1 /*
2 * Copyright (c) 2007, 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
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
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24 */
25
26 package sun.java2d.marlin;
27
28 import java.util.Arrays;
29 import sun.java2d.marlin.DHelpers.PolyStack;
30
31 // TODO: some of the arithmetic here is too verbose and prone to hard to
32 // debug typos. We should consider making a small Point/Vector class that
33 // has methods like plus(Point), minus(Point), dot(Point), cross(Point)and such
34 final class DStroker implements DPathConsumer2D, MarlinConst {
35
36 private static final int MOVE_TO = 0;
37 private static final int DRAWING_OP_TO = 1; // ie. curve, line, or quad
38 private static final int CLOSE = 2;
39
40 /**
41 * Constant value for join style.
42 */
43 public static final int JOIN_MITER = 0;
44
45 /**
46 * Constant value for join style.
47 */
48 public static final int JOIN_ROUND = 1;
49
50 /**
51 * Constant value for join style.
52 */
53 public static final int JOIN_BEVEL = 2;
54
55 /**
56 * Constant value for end cap style.
57 */
58 public static final int CAP_BUTT = 0;
59
60 /**
61 * Constant value for end cap style.
62 */
63 public static final int CAP_ROUND = 1;
64
65 /**
66 * Constant value for end cap style.
67 */
68 public static final int CAP_SQUARE = 2;
69
70 // pisces used to use fixed point arithmetic with 16 decimal digits. I
71 // didn't want to change the values of the constant below when I converted
72 // it to floating point, so that's why the divisions by 2^16 are there.
73 private static final double ROUND_JOIN_THRESHOLD = 1000.0d/65536.0d;
74
75 // kappa = (4/3) * (SQRT(2) - 1)
76 private static final double C = (4.0d * (Math.sqrt(2.0d) - 1.0d) / 3.0d);
77
78 // SQRT(2)
79 private static final double SQRT_2 = Math.sqrt(2.0d);
80
81 private static final int MAX_N_CURVES = 11;
82
83 private DPathConsumer2D out;
84
85 private int capStyle;
86 private int joinStyle;
87
88 private double lineWidth2;
89 private double invHalfLineWidth2Sq;
90
91 private final double[] offset0 = new double[2];
92 private final double[] offset1 = new double[2];
93 private final double[] offset2 = new double[2];
94 private final double[] miter = new double[2];
95 private double miterLimitSq;
96
97 private int prev;
98
99 // The starting point of the path, and the slope there.
100 private double sx0, sy0, sdx, sdy;
101 // the current point and the slope there.
102 private double cx0, cy0, cdx, cdy; // c stands for current
103 // vectors that when added to (sx0,sy0) and (cx0,cy0) respectively yield the
104 // first and last points on the left parallel path. Since this path is
105 // parallel, it's slope at any point is parallel to the slope of the
106 // original path (thought they may have different directions), so these
107 // could be computed from sdx,sdy and cdx,cdy (and vice versa), but that
108 // would be error prone and hard to read, so we keep these anyway.
109 private double smx, smy, cmx, cmy;
110
111 private final PolyStack reverse;
112
113 // This is where the curve to be processed is put. We give it
114 // enough room to store all curves.
115 private final double[] middle = new double[MAX_N_CURVES * 6 + 2];
116 private final double[] lp = new double[8];
117 private final double[] rp = new double[8];
118 private final double[] subdivTs = new double[MAX_N_CURVES - 1];
119
120 // per-thread renderer context
121 final DRendererContext rdrCtx;
122
123 // dirty curve
124 final DCurve curve;
125
126 // Bounds of the drawing region, at pixel precision.
127 private double[] clipRect;
128
129 // the outcode of the current point
130 private int cOutCode = 0;
131
132 // the outcode of the starting point
133 private int sOutCode = 0;
134
135 // flag indicating if the path is opened (clipped)
136 private boolean opened = false;
137 // flag indicating if the starting point's cap is done
138 private boolean capStart = false;
139
140 /**
141 * Constructs a <code>DStroker</code>.
142 * @param rdrCtx per-thread renderer context
143 */
144 DStroker(final DRendererContext rdrCtx) {
145 this.rdrCtx = rdrCtx;
146
147 this.reverse = (rdrCtx.stats != null) ?
148 new PolyStack(rdrCtx,
149 rdrCtx.stats.stat_str_polystack_types,
150 rdrCtx.stats.stat_str_polystack_curves,
151 rdrCtx.stats.hist_str_polystack_curves,
152 rdrCtx.stats.stat_array_str_polystack_curves,
153 rdrCtx.stats.stat_array_str_polystack_types)
154 : new PolyStack(rdrCtx);
155
156 this.curve = rdrCtx.curve;
157 }
158
159 /**
160 * Inits the <code>DStroker</code>.
161 *
162 * @param pc2d an output <code>DPathConsumer2D</code>.
163 * @param lineWidth the desired line width in pixels
164 * @param capStyle the desired end cap style, one of
165 * <code>CAP_BUTT</code>, <code>CAP_ROUND</code> or
166 * <code>CAP_SQUARE</code>.
167 * @param joinStyle the desired line join style, one of
168 * <code>JOIN_MITER</code>, <code>JOIN_ROUND</code> or
169 * <code>JOIN_BEVEL</code>.
170 * @param miterLimit the desired miter limit
171 * @param scale scaling factor applied to clip boundaries
172 * @return this instance
173 */
174 DStroker init(final DPathConsumer2D pc2d,
175 final double lineWidth,
176 final int capStyle,
177 final int joinStyle,
178 final double miterLimit,
179 final double scale)
180 {
181 this.out = pc2d;
182
183 this.lineWidth2 = lineWidth / 2.0d;
184 this.invHalfLineWidth2Sq = 1.0d / (2.0d * lineWidth2 * lineWidth2);
185 this.capStyle = capStyle;
186 this.joinStyle = joinStyle;
187
188 final double limit = miterLimit * lineWidth2;
189 this.miterLimitSq = limit * limit;
190
191 this.prev = CLOSE;
192
193 rdrCtx.stroking = 1;
194
195 if (rdrCtx.doClip) {
196 // Adjust the clipping rectangle with the stroker margin (miter limit, width)
197 double rdrOffX = 0.0d, rdrOffY = 0.0d;
198 double margin = lineWidth2;
199
200 if (capStyle == CAP_SQUARE) {
201 margin *= SQRT_2;
202 }
203 if ((joinStyle == JOIN_MITER) && (margin < limit)) {
204 margin = limit;
205 }
206 if (scale != 1.0d) {
207 margin *= scale;
208 rdrOffX = scale * DRenderer.RDR_OFFSET_X;
209 rdrOffY = scale * DRenderer.RDR_OFFSET_Y;
210 }
211
212 // bounds as half-open intervals: minX <= x < maxX and minY <= y < maxY
213 // adjust clip rectangle (ymin, ymax, xmin, xmax):
214 final double[] _clipRect = rdrCtx.clipRect;
215 _clipRect[0] -= margin - rdrOffY;
216 _clipRect[1] += margin + rdrOffY;
217 _clipRect[2] -= margin - rdrOffX;
218 _clipRect[3] += margin + rdrOffX;
219 this.clipRect = _clipRect;
220 } else {
221 this.clipRect = null;
222 }
223 return this; // fluent API
224 }
225
226 /**
227 * Disposes this stroker:
228 * clean up before reusing this instance
229 */
230 void dispose() {
231 reverse.dispose();
232
233 opened = false;
234 capStart = false;
235
236 if (DO_CLEAN_DIRTY) {
237 // Force zero-fill dirty arrays:
238 Arrays.fill(offset0, 0.0d);
239 Arrays.fill(offset1, 0.0d);
240 Arrays.fill(offset2, 0.0d);
241 Arrays.fill(miter, 0.0d);
242 Arrays.fill(middle, 0.0d);
243 Arrays.fill(lp, 0.0d);
244 Arrays.fill(rp, 0.0d);
245 Arrays.fill(subdivTs, 0.0d);
246 }
247 }
248
249 private static void computeOffset(final double lx, final double ly,
250 final double w, final double[] m)
251 {
252 double len = lx*lx + ly*ly;
253 if (len == 0.0d) {
254 m[0] = 0.0d;
255 m[1] = 0.0d;
256 } else {
257 len = Math.sqrt(len);
258 m[0] = (ly * w) / len;
259 m[1] = -(lx * w) / len;
260 }
261 }
262
263 // Returns true if the vectors (dx1, dy1) and (dx2, dy2) are
264 // clockwise (if dx1,dy1 needs to be rotated clockwise to close
265 // the smallest angle between it and dx2,dy2).
266 // This is equivalent to detecting whether a point q is on the right side
267 // of a line passing through points p1, p2 where p2 = p1+(dx1,dy1) and
268 // q = p2+(dx2,dy2), which is the same as saying p1, p2, q are in a
269 // clockwise order.
270 // NOTE: "clockwise" here assumes coordinates with 0,0 at the bottom left.
271 private static boolean isCW(final double dx1, final double dy1,
272 final double dx2, final double dy2)
273 {
274 return dx1 * dy2 <= dy1 * dx2;
275 }
276
277 private void drawRoundJoin(double x, double y,
278 double omx, double omy, double mx, double my,
279 boolean rev,
280 double threshold)
281 {
282 if ((omx == 0.0d && omy == 0.0d) || (mx == 0.0d && my == 0.0d)) {
283 return;
284 }
285
286 double domx = omx - mx;
287 double domy = omy - my;
288 double len = domx*domx + domy*domy;
289 if (len < threshold) {
290 return;
291 }
292
293 if (rev) {
294 omx = -omx;
295 omy = -omy;
296 mx = -mx;
297 my = -my;
298 }
299 drawRoundJoin(x, y, omx, omy, mx, my, rev);
300 }
301
302 private void drawRoundJoin(double cx, double cy,
303 double omx, double omy,
304 double mx, double my,
305 boolean rev)
306 {
307 // The sign of the dot product of mx,my and omx,omy is equal to the
308 // the sign of the cosine of ext
309 // (ext is the angle between omx,omy and mx,my).
310 final double cosext = omx * mx + omy * my;
311 // If it is >=0, we know that abs(ext) is <= 90 degrees, so we only
312 // need 1 curve to approximate the circle section that joins omx,omy
313 // and mx,my.
314 final int numCurves = (cosext >= 0.0d) ? 1 : 2;
315
316 switch (numCurves) {
317 case 1:
318 drawBezApproxForArc(cx, cy, omx, omy, mx, my, rev);
319 break;
320 case 2:
321 // we need to split the arc into 2 arcs spanning the same angle.
322 // The point we want will be one of the 2 intersections of the
323 // perpendicular bisector of the chord (omx,omy)->(mx,my) and the
324 // circle. We could find this by scaling the vector
325 // (omx+mx, omy+my)/2 so that it has length=lineWidth2 (and thus lies
326 // on the circle), but that can have numerical problems when the angle
327 // between omx,omy and mx,my is close to 180 degrees. So we compute a
328 // normal of (omx,omy)-(mx,my). This will be the direction of the
329 // perpendicular bisector. To get one of the intersections, we just scale
330 // this vector that its length is lineWidth2 (this works because the
331 // perpendicular bisector goes through the origin). This scaling doesn't
332 // have numerical problems because we know that lineWidth2 divided by
333 // this normal's length is at least 0.5 and at most sqrt(2)/2 (because
334 // we know the angle of the arc is > 90 degrees).
335 double nx = my - omy, ny = omx - mx;
336 double nlen = Math.sqrt(nx*nx + ny*ny);
337 double scale = lineWidth2/nlen;
338 double mmx = nx * scale, mmy = ny * scale;
339
340 // if (isCW(omx, omy, mx, my) != isCW(mmx, mmy, mx, my)) then we've
341 // computed the wrong intersection so we get the other one.
342 // The test above is equivalent to if (rev).
343 if (rev) {
344 mmx = -mmx;
345 mmy = -mmy;
346 }
347 drawBezApproxForArc(cx, cy, omx, omy, mmx, mmy, rev);
348 drawBezApproxForArc(cx, cy, mmx, mmy, mx, my, rev);
349 break;
350 default:
351 }
352 }
353
354 // the input arc defined by omx,omy and mx,my must span <= 90 degrees.
355 private void drawBezApproxForArc(final double cx, final double cy,
356 final double omx, final double omy,
357 final double mx, final double my,
358 boolean rev)
359 {
360 final double cosext2 = (omx * mx + omy * my) * invHalfLineWidth2Sq;
361
362 // check round off errors producing cos(ext) > 1 and a NaN below
363 // cos(ext) == 1 implies colinear segments and an empty join anyway
364 if (cosext2 >= 0.5d) {
365 // just return to avoid generating a flat curve:
366 return;
367 }
368
369 // cv is the length of P1-P0 and P2-P3 divided by the radius of the arc
370 // (so, cv assumes the arc has radius 1). P0, P1, P2, P3 are the points that
371 // define the bezier curve we're computing.
372 // It is computed using the constraints that P1-P0 and P3-P2 are parallel
373 // to the arc tangents at the endpoints, and that |P1-P0|=|P3-P2|.
374 double cv = ((4.0d / 3.0d) * Math.sqrt(0.5d - cosext2) /
375 (1.0d + Math.sqrt(cosext2 + 0.5d)));
376 // if clockwise, we need to negate cv.
377 if (rev) { // rev is equivalent to isCW(omx, omy, mx, my)
378 cv = -cv;
379 }
380 final double x1 = cx + omx;
381 final double y1 = cy + omy;
382 final double x2 = x1 - cv * omy;
383 final double y2 = y1 + cv * omx;
384
385 final double x4 = cx + mx;
386 final double y4 = cy + my;
387 final double x3 = x4 + cv * my;
388 final double y3 = y4 - cv * mx;
389
390 emitCurveTo(x1, y1, x2, y2, x3, y3, x4, y4, rev);
391 }
392
393 private void drawRoundCap(double cx, double cy, double mx, double my) {
394 final double Cmx = C * mx;
395 final double Cmy = C * my;
396 emitCurveTo(cx + mx - Cmy, cy + my + Cmx,
397 cx - my + Cmx, cy + mx + Cmy,
398 cx - my, cy + mx);
399 emitCurveTo(cx - my - Cmx, cy + mx - Cmy,
400 cx - mx - Cmy, cy - my + Cmx,
401 cx - mx, cy - my);
402 }
403
404 // Return the intersection point of the lines (x0, y0) -> (x1, y1)
405 // and (x0p, y0p) -> (x1p, y1p) in m[off] and m[off+1]
406 private static void computeMiter(final double x0, final double y0,
407 final double x1, final double y1,
408 final double x0p, final double y0p,
409 final double x1p, final double y1p,
410 final double[] m, int off)
411 {
412 double x10 = x1 - x0;
413 double y10 = y1 - y0;
414 double x10p = x1p - x0p;
415 double y10p = y1p - y0p;
416
417 // if this is 0, the lines are parallel. If they go in the
418 // same direction, there is no intersection so m[off] and
419 // m[off+1] will contain infinity, so no miter will be drawn.
420 // If they go in the same direction that means that the start of the
421 // current segment and the end of the previous segment have the same
422 // tangent, in which case this method won't even be involved in
423 // miter drawing because it won't be called by drawMiter (because
424 // (mx == omx && my == omy) will be true, and drawMiter will return
425 // immediately).
426 double den = x10*y10p - x10p*y10;
427 double t = x10p*(y0-y0p) - y10p*(x0-x0p);
428 t /= den;
429 m[off++] = x0 + t*x10;
430 m[off] = y0 + t*y10;
431 }
432
433 // Return the intersection point of the lines (x0, y0) -> (x1, y1)
434 // and (x0p, y0p) -> (x1p, y1p) in m[off] and m[off+1]
435 private static void safeComputeMiter(final double x0, final double y0,
436 final double x1, final double y1,
437 final double x0p, final double y0p,
438 final double x1p, final double y1p,
439 final double[] m, int off)
440 {
441 double x10 = x1 - x0;
442 double y10 = y1 - y0;
443 double x10p = x1p - x0p;
444 double y10p = y1p - y0p;
445
446 // if this is 0, the lines are parallel. If they go in the
447 // same direction, there is no intersection so m[off] and
448 // m[off+1] will contain infinity, so no miter will be drawn.
449 // If they go in the same direction that means that the start of the
450 // current segment and the end of the previous segment have the same
451 // tangent, in which case this method won't even be involved in
452 // miter drawing because it won't be called by drawMiter (because
453 // (mx == omx && my == omy) will be true, and drawMiter will return
454 // immediately).
455 double den = x10*y10p - x10p*y10;
456 if (den == 0.0d) {
457 m[off++] = (x0 + x0p) / 2.0d;
458 m[off] = (y0 + y0p) / 2.0d;
459 return;
460 }
461 double t = x10p*(y0-y0p) - y10p*(x0-x0p);
462 t /= den;
463 m[off++] = x0 + t*x10;
464 m[off] = y0 + t*y10;
465 }
466
467 private void drawMiter(final double pdx, final double pdy,
468 final double x0, final double y0,
469 final double dx, final double dy,
470 double omx, double omy, double mx, double my,
471 boolean rev)
472 {
473 if ((mx == omx && my == omy) ||
474 (pdx == 0.0d && pdy == 0.0d) ||
475 (dx == 0.0d && dy == 0.0d))
476 {
477 return;
478 }
479
480 if (rev) {
481 omx = -omx;
482 omy = -omy;
483 mx = -mx;
484 my = -my;
485 }
486
487 computeMiter((x0 - pdx) + omx, (y0 - pdy) + omy, x0 + omx, y0 + omy,
488 (dx + x0) + mx, (dy + y0) + my, x0 + mx, y0 + my,
489 miter, 0);
490
491 final double miterX = miter[0];
492 final double miterY = miter[1];
493 double lenSq = (miterX-x0)*(miterX-x0) + (miterY-y0)*(miterY-y0);
494
495 // If the lines are parallel, lenSq will be either NaN or +inf
496 // (actually, I'm not sure if the latter is possible. The important
497 // thing is that -inf is not possible, because lenSq is a square).
498 // For both of those values, the comparison below will fail and
499 // no miter will be drawn, which is correct.
500 if (lenSq < miterLimitSq) {
501 emitLineTo(miterX, miterY, rev);
502 }
503 }
504
505 @Override
506 public void moveTo(final double x0, final double y0) {
507 moveTo(x0, y0, cOutCode);
508 // update starting point:
509 this.sx0 = x0;
510 this.sy0 = y0;
511 this.sdx = 1.0d;
512 this.sdy = 0.0d;
513 this.opened = false;
514 this.capStart = false;
515
516 if (clipRect != null) {
517 final int outcode = DHelpers.outcode(x0, y0, clipRect);
518 this.cOutCode = outcode;
519 this.sOutCode = outcode;
520 }
521 }
522
523 private void moveTo(final double x0, final double y0,
524 final int outcode)
525 {
526 if (prev == MOVE_TO) {
527 this.cx0 = x0;
528 this.cy0 = y0;
529 } else {
530 if (prev == DRAWING_OP_TO) {
531 finish(outcode);
532 }
533 this.prev = MOVE_TO;
534 this.cx0 = x0;
535 this.cy0 = y0;
536 this.cdx = 1.0d;
537 this.cdy = 0.0d;
538 }
539 }
540
541 @Override
542 public void lineTo(final double x1, final double y1) {
543 lineTo(x1, y1, false);
544 }
545
546 private void lineTo(final double x1, final double y1,
547 final boolean force)
548 {
549 final int outcode0 = this.cOutCode;
550 if (!force && clipRect != null) {
551 final int outcode1 = DHelpers.outcode(x1, y1, clipRect);
552 this.cOutCode = outcode1;
553
554 // basic rejection criteria
555 if ((outcode0 & outcode1) != 0) {
556 moveTo(x1, y1, outcode0);
557 opened = true;
558 return;
559 }
560 }
561
562 double dx = x1 - cx0;
563 double dy = y1 - cy0;
564 if (dx == 0.0d && dy == 0.0d) {
565 dx = 1.0d;
566 }
567 computeOffset(dx, dy, lineWidth2, offset0);
568 final double mx = offset0[0];
569 final double my = offset0[1];
570
571 drawJoin(cdx, cdy, cx0, cy0, dx, dy, cmx, cmy, mx, my, outcode0);
572
573 emitLineTo(cx0 + mx, cy0 + my);
574 emitLineTo( x1 + mx, y1 + my);
575
576 emitLineToRev(cx0 - mx, cy0 - my);
577 emitLineToRev( x1 - mx, y1 - my);
578
579 this.prev = DRAWING_OP_TO;
580 this.cx0 = x1;
581 this.cy0 = y1;
582 this.cdx = dx;
583 this.cdy = dy;
584 this.cmx = mx;
585 this.cmy = my;
586 }
587
588 @Override
589 public void closePath() {
590 // distinguish empty path at all vs opened path ?
591 if (prev != DRAWING_OP_TO && !opened) {
592 if (prev == CLOSE) {
593 return;
594 }
595 emitMoveTo(cx0, cy0 - lineWidth2);
596
597 this.sdx = 1.0d;
598 this.sdy = 0.0d;
599 this.cdx = 1.0d;
600 this.cdy = 0.0d;
601
602 this.smx = 0.0d;
603 this.smy = -lineWidth2;
604 this.cmx = 0.0d;
605 this.cmy = -lineWidth2;
606
607 finish(cOutCode);
608 return;
609 }
610
611 if (sOutCode == 0) {
612 if (cx0 != sx0 || cy0 != sy0) {
613 lineTo(sx0, sy0, true);
614 }
615
616 drawJoin(cdx, cdy, cx0, cy0, sdx, sdy, cmx, cmy, smx, smy, cOutCode);
617
618 emitLineTo(sx0 + smx, sy0 + smy);
619
620 if (opened) {
621 emitLineTo(sx0 - smx, sy0 - smy);
622 } else {
623 emitMoveTo(sx0 - smx, sy0 - smy);
624 }
625 }
626 // Ignore caps like finish(false)
627 emitReverse();
628
629 this.prev = CLOSE;
630
631 if (opened) {
632 // do not emit close
633 opened = false;
634 } else {
635 emitClose();
636 }
637 }
638
639 private void emitReverse() {
640 reverse.popAll(out);
641 }
642
643 @Override
644 public void pathDone() {
645 if (prev == DRAWING_OP_TO) {
646 finish(cOutCode);
647 }
648
649 out.pathDone();
650
651 // this shouldn't matter since this object won't be used
652 // after the call to this method.
653 this.prev = CLOSE;
654
655 // Dispose this instance:
656 dispose();
657 }
658
659 private void finish(final int outcode) {
660 // Problem: impossible to guess if the path will be closed in advance
661 // i.e. if caps must be drawn or not ?
662 // Solution: use the ClosedPathDetector before Stroker to determine
663 // if the path is a closed path or not
664 if (!rdrCtx.closedPath) {
665 if (outcode == 0) {
666 // current point = end's cap:
667 if (capStyle == CAP_ROUND) {
668 drawRoundCap(cx0, cy0, cmx, cmy);
669 } else if (capStyle == CAP_SQUARE) {
670 emitLineTo(cx0 - cmy + cmx, cy0 + cmx + cmy);
671 emitLineTo(cx0 - cmy - cmx, cy0 + cmx - cmy);
672 }
673 }
674 emitReverse();
675
676 if (!capStart) {
677 capStart = true;
678
679 if (sOutCode == 0) {
680 // starting point = initial cap:
681 if (capStyle == CAP_ROUND) {
682 drawRoundCap(sx0, sy0, -smx, -smy);
683 } else if (capStyle == CAP_SQUARE) {
684 emitLineTo(sx0 + smy - smx, sy0 - smx - smy);
685 emitLineTo(sx0 + smy + smx, sy0 - smx + smy);
686 }
687 }
688 }
689 } else {
690 emitReverse();
691 }
692 emitClose();
693 }
694
695 private void emitMoveTo(final double x0, final double y0) {
696 out.moveTo(x0, y0);
697 }
698
699 private void emitLineTo(final double x1, final double y1) {
700 out.lineTo(x1, y1);
701 }
702
703 private void emitLineToRev(final double x1, final double y1) {
704 reverse.pushLine(x1, y1);
705 }
706
707 private void emitLineTo(final double x1, final double y1,
708 final boolean rev)
709 {
710 if (rev) {
711 emitLineToRev(x1, y1);
712 } else {
713 emitLineTo(x1, y1);
714 }
715 }
716
717 private void emitQuadTo(final double x1, final double y1,
718 final double x2, final double y2)
719 {
720 out.quadTo(x1, y1, x2, y2);
721 }
722
723 private void emitQuadToRev(final double x0, final double y0,
724 final double x1, final double y1)
725 {
726 reverse.pushQuad(x0, y0, x1, y1);
727 }
728
729 private void emitCurveTo(final double x1, final double y1,
730 final double x2, final double y2,
731 final double x3, final double y3)
732 {
733 out.curveTo(x1, y1, x2, y2, x3, y3);
734 }
735
736 private void emitCurveToRev(final double x0, final double y0,
737 final double x1, final double y1,
738 final double x2, final double y2)
739 {
740 reverse.pushCubic(x0, y0, x1, y1, x2, y2);
741 }
742
743 private void emitCurveTo(final double x0, final double y0,
744 final double x1, final double y1,
745 final double x2, final double y2,
746 final double x3, final double y3, final boolean rev)
747 {
748 if (rev) {
749 reverse.pushCubic(x0, y0, x1, y1, x2, y2);
750 } else {
751 out.curveTo(x1, y1, x2, y2, x3, y3);
752 }
753 }
754
755 private void emitClose() {
756 out.closePath();
757 }
758
759 private void drawJoin(double pdx, double pdy,
760 double x0, double y0,
761 double dx, double dy,
762 double omx, double omy,
763 double mx, double my,
764 final int outcode)
765 {
766 if (prev != DRAWING_OP_TO) {
767 emitMoveTo(x0 + mx, y0 + my);
768 if (!opened) {
769 this.sdx = dx;
770 this.sdy = dy;
771 this.smx = mx;
772 this.smy = my;
773 }
774 } else {
775 final boolean cw = isCW(pdx, pdy, dx, dy);
776 if (outcode == 0) {
777 if (joinStyle == JOIN_MITER) {
778 drawMiter(pdx, pdy, x0, y0, dx, dy, omx, omy, mx, my, cw);
779 } else if (joinStyle == JOIN_ROUND) {
780 drawRoundJoin(x0, y0,
781 omx, omy,
782 mx, my, cw,
783 ROUND_JOIN_THRESHOLD);
784 }
785 }
786 emitLineTo(x0, y0, !cw);
787 }
788 prev = DRAWING_OP_TO;
789 }
790
791 private static boolean within(final double x1, final double y1,
792 final double x2, final double y2,
793 final double ERR)
794 {
795 assert ERR > 0 : "";
796 // compare taxicab distance. ERR will always be small, so using
797 // true distance won't give much benefit
798 return (DHelpers.within(x1, x2, ERR) && // we want to avoid calling Math.abs
799 DHelpers.within(y1, y2, ERR)); // this is just as good.
800 }
801
802 private void getLineOffsets(double x1, double y1,
803 double x2, double y2,
804 double[] left, double[] right) {
805 computeOffset(x2 - x1, y2 - y1, lineWidth2, offset0);
806 final double mx = offset0[0];
807 final double my = offset0[1];
808 left[0] = x1 + mx;
809 left[1] = y1 + my;
810 left[2] = x2 + mx;
811 left[3] = y2 + my;
812 right[0] = x1 - mx;
813 right[1] = y1 - my;
814 right[2] = x2 - mx;
815 right[3] = y2 - my;
816 }
817
818 private int computeOffsetCubic(double[] pts, final int off,
819 double[] leftOff, double[] rightOff)
820 {
821 // if p1=p2 or p3=p4 it means that the derivative at the endpoint
822 // vanishes, which creates problems with computeOffset. Usually
823 // this happens when this stroker object is trying to widen
824 // a curve with a cusp. What happens is that curveTo splits
825 // the input curve at the cusp, and passes it to this function.
826 // because of inaccuracies in the splitting, we consider points
827 // equal if they're very close to each other.
828 final double x1 = pts[off + 0], y1 = pts[off + 1];
829 final double x2 = pts[off + 2], y2 = pts[off + 3];
830 final double x3 = pts[off + 4], y3 = pts[off + 5];
831 final double x4 = pts[off + 6], y4 = pts[off + 7];
832
833 double dx4 = x4 - x3;
834 double dy4 = y4 - y3;
835 double dx1 = x2 - x1;
836 double dy1 = y2 - y1;
837
838 // if p1 == p2 && p3 == p4: draw line from p1->p4, unless p1 == p4,
839 // in which case ignore if p1 == p2
840 final boolean p1eqp2 = within(x1, y1, x2, y2, 6.0d * Math.ulp(y2));
841 final boolean p3eqp4 = within(x3, y3, x4, y4, 6.0d * Math.ulp(y4));
842 if (p1eqp2 && p3eqp4) {
843 getLineOffsets(x1, y1, x4, y4, leftOff, rightOff);
844 return 4;
845 } else if (p1eqp2) {
846 dx1 = x3 - x1;
847 dy1 = y3 - y1;
848 } else if (p3eqp4) {
849 dx4 = x4 - x2;
850 dy4 = y4 - y2;
851 }
852
853 // if p2-p1 and p4-p3 are parallel, that must mean this curve is a line
854 double dotsq = (dx1 * dx4 + dy1 * dy4);
855 dotsq *= dotsq;
856 double l1sq = dx1 * dx1 + dy1 * dy1, l4sq = dx4 * dx4 + dy4 * dy4;
857 if (DHelpers.within(dotsq, l1sq * l4sq, 4.0d * Math.ulp(dotsq))) {
858 getLineOffsets(x1, y1, x4, y4, leftOff, rightOff);
859 return 4;
860 }
861
862 // What we're trying to do in this function is to approximate an ideal
863 // offset curve (call it I) of the input curve B using a bezier curve Bp.
864 // The constraints I use to get the equations are:
865 //
866 // 1. The computed curve Bp should go through I(0) and I(1). These are
867 // x1p, y1p, x4p, y4p, which are p1p and p4p. We still need to find
868 // 4 variables: the x and y components of p2p and p3p (i.e. x2p, y2p, x3p, y3p).
869 //
870 // 2. Bp should have slope equal in absolute value to I at the endpoints. So,
871 // (by the way, the operator || in the comments below means "aligned with".
872 // It is defined on vectors, so when we say I'(0) || Bp'(0) we mean that
873 // vectors I'(0) and Bp'(0) are aligned, which is the same as saying
874 // that the tangent lines of I and Bp at 0 are parallel. Mathematically
875 // this means (I'(t) || Bp'(t)) <==> (I'(t) = c * Bp'(t)) where c is some
876 // nonzero constant.)
877 // I'(0) || Bp'(0) and I'(1) || Bp'(1). Obviously, I'(0) || B'(0) and
878 // I'(1) || B'(1); therefore, Bp'(0) || B'(0) and Bp'(1) || B'(1).
879 // We know that Bp'(0) || (p2p-p1p) and Bp'(1) || (p4p-p3p) and the same
880 // is true for any bezier curve; therefore, we get the equations
881 // (1) p2p = c1 * (p2-p1) + p1p
882 // (2) p3p = c2 * (p4-p3) + p4p
883 // We know p1p, p4p, p2, p1, p3, and p4; therefore, this reduces the number
884 // of unknowns from 4 to 2 (i.e. just c1 and c2).
885 // To eliminate these 2 unknowns we use the following constraint:
886 //
887 // 3. Bp(0.5) == I(0.5). Bp(0.5)=(x,y) and I(0.5)=(xi,yi), and I should note
888 // that I(0.5) is *the only* reason for computing dxm,dym. This gives us
889 // (3) Bp(0.5) = (p1p + 3 * (p2p + p3p) + p4p)/8, which is equivalent to
890 // (4) p2p + p3p = (Bp(0.5)*8 - p1p - p4p) / 3
891 // We can substitute (1) and (2) from above into (4) and we get:
892 // (5) c1*(p2-p1) + c2*(p4-p3) = (Bp(0.5)*8 - p1p - p4p)/3 - p1p - p4p
893 // which is equivalent to
894 // (6) c1*(p2-p1) + c2*(p4-p3) = (4/3) * (Bp(0.5) * 2 - p1p - p4p)
895 //
896 // The right side of this is a 2D vector, and we know I(0.5), which gives us
897 // Bp(0.5), which gives us the value of the right side.
898 // The left side is just a matrix vector multiplication in disguise. It is
899 //
900 // [x2-x1, x4-x3][c1]
901 // [y2-y1, y4-y3][c2]
902 // which, is equal to
903 // [dx1, dx4][c1]
904 // [dy1, dy4][c2]
905 // At this point we are left with a simple linear system and we solve it by
906 // getting the inverse of the matrix above. Then we use [c1,c2] to compute
907 // p2p and p3p.
908
909 double x = (x1 + 3.0d * (x2 + x3) + x4) / 8.0d;
910 double y = (y1 + 3.0d * (y2 + y3) + y4) / 8.0d;
911 // (dxm,dym) is some tangent of B at t=0.5. This means it's equal to
912 // c*B'(0.5) for some constant c.
913 double dxm = x3 + x4 - x1 - x2, dym = y3 + y4 - y1 - y2;
914
915 // this computes the offsets at t=0, 0.5, 1, using the property that
916 // for any bezier curve the vectors p2-p1 and p4-p3 are parallel to
917 // the (dx/dt, dy/dt) vectors at the endpoints.
918 computeOffset(dx1, dy1, lineWidth2, offset0);
919 computeOffset(dxm, dym, lineWidth2, offset1);
920 computeOffset(dx4, dy4, lineWidth2, offset2);
921 double x1p = x1 + offset0[0]; // start
922 double y1p = y1 + offset0[1]; // point
923 double xi = x + offset1[0]; // interpolation
924 double yi = y + offset1[1]; // point
925 double x4p = x4 + offset2[0]; // end
926 double y4p = y4 + offset2[1]; // point
927
928 double invdet43 = 4.0d / (3.0d * (dx1 * dy4 - dy1 * dx4));
929
930 double two_pi_m_p1_m_p4x = 2.0d * xi - x1p - x4p;
931 double two_pi_m_p1_m_p4y = 2.0d * yi - y1p - y4p;
932 double c1 = invdet43 * (dy4 * two_pi_m_p1_m_p4x - dx4 * two_pi_m_p1_m_p4y);
933 double c2 = invdet43 * (dx1 * two_pi_m_p1_m_p4y - dy1 * two_pi_m_p1_m_p4x);
934
935 double x2p, y2p, x3p, y3p;
936 x2p = x1p + c1*dx1;
937 y2p = y1p + c1*dy1;
938 x3p = x4p + c2*dx4;
939 y3p = y4p + c2*dy4;
940
941 leftOff[0] = x1p; leftOff[1] = y1p;
942 leftOff[2] = x2p; leftOff[3] = y2p;
943 leftOff[4] = x3p; leftOff[5] = y3p;
944 leftOff[6] = x4p; leftOff[7] = y4p;
945
946 x1p = x1 - offset0[0]; y1p = y1 - offset0[1];
947 xi = xi - 2.0d * offset1[0]; yi = yi - 2.0d * offset1[1];
948 x4p = x4 - offset2[0]; y4p = y4 - offset2[1];
949
950 two_pi_m_p1_m_p4x = 2.0d * xi - x1p - x4p;
951 two_pi_m_p1_m_p4y = 2.0d * yi - y1p - y4p;
952 c1 = invdet43 * (dy4 * two_pi_m_p1_m_p4x - dx4 * two_pi_m_p1_m_p4y);
953 c2 = invdet43 * (dx1 * two_pi_m_p1_m_p4y - dy1 * two_pi_m_p1_m_p4x);
954
955 x2p = x1p + c1*dx1;
956 y2p = y1p + c1*dy1;
957 x3p = x4p + c2*dx4;
958 y3p = y4p + c2*dy4;
959
960 rightOff[0] = x1p; rightOff[1] = y1p;
961 rightOff[2] = x2p; rightOff[3] = y2p;
962 rightOff[4] = x3p; rightOff[5] = y3p;
963 rightOff[6] = x4p; rightOff[7] = y4p;
964 return 8;
965 }
966
967 // compute offset curves using bezier spline through t=0.5 (i.e.
968 // ComputedCurve(0.5) == IdealParallelCurve(0.5))
969 // return the kind of curve in the right and left arrays.
970 private int computeOffsetQuad(double[] pts, final int off,
971 double[] leftOff, double[] rightOff)
972 {
973 final double x1 = pts[off + 0], y1 = pts[off + 1];
974 final double x2 = pts[off + 2], y2 = pts[off + 3];
975 final double x3 = pts[off + 4], y3 = pts[off + 5];
976
977 final double dx3 = x3 - x2;
978 final double dy3 = y3 - y2;
979 final double dx1 = x2 - x1;
980 final double dy1 = y2 - y1;
981
982 // if p1=p2 or p3=p4 it means that the derivative at the endpoint
983 // vanishes, which creates problems with computeOffset. Usually
984 // this happens when this stroker object is trying to widen
985 // a curve with a cusp. What happens is that curveTo splits
986 // the input curve at the cusp, and passes it to this function.
987 // because of inaccuracies in the splitting, we consider points
988 // equal if they're very close to each other.
989
990 // if p1 == p2 && p3 == p4: draw line from p1->p4, unless p1 == p4,
991 // in which case ignore.
992 final boolean p1eqp2 = within(x1, y1, x2, y2, 6.0d * Math.ulp(y2));
993 final boolean p2eqp3 = within(x2, y2, x3, y3, 6.0d * Math.ulp(y3));
994 if (p1eqp2 || p2eqp3) {
995 getLineOffsets(x1, y1, x3, y3, leftOff, rightOff);
996 return 4;
997 }
998
999 // if p2-p1 and p4-p3 are parallel, that must mean this curve is a line
1000 double dotsq = (dx1 * dx3 + dy1 * dy3);
1001 dotsq *= dotsq;
1002 double l1sq = dx1 * dx1 + dy1 * dy1, l3sq = dx3 * dx3 + dy3 * dy3;
1003 if (DHelpers.within(dotsq, l1sq * l3sq, 4.0d * Math.ulp(dotsq))) {
1004 getLineOffsets(x1, y1, x3, y3, leftOff, rightOff);
1005 return 4;
1006 }
1007
1008 // this computes the offsets at t=0, 0.5, 1, using the property that
1009 // for any bezier curve the vectors p2-p1 and p4-p3 are parallel to
1010 // the (dx/dt, dy/dt) vectors at the endpoints.
1011 computeOffset(dx1, dy1, lineWidth2, offset0);
1012 computeOffset(dx3, dy3, lineWidth2, offset1);
1013
1014 double x1p = x1 + offset0[0]; // start
1015 double y1p = y1 + offset0[1]; // point
1016 double x3p = x3 + offset1[0]; // end
1017 double y3p = y3 + offset1[1]; // point
1018 safeComputeMiter(x1p, y1p, x1p+dx1, y1p+dy1, x3p, y3p, x3p-dx3, y3p-dy3, leftOff, 2);
1019 leftOff[0] = x1p; leftOff[1] = y1p;
1020 leftOff[4] = x3p; leftOff[5] = y3p;
1021
1022 x1p = x1 - offset0[0]; y1p = y1 - offset0[1];
1023 x3p = x3 - offset1[0]; y3p = y3 - offset1[1];
1024 safeComputeMiter(x1p, y1p, x1p+dx1, y1p+dy1, x3p, y3p, x3p-dx3, y3p-dy3, rightOff, 2);
1025 rightOff[0] = x1p; rightOff[1] = y1p;
1026 rightOff[4] = x3p; rightOff[5] = y3p;
1027 return 6;
1028 }
1029
1030 // finds values of t where the curve in pts should be subdivided in order
1031 // to get good offset curves a distance of w away from the middle curve.
1032 // Stores the points in ts, and returns how many of them there were.
1033 private static int findSubdivPoints(final DCurve c, double[] pts, double[] ts,
1034 final int type, final double w)
1035 {
1036 final double x12 = pts[2] - pts[0];
1037 final double y12 = pts[3] - pts[1];
1038 // if the curve is already parallel to either axis we gain nothing
1039 // from rotating it.
1040 if (y12 != 0.0d && x12 != 0.0d) {
1041 // we rotate it so that the first vector in the control polygon is
1042 // parallel to the x-axis. This will ensure that rotated quarter
1043 // circles won't be subdivided.
1044 final double hypot = Math.sqrt(x12 * x12 + y12 * y12);
1045 final double cos = x12 / hypot;
1046 final double sin = y12 / hypot;
1047 final double x1 = cos * pts[0] + sin * pts[1];
1048 final double y1 = cos * pts[1] - sin * pts[0];
1049 final double x2 = cos * pts[2] + sin * pts[3];
1050 final double y2 = cos * pts[3] - sin * pts[2];
1051 final double x3 = cos * pts[4] + sin * pts[5];
1052 final double y3 = cos * pts[5] - sin * pts[4];
1053
1054 switch(type) {
1055 case 8:
1056 final double x4 = cos * pts[6] + sin * pts[7];
1057 final double y4 = cos * pts[7] - sin * pts[6];
1058 c.set(x1, y1, x2, y2, x3, y3, x4, y4);
1059 break;
1060 case 6:
1061 c.set(x1, y1, x2, y2, x3, y3);
1062 break;
1063 default:
1064 }
1065 } else {
1066 c.set(pts, type);
1067 }
1068
1069 int ret = 0;
1070 // we subdivide at values of t such that the remaining rotated
1071 // curves are monotonic in x and y.
1072 ret += c.dxRoots(ts, ret);
1073 ret += c.dyRoots(ts, ret);
1074 // subdivide at inflection points.
1075 if (type == 8) {
1076 // quadratic curves can't have inflection points
1077 ret += c.infPoints(ts, ret);
1078 }
1079
1080 // now we must subdivide at points where one of the offset curves will have
1081 // a cusp. This happens at ts where the radius of curvature is equal to w.
1082 ret += c.rootsOfROCMinusW(ts, ret, w, 0.0001d);
1083
1084 ret = DHelpers.filterOutNotInAB(ts, 0, ret, 0.0001d, 0.9999d);
1085 DHelpers.isort(ts, 0, ret);
1086 return ret;
1087 }
1088
1089 @Override
1090 public void curveTo(final double x1, final double y1,
1091 final double x2, final double y2,
1092 final double x3, final double y3)
1093 {
1094 final int outcode0 = this.cOutCode;
1095 if (clipRect != null) {
1096 final int outcode3 = DHelpers.outcode(x3, y3, clipRect);
1097 this.cOutCode = outcode3;
1098
1099 if (outcode3 != 0) {
1100 final int outcode1 = DHelpers.outcode(x1, y1, clipRect);
1101 final int outcode2 = DHelpers.outcode(x2, y2, clipRect);
1102
1103 // basic rejection criteria
1104 if ((outcode0 & outcode1 & outcode2 & outcode3) != 0) {
1105 moveTo(x3, y3, outcode0);
1106 opened = true;
1107 return;
1108 }
1109 }
1110 }
1111
1112 final double[] mid = middle;
1113
1114 mid[0] = cx0; mid[1] = cy0;
1115 mid[2] = x1; mid[3] = y1;
1116 mid[4] = x2; mid[5] = y2;
1117 mid[6] = x3; mid[7] = y3;
1118
1119 // need these so we can update the state at the end of this method
1120 final double xf = x3, yf = y3;
1121 double dxs = mid[2] - mid[0];
1122 double dys = mid[3] - mid[1];
1123 double dxf = mid[6] - mid[4];
1124 double dyf = mid[7] - mid[5];
1125
1126 boolean p1eqp2 = (dxs == 0.0d && dys == 0.0d);
1127 boolean p3eqp4 = (dxf == 0.0d && dyf == 0.0d);
1128 if (p1eqp2) {
1129 dxs = mid[4] - mid[0];
1130 dys = mid[5] - mid[1];
1131 if (dxs == 0.0d && dys == 0.0d) {
1132 dxs = mid[6] - mid[0];
1133 dys = mid[7] - mid[1];
1134 }
1135 }
1136 if (p3eqp4) {
1137 dxf = mid[6] - mid[2];
1138 dyf = mid[7] - mid[3];
1139 if (dxf == 0.0d && dyf == 0.0d) {
1140 dxf = mid[6] - mid[0];
1141 dyf = mid[7] - mid[1];
1142 }
1143 }
1144 if (dxs == 0.0d && dys == 0.0d) {
1145 // this happens if the "curve" is just a point
1146 // fix outcode0 for lineTo() call:
1147 if (clipRect != null) {
1148 this.cOutCode = outcode0;
1149 }
1150 lineTo(mid[0], mid[1]);
1151 return;
1152 }
1153
1154 // if these vectors are too small, normalize them, to avoid future
1155 // precision problems.
1156 if (Math.abs(dxs) < 0.1d && Math.abs(dys) < 0.1d) {
1157 double len = Math.sqrt(dxs*dxs + dys*dys);
1158 dxs /= len;
1159 dys /= len;
1160 }
1161 if (Math.abs(dxf) < 0.1d && Math.abs(dyf) < 0.1d) {
1162 double len = Math.sqrt(dxf*dxf + dyf*dyf);
1163 dxf /= len;
1164 dyf /= len;
1165 }
1166
1167 computeOffset(dxs, dys, lineWidth2, offset0);
1168 drawJoin(cdx, cdy, cx0, cy0, dxs, dys, cmx, cmy, offset0[0], offset0[1], outcode0);
1169
1170 final int nSplits = findSubdivPoints(curve, mid, subdivTs, 8, lineWidth2);
1171
1172 double prevT = 0.0d;
1173 for (int i = 0, off = 0; i < nSplits; i++, off += 6) {
1174 final double t = subdivTs[i];
1175 DHelpers.subdivideCubicAt((t - prevT) / (1.0d - prevT),
1176 mid, off, mid, off, mid, off + 6);
1177 prevT = t;
1178 }
1179
1180 final double[] l = lp;
1181 final double[] r = rp;
1182
1183 int kind = 0;
1184 for (int i = 0, off = 0; i <= nSplits; i++, off += 6) {
1185 kind = computeOffsetCubic(mid, off, l, r);
1186
1187 emitLineTo(l[0], l[1]);
1188
1189 switch(kind) {
1190 case 8:
1191 emitCurveTo(l[2], l[3], l[4], l[5], l[6], l[7]);
1192 emitCurveToRev(r[0], r[1], r[2], r[3], r[4], r[5]);
1193 break;
1194 case 4:
1195 emitLineTo(l[2], l[3]);
1196 emitLineToRev(r[0], r[1]);
1197 break;
1198 default:
1199 }
1200 emitLineToRev(r[kind - 2], r[kind - 1]);
1201 }
1202
1203 this.prev = DRAWING_OP_TO;
1204 this.cx0 = xf;
1205 this.cy0 = yf;
1206 this.cdx = dxf;
1207 this.cdy = dyf;
1208 this.cmx = (l[kind - 2] - r[kind - 2]) / 2.0d;
1209 this.cmy = (l[kind - 1] - r[kind - 1]) / 2.0d;
1210 }
1211
1212 @Override
1213 public void quadTo(final double x1, final double y1,
1214 final double x2, final double y2)
1215 {
1216 final int outcode0 = this.cOutCode;
1217 if (clipRect != null) {
1218 final int outcode2 = DHelpers.outcode(x2, y2, clipRect);
1219 this.cOutCode = outcode2;
1220
1221 if (outcode2 != 0) {
1222 final int outcode1 = DHelpers.outcode(x1, y1, clipRect);
1223
1224 // basic rejection criteria
1225 if ((outcode0 & outcode1 & outcode2) != 0) {
1226 moveTo(x2, y2, outcode0);
1227 opened = true;
1228 return;
1229 }
1230 }
1231 }
1232
1233 final double[] mid = middle;
1234
1235 mid[0] = cx0; mid[1] = cy0;
1236 mid[2] = x1; mid[3] = y1;
1237 mid[4] = x2; mid[5] = y2;
1238
1239 // need these so we can update the state at the end of this method
1240 final double xf = x2, yf = y2;
1241 double dxs = mid[2] - mid[0];
1242 double dys = mid[3] - mid[1];
1243 double dxf = mid[4] - mid[2];
1244 double dyf = mid[5] - mid[3];
1245 if ((dxs == 0.0d && dys == 0.0d) || (dxf == 0.0d && dyf == 0.0d)) {
1246 dxs = dxf = mid[4] - mid[0];
1247 dys = dyf = mid[5] - mid[1];
1248 }
1249 if (dxs == 0.0d && dys == 0.0d) {
1250 // this happens if the "curve" is just a point
1251 // fix outcode0 for lineTo() call:
1252 if (clipRect != null) {
1253 this.cOutCode = outcode0;
1254 }
1255 lineTo(mid[0], mid[1]);
1256 return;
1257 }
1258 // if these vectors are too small, normalize them, to avoid future
1259 // precision problems.
1260 if (Math.abs(dxs) < 0.1d && Math.abs(dys) < 0.1d) {
1261 double len = Math.sqrt(dxs*dxs + dys*dys);
1262 dxs /= len;
1263 dys /= len;
1264 }
1265 if (Math.abs(dxf) < 0.1d && Math.abs(dyf) < 0.1d) {
1266 double len = Math.sqrt(dxf*dxf + dyf*dyf);
1267 dxf /= len;
1268 dyf /= len;
1269 }
1270
1271 computeOffset(dxs, dys, lineWidth2, offset0);
1272 drawJoin(cdx, cdy, cx0, cy0, dxs, dys, cmx, cmy, offset0[0], offset0[1], outcode0);
1273
1274 int nSplits = findSubdivPoints(curve, mid, subdivTs, 6, lineWidth2);
1275
1276 double prevt = 0.0d;
1277 for (int i = 0, off = 0; i < nSplits; i++, off += 4) {
1278 final double t = subdivTs[i];
1279 DHelpers.subdivideQuadAt((t - prevt) / (1.0d - prevt),
1280 mid, off, mid, off, mid, off + 4);
1281 prevt = t;
1282 }
1283
1284 final double[] l = lp;
1285 final double[] r = rp;
1286
1287 int kind = 0;
1288 for (int i = 0, off = 0; i <= nSplits; i++, off += 4) {
1289 kind = computeOffsetQuad(mid, off, l, r);
1290
1291 emitLineTo(l[0], l[1]);
1292
1293 switch(kind) {
1294 case 6:
1295 emitQuadTo(l[2], l[3], l[4], l[5]);
1296 emitQuadToRev(r[0], r[1], r[2], r[3]);
1297 break;
1298 case 4:
1299 emitLineTo(l[2], l[3]);
1300 emitLineToRev(r[0], r[1]);
1301 break;
1302 default:
1303 }
1304 emitLineToRev(r[kind - 2], r[kind - 1]);
1305 }
1306
1307 this.prev = DRAWING_OP_TO;
1308 this.cx0 = xf;
1309 this.cy0 = yf;
1310 this.cdx = dxf;
1311 this.cdy = dyf;
1312 this.cmx = (l[kind - 2] - r[kind - 2]) / 2.0d;
1313 this.cmy = (l[kind - 1] - r[kind - 1]) / 2.0d;
1314 }
1315
1316 @Override public long getNativeConsumer() {
1317 throw new InternalError("Stroker doesn't use a native consumer");
1318 }
1319 }