diff options
| -rw-r--r-- | src/core/SkGeometry.cpp | 107 | ||||
| -rw-r--r-- | tests/GeometryTest.cpp | 20 |
2 files changed, 74 insertions, 53 deletions
diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp index 46fd683512..a1e8419a41 100644 --- a/src/core/SkGeometry.cpp +++ b/src/core/SkGeometry.cpp @@ -601,62 +601,63 @@ static void sort_and_orient_t_s(double t[2], double s[2]) { // d1 = d2 = 0, d3 != 0 Quadratic // d1 = d2 = d3 = 0 Line or Point static SkCubicType classify_cubic(const double d[4], double t[2], double s[2]) { - double tolerance = SkTMax(fabs(d[1]), fabs(d[2])); - tolerance = SkTMax(tolerance, fabs(d[3])); - tolerance = tolerance * 1e-4; - if (fabs(d[1]) > tolerance) { - const double discr = 3 * d[2] * d[2] - 4 * d[1] * d[3]; - if (discr > 0) { - if (t && s) { - const double q = 3 * d[2] + copysign(sqrt(3 * discr), d[2]); - t[0] = q; - s[0] = 6 * d[1]; - t[1] = 2 * d[3]; - s[1] = q; - normalize_t_s(t, s, 2); - sort_and_orient_t_s(t, s); - } - return SkCubicType::kSerpentine; - } else if (discr < 0) { - if (t && s) { - const double q = d[2] + copysign(sqrt(-discr), d[2]); - t[0] = q; - s[0] = 2 * d[1]; - t[1] = 2 * (d[2] * d[2] - d[3] * d[1]); - s[1] = d[1] * q; - normalize_t_s(t, s, 2); - sort_and_orient_t_s(t, s); - } - return SkCubicType::kLoop; - } else { - SkASSERT(0 == discr); // Detect NaN. - if (t && s) { - t[0] = d[2]; - s[0] = 2 * d[1]; - normalize_t_s(t, s, 1); - t[1] = t[0]; - s[1] = s[0]; - sort_and_orient_t_s(t, s); - } - return SkCubicType::kLocalCusp; + // Check for degenerate cubics (quadratics, lines, and points). + // This also attempts to detect near-quadratics in a resolution independent fashion, however it + // is still up to the caller to check for almost-linear curves if needed. + if (fabs(d[1]) + fabs(d[2]) <= fabs(d[3]) * 1e-3) { + if (t && s) { + t[0] = t[1] = 1; + s[0] = s[1] = 0; // infinity + } + return 0 == d[3] ? SkCubicType::kLineOrPoint : SkCubicType::kQuadratic; + } + + if (0 == d[1]) { + SkASSERT(0 != d[2]); // captured in check for degeneracy above. + if (t && s) { + t[0] = d[3]; + s[0] = 3 * d[2]; + normalize_t_s(t, s, 1); + t[1] = 1; + s[1] = 0; // infinity } + return SkCubicType::kCuspAtInfinity; + } + + const double discr = 3 * d[2] * d[2] - 4 * d[1] * d[3]; + if (discr > 0) { + if (t && s) { + const double q = 3 * d[2] + copysign(sqrt(3 * discr), d[2]); + t[0] = q; + s[0] = 6 * d[1]; + t[1] = 2 * d[3]; + s[1] = q; + normalize_t_s(t, s, 2); + sort_and_orient_t_s(t, s); + } + return SkCubicType::kSerpentine; + } else if (discr < 0) { + if (t && s) { + const double q = d[2] + copysign(sqrt(-discr), d[2]); + t[0] = q; + s[0] = 2 * d[1]; + t[1] = 2 * (d[2] * d[2] - d[3] * d[1]); + s[1] = d[1] * q; + normalize_t_s(t, s, 2); + sort_and_orient_t_s(t, s); + } + return SkCubicType::kLoop; } else { - if (fabs(d[2]) > tolerance) { - if (t && s) { - t[0] = d[3]; - s[0] = 3 * d[2]; - normalize_t_s(t, s, 1); - t[1] = 1; - s[1] = 0; // infinity - } - return SkCubicType::kCuspAtInfinity; - } else { - if (t && s) { - t[0] = t[1] = 1; - s[0] = s[1] = 0; // infinity - } - return fabs(d[3]) > tolerance ? SkCubicType::kQuadratic : SkCubicType::kLineOrPoint; + SkASSERT(0 == discr); // Detect NaN. + if (t && s) { + t[0] = d[2]; + s[0] = 2 * d[1]; + normalize_t_s(t, s, 1); + t[1] = t[0]; + s[1] = s[0]; + sort_and_orient_t_s(t, s); } + return SkCubicType::kLocalCusp; } } diff --git a/tests/GeometryTest.cpp b/tests/GeometryTest.cpp index 91136e0240..4d955b5b13 100644 --- a/tests/GeometryTest.cpp +++ b/tests/GeometryTest.cpp @@ -8,6 +8,7 @@ #include "SkGeometry.h" #include "Test.h" #include "SkRandom.h" +#include <array> static bool nearly_equal(const SkPoint& a, const SkPoint& b) { return SkScalarNearlyEqual(a.fX, b.fX) && SkScalarNearlyEqual(a.fY, b.fY); @@ -205,6 +206,24 @@ static void test_cubic_tangents(skiatest::Reporter* reporter) { } } +static void check_cubic_type(skiatest::Reporter* reporter, + const std::array<SkPoint, 4>& bezierPoints, SkCubicType expectedType) { + SkCubicType actualType = SkClassifyCubic(bezierPoints.data()); + REPORTER_ASSERT(reporter, actualType == expectedType); +} + +static void test_classify_cubic(skiatest::Reporter* reporter) { + check_cubic_type(reporter, {{{149.325f, 107.705f}, {149.325f, 103.783f}, + {151.638f, 100.127f}, {156.263f, 96.736f}}}, + SkCubicType::kQuadratic); + check_cubic_type(reporter, {{{225.694f, 223.15f}, {209.831f, 224.837f}, + {195.994f, 230.237f}, {184.181f, 239.35f}}}, + SkCubicType::kQuadratic); + check_cubic_type(reporter, {{{4.873f, 5.581f}, {5.083f, 5.2783f}, + {5.182f, 4.8593f}, {5.177f, 4.3242f}}}, + SkCubicType::kSerpentine); +} + DEF_TEST(Geometry, reporter) { SkPoint pts[3], dst[5]; @@ -233,4 +252,5 @@ DEF_TEST(Geometry, reporter) { test_quad_tangents(reporter); test_conic_tangents(reporter); test_conic_to_quads(reporter); + test_classify_cubic(reporter); } |