3 * Copyright 2006 The Android Open Source Project
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
10 #include "SkGeometry.h"
14 bool SkXRayCrossesLine(const SkXRay& pt, const SkPoint pts[2], bool* ambiguous) {
18 // Determine quick discards.
19 // Consider query line going exactly through point 0 to not
20 // intersect, for symmetry with SkXRayCrossesMonotonicCubic.
21 if (pt.fY == pts[0].fY) {
27 if (pt.fY < pts[0].fY && pt.fY < pts[1].fY)
29 if (pt.fY > pts[0].fY && pt.fY > pts[1].fY)
31 if (pt.fX > pts[0].fX && pt.fX > pts[1].fX)
33 // Determine degenerate cases
34 if (SkScalarNearlyZero(pts[0].fY - pts[1].fY))
36 if (SkScalarNearlyZero(pts[0].fX - pts[1].fX)) {
37 // We've already determined the query point lies within the
38 // vertical range of the line segment.
39 if (pt.fX <= pts[0].fX) {
41 *ambiguous = (pt.fY == pts[1].fY);
48 if (pt.fY == pts[1].fY) {
49 if (pt.fX <= pts[1].fX) {
57 // Full line segment evaluation
58 SkScalar delta_y = pts[1].fY - pts[0].fY;
59 SkScalar delta_x = pts[1].fX - pts[0].fX;
60 SkScalar slope = SkScalarDiv(delta_y, delta_x);
61 SkScalar b = pts[0].fY - SkScalarMul(slope, pts[0].fX);
62 // Solve for x coordinate at y = pt.fY
63 SkScalar x = SkScalarDiv(pt.fY - b, slope);
67 /** If defined, this makes eval_quad and eval_cubic do more setup (sometimes
68 involving integer multiplies by 2 or 3, but fewer calls to SkScalarMul.
69 May also introduce overflow of fixed when we compute our setup.
71 #ifdef SK_SCALAR_IS_FIXED
72 #define DIRECT_EVAL_OF_POLYNOMIALS
75 ////////////////////////////////////////////////////////////////////////
77 #ifdef SK_SCALAR_IS_FIXED
78 static int is_not_monotonic(int a, int b, int c, int d)
80 return (((a - b) | (b - c) | (c - d)) & ((b - a) | (c - b) | (d - c))) >> 31;
83 static int is_not_monotonic(int a, int b, int c)
85 return (((a - b) | (b - c)) & ((b - a) | (c - b))) >> 31;
88 static int is_not_monotonic(float a, float b, float c)
94 return ab == 0 || bc < 0;
98 ////////////////////////////////////////////////////////////////////////
100 static bool is_unit_interval(SkScalar x)
102 return x > 0 && x < SK_Scalar1;
105 static int valid_unit_divide(SkScalar numer, SkScalar denom, SkScalar* ratio)
115 if (denom == 0 || numer == 0 || numer >= denom)
118 SkScalar r = SkScalarDiv(numer, denom);
119 if (SkScalarIsNaN(r)) {
122 SkASSERT(r >= 0 && r < SK_Scalar1);
123 if (r == 0) // catch underflow if numer <<<< denom
129 /** From Numerical Recipes in C.
131 Q = -1/2 (B + sign(B) sqrt[B*B - 4*A*C])
135 int SkFindUnitQuadRoots(SkScalar A, SkScalar B, SkScalar C, SkScalar roots[2])
140 return valid_unit_divide(-C, B, roots);
144 #ifdef SK_SCALAR_IS_FLOAT
145 float R = B*B - 4*A*C;
146 if (R < 0 || SkScalarIsNaN(R)) { // complex roots
149 R = sk_float_sqrt(R);
159 SkFixed R = RR.getSqrt();
162 SkScalar Q = (B < 0) ? -(B-R)/2 : -(B+R)/2;
163 r += valid_unit_divide(Q, A, r);
164 r += valid_unit_divide(C, Q, r);
167 if (roots[0] > roots[1])
168 SkTSwap<SkScalar>(roots[0], roots[1]);
169 else if (roots[0] == roots[1]) // nearly-equal?
170 r -= 1; // skip the double root
172 return (int)(r - roots);
175 #ifdef SK_SCALAR_IS_FIXED
176 /** Trim A/B/C down so that they are all <= 32bits
177 and then call SkFindUnitQuadRoots()
179 static int Sk64FindFixedQuadRoots(const Sk64& A, const Sk64& B, const Sk64& C, SkFixed roots[2])
181 int na = A.shiftToMake32();
182 int nb = B.shiftToMake32();
183 int nc = C.shiftToMake32();
185 int shift = SkMax32(na, SkMax32(nb, nc));
186 SkASSERT(shift >= 0);
188 return SkFindUnitQuadRoots(A.getShiftRight(shift), B.getShiftRight(shift), C.getShiftRight(shift), roots);
192 /////////////////////////////////////////////////////////////////////////////////////
193 /////////////////////////////////////////////////////////////////////////////////////
195 static SkScalar eval_quad(const SkScalar src[], SkScalar t)
198 SkASSERT(t >= 0 && t <= SK_Scalar1);
200 #ifdef DIRECT_EVAL_OF_POLYNOMIALS
202 SkScalar A = src[4] - 2 * src[2] + C;
203 SkScalar B = 2 * (src[2] - C);
204 return SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C);
206 SkScalar ab = SkScalarInterp(src[0], src[2], t);
207 SkScalar bc = SkScalarInterp(src[2], src[4], t);
208 return SkScalarInterp(ab, bc, t);
212 static SkScalar eval_quad_derivative(const SkScalar src[], SkScalar t)
214 SkScalar A = src[4] - 2 * src[2] + src[0];
215 SkScalar B = src[2] - src[0];
217 return 2 * SkScalarMulAdd(A, t, B);
220 static SkScalar eval_quad_derivative_at_half(const SkScalar src[])
222 SkScalar A = src[4] - 2 * src[2] + src[0];
223 SkScalar B = src[2] - src[0];
227 void SkEvalQuadAt(const SkPoint src[3], SkScalar t, SkPoint* pt, SkVector* tangent)
230 SkASSERT(t >= 0 && t <= SK_Scalar1);
233 pt->set(eval_quad(&src[0].fX, t), eval_quad(&src[0].fY, t));
235 tangent->set(eval_quad_derivative(&src[0].fX, t),
236 eval_quad_derivative(&src[0].fY, t));
239 void SkEvalQuadAtHalf(const SkPoint src[3], SkPoint* pt, SkVector* tangent)
245 SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX);
246 SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY);
247 SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX);
248 SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY);
249 pt->set(SkScalarAve(x01, x12), SkScalarAve(y01, y12));
252 tangent->set(eval_quad_derivative_at_half(&src[0].fX),
253 eval_quad_derivative_at_half(&src[0].fY));
256 static void interp_quad_coords(const SkScalar* src, SkScalar* dst, SkScalar t)
258 SkScalar ab = SkScalarInterp(src[0], src[2], t);
259 SkScalar bc = SkScalarInterp(src[2], src[4], t);
263 dst[4] = SkScalarInterp(ab, bc, t);
268 void SkChopQuadAt(const SkPoint src[3], SkPoint dst[5], SkScalar t)
270 SkASSERT(t > 0 && t < SK_Scalar1);
272 interp_quad_coords(&src[0].fX, &dst[0].fX, t);
273 interp_quad_coords(&src[0].fY, &dst[0].fY, t);
276 void SkChopQuadAtHalf(const SkPoint src[3], SkPoint dst[5])
278 SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX);
279 SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY);
280 SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX);
281 SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY);
284 dst[1].set(x01, y01);
285 dst[2].set(SkScalarAve(x01, x12), SkScalarAve(y01, y12));
286 dst[3].set(x12, y12);
290 /** Quad'(t) = At + B, where
293 Solve for t, only if it fits between 0 < t < 1
295 int SkFindQuadExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar tValue[1])
300 #ifdef SK_SCALAR_IS_FIXED
301 return is_not_monotonic(a, b, c) && valid_unit_divide(a - b, a - b - b + c, tValue);
303 return valid_unit_divide(a - b, a - b - b + c, tValue);
307 static inline void flatten_double_quad_extrema(SkScalar coords[14])
309 coords[2] = coords[6] = coords[4];
312 /* Returns 0 for 1 quad, and 1 for two quads, either way the answer is
313 stored in dst[]. Guarantees that the 1/2 quads will be monotonic.
315 int SkChopQuadAtYExtrema(const SkPoint src[3], SkPoint dst[5])
321 static bool once = true;
325 SkPoint s[3] = { 0, 26398, 0, 26331, 0, 20621428 };
328 int n = SkChopQuadAtYExtrema(s, d);
329 SkDebugf("chop=%d, Y=[%x %x %x %x %x %x]\n", n, d[0].fY, d[1].fY, d[2].fY, d[3].fY, d[4].fY, d[5].fY);
333 SkScalar a = src[0].fY;
334 SkScalar b = src[1].fY;
335 SkScalar c = src[2].fY;
337 if (is_not_monotonic(a, b, c))
340 if (valid_unit_divide(a - b, a - b - b + c, &tValue))
342 SkChopQuadAt(src, dst, tValue);
343 flatten_double_quad_extrema(&dst[0].fY);
346 // if we get here, we need to force dst to be monotonic, even though
347 // we couldn't compute a unit_divide value (probably underflow).
348 b = SkScalarAbs(a - b) < SkScalarAbs(b - c) ? a : c;
350 dst[0].set(src[0].fX, a);
351 dst[1].set(src[1].fX, b);
352 dst[2].set(src[2].fX, c);
356 /* Returns 0 for 1 quad, and 1 for two quads, either way the answer is
357 stored in dst[]. Guarantees that the 1/2 quads will be monotonic.
359 int SkChopQuadAtXExtrema(const SkPoint src[3], SkPoint dst[5])
364 SkScalar a = src[0].fX;
365 SkScalar b = src[1].fX;
366 SkScalar c = src[2].fX;
368 if (is_not_monotonic(a, b, c)) {
370 if (valid_unit_divide(a - b, a - b - b + c, &tValue)) {
371 SkChopQuadAt(src, dst, tValue);
372 flatten_double_quad_extrema(&dst[0].fX);
375 // if we get here, we need to force dst to be monotonic, even though
376 // we couldn't compute a unit_divide value (probably underflow).
377 b = SkScalarAbs(a - b) < SkScalarAbs(b - c) ? a : c;
379 dst[0].set(a, src[0].fY);
380 dst[1].set(b, src[1].fY);
381 dst[2].set(c, src[2].fY);
385 // F(t) = a (1 - t) ^ 2 + 2 b t (1 - t) + c t ^ 2
386 // F'(t) = 2 (b - a) + 2 (a - 2b + c) t
387 // F''(t) = 2 (a - 2b + c)
390 // B = 2 (a - 2b + c)
392 // Maximum curvature for a quadratic means solving
393 // Fx' Fx'' + Fy' Fy'' = 0
395 // t = - (Ax Bx + Ay By) / (Bx ^ 2 + By ^ 2)
397 float SkFindQuadMaxCurvature(const SkPoint src[3]) {
398 SkScalar Ax = src[1].fX - src[0].fX;
399 SkScalar Ay = src[1].fY - src[0].fY;
400 SkScalar Bx = src[0].fX - src[1].fX - src[1].fX + src[2].fX;
401 SkScalar By = src[0].fY - src[1].fY - src[1].fY + src[2].fY;
402 SkScalar t = 0; // 0 means don't chop
404 #ifdef SK_SCALAR_IS_FLOAT
405 (void)valid_unit_divide(-(Ax * Bx + Ay * By), Bx * Bx + By * By, &t);
407 // !!! should I use SkFloat here? seems like it
408 Sk64 numer, denom, tmp;
410 numer.setMul(Ax, -Bx);
414 if (numer.isPos()) // do nothing if numer <= 0
416 denom.setMul(Bx, Bx);
419 SkASSERT(!denom.isNeg());
422 t = numer.getFixedDiv(denom);
423 SkASSERT(t >= 0 && t <= SK_Fixed1); // assert that we're numerically stable (ha!)
424 if ((unsigned)t >= SK_Fixed1) // runtime check for numerical stability
425 t = 0; // ignore the chop
432 int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5])
434 SkScalar t = SkFindQuadMaxCurvature(src);
436 memcpy(dst, src, 3 * sizeof(SkPoint));
439 SkChopQuadAt(src, dst, t);
444 #ifdef SK_SCALAR_IS_FLOAT
445 #define SK_ScalarTwoThirds (0.666666666f)
447 #define SK_ScalarTwoThirds ((SkFixed)(43691))
450 void SkConvertQuadToCubic(const SkPoint src[3], SkPoint dst[4]) {
451 const SkScalar scale = SK_ScalarTwoThirds;
453 dst[1].set(src[0].fX + SkScalarMul(src[1].fX - src[0].fX, scale),
454 src[0].fY + SkScalarMul(src[1].fY - src[0].fY, scale));
455 dst[2].set(src[2].fX + SkScalarMul(src[1].fX - src[2].fX, scale),
456 src[2].fY + SkScalarMul(src[1].fY - src[2].fY, scale));
460 ////////////////////////////////////////////////////////////////////////////////////////
461 ///// CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS /////
462 ////////////////////////////////////////////////////////////////////////////////////////
464 static void get_cubic_coeff(const SkScalar pt[], SkScalar coeff[4])
466 coeff[0] = pt[6] + 3*(pt[2] - pt[4]) - pt[0];
467 coeff[1] = 3*(pt[4] - pt[2] - pt[2] + pt[0]);
468 coeff[2] = 3*(pt[2] - pt[0]);
472 void SkGetCubicCoeff(const SkPoint pts[4], SkScalar cx[4], SkScalar cy[4])
477 get_cubic_coeff(&pts[0].fX, cx);
479 get_cubic_coeff(&pts[0].fY, cy);
482 static SkScalar eval_cubic(const SkScalar src[], SkScalar t)
485 SkASSERT(t >= 0 && t <= SK_Scalar1);
490 #ifdef DIRECT_EVAL_OF_POLYNOMIALS
492 SkScalar A = src[6] + 3*(src[2] - src[4]) - D;
493 SkScalar B = 3*(src[4] - src[2] - src[2] + D);
494 SkScalar C = 3*(src[2] - D);
496 return SkScalarMulAdd(SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C), t, D);
498 SkScalar ab = SkScalarInterp(src[0], src[2], t);
499 SkScalar bc = SkScalarInterp(src[2], src[4], t);
500 SkScalar cd = SkScalarInterp(src[4], src[6], t);
501 SkScalar abc = SkScalarInterp(ab, bc, t);
502 SkScalar bcd = SkScalarInterp(bc, cd, t);
503 return SkScalarInterp(abc, bcd, t);
507 /** return At^2 + Bt + C
509 static SkScalar eval_quadratic(SkScalar A, SkScalar B, SkScalar C, SkScalar t)
511 SkASSERT(t >= 0 && t <= SK_Scalar1);
513 return SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C);
516 static SkScalar eval_cubic_derivative(const SkScalar src[], SkScalar t)
518 SkScalar A = src[6] + 3*(src[2] - src[4]) - src[0];
519 SkScalar B = 2*(src[4] - 2 * src[2] + src[0]);
520 SkScalar C = src[2] - src[0];
522 return eval_quadratic(A, B, C, t);
525 static SkScalar eval_cubic_2ndDerivative(const SkScalar src[], SkScalar t)
527 SkScalar A = src[6] + 3*(src[2] - src[4]) - src[0];
528 SkScalar B = src[4] - 2 * src[2] + src[0];
530 return SkScalarMulAdd(A, t, B);
533 void SkEvalCubicAt(const SkPoint src[4], SkScalar t, SkPoint* loc, SkVector* tangent, SkVector* curvature)
536 SkASSERT(t >= 0 && t <= SK_Scalar1);
539 loc->set(eval_cubic(&src[0].fX, t), eval_cubic(&src[0].fY, t));
541 tangent->set(eval_cubic_derivative(&src[0].fX, t),
542 eval_cubic_derivative(&src[0].fY, t));
544 curvature->set(eval_cubic_2ndDerivative(&src[0].fX, t),
545 eval_cubic_2ndDerivative(&src[0].fY, t));
548 /** Cubic'(t) = At^2 + Bt + C, where
549 A = 3(-a + 3(b - c) + d)
552 Solve for t, keeping only those that fit betwee 0 < t < 1
554 int SkFindCubicExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar d, SkScalar tValues[2])
556 #ifdef SK_SCALAR_IS_FIXED
557 if (!is_not_monotonic(a, b, c, d))
561 // we divide A,B,C by 3 to simplify
562 SkScalar A = d - a + 3*(b - c);
563 SkScalar B = 2*(a - b - b + c);
566 return SkFindUnitQuadRoots(A, B, C, tValues);
569 static void interp_cubic_coords(const SkScalar* src, SkScalar* dst, SkScalar t)
571 SkScalar ab = SkScalarInterp(src[0], src[2], t);
572 SkScalar bc = SkScalarInterp(src[2], src[4], t);
573 SkScalar cd = SkScalarInterp(src[4], src[6], t);
574 SkScalar abc = SkScalarInterp(ab, bc, t);
575 SkScalar bcd = SkScalarInterp(bc, cd, t);
576 SkScalar abcd = SkScalarInterp(abc, bcd, t);
587 void SkChopCubicAt(const SkPoint src[4], SkPoint dst[7], SkScalar t)
589 SkASSERT(t > 0 && t < SK_Scalar1);
591 interp_cubic_coords(&src[0].fX, &dst[0].fX, t);
592 interp_cubic_coords(&src[0].fY, &dst[0].fY, t);
595 /* http://code.google.com/p/skia/issues/detail?id=32
597 This test code would fail when we didn't check the return result of
598 valid_unit_divide in SkChopCubicAt(... tValues[], int roots). The reason is
599 that after the first chop, the parameters to valid_unit_divide are equal
600 (thanks to finite float precision and rounding in the subtracts). Thus
601 even though the 2nd tValue looks < 1.0, after we renormalize it, we end
602 up with 1.0, hence the need to check and just return the last cubic as
603 a degenerate clump of 4 points in the sampe place.
605 static void test_cubic() {
607 { 556.25000, 523.03003 },
608 { 556.23999, 522.96002 },
609 { 556.21997, 522.89001 },
610 { 556.21997, 522.82001 }
613 SkScalar tval[] = { 0.33333334f, 0.99999994f };
614 SkChopCubicAt(src, dst, tval, 2);
618 void SkChopCubicAt(const SkPoint src[4], SkPoint dst[], const SkScalar tValues[], int roots)
622 for (int i = 0; i < roots - 1; i++)
624 SkASSERT(is_unit_interval(tValues[i]));
625 SkASSERT(is_unit_interval(tValues[i+1]));
626 SkASSERT(tValues[i] < tValues[i+1]);
633 if (roots == 0) // nothing to chop
634 memcpy(dst, src, 4*sizeof(SkPoint));
637 SkScalar t = tValues[0];
640 for (int i = 0; i < roots; i++)
642 SkChopCubicAt(src, dst, t);
647 // have src point to the remaining cubic (after the chop)
648 memcpy(tmp, dst, 4 * sizeof(SkPoint));
651 // watch out in case the renormalized t isn't in range
652 if (!valid_unit_divide(tValues[i+1] - tValues[i],
653 SK_Scalar1 - tValues[i], &t)) {
654 // if we can't, just create a degenerate cubic
655 dst[4] = dst[5] = dst[6] = src[3];
663 void SkChopCubicAtHalf(const SkPoint src[4], SkPoint dst[7])
665 SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX);
666 SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY);
667 SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX);
668 SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY);
669 SkScalar x23 = SkScalarAve(src[2].fX, src[3].fX);
670 SkScalar y23 = SkScalarAve(src[2].fY, src[3].fY);
672 SkScalar x012 = SkScalarAve(x01, x12);
673 SkScalar y012 = SkScalarAve(y01, y12);
674 SkScalar x123 = SkScalarAve(x12, x23);
675 SkScalar y123 = SkScalarAve(y12, y23);
678 dst[1].set(x01, y01);
679 dst[2].set(x012, y012);
680 dst[3].set(SkScalarAve(x012, x123), SkScalarAve(y012, y123));
681 dst[4].set(x123, y123);
682 dst[5].set(x23, y23);
686 static void flatten_double_cubic_extrema(SkScalar coords[14])
688 coords[4] = coords[8] = coords[6];
691 /** Given 4 points on a cubic bezier, chop it into 1, 2, 3 beziers such that
692 the resulting beziers are monotonic in Y. This is called by the scan converter.
693 Depending on what is returned, dst[] is treated as follows
694 0 dst[0..3] is the original cubic
695 1 dst[0..3] and dst[3..6] are the two new cubics
696 2 dst[0..3], dst[3..6], dst[6..9] are the three new cubics
697 If dst == null, it is ignored and only the count is returned.
699 int SkChopCubicAtYExtrema(const SkPoint src[4], SkPoint dst[10]) {
701 int roots = SkFindCubicExtrema(src[0].fY, src[1].fY, src[2].fY,
704 SkChopCubicAt(src, dst, tValues, roots);
705 if (dst && roots > 0) {
706 // we do some cleanup to ensure our Y extrema are flat
707 flatten_double_cubic_extrema(&dst[0].fY);
709 flatten_double_cubic_extrema(&dst[3].fY);
715 int SkChopCubicAtXExtrema(const SkPoint src[4], SkPoint dst[10]) {
717 int roots = SkFindCubicExtrema(src[0].fX, src[1].fX, src[2].fX,
720 SkChopCubicAt(src, dst, tValues, roots);
721 if (dst && roots > 0) {
722 // we do some cleanup to ensure our Y extrema are flat
723 flatten_double_cubic_extrema(&dst[0].fX);
725 flatten_double_cubic_extrema(&dst[3].fX);
731 /** http://www.faculty.idc.ac.il/arik/quality/appendixA.html
733 Inflection means that curvature is zero.
734 Curvature is [F' x F''] / [F'^3]
735 So we solve F'x X F''y - F'y X F''y == 0
736 After some canceling of the cubic term, we get
740 (BxCy - ByCx)t^2 + (AxCy - AyCx)t + AxBy - AyBx == 0
742 int SkFindCubicInflections(const SkPoint src[4], SkScalar tValues[])
744 SkScalar Ax = src[1].fX - src[0].fX;
745 SkScalar Ay = src[1].fY - src[0].fY;
746 SkScalar Bx = src[2].fX - 2 * src[1].fX + src[0].fX;
747 SkScalar By = src[2].fY - 2 * src[1].fY + src[0].fY;
748 SkScalar Cx = src[3].fX + 3 * (src[1].fX - src[2].fX) - src[0].fX;
749 SkScalar Cy = src[3].fY + 3 * (src[1].fY - src[2].fY) - src[0].fY;
752 #ifdef SK_SCALAR_IS_FLOAT
753 count = SkFindUnitQuadRoots(Bx*Cy - By*Cx, Ax*Cy - Ay*Cx, Ax*By - Ay*Bx, tValues);
769 count = Sk64FindFixedQuadRoots(A, B, C, tValues);
775 int SkChopCubicAtInflections(const SkPoint src[], SkPoint dst[10])
778 int count = SkFindCubicInflections(src, tValues);
783 memcpy(dst, src, 4 * sizeof(SkPoint));
785 SkChopCubicAt(src, dst, tValues, count);
790 template <typename T> void bubble_sort(T array[], int count)
792 for (int i = count - 1; i > 0; --i)
793 for (int j = i; j > 0; --j)
794 if (array[j] < array[j-1])
797 array[j] = array[j-1];
806 static SkScalar refine_cubic_root(const SkFP coeff[4], SkScalar root)
808 // x1 = x0 - f(t) / f'(t)
810 SkFP T = SkScalarToFloat(root);
813 // f' = 3*coeff[0]*T^2 + 2*coeff[1]*T + coeff[2]
814 D = SkFPMul(SkFPMul(coeff[0], SkFPMul(T,T)), 3);
815 D = SkFPAdd(D, SkFPMulInt(SkFPMul(coeff[1], T), 2));
816 D = SkFPAdd(D, coeff[2]);
821 // f = coeff[0]*T^3 + coeff[1]*T^2 + coeff[2]*T + coeff[3]
822 N = SkFPMul(SkFPMul(SkFPMul(T, T), T), coeff[0]);
823 N = SkFPAdd(N, SkFPMul(SkFPMul(T, T), coeff[1]));
824 N = SkFPAdd(N, SkFPMul(T, coeff[2]));
825 N = SkFPAdd(N, coeff[3]);
829 SkScalar delta = SkFPToScalar(SkFPDiv(N, D));
839 * Given an array and count, remove all pair-wise duplicates from the array,
840 * keeping the existing sorting, and return the new count
842 static int collaps_duplicates(float array[], int count) {
843 for (int n = count; n > 1; --n) {
844 if (array[0] == array[1]) {
845 for (int i = 1; i < n; ++i) {
846 array[i - 1] = array[i];
858 #define TEST_COLLAPS_ENTRY(array) array, SK_ARRAY_COUNT(array)
860 static void test_collaps_duplicates() {
862 if (gOnce) { return; }
864 const float src0[] = { 0 };
865 const float src1[] = { 0, 0 };
866 const float src2[] = { 0, 1 };
867 const float src3[] = { 0, 0, 0 };
868 const float src4[] = { 0, 0, 1 };
869 const float src5[] = { 0, 1, 1 };
870 const float src6[] = { 0, 1, 2 };
876 { TEST_COLLAPS_ENTRY(src0), 1 },
877 { TEST_COLLAPS_ENTRY(src1), 1 },
878 { TEST_COLLAPS_ENTRY(src2), 2 },
879 { TEST_COLLAPS_ENTRY(src3), 1 },
880 { TEST_COLLAPS_ENTRY(src4), 2 },
881 { TEST_COLLAPS_ENTRY(src5), 2 },
882 { TEST_COLLAPS_ENTRY(src6), 3 },
884 for (size_t i = 0; i < SK_ARRAY_COUNT(data); ++i) {
886 memcpy(dst, data[i].fData, data[i].fCount * sizeof(dst[0]));
887 int count = collaps_duplicates(dst, data[i].fCount);
888 SkASSERT(data[i].fCollapsedCount == count);
889 for (int j = 1; j < count; ++j) {
890 SkASSERT(dst[j-1] < dst[j]);
896 #if defined _WIN32 && _MSC_VER >= 1300 && defined SK_SCALAR_IS_FIXED // disable warning : unreachable code if building fixed point for windows desktop
897 #pragma warning ( disable : 4702 )
900 /* Solve coeff(t) == 0, returning the number of roots that
901 lie withing 0 < t < 1.
902 coeff[0]t^3 + coeff[1]t^2 + coeff[2]t + coeff[3]
904 Eliminates repeated roots (so that all tValues are distinct, and are always
907 static int solve_cubic_polynomial(const SkFP coeff[4], SkScalar tValues[3])
909 #ifndef SK_SCALAR_IS_FLOAT
910 return 0; // this is not yet implemented for software float
913 if (SkScalarNearlyZero(coeff[0])) // we're just a quadratic
915 return SkFindUnitQuadRoots(coeff[1], coeff[2], coeff[3], tValues);
921 SkASSERT(coeff[0] != 0);
923 SkFP inva = SkFPInvert(coeff[0]);
924 a = SkFPMul(coeff[1], inva);
925 b = SkFPMul(coeff[2], inva);
926 c = SkFPMul(coeff[3], inva);
928 Q = SkFPDivInt(SkFPSub(SkFPMul(a,a), SkFPMulInt(b, 3)), 9);
929 // R = (2*a*a*a - 9*a*b + 27*c) / 54;
930 R = SkFPMulInt(SkFPMul(SkFPMul(a, a), a), 2);
931 R = SkFPSub(R, SkFPMulInt(SkFPMul(a, b), 9));
932 R = SkFPAdd(R, SkFPMulInt(c, 27));
933 R = SkFPDivInt(R, 54);
935 SkFP Q3 = SkFPMul(SkFPMul(Q, Q), Q);
936 SkFP R2MinusQ3 = SkFPSub(SkFPMul(R,R), Q3);
937 SkFP adiv3 = SkFPDivInt(a, 3);
939 SkScalar* roots = tValues;
942 if (SkFPLT(R2MinusQ3, 0)) // we have 3 real roots
944 #ifdef SK_SCALAR_IS_FLOAT
945 float theta = sk_float_acos(R / sk_float_sqrt(Q3));
946 float neg2RootQ = -2 * sk_float_sqrt(Q);
948 r = neg2RootQ * sk_float_cos(theta/3) - adiv3;
949 if (is_unit_interval(r))
952 r = neg2RootQ * sk_float_cos((theta + 2*SK_ScalarPI)/3) - adiv3;
953 if (is_unit_interval(r))
956 r = neg2RootQ * sk_float_cos((theta - 2*SK_ScalarPI)/3) - adiv3;
957 if (is_unit_interval(r))
960 SkDEBUGCODE(test_collaps_duplicates();)
962 // now sort the roots
963 int count = (int)(roots - tValues);
964 SkASSERT((unsigned)count <= 3);
965 bubble_sort(tValues, count);
966 count = collaps_duplicates(tValues, count);
967 roots = tValues + count; // so we compute the proper count below
970 else // we have 1 real root
972 SkFP A = SkFPAdd(SkFPAbs(R), SkFPSqrt(R2MinusQ3));
978 A = SkFPAdd(A, SkFPDiv(Q, A));
979 r = SkFPToScalar(SkFPSub(A, adiv3));
980 if (is_unit_interval(r))
984 return (int)(roots - tValues);
987 /* Looking for F' dot F'' == 0
993 F' = 3Ct^2 + 6Bt + 3A
996 F' dot F'' -> CCt^3 + 3BCt^2 + (2BB + CA)t + AB
998 static void formulate_F1DotF2(const SkScalar src[], SkFP coeff[4])
1000 SkScalar a = src[2] - src[0];
1001 SkScalar b = src[4] - 2 * src[2] + src[0];
1002 SkScalar c = src[6] + 3 * (src[2] - src[4]) - src[0];
1004 SkFP A = SkScalarToFP(a);
1005 SkFP B = SkScalarToFP(b);
1006 SkFP C = SkScalarToFP(c);
1008 coeff[0] = SkFPMul(C, C);
1009 coeff[1] = SkFPMulInt(SkFPMul(B, C), 3);
1010 coeff[2] = SkFPMulInt(SkFPMul(B, B), 2);
1011 coeff[2] = SkFPAdd(coeff[2], SkFPMul(C, A));
1012 coeff[3] = SkFPMul(A, B);
1015 // EXPERIMENTAL: can set this to zero to accept all t-values 0 < t < 1
1016 //#define kMinTValueForChopping (SK_Scalar1 / 256)
1017 #define kMinTValueForChopping 0
1019 /* Looking for F' dot F'' == 0
1025 F' = 3Ct^2 + 6Bt + 3A
1028 F' dot F'' -> CCt^3 + 3BCt^2 + (2BB + CA)t + AB
1030 int SkFindCubicMaxCurvature(const SkPoint src[4], SkScalar tValues[3])
1032 SkFP coeffX[4], coeffY[4];
1035 formulate_F1DotF2(&src[0].fX, coeffX);
1036 formulate_F1DotF2(&src[0].fY, coeffY);
1038 for (i = 0; i < 4; i++)
1039 coeffX[i] = SkFPAdd(coeffX[i],coeffY[i]);
1042 int count = solve_cubic_polynomial(coeffX, t);
1045 // now remove extrema where the curvature is zero (mins)
1046 // !!!! need a test for this !!!!
1047 for (i = 0; i < count; i++)
1049 // if (not_min_curvature())
1050 if (t[i] > kMinTValueForChopping && t[i] < SK_Scalar1 - kMinTValueForChopping)
1051 tValues[maxCount++] = t[i];
1056 int SkChopCubicAtMaxCurvature(const SkPoint src[4], SkPoint dst[13], SkScalar tValues[3])
1058 SkScalar t_storage[3];
1060 if (tValues == NULL)
1061 tValues = t_storage;
1063 int count = SkFindCubicMaxCurvature(src, tValues);
1067 memcpy(dst, src, 4 * sizeof(SkPoint));
1069 SkChopCubicAt(src, dst, tValues, count);
1074 bool SkXRayCrossesMonotonicCubic(const SkXRay& pt, const SkPoint cubic[4], bool* ambiguous) {
1079 // Find the minimum and maximum y of the extrema, which are the
1080 // first and last points since this cubic is monotonic
1081 SkScalar min_y = SkMinScalar(cubic[0].fY, cubic[3].fY);
1082 SkScalar max_y = SkMaxScalar(cubic[0].fY, cubic[3].fY);
1084 if (pt.fY == cubic[0].fY
1087 // The query line definitely does not cross the curve
1089 *ambiguous = (pt.fY == cubic[0].fY);
1094 bool pt_at_extremum = (pt.fY == cubic[3].fY);
1099 SkMinScalar(cubic[0].fX, cubic[1].fX),
1102 if (pt.fX < min_x) {
1103 // The query line definitely crosses the curve
1105 *ambiguous = pt_at_extremum;
1113 SkMaxScalar(cubic[0].fX, cubic[1].fX),
1116 if (pt.fX > max_x) {
1117 // The query line definitely does not cross the curve
1121 // Do a binary search to find the parameter value which makes y as
1122 // close as possible to the query point. See whether the query
1123 // line's origin is to the left of the associated x coordinate.
1125 // kMaxIter is chosen as the number of mantissa bits for a float,
1126 // since there's no way we are going to get more precision by
1127 // iterating more times than that.
1128 const int kMaxIter = 23;
1133 // Need to invert direction of t parameter if cubic goes up
1135 if (cubic[3].fY > cubic[0].fY) {
1136 upper_t = SK_Scalar1;
1137 lower_t = SkFloatToScalar(0);
1139 upper_t = SkFloatToScalar(0);
1140 lower_t = SK_Scalar1;
1143 SkScalar t = SkScalarAve(upper_t, lower_t);
1144 SkEvalCubicAt(cubic, t, &eval, NULL, NULL);
1145 if (pt.fY > eval.fY) {
1150 } while (++iter < kMaxIter
1151 && !SkScalarNearlyZero(eval.fY - pt.fY));
1152 if (pt.fX <= eval.fX) {
1154 *ambiguous = pt_at_extremum;
1161 int SkNumXRayCrossingsForCubic(const SkXRay& pt, const SkPoint cubic[4], bool* ambiguous) {
1162 int num_crossings = 0;
1163 SkPoint monotonic_cubics[10];
1164 int num_monotonic_cubics = SkChopCubicAtYExtrema(cubic, monotonic_cubics);
1168 bool locally_ambiguous;
1169 if (SkXRayCrossesMonotonicCubic(pt, &monotonic_cubics[0], &locally_ambiguous))
1172 *ambiguous |= locally_ambiguous;
1174 if (num_monotonic_cubics > 0)
1175 if (SkXRayCrossesMonotonicCubic(pt, &monotonic_cubics[3], &locally_ambiguous))
1178 *ambiguous |= locally_ambiguous;
1180 if (num_monotonic_cubics > 1)
1181 if (SkXRayCrossesMonotonicCubic(pt, &monotonic_cubics[6], &locally_ambiguous))
1184 *ambiguous |= locally_ambiguous;
1186 return num_crossings;
1188 ////////////////////////////////////////////////////////////////////////////////
1190 /* Find t value for quadratic [a, b, c] = d.
1191 Return 0 if there is no solution within [0, 1)
1193 static SkScalar quad_solve(SkScalar a, SkScalar b, SkScalar c, SkScalar d)
1195 // At^2 + Bt + C = d
1196 SkScalar A = a - 2 * b + c;
1197 SkScalar B = 2 * (b - a);
1201 int count = SkFindUnitQuadRoots(A, B, C, roots);
1203 SkASSERT(count <= 1);
1204 return count == 1 ? roots[0] : 0;
1207 /* given a quad-curve and a point (x,y), chop the quad at that point and place
1208 the new off-curve point and endpoint into 'dest'.
1209 Should only return false if the computed pos is the start of the curve
1212 static bool truncate_last_curve(const SkPoint quad[3], SkScalar x, SkScalar y, SkPoint* dest)
1214 const SkScalar* base;
1217 if (SkScalarAbs(x) < SkScalarAbs(y)) {
1225 // note: this returns 0 if it thinks value is out of range, meaning the
1226 // root might return something outside of [0, 1)
1227 SkScalar t = quad_solve(base[0], base[2], base[4], value);
1232 SkChopQuadAt(quad, tmp, t);
1237 /* t == 0 means either the value triggered a root outside of [0, 1)
1238 For our purposes, we can ignore the <= 0 roots, but we want to
1239 catch the >= 1 roots (which given our caller, will basically mean
1240 a root of 1, give-or-take numerical instability). If we are in the
1241 >= 1 case, return the existing offCurve point.
1243 The test below checks to see if we are close to the "end" of the
1244 curve (near base[4]). Rather than specifying a tolerance, I just
1245 check to see if value is on to the right/left of the middle point
1246 (depending on the direction/sign of the end points).
1248 if ((base[0] < base[4] && value > base[2]) ||
1249 (base[0] > base[4] && value < base[2])) // should root have been 1
1259 static const SkPoint gQuadCirclePts[kSkBuildQuadArcStorage] = {
1260 // The mid point of the quadratic arc approximation is half way between the two
1261 // control points. The float epsilon adjustment moves the on curve point out by
1262 // two bits, distributing the convex test error between the round rect approximation
1263 // and the convex cross product sign equality test.
1264 #define SK_MID_RRECT_OFFSET (SK_Scalar1 + SK_ScalarTanPIOver8 + FLT_EPSILON * 4) / 2
1266 { SK_Scalar1, SK_ScalarTanPIOver8 },
1267 { SK_MID_RRECT_OFFSET, SK_MID_RRECT_OFFSET },
1268 { SK_ScalarTanPIOver8, SK_Scalar1 },
1271 { -SK_ScalarTanPIOver8, SK_Scalar1 },
1272 { -SK_MID_RRECT_OFFSET, SK_MID_RRECT_OFFSET },
1273 { -SK_Scalar1, SK_ScalarTanPIOver8 },
1276 { -SK_Scalar1, -SK_ScalarTanPIOver8 },
1277 { -SK_MID_RRECT_OFFSET, -SK_MID_RRECT_OFFSET },
1278 { -SK_ScalarTanPIOver8, -SK_Scalar1 },
1281 { SK_ScalarTanPIOver8, -SK_Scalar1 },
1282 { SK_MID_RRECT_OFFSET, -SK_MID_RRECT_OFFSET },
1283 { SK_Scalar1, -SK_ScalarTanPIOver8 },
1286 #undef SK_MID_RRECT_OFFSET
1289 int SkBuildQuadArc(const SkVector& uStart, const SkVector& uStop,
1290 SkRotationDirection dir, const SkMatrix* userMatrix,
1291 SkPoint quadPoints[])
1293 // rotate by x,y so that uStart is (1.0)
1294 SkScalar x = SkPoint::DotProduct(uStart, uStop);
1295 SkScalar y = SkPoint::CrossProduct(uStart, uStop);
1297 SkScalar absX = SkScalarAbs(x);
1298 SkScalar absY = SkScalarAbs(y);
1302 // check for (effectively) coincident vectors
1303 // this can happen if our angle is nearly 0 or nearly 180 (y == 0)
1304 // ... we use the dot-prod to distinguish between 0 and 180 (x > 0)
1305 if (absY <= SK_ScalarNearlyZero && x > 0 &&
1306 ((y >= 0 && kCW_SkRotationDirection == dir) ||
1307 (y <= 0 && kCCW_SkRotationDirection == dir))) {
1309 // just return the start-point
1310 quadPoints[0].set(SK_Scalar1, 0);
1313 if (dir == kCCW_SkRotationDirection)
1316 // what octant (quadratic curve) is [xy] in?
1318 bool sameSign = true;
1323 SkASSERT(SkScalarAbs(x + SK_Scalar1) <= SK_ScalarNearlyZero);
1327 SkASSERT(absY - SK_Scalar1 <= SK_ScalarNearlyZero);
1337 if ((x < 0) != (y < 0))
1342 if ((absX < absY) == sameSign)
1346 int wholeCount = oct << 1;
1347 memcpy(quadPoints, gQuadCirclePts, (wholeCount + 1) * sizeof(SkPoint));
1349 const SkPoint* arc = &gQuadCirclePts[wholeCount];
1350 if (truncate_last_curve(arc, x, y, &quadPoints[wholeCount + 1]))
1354 pointCount = wholeCount + 1;
1357 // now handle counter-clockwise and the initial unitStart rotation
1359 matrix.setSinCos(uStart.fY, uStart.fX);
1360 if (dir == kCCW_SkRotationDirection) {
1361 matrix.preScale(SK_Scalar1, -SK_Scalar1);
1364 matrix.postConcat(*userMatrix);
1366 matrix.mapPoints(quadPoints, pointCount);
1370 ///////////////////////////////////////////////////////////////////////////////
1372 // F = (A (1 - t)^2 + C t^2 + 2 B (1 - t) t w)
1373 // ------------------------------------------
1374 // ((1 - t)^2 + t^2 + 2 (1 - t) t w)
1376 // = {t^2 (P0 + P2 - 2 P1 w), t (-2 P0 + 2 P1 w), P0}
1377 // ------------------------------------------------
1378 // {t^2 (2 - 2 w), t (-2 + 2 w), 1}
1381 // Take the parametric specification for the conic (either X or Y) and return
1382 // in coeff[] the coefficients for the simple quadratic polynomial
1385 // coeff[2] for constant term
1387 static SkScalar conic_eval_pos(const SkScalar src[], SkScalar w, SkScalar t) {
1389 SkASSERT(t >= 0 && t <= SK_Scalar1);
1391 SkScalar src2w = SkScalarMul(src[2], w);
1392 SkScalar C = src[0];
1393 SkScalar A = src[4] - 2 * src2w + C;
1394 SkScalar B = 2 * (src2w - C);
1395 SkScalar numer = SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C);
1397 B = 2 * (w - SK_Scalar1);
1400 SkScalar denom = SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C);
1402 return SkScalarDiv(numer, denom);
1405 // F' = 2 (C t (1 + t (-1 + w)) - A (-1 + t) (t (-1 + w) - w) + B (1 - 2 t) w)
1407 // t^2 : (2 P0 - 2 P2 - 2 P0 w + 2 P2 w)
1408 // t^1 : (-2 P0 + 2 P2 + 4 P0 w - 4 P1 w)
1409 // t^0 : -2 P0 w + 2 P1 w
1411 // We disregard magnitude, so we can freely ignore the denominator of F', and
1412 // divide the numerator by 2
1418 static void conic_deriv_coeff(const SkScalar src[], SkScalar w, SkScalar coeff[3]) {
1419 const SkScalar P20 = src[4] - src[0];
1420 const SkScalar P10 = src[2] - src[0];
1421 const SkScalar wP10 = w * P10;
1422 coeff[0] = w * P20 - P20;
1423 coeff[1] = P20 - 2 * wP10;
1427 static SkScalar conic_eval_tan(const SkScalar coord[], SkScalar w, SkScalar t) {
1429 conic_deriv_coeff(coord, w, coeff);
1430 return t * (t * coeff[0] + coeff[1]) + coeff[2];
1433 static bool conic_find_extrema(const SkScalar src[], SkScalar w, SkScalar* t) {
1435 conic_deriv_coeff(src, w, coeff);
1437 SkScalar tValues[2];
1438 int roots = SkFindUnitQuadRoots(coeff[0], coeff[1], coeff[2], tValues);
1439 SkASSERT(0 == roots || 1 == roots);
1449 SkScalar fX, fY, fZ;
1451 void set(SkScalar x, SkScalar y, SkScalar z) {
1452 fX = x; fY = y; fZ = z;
1455 void projectDown(SkPoint* dst) const {
1456 dst->set(fX / fZ, fY / fZ);
1460 // we just return the middle 3 points, since the first and last are dups of src
1462 static void p3d_interp(const SkScalar src[3], SkScalar dst[3], SkScalar t) {
1463 SkScalar ab = SkScalarInterp(src[0], src[3], t);
1464 SkScalar bc = SkScalarInterp(src[3], src[6], t);
1466 dst[3] = SkScalarInterp(ab, bc, t);
1470 static void ratquad_mapTo3D(const SkPoint src[3], SkScalar w, SkP3D dst[]) {
1471 dst[0].set(src[0].fX * 1, src[0].fY * 1, 1);
1472 dst[1].set(src[1].fX * w, src[1].fY * w, w);
1473 dst[2].set(src[2].fX * 1, src[2].fY * 1, 1);
1476 void SkConic::evalAt(SkScalar t, SkPoint* pt, SkVector* tangent) const {
1477 SkASSERT(t >= 0 && t <= SK_Scalar1);
1480 pt->set(conic_eval_pos(&fPts[0].fX, fW, t),
1481 conic_eval_pos(&fPts[0].fY, fW, t));
1484 tangent->set(conic_eval_tan(&fPts[0].fX, fW, t),
1485 conic_eval_tan(&fPts[0].fY, fW, t));
1489 void SkConic::chopAt(SkScalar t, SkConic dst[2]) const {
1490 SkP3D tmp[3], tmp2[3];
1492 ratquad_mapTo3D(fPts, fW, tmp);
1494 p3d_interp(&tmp[0].fX, &tmp2[0].fX, t);
1495 p3d_interp(&tmp[0].fY, &tmp2[0].fY, t);
1496 p3d_interp(&tmp[0].fZ, &tmp2[0].fZ, t);
1498 dst[0].fPts[0] = fPts[0];
1499 tmp2[0].projectDown(&dst[0].fPts[1]);
1500 tmp2[1].projectDown(&dst[0].fPts[2]); dst[1].fPts[0] = dst[0].fPts[2];
1501 tmp2[2].projectDown(&dst[1].fPts[1]);
1502 dst[1].fPts[2] = fPts[2];
1504 // to put in "standard form", where w0 and w2 are both 1, we compute the
1505 // new w1 as sqrt(w1*w1/w0*w2)
1507 // w1 /= sqrt(w0*w2)
1509 // However, in our case, we know that for dst[0], w0 == 1, and for dst[1], w2 == 1
1511 SkScalar root = SkScalarSqrt(tmp2[1].fZ);
1512 dst[0].fW = tmp2[0].fZ / root;
1513 dst[1].fW = tmp2[2].fZ / root;
1516 static SkScalar subdivide_w_value(SkScalar w) {
1517 return SkScalarSqrt(SK_ScalarHalf + w * SK_ScalarHalf);
1520 void SkConic::chop(SkConic dst[2]) const {
1521 SkScalar scale = SkScalarInvert(SK_Scalar1 + fW);
1522 SkScalar p1x = fW * fPts[1].fX;
1523 SkScalar p1y = fW * fPts[1].fY;
1524 SkScalar mx = (fPts[0].fX + 2 * p1x + fPts[2].fX) * scale * SK_ScalarHalf;
1525 SkScalar my = (fPts[0].fY + 2 * p1y + fPts[2].fY) * scale * SK_ScalarHalf;
1527 dst[0].fPts[0] = fPts[0];
1528 dst[0].fPts[1].set((fPts[0].fX + p1x) * scale,
1529 (fPts[0].fY + p1y) * scale);
1530 dst[0].fPts[2].set(mx, my);
1532 dst[1].fPts[0].set(mx, my);
1533 dst[1].fPts[1].set((p1x + fPts[2].fX) * scale,
1534 (p1y + fPts[2].fY) * scale);
1535 dst[1].fPts[2] = fPts[2];
1537 dst[0].fW = dst[1].fW = subdivide_w_value(fW);
1541 * "High order approximation of conic sections by quadratic splines"
1542 * by Michael Floater, 1993
1544 #define AS_QUAD_ERROR_SETUP \
1545 SkScalar a = fW - 1; \
1546 SkScalar k = a / (4 * (2 + a)); \
1547 SkScalar x = k * (fPts[0].fX - 2 * fPts[1].fX + fPts[2].fX); \
1548 SkScalar y = k * (fPts[0].fY - 2 * fPts[1].fY + fPts[2].fY);
1550 void SkConic::computeAsQuadError(SkVector* err) const {
1555 bool SkConic::asQuadTol(SkScalar tol) const {
1557 return (x * x + y * y) <= tol * tol;
1560 int SkConic::computeQuadPOW2(SkScalar tol) const {
1562 SkScalar error = SkScalarSqrt(x * x + y * y) - tol;
1567 uint32_t ierr = (uint32_t)error;
1568 return (34 - SkCLZ(ierr)) >> 1;
1571 static SkPoint* subdivide(const SkConic& src, SkPoint pts[], int level) {
1572 SkASSERT(level >= 0);
1575 memcpy(pts, &src.fPts[1], 2 * sizeof(SkPoint));
1581 pts = subdivide(dst[0], pts, level);
1582 return subdivide(dst[1], pts, level);
1586 int SkConic::chopIntoQuadsPOW2(SkPoint pts[], int pow2) const {
1587 SkASSERT(pow2 >= 0);
1589 SkDEBUGCODE(SkPoint* endPts =) subdivide(*this, pts + 1, pow2);
1590 SkASSERT(endPts - pts == (2 * (1 << pow2) + 1));
1594 bool SkConic::findXExtrema(SkScalar* t) const {
1595 return conic_find_extrema(&fPts[0].fX, fW, t);
1598 bool SkConic::findYExtrema(SkScalar* t) const {
1599 return conic_find_extrema(&fPts[0].fY, fW, t);
1602 bool SkConic::chopAtXExtrema(SkConic dst[2]) const {
1604 if (this->findXExtrema(&t)) {
1605 this->chopAt(t, dst);
1606 // now clean-up the middle, since we know t was meant to be at
1608 SkScalar value = dst[0].fPts[2].fX;
1609 dst[0].fPts[1].fX = value;
1610 dst[1].fPts[0].fX = value;
1611 dst[1].fPts[1].fX = value;
1617 bool SkConic::chopAtYExtrema(SkConic dst[2]) const {
1619 if (this->findYExtrema(&t)) {
1620 this->chopAt(t, dst);
1621 // now clean-up the middle, since we know t was meant to be at
1623 SkScalar value = dst[0].fPts[2].fY;
1624 dst[0].fPts[1].fY = value;
1625 dst[1].fPts[0].fY = value;
1626 dst[1].fPts[1].fY = value;
1632 void SkConic::computeTightBounds(SkRect* bounds) const {
1639 if (this->findXExtrema(&t)) {
1640 this->evalAt(t, &pts[count++]);
1642 if (this->findYExtrema(&t)) {
1643 this->evalAt(t, &pts[count++]);
1645 bounds->set(pts, count);
1648 void SkConic::computeFastBounds(SkRect* bounds) const {
1649 bounds->set(fPts, 3);