352:     hash ^= Float.floatToIntBits(limit);
 353: 
 354:     if (dash != null)
 355:       for (int i = 0; i < dash.length; i++)
 356:         hash ^=  Float.floatToIntBits(dash[i]);
 357: 
 358:     hash ^= Float.floatToIntBits(phase);
 359: 
 360:     return hash;
 361:   }
 362: 
 363:   /**
 364:    * Compares this <code>BasicStroke</code> for equality with an arbitrary
 365:    * object.  This method returns <code>true</code> if and only if:
 366:    * <ul>
 367:    * <li><code>o</code> is an instanceof <code>BasicStroke</code>;</li>
 368:    * <li>this object has the same width, line cap style, line join style,
 369:    * miter limit, dash array and dash phase as <code>o</code>.</li>
 370:    * </ul>
 371:    *
 372:    * @param o  the object (<code>null</code> permitted).
 373:    *
 374:    * @return <code>true</code> if this stroke is equal to <code>o</code> and
 375:    *         <code>false</code> otherwise.
 376:    */
 377:   public boolean equals(Object o)
 378:   {
 379:     if (! (o instanceof BasicStroke))
 380:       return false;
 381:     BasicStroke s = (BasicStroke) o;
 382:     return width == s.width && cap == s.cap && join == s.join
 383:       && limit == s.limit && Arrays.equals(dash, s.dash) && phase == s.phase;
 384:   }
 385: 
 386:   private Shape solidStroke(PathIterator pi)
 387:   {
 388:     double[] coords = new double[6];
 389:     double x, y, x0, y0;
 390:     boolean pathOpen = false;
 391:     GeneralPath output = new GeneralPath( );
 392:     Segment[] p;
 393:     x = x0 = y = y0 = 0;
 394: 
 395:     while( !pi.isDone() )
 396:       {
 397:         switch( pi.currentSegment(coords) )
 398:           {
 399:           case PathIterator.SEG_MOVETO:
 400:             x0 = x = coords[0];
 401:             y0 = y = coords[1];
 402:             if( pathOpen )
 403:               {
 404:                 capEnds();
 405:                 convertPath(output, start);
 406:                 start = end = null;
 407:                 pathOpen = false;
 408:               }
 409:             break;
 410: 
 411:           case PathIterator.SEG_LINETO:
 412:             p = (new LineSegment(x, y, coords[0], coords[1])).
 413:               getDisplacedSegments(width/2.0);
 414:             if( !pathOpen )
 415:               {
 416:                 start = p[0];
 417:                 end = p[1];
 418:                 pathOpen = true;
 419:               }
 420:             else
 421:               addSegments(p);
 422: 
 423:             x = coords[0];
 424:             y = coords[1];
 425:             break;
 426: 
 427:           case PathIterator.SEG_QUADTO:
 428:             p = (new QuadSegment(x, y, coords[0], coords[1], coords[2],
 429:                                  coords[3])).getDisplacedSegments(width/2.0);
 430:             if( !pathOpen )
 431:               {
 432:                 start = p[0];
 433:                 end = p[1];
 434:                 pathOpen = true;
 435:               }
 436:             else
 437:               addSegments(p);
 438: 
 439:             x = coords[2];
 440:             y = coords[3];
 441:             break;
 442: 
 443:           case PathIterator.SEG_CUBICTO:
 444:             p = new CubicSegment(x, y, coords[0], coords[1],
 445:                                  coords[2], coords[3],
 446:                                  coords[4], coords[5]).getDisplacedSegments(width/2.0);
 447:             if( !pathOpen )
 448:               {
 449:                 start = p[0];
 450:                 end = p[1];
 451:                 pathOpen = true;
 452:               }
 453:             else
 454:               addSegments(p);
 455: 
 456:             x = coords[4];
 457:             y = coords[5];
 458:             break;
 459: 
 460:           case PathIterator.SEG_CLOSE:
 461:             if (x == x0 && y == y0)
 462:               {
 463:                 joinSegments(new Segment[] { start.first, end.first });
 464:               }
 465:             else
 466:               {
 467:                 p = (new LineSegment(x, y, x0, y0)).getDisplacedSegments(width / 2.0);
 468:                 addSegments(p);
 469:               }
 470:             convertPath(output, start);
 471:             convertPath(output, end);
 472:             start = end = null;
 473:             pathOpen = false;
 474:             output.setWindingRule(GeneralPath.WIND_EVEN_ODD);
 475:             break;
 476:           }
 477:         pi.next();
 478:       }
 479: 
 480:     if( pathOpen )
 481:       {
 482:         capEnds();
 483:         convertPath(output, start);
 484:       }
 485:     return output;
 486:   }
 487: 
 488:   private Shape dashedStroke(PathIterator pi)
 489:   {
 490:     // The choice of (flatnessSq == width / 3) is made to be consistent with
 491:     // the flattening in CubicSegment.getDisplacedSegments
 492:     FlatteningPathIterator flat = new FlatteningPathIterator(pi,
 493:                                                              Math.sqrt(width / 3));
 494: 
 495:     // Holds the endpoint of the current segment (or piece of a segment)
 496:     double[] coords = new double[2];
 497: 
 498:     // Holds end of the last segment
 499:     double x, y, x0, y0;
 500:     x = x0 = y = y0 = 0;
 501: 
 502:     // Various useful flags
 503:     boolean pathOpen = false;
 504:     boolean dashOn = true;
 505:     boolean offsetting = (phase != 0);
 506: 
 507:     // How far we are into the current dash
 508:     double distance = 0;
 509:     int dashIndex = 0;
 510: 
 511:     // And variables to hold the final output
 512:     GeneralPath output = new GeneralPath();
 513:     Segment[] p;
 514: 
 515:     // Iterate over the FlatteningPathIterator
 516:     while (! flat.isDone())
 517:       {
 518:         switch (flat.currentSegment(coords))
 519:           {
 520:           case PathIterator.SEG_MOVETO:
 521:             x0 = x = coords[0];
 522:             y0 = y = coords[1];
 523: 
 524:             if (pathOpen)
 525:               {
 526:                 capEnds();
 527:                 convertPath(output, start);
 528:                 start = end = null;
 529:                 pathOpen = false;
 530:               }
 531: 
 532:             break;
 533: 
 534:           case PathIterator.SEG_LINETO:
 535:             boolean segmentConsumed = false;
 536: 
 537:             while (! segmentConsumed)
 538:               {
 539:                 // Find the total remaining length of this segment
 540:                 double segLength = Math.sqrt((x - coords[0]) * (x - coords[0])
 541:                                              + (y - coords[1])
 542:                                              * (y - coords[1]));
 543:                 boolean spanBoundary = true;
 544:                 double[] segmentEnd = null;
 545: 
 546:                 // The current segment fits entirely inside the current dash
 547:                 if ((offsetting && distance + segLength <= phase)
 548:                     || distance + segLength <= dash[dashIndex])
 549:                   {
 550:                     spanBoundary = false;
 551:                   }
 552: 
 553:                 // Otherwise, we need to split the segment in two, as this
 554:                 // segment spans a dash boundry
 555:                 else
 556:                   {
 557:                     segmentEnd = (double[]) coords.clone();
 558: 
 559:                     // Calculate the remaining distance in this dash,
 560:                     // and coordinates of the dash boundary
 561:                     double reqLength;
 562:                     if (offsetting)
 563:                       reqLength = phase - distance;
 564:                     else
 565:                       reqLength = dash[dashIndex] - distance;
 566: 
 567:                     coords[0] = x + ((coords[0] - x) * reqLength / segLength);
 568:                     coords[1] = y + ((coords[1] - y) * reqLength / segLength);
 569:                   }
 570: 
 571:                 if (offsetting || ! dashOn)
 572:                   {
 573:                     // Dash is off, or we are in offset - treat this as a
 574:                     // moveTo
 575:                     x0 = x = coords[0];
 576:                     y0 = y = coords[1];
 577: 
 578:                     if (pathOpen)
 579:                       {
 580:                         capEnds();
 581:                         convertPath(output, start);
 582:                         start = end = null;
 583:                         pathOpen = false;
 584:                       }
 585:                   }
 586:                 else
 587:                   {
 588:                     // Dash is on - treat this as a lineTo
 589:                     p = (new LineSegment(x, y, coords[0], coords[1])).getDisplacedSegments(width / 2.0);
 590: 
 591:                     if (! pathOpen)
 592:                       {
 593:                         start = p[0];
 594:                         end = p[1];
 595:                         pathOpen = true;
 596:                       }
 597:                     else
 598:                       addSegments(p);
 599: 
 600:                     x = coords[0];
 601:                     y = coords[1];
 602:                   }
 603: 
 604:                 // Update variables depending on whether we spanned a
 605:                 // dash boundary or not
 606:                 if (! spanBoundary)
 607:                   {
 608:                     distance += segLength;
 609:                     segmentConsumed = true;
 610:                   }
 611:                 else
 612:                   {
 613:                     if (offsetting)
 614:                       offsetting = false;
 615:                     dashOn = ! dashOn;
 616:                     distance = 0;
 617:                     coords = segmentEnd;
 618: 
 619:                     if (dashIndex + 1 == dash.length)
 620:                       dashIndex = 0;
 621:                     else
 622:                       dashIndex++;
 623: 
 624:                     // Since the value of segmentConsumed is still false,
 625:                     // the next run of the while loop will complete the segment
 626:                   }
 627:               }
 628:             break;
 629: 
 630:           // This is a flattened path, so we don't need to deal with curves
 631:           }
 632:         flat.next();
 633:       }
 634: 
 635:     if (pathOpen)
 636:       {
 637:         capEnds();
 638:         convertPath(output, start);
 639:       }
 640:     return output;
 641:   }
 642: 
 643:   /**
 644:    * Cap the ends of the path (joining the start and end list of segments)
 645:    */
 646:   private void capEnds()
 647:   {
 648:     Segment returnPath = end.last;
 649: 
 650:     end.reverseAll(); // reverse the path.
 651:     end = null;
 652:     capEnd(start, returnPath);
 653:     start.last = returnPath.last;
 654:     end = null;
 655: 
 656:     capEnd(start, start);
 657:   }
 658: 
 659:   /**
 660:    * Append the Segments in s to the GeneralPath p
 661:    */
 662:   private void convertPath(GeneralPath p, Segment s)
 663:   {
 664:     Segment v = s;
 665:     p.moveTo((float)s.P1.getX(), (float)s.P1.getY());
 666: 
 667:     do
 668:       {
 669:         if(v instanceof LineSegment)
 670:           p.lineTo((float)v.P2.getX(), (float)v.P2.getY());
 671:         else if(v instanceof QuadSegment)
 672:           p.quadTo((float)((QuadSegment)v).cp.getX(),
 673:                    (float)((QuadSegment)v).cp.getY(),
 674:                    (float)v.P2.getX(),
 675:                    (float)v.P2.getY());
 676:         else if(v instanceof CubicSegment)
 677:           p.curveTo((float)((CubicSegment)v).cp1.getX(),
 678:                     (float)((CubicSegment)v).cp1.getY(),
 679:                     (float)((CubicSegment)v).cp2.getX(),
 680:                     (float)((CubicSegment)v).cp2.getY(),
 681:                     (float)v.P2.getX(),
 682:                     (float)v.P2.getY());
 683:         v = v.next;
 684:       } while(v != s && v != null);
 685: 
 686:     p.closePath();
 687:   }
 688: 
 689:   /**
 690:    * Add the segments to start and end (the inner and outer edges of the stroke)
 691:    */
 692:   private void addSegments(Segment[] segments)
 693:   {
 694:     joinSegments(segments);
 695:     start.add(segments[0]);
 696:     end.add(segments[1]);
 697:   }
 698: 
 699:   private void joinSegments(Segment[] segments)
 700:   {
 701:     double[] p0 = start.last.cp2();
 702:     double[] p1 = new double[]{start.last.P2.getX(), start.last.P2.getY()};
 703:     double[] p2 = new double[]{segments[0].first.P1.getX(), segments[0].first.P1.getY()};
 704:     double[] p3 = segments[0].cp1();
 705:     Point2D p;
 706: 
 707:     p = lineIntersection(p0[0],p0[1],p1[0],p1[1],
 708:                                  p2[0],p2[1],p3[0],p3[1], false);
 709: 
 710:     double det = (p1[0] - p0[0])*(p3[1] - p2[1]) -
 711:       (p3[0] - p2[0])*(p1[1] - p0[1]);
 712: 
 713:     if( det > 0 )
 714:       {
 715:         // start and segment[0] form the 'inner' part of a join,
 716:         // connect the overlapping segments
 717:         joinInnerSegments(start, segments[0], p);
 718:         joinOuterSegments(end, segments[1], p);
 719:       }
 720:     else
 721:       {
 722:         // end and segment[1] form the 'inner' part
 723:         joinInnerSegments(end, segments[1], p);
 724:         joinOuterSegments(start, segments[0], p);
 725:       }
 726:   }
 727: 
 728:   /**
 729:    * Make a cap between a and b segments,
 730:    * where a-->b is the direction of iteration.
 731:    */
 732:   private void capEnd(Segment a, Segment b)
 733:   {
 734:     double[] p0, p1;
 735:     double dx, dy, l;
 736:     Point2D c1,c2;
 737: 
 738:     switch( cap )
 739:       {
 740:       case CAP_BUTT:
 741:         a.add(new LineSegment(a.last.P2, b.P1));
 742:         break;
 743: 
 744:       case CAP_SQUARE:
 745:         p0 = a.last.cp2();
 746:         p1 = new double[]{a.last.P2.getX(), a.last.P2.getY()};
 747:         dx = p1[0] - p0[0];
 748:         dy = p1[1] - p0[1];
 749:         l = Math.sqrt(dx * dx + dy * dy);
 750:         dx = 0.5*width*dx/l;
 751:         dy = 0.5*width*dy/l;
 752:         c1 = new Point2D.Double(p1[0] + dx, p1[1] + dy);
 753:         c2 = new Point2D.Double(b.P1.getX() + dx, b.P1.getY() + dy);
 754:         a.add(new LineSegment(a.last.P2, c1));
 755:         a.add(new LineSegment(c1, c2));
 756:         a.add(new LineSegment(c2, b.P1));
 757:         break;
 758: 
 759:       case CAP_ROUND:
 760:         p0 = a.last.cp2();
 761:         p1 = new double[]{a.last.P2.getX(), a.last.P2.getY()};
 762:         dx = p1[0] - p0[0];
 763:         dy = p1[1] - p0[1];
 764:         if (dx != 0 && dy != 0)
 765:           {
 766:             l = Math.sqrt(dx * dx + dy * dy);
 767:             dx = (2.0/3.0)*width*dx/l;
 768:             dy = (2.0/3.0)*width*dy/l;
 769:           }
 770: 
 771:         c1 = new Point2D.Double(p1[0] + dx, p1[1] + dy);
 772:         c2 = new Point2D.Double(b.P1.getX() + dx, b.P1.getY() + dy);
 773:         a.add(new CubicSegment(a.last.P2, c1, c2, b.P1));
 774:         break;
 775:       }
 776:     a.add(b);
 777:   }
 778: 
 779:   /**
 780:    * Returns the intersection of two lines, or null if there isn't one.
 781:    * @param infinite - true if the lines should be regarded as infinite, false
 782:    * if the intersection must be within the given segments.
 783:    * @return a Point2D or null.
 784:    */
 785:   private Point2D lineIntersection(double X1, double Y1,
 786:                                    double X2, double Y2,
 787:                                    double X3, double Y3,
 788:                                    double X4, double Y4,
 789:                                    boolean infinite)
 790:   {
 791:     double x1 = X1;
 792:     double y1 = Y1;
 793:     double rx = X2 - x1;
 794:     double ry = Y2 - y1;
 795: 
 796:     double x2 = X3;
 797:     double y2 = Y3;
 798:     double sx = X4 - x2;
 799:     double sy = Y4 - y2;
 800: 
 801:     double determinant = sx * ry - sy * rx;
 802:     double nom = (sx * (y2 - y1) + sy * (x1 - x2));
 803: 
 804:     // lines can be considered parallel.
 805:     if (Math.abs(determinant) < 1E-6)
 806:       return null;
 807: 
 808:     nom = nom / determinant;
 809: 
 810:     // check if lines are within the bounds
 811:     if(!infinite && (nom > 1.0 || nom < 0.0))
 812:       return null;
 813: 
 814:     return new Point2D.Double(x1 + nom * rx, y1 + nom * ry);
 815:   }
 816: 
 817:   /**
 818:    * Join a and b segments, where a-->b is the direction of iteration.
 819:    *
 820:    * insideP is the inside intersection point of the join, needed for
 821:    * calculating miter lengths.
 822:    */
 823:   private void joinOuterSegments(Segment a, Segment b, Point2D insideP)
 824:   {
 825:     double[] p0, p1;
 826:     double dx, dy, l;
 827:     Point2D c1,c2;
 828: 
 829:     switch( join )
 830:       {
 831:       case JOIN_MITER:
 832:         p0 = a.last.cp2();
 833:         p1 = new double[]{a.last.P2.getX(), a.last.P2.getY()};
 834:         double[] p2 = new double[]{b.P1.getX(), b.P1.getY()};
 835:         double[] p3 = b.cp1();
 836:         Point2D p = lineIntersection(p0[0],p0[1],p1[0],p1[1],p2[0],p2[1],p3[0],p3[1], true);
 837:         if( p == null || insideP == null )
 838:           a.add(new LineSegment(a.last.P2, b.P1));
 839:         else if((p.distance(insideP)/width) < limit)
 840:           {
 841:             a.add(new LineSegment(a.last.P2, p));
 842:             a.add(new LineSegment(p, b.P1));
 843:           }
 844:         else
 845:           {
 846:             // outside miter limit, do a bevel join.
 847:             a.add(new LineSegment(a.last.P2, b.P1));
 848:           }
 849:         break;
 850: 
 851:       case JOIN_ROUND:
 852:         p0 = a.last.cp2();
 853:         p1 = new double[]{a.last.P2.getX(), a.last.P2.getY()};
 854:         dx = p1[0] - p0[0];
 855:         dy = p1[1] - p0[1];
 856:         l = Math.sqrt(dx * dx + dy * dy);
 857:         dx = 0.5*width*dx/l;
 858:         dy = 0.5*width*dy/l;
 859:         c1 = new Point2D.Double(p1[0] + dx, p1[1] + dy);
 860: 
 861:         p0 = new double[]{b.P1.getX(), b.P1.getY()};
 862:         p1 = b.cp1();
 863: 
 864:         dx = p0[0] - p1[0]; // backwards direction.
 865:         dy = p0[1] - p1[1];
 866:         l = Math.sqrt(dx * dx + dy * dy);
 867:         dx = 0.5*width*dx/l;
 868:         dy = 0.5*width*dy/l;
 869:         c2 = new Point2D.Double(p0[0] + dx, p0[1] + dy);
 870:         a.add(new CubicSegment(a.last.P2, c1, c2, b.P1));
 871:         break;
 872: 
 873:       case JOIN_BEVEL:
 874:         a.add(new LineSegment(a.last.P2, b.P1));
 875:         break;
 876:       }
 877:   }
 878: 
 879:   /**
 880:    * Join a and b segments, removing any overlap
 881:    */
 882:   private void joinInnerSegments(Segment a, Segment b, Point2D p)
 883:   {
 884:     double[] p0 = a.last.cp2();
 885:     double[] p1 = new double[] { a.last.P2.getX(), a.last.P2.getY() };
 886:     double[] p2 = new double[] { b.P1.getX(), b.P1.getY() };
 887:     double[] p3 = b.cp1();
 888: 
 889:     if (p == null)
 890:       {
 891:         // Dodgy.
 892:         a.add(new LineSegment(a.last.P2, b.P1));
 893:         p = new Point2D.Double((b.P1.getX() + a.last.P2.getX()) / 2.0,
 894:                                (b.P1.getY() + a.last.P2.getY()) / 2.0);
 895:       }
 896:     else
 897:       // This assumes segments a and b are single segments, which is
 898:       // incorrect - if they are a linked list of segments (ie, passed in
 899:       // from a flattening operation), this produces strange results!!
 900:       a.last.P2 = b.P1 = p;
 901:   }
 902: }