diff options
author | caryclark <caryclark@google.com> | 2015-08-25 10:02:46 -0700 |
---|---|---|
committer | Commit bot <commit-bot@chromium.org> | 2015-08-25 10:02:46 -0700 |
commit | 91298b47c547b2ab4697038c04685af957bd1416 (patch) | |
tree | e30ceb981717c4ad9ac2600b723d11bbab1cbeb5 | |
parent | 6ec8b7cee7a8016ee8871faab58424ea7786c879 (diff) |
Revert of fix zero-length tangent (patchset #2 id:20001 of https://codereview.chromium.org/1311273002/ )
Reason for revert:
causes layout test to draw differently -- new drawing is more correct. Reverting until layout test ignore is landed.
Original issue's description:
> fix zero-length tangent
>
> If the end point and the control point are the same, computing
> the tangent will result in (0, 0). In this case, use the prior
> control point instead.
>
> R=reed@google.com
>
> BUG=skia:4191
>
> Committed: https://skia.googlesource.com/skia/+/7544124fb8ee744f68f549a353f8a9163cd7432d
TBR=reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:4191
Review URL: https://codereview.chromium.org/1312243002
-rw-r--r-- | gm/strokes.cpp | 56 | ||||
-rw-r--r-- | src/core/SkGeometry.cpp | 49 | ||||
-rw-r--r-- | tests/GeometryTest.cpp | 64 |
3 files changed, 19 insertions, 150 deletions
diff --git a/gm/strokes.cpp b/gm/strokes.cpp index 0bcb039783..73823907a3 100644 --- a/gm/strokes.cpp +++ b/gm/strokes.cpp @@ -266,60 +266,6 @@ private: typedef skiagm::GM INHERITED; }; -// Test stroking for curves that produce degenerate tangents when t is 0 or 1 (see bug 4191) -class Strokes5GM : public skiagm::GM { -public: - Strokes5GM() {} - -protected: - - SkString onShortName() override { - return SkString("zero_control_stroke"); - } - - SkISize onISize() override { - return SkISize::Make(W, H*2); - } - - void onDraw(SkCanvas* canvas) override { - SkPaint p; - p.setColor(SK_ColorRED); - p.setAntiAlias(true); - p.setStyle(SkPaint::kStroke_Style); - p.setStrokeWidth(40); - p.setStrokeCap(SkPaint::kButt_Cap); - - SkPath path; - path.moveTo(157.474f,111.753f); - path.cubicTo(128.5f,111.5f,35.5f,29.5f,35.5f,29.5f); - canvas->drawPath(path, p); - path.reset(); - path.moveTo(250, 50); - path.quadTo(280, 80, 280, 80); - canvas->drawPath(path, p); - path.reset(); - path.moveTo(150, 50); - path.conicTo(180, 80, 180, 80, 0.707f); - canvas->drawPath(path, p); - - path.reset(); - path.moveTo(157.474f,311.753f); - path.cubicTo(157.474f,311.753f,85.5f,229.5f,35.5f,229.5f); - canvas->drawPath(path, p); - path.reset(); - path.moveTo(280, 250); - path.quadTo(280, 250, 310, 280); - canvas->drawPath(path, p); - path.reset(); - path.moveTo(180, 250); - path.conicTo(180, 250, 210, 280, 0.707f); - canvas->drawPath(path, p); - } - -private: - typedef skiagm::GM INHERITED; -}; - ////////////////////////////////////////////////////////////////////////////// @@ -327,10 +273,8 @@ static skiagm::GM* F0(void*) { return new StrokesGM; } static skiagm::GM* F1(void*) { return new Strokes2GM; } static skiagm::GM* F2(void*) { return new Strokes3GM; } static skiagm::GM* F3(void*) { return new Strokes4GM; } -static skiagm::GM* F4(void*) { return new Strokes5GM; } static skiagm::GMRegistry R0(F0); static skiagm::GMRegistry R1(F1); static skiagm::GMRegistry R2(F2); static skiagm::GMRegistry R3(F3); -static skiagm::GMRegistry R4(F4); diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp index 7462009479..6afd9d7ffb 100644 --- a/src/core/SkGeometry.cpp +++ b/src/core/SkGeometry.cpp @@ -130,6 +130,13 @@ static SkScalar eval_quad(const SkScalar src[], SkScalar t) { #endif } +static SkScalar eval_quad_derivative(const SkScalar src[], SkScalar t) { + SkScalar A = src[4] - 2 * src[2] + src[0]; + SkScalar B = src[2] - src[0]; + + return 2 * SkScalarMulAdd(A, t, B); +} + void SkQuadToCoeff(const SkPoint pts[3], SkPoint coeff[3]) { Sk2s p0 = from_point(pts[0]); Sk2s p1 = from_point(pts[1]); @@ -150,7 +157,8 @@ void SkEvalQuadAt(const SkPoint src[3], SkScalar t, SkPoint* pt, SkVector* tange pt->set(eval_quad(&src[0].fX, t), eval_quad(&src[0].fY, t)); } if (tangent) { - *tangent = SkEvalQuadTangentAt(src, t); + tangent->set(eval_quad_derivative(&src[0].fX, t), + eval_quad_derivative(&src[0].fY, t)); } } @@ -171,12 +179,6 @@ SkPoint SkEvalQuadAt(const SkPoint src[3], SkScalar t) { } SkVector SkEvalQuadTangentAt(const SkPoint src[3], SkScalar t) { - // The derivative equation is 2(b - a +(a - 2b +c)t). This returns a - // zero tangent vector when t is 0 or 1, and the control point is equal - // to the end point. In this case, use the quad end points to compute the tangent. - if ((t == 0 && src[0] == src[1]) || (t == 1 && src[1] == src[2])) { - return src[2] - src[0]; - } SkASSERT(src); SkASSERT(t >= 0 && t <= SK_Scalar1); @@ -396,22 +398,8 @@ void SkEvalCubicAt(const SkPoint src[4], SkScalar t, SkPoint* loc, loc->set(eval_cubic(&src[0].fX, t), eval_cubic(&src[0].fY, t)); } if (tangent) { - // The derivative equation returns a zero tangent vector when t is 0 or 1, and the - // adjacent control point is equal to the end point. In this case, use the - // next control point or the end points to compute the tangent. - if ((t == 0 && src[0] == src[1]) || (t == 1 && src[2] == src[3])) { - if (t == 0) { - *tangent = src[2] - src[0]; - } else { - *tangent = src[3] - src[1]; - } - if (!tangent->fX && !tangent->fY) { - *tangent = src[3] - src[0]; - } - } else { - tangent->set(eval_cubic_derivative(&src[0].fX, t), - eval_cubic_derivative(&src[0].fY, t)); - } + tangent->set(eval_cubic_derivative(&src[0].fX, t), + eval_cubic_derivative(&src[0].fY, t)); } if (curvature) { curvature->set(eval_cubic_2ndDerivative(&src[0].fX, t), @@ -1188,6 +1176,12 @@ static void conic_deriv_coeff(const SkScalar src[], coeff[2] = wP10; } +static SkScalar conic_eval_tan(const SkScalar coord[], SkScalar w, SkScalar t) { + SkScalar coeff[3]; + conic_deriv_coeff(coord, w, coeff); + return t * (t * coeff[0] + coeff[1]) + coeff[2]; +} + static bool conic_find_extrema(const SkScalar src[], SkScalar w, SkScalar* t) { SkScalar coeff[3]; conic_deriv_coeff(src, w, coeff); @@ -1238,7 +1232,8 @@ void SkConic::evalAt(SkScalar t, SkPoint* pt, SkVector* tangent) const { conic_eval_pos(&fPts[0].fY, fW, t)); } if (tangent) { - *tangent = evalTangentAt(t); + tangent->set(conic_eval_tan(&fPts[0].fX, fW, t), + conic_eval_tan(&fPts[0].fY, fW, t)); } } @@ -1296,12 +1291,6 @@ SkPoint SkConic::evalAt(SkScalar t) const { } SkVector SkConic::evalTangentAt(SkScalar t) const { - // The derivative equation returns a zero tangent vector when t is 0 or 1, - // and the control point is equal to the end point. - // In this case, use the conic endpoints to compute the tangent. - if ((t == 0 && fPts[0] == fPts[1]) || (t == 1 && fPts[1] == fPts[2])) { - return fPts[2] - fPts[0]; - } Sk2s p0 = from_point(fPts[0]); Sk2s p1 = from_point(fPts[1]); Sk2s p2 = from_point(fPts[2]); diff --git a/tests/GeometryTest.cpp b/tests/GeometryTest.cpp index 5aa80d0b1f..00fc7797dc 100644 --- a/tests/GeometryTest.cpp +++ b/tests/GeometryTest.cpp @@ -105,67 +105,6 @@ static void test_conic(skiatest::Reporter* reporter) { } } -static void test_quad_tangents(skiatest::Reporter* reporter) { - SkPoint pts[] = { - {10, 20}, {10, 20}, {20, 30}, - {10, 20}, {15, 25}, {20, 30}, - {10, 20}, {20, 30}, {20, 30}, - }; - int count = (int) SK_ARRAY_COUNT(pts) / 3; - for (int index = 0; index < count; ++index) { - SkConic conic(&pts[index * 3], 0.707f); - SkVector start = SkEvalQuadTangentAt(&pts[index * 3], 0); - SkVector mid = SkEvalQuadTangentAt(&pts[index * 3], .5f); - SkVector end = SkEvalQuadTangentAt(&pts[index * 3], 1); - REPORTER_ASSERT(reporter, start.fX && start.fY); - REPORTER_ASSERT(reporter, mid.fX && mid.fY); - REPORTER_ASSERT(reporter, end.fX && end.fY); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid))); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end))); - } -} - -static void test_conic_tangents(skiatest::Reporter* reporter) { - SkPoint pts[] = { - { 10, 20}, {10, 20}, {20, 30}, - { 10, 20}, {15, 25}, {20, 30}, - { 10, 20}, {20, 30}, {20, 30} - }; - int count = (int) SK_ARRAY_COUNT(pts) / 3; - for (int index = 0; index < count; ++index) { - SkConic conic(&pts[index * 3], 0.707f); - SkVector start = conic.evalTangentAt(0); - SkVector mid = conic.evalTangentAt(.5f); - SkVector end = conic.evalTangentAt(1); - REPORTER_ASSERT(reporter, start.fX && start.fY); - REPORTER_ASSERT(reporter, mid.fX && mid.fY); - REPORTER_ASSERT(reporter, end.fX && end.fY); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid))); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end))); - } -} - -static void test_cubic_tangents(skiatest::Reporter* reporter) { - SkPoint pts[] = { - { 10, 20}, {10, 20}, {20, 30}, {30, 40}, - { 10, 20}, {15, 25}, {20, 30}, {30, 40}, - { 10, 20}, {20, 30}, {30, 40}, {30, 40}, - }; - int count = (int) SK_ARRAY_COUNT(pts) / 4; - for (int index = 0; index < count; ++index) { - SkConic conic(&pts[index * 3], 0.707f); - SkVector start, mid, end; - SkEvalCubicAt(&pts[index * 4], 0, NULL, &start, NULL); - SkEvalCubicAt(&pts[index * 4], .5f, NULL, &mid, NULL); - SkEvalCubicAt(&pts[index * 4], 1, NULL, &end, NULL); - REPORTER_ASSERT(reporter, start.fX && start.fY); - REPORTER_ASSERT(reporter, mid.fX && mid.fY); - REPORTER_ASSERT(reporter, end.fX && end.fY); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid))); - REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end))); - } -} - DEF_TEST(Geometry, reporter) { SkPoint pts[3], dst[5]; @@ -190,7 +129,4 @@ DEF_TEST(Geometry, reporter) { testChopCubic(reporter); test_evalquadat(reporter); test_conic(reporter); - test_cubic_tangents(reporter); - test_quad_tangents(reporter); - test_conic_tangents(reporter); } |