xref: /third_party/skia/tests/GeometryTest.cpp (revision cb93a386)
1/*
2 * Copyright 2011 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "include/utils/SkRandom.h"
9#include "src/core/SkGeometry.h"
10#include "src/core/SkPointPriv.h"
11#include "tests/Test.h"
12
13#include <array>
14#include <numeric>
15
16static bool nearly_equal(const SkPoint& a, const SkPoint& b) {
17    return SkScalarNearlyEqual(a.fX, b.fX) && SkScalarNearlyEqual(a.fY, b.fY);
18}
19
20static void testChopCubic(skiatest::Reporter* reporter) {
21    /*
22        Inspired by this test, which used to assert that the tValues had dups
23
24        <path stroke="#202020" d="M0,0 C0,0 1,1 2190,5130 C2190,5070 2220,5010 2205,4980" />
25     */
26    const SkPoint src[] = {
27        { SkIntToScalar(2190), SkIntToScalar(5130) },
28        { SkIntToScalar(2190), SkIntToScalar(5070) },
29        { SkIntToScalar(2220), SkIntToScalar(5010) },
30        { SkIntToScalar(2205), SkIntToScalar(4980) },
31    };
32    SkPoint dst[13];
33    SkScalar tValues[3];
34    // make sure we don't assert internally
35    int count = SkChopCubicAtMaxCurvature(src, dst, tValues);
36    if (false) { // avoid bit rot, suppress warning
37        REPORTER_ASSERT(reporter, count);
38    }
39    // Make sure src and dst can be the same pointer.
40    {
41        SkPoint pts[7];
42        for (int i = 0; i < 7; ++i) {
43            pts[i].set(i, i);
44        }
45        SkChopCubicAt(pts, pts, .5f);
46        for (int i = 0; i < 7; ++i) {
47            REPORTER_ASSERT(reporter, pts[i].fX == pts[i].fY);
48            REPORTER_ASSERT(reporter, pts[i].fX == i * .5f);
49        }
50    }
51
52    static const float chopTs[] = {
53        0, 3/83.f, 3/79.f, 3/73.f, 3/71.f, 3/67.f, 3/61.f, 3/59.f, 3/53.f, 3/47.f, 3/43.f, 3/41.f,
54        3/37.f, 3/31.f, 3/29.f, 3/23.f, 3/19.f, 3/17.f, 3/13.f, 3/11.f, 3/7.f, 3/5.f, 1,
55    };
56    float ones[] = {1,1,1,1,1};
57
58    // Ensure an odd number of T values so we exercise the single chop code at the end of
59    // SkChopCubicAt form multiple T.
60    static_assert(SK_ARRAY_COUNT(chopTs) % 2 == 1);
61    static_assert(SK_ARRAY_COUNT(ones) % 2 == 1);
62
63    SkRandom rand;
64    for (int iterIdx = 0; iterIdx < 5; ++iterIdx) {
65        SkPoint pts[4] = {{rand.nextF(), rand.nextF()}, {rand.nextF(), rand.nextF()},
66                          {rand.nextF(), rand.nextF()}, {rand.nextF(), rand.nextF()}};
67
68        SkPoint allChops[4 + SK_ARRAY_COUNT(chopTs)*3];
69        SkChopCubicAt(pts, allChops, chopTs, SK_ARRAY_COUNT(chopTs));
70        int i = 3;
71        for (float chopT : chopTs) {
72            // Ensure we chop at approximately the correct points when we chop an entire list.
73            SkPoint expectedPt;
74            SkEvalCubicAt(pts, chopT, &expectedPt, nullptr, nullptr);
75            REPORTER_ASSERT(reporter, SkScalarNearlyEqual(allChops[i].x(), expectedPt.x()));
76            REPORTER_ASSERT(reporter, SkScalarNearlyEqual(allChops[i].y(), expectedPt.y()));
77            if (chopT == 0) {
78                REPORTER_ASSERT(reporter, allChops[i] == pts[0]);
79            }
80            if (chopT == 1) {
81                REPORTER_ASSERT(reporter, allChops[i] == pts[3]);
82            }
83            i += 3;
84
85            // Ensure the middle is exactly degenerate when we chop at two equal points.
86            SkPoint localChops[10];
87            SkChopCubicAt(pts, localChops, chopT, chopT);
88            REPORTER_ASSERT(reporter, localChops[3] == localChops[4]);
89            REPORTER_ASSERT(reporter, localChops[3] == localChops[5]);
90            REPORTER_ASSERT(reporter, localChops[3] == localChops[6]);
91            if (chopT == 0) {
92                // Also ensure the first curve is exactly p0 when we chop at T=0.
93                REPORTER_ASSERT(reporter, localChops[0] == pts[0]);
94                REPORTER_ASSERT(reporter, localChops[1] == pts[0]);
95                REPORTER_ASSERT(reporter, localChops[2] == pts[0]);
96                REPORTER_ASSERT(reporter, localChops[3] == pts[0]);
97            }
98            if (chopT == 1) {
99                // Also ensure the last curve is exactly p3 when we chop at T=1.
100                REPORTER_ASSERT(reporter, localChops[6] == pts[3]);
101                REPORTER_ASSERT(reporter, localChops[7] == pts[3]);
102                REPORTER_ASSERT(reporter, localChops[8] == pts[3]);
103                REPORTER_ASSERT(reporter, localChops[9] == pts[3]);
104            }
105        }
106
107        // Now test what happens when SkChopCubicAt does 0/0 and gets NaN values.
108        SkPoint oneChops[4 + SK_ARRAY_COUNT(ones)*3];
109        SkChopCubicAt(pts, oneChops, ones, SK_ARRAY_COUNT(ones));
110        REPORTER_ASSERT(reporter, oneChops[0] == pts[0]);
111        REPORTER_ASSERT(reporter, oneChops[1] == pts[1]);
112        REPORTER_ASSERT(reporter, oneChops[2] == pts[2]);
113        for (size_t index = 3; index < SK_ARRAY_COUNT(oneChops); ++index) {
114            REPORTER_ASSERT(reporter, oneChops[index] == pts[3]);
115        }
116    }
117}
118
119static void check_pairs(skiatest::Reporter* reporter, int index, SkScalar t, const char name[],
120                        SkScalar x0, SkScalar y0, SkScalar x1, SkScalar y1) {
121    bool eq = SkScalarNearlyEqual(x0, x1) && SkScalarNearlyEqual(y0, y1);
122    if (!eq) {
123        SkDebugf("%s [%d %g] p0 [%10.8f %10.8f] p1 [%10.8f %10.8f]\n",
124                 name, index, t, x0, y0, x1, y1);
125        REPORTER_ASSERT(reporter, eq);
126    }
127}
128
129static void test_evalquadat(skiatest::Reporter* reporter) {
130    SkRandom rand;
131    for (int i = 0; i < 1000; ++i) {
132        SkPoint pts[3];
133        for (int j = 0; j < 3; ++j) {
134            pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
135        }
136        const SkScalar dt = SK_Scalar1 / 128;
137        SkScalar t = dt;
138        for (int j = 1; j < 128; ++j) {
139            SkPoint r0;
140            SkEvalQuadAt(pts, t, &r0);
141            SkPoint r1 = SkEvalQuadAt(pts, t);
142            check_pairs(reporter, i, t, "quad-pos", r0.fX, r0.fY, r1.fX, r1.fY);
143
144            SkVector v0;
145            SkEvalQuadAt(pts, t, nullptr, &v0);
146            SkVector v1 = SkEvalQuadTangentAt(pts, t);
147            check_pairs(reporter, i, t, "quad-tan", v0.fX, v0.fY, v1.fX, v1.fY);
148
149            t += dt;
150        }
151    }
152}
153
154static void test_conic_eval_pos(skiatest::Reporter* reporter, const SkConic& conic, SkScalar t) {
155    SkPoint p0, p1;
156    conic.evalAt(t, &p0, nullptr);
157    p1 = conic.evalAt(t);
158    check_pairs(reporter, 0, t, "conic-pos", p0.fX, p0.fY, p1.fX, p1.fY);
159}
160
161static void test_conic_eval_tan(skiatest::Reporter* reporter, const SkConic& conic, SkScalar t) {
162    SkVector v0, v1;
163    conic.evalAt(t, nullptr, &v0);
164    v1 = conic.evalTangentAt(t);
165    check_pairs(reporter, 0, t, "conic-tan", v0.fX, v0.fY, v1.fX, v1.fY);
166}
167
168static void test_conic(skiatest::Reporter* reporter) {
169    SkRandom rand;
170    for (int i = 0; i < 1000; ++i) {
171        SkPoint pts[3];
172        for (int j = 0; j < 3; ++j) {
173            pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
174        }
175        for (int k = 0; k < 10; ++k) {
176            SkScalar w = rand.nextUScalar1() * 2;
177            SkConic conic(pts, w);
178
179            const SkScalar dt = SK_Scalar1 / 128;
180            SkScalar t = dt;
181            for (int j = 1; j < 128; ++j) {
182                test_conic_eval_pos(reporter, conic, t);
183                test_conic_eval_tan(reporter, conic, t);
184                t += dt;
185            }
186        }
187    }
188}
189
190static void test_quad_tangents(skiatest::Reporter* reporter) {
191    SkPoint pts[] = {
192        {10, 20}, {10, 20}, {20, 30},
193        {10, 20}, {15, 25}, {20, 30},
194        {10, 20}, {20, 30}, {20, 30},
195    };
196    int count = (int) SK_ARRAY_COUNT(pts) / 3;
197    for (int index = 0; index < count; ++index) {
198        SkConic conic(&pts[index * 3], 0.707f);
199        SkVector start = SkEvalQuadTangentAt(&pts[index * 3], 0);
200        SkVector mid = SkEvalQuadTangentAt(&pts[index * 3], .5f);
201        SkVector end = SkEvalQuadTangentAt(&pts[index * 3], 1);
202        REPORTER_ASSERT(reporter, start.fX && start.fY);
203        REPORTER_ASSERT(reporter, mid.fX && mid.fY);
204        REPORTER_ASSERT(reporter, end.fX && end.fY);
205        REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
206        REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
207    }
208}
209
210static void test_conic_tangents(skiatest::Reporter* reporter) {
211    SkPoint pts[] = {
212        { 10, 20}, {10, 20}, {20, 30},
213        { 10, 20}, {15, 25}, {20, 30},
214        { 10, 20}, {20, 30}, {20, 30}
215    };
216    int count = (int) SK_ARRAY_COUNT(pts) / 3;
217    for (int index = 0; index < count; ++index) {
218        SkConic conic(&pts[index * 3], 0.707f);
219        SkVector start = conic.evalTangentAt(0);
220        SkVector mid = conic.evalTangentAt(.5f);
221        SkVector end = conic.evalTangentAt(1);
222        REPORTER_ASSERT(reporter, start.fX && start.fY);
223        REPORTER_ASSERT(reporter, mid.fX && mid.fY);
224        REPORTER_ASSERT(reporter, end.fX && end.fY);
225        REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
226        REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
227    }
228}
229
230static void test_this_conic_to_quad(skiatest::Reporter* r, const SkPoint pts[3], SkScalar w) {
231    SkAutoConicToQuads quadder;
232    const SkPoint* qpts = quadder.computeQuads(pts, w, 0.25);
233    const int qcount = quadder.countQuads();
234    const int pcount = qcount * 2 + 1;
235
236    REPORTER_ASSERT(r, SkPointPriv::AreFinite(qpts, pcount));
237}
238
239/**
240 *  We need to ensure that when a conic is approximated by quads, that we always return finite
241 *  values in the quads.
242 *
243 *  Inspired by crbug_627414
244 */
245static void test_conic_to_quads(skiatest::Reporter* reporter) {
246    const SkPoint triples[] = {
247        { 0, 0 }, { 1, 0 }, { 1, 1 },
248        { 0, 0 }, { 3.58732e-43f, 2.72084f }, { 3.00392f, 3.00392f },
249        { 0, 0 }, { 100000, 0 }, { 100000, 100000 },
250        { 0, 0 }, { 1e30f, 0 }, { 1e30f, 1e30f },
251    };
252    const int N = sizeof(triples) / sizeof(SkPoint);
253
254    for (int i = 0; i < N; i += 3) {
255        const SkPoint* pts = &triples[i];
256
257        SkScalar w = 1e30f;
258        do {
259            w *= 2;
260            test_this_conic_to_quad(reporter, pts, w);
261        } while (SkScalarIsFinite(w));
262        test_this_conic_to_quad(reporter, pts, SK_ScalarNaN);
263    }
264}
265
266static void test_cubic_tangents(skiatest::Reporter* reporter) {
267    SkPoint pts[] = {
268        { 10, 20}, {10, 20}, {20, 30}, {30, 40},
269        { 10, 20}, {15, 25}, {20, 30}, {30, 40},
270        { 10, 20}, {20, 30}, {30, 40}, {30, 40},
271    };
272    int count = (int) SK_ARRAY_COUNT(pts) / 4;
273    for (int index = 0; index < count; ++index) {
274        SkConic conic(&pts[index * 3], 0.707f);
275        SkVector start, mid, end;
276        SkEvalCubicAt(&pts[index * 4], 0, nullptr, &start, nullptr);
277        SkEvalCubicAt(&pts[index * 4], .5f, nullptr, &mid, nullptr);
278        SkEvalCubicAt(&pts[index * 4], 1, nullptr, &end, nullptr);
279        REPORTER_ASSERT(reporter, start.fX && start.fY);
280        REPORTER_ASSERT(reporter, mid.fX && mid.fY);
281        REPORTER_ASSERT(reporter, end.fX && end.fY);
282        REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
283        REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
284    }
285}
286
287static void check_cubic_type(skiatest::Reporter* reporter,
288                             const std::array<SkPoint, 4>& bezierPoints, SkCubicType expectedType,
289                             bool undefined = false) {
290    // Classify the cubic even if the results will be undefined: check for crashes and asserts.
291    SkCubicType actualType = SkClassifyCubic(bezierPoints.data());
292    if (!undefined) {
293        REPORTER_ASSERT(reporter, actualType == expectedType);
294    }
295}
296
297static void check_cubic_around_rect(skiatest::Reporter* reporter,
298                                    float x1, float y1, float x2, float y2,
299                                    bool undefined = false) {
300    static constexpr SkCubicType expectations[24] = {
301        SkCubicType::kLoop,
302        SkCubicType::kCuspAtInfinity,
303        SkCubicType::kLocalCusp,
304        SkCubicType::kLocalCusp,
305        SkCubicType::kCuspAtInfinity,
306        SkCubicType::kLoop,
307        SkCubicType::kCuspAtInfinity,
308        SkCubicType::kLoop,
309        SkCubicType::kCuspAtInfinity,
310        SkCubicType::kLoop,
311        SkCubicType::kLocalCusp,
312        SkCubicType::kLocalCusp,
313        SkCubicType::kLocalCusp,
314        SkCubicType::kLocalCusp,
315        SkCubicType::kLoop,
316        SkCubicType::kCuspAtInfinity,
317        SkCubicType::kLoop,
318        SkCubicType::kCuspAtInfinity,
319        SkCubicType::kLoop,
320        SkCubicType::kCuspAtInfinity,
321        SkCubicType::kLocalCusp,
322        SkCubicType::kLocalCusp,
323        SkCubicType::kCuspAtInfinity,
324        SkCubicType::kLoop,
325    };
326    SkPoint points[] = {{x1, y1}, {x2, y1}, {x2, y2}, {x1, y2}};
327    std::array<SkPoint, 4> bezier;
328    for (int i=0; i < 4; ++i) {
329        bezier[0] = points[i];
330        for (int j=0; j < 3; ++j) {
331            int jidx = (j < i) ? j : j+1;
332            bezier[1] = points[jidx];
333            for (int k=0, kidx=0; k < 2; ++k, ++kidx) {
334                for (int n = 0; n < 2; ++n) {
335                    kidx = (kidx == i || kidx == jidx) ? kidx+1 : kidx;
336                }
337                bezier[2] = points[kidx];
338                for (int l = 0; l < 4; ++l) {
339                    if (l != i && l != jidx && l != kidx) {
340                        bezier[3] = points[l];
341                        break;
342                    }
343                }
344                check_cubic_type(reporter, bezier, expectations[i*6 + j*2 + k], undefined);
345            }
346        }
347    }
348    for (int i=0; i < 4; ++i) {
349        bezier[0] = points[i];
350        for (int j=0; j < 3; ++j) {
351            int jidx = (j < i) ? j : j+1;
352            bezier[1] = points[jidx];
353            bezier[2] = points[jidx];
354            for (int k=0, kidx=0; k < 2; ++k, ++kidx) {
355                for (int n = 0; n < 2; ++n) {
356                    kidx = (kidx == i || kidx == jidx) ? kidx+1 : kidx;
357                }
358                bezier[3] = points[kidx];
359                check_cubic_type(reporter, bezier, SkCubicType::kSerpentine, undefined);
360            }
361        }
362    }
363}
364
365static std::array<SkPoint, 4> kSerpentines[] = {
366    {{{149.325f, 107.705f}, {149.325f, 103.783f}, {151.638f, 100.127f}, {156.263f, 96.736f}}},
367    {{{225.694f, 223.15f}, {209.831f, 224.837f}, {195.994f, 230.237f}, {184.181f, 239.35f}}},
368    {{{4.873f, 5.581f}, {5.083f, 5.2783f}, {5.182f, 4.8593f}, {5.177f, 4.3242f}}},
369    {{{285.625f, 499.687f}, {411.625f, 808.188f}, {1064.62f, 135.688f}, {1042.63f, 585.187f}}}
370};
371
372static std::array<SkPoint, 4> kLoops[] = {
373    {{{635.625f, 614.687f}, {171.625f, 236.188f}, {1064.62f, 135.688f}, {516.625f, 570.187f}}},
374    {{{653.050f, 725.049f}, {663.000f, 176.000f}, {1189.000f, 508.000f}, {288.050f, 564.950f}}},
375    {{{631.050f, 478.049f}, {730.000f, 302.000f}, {870.000f, 350.000f}, {905.050f, 528.950f}}},
376    {{{631.050f, 478.0499f}, {221.000f, 230.000f}, {1265.000f, 451.000f}, {905.050f, 528.950f}}}
377};
378
379static std::array<SkPoint, 4> kLinearCubics[] = {
380    {{{0, 0}, {0, 1}, {0, 2}, {0, 3}}},  // 0-degree flat line.
381    {{{0, 0}, {1, 0}, {1, 0}, {0, 0}}},  // 180-degree flat line
382    {{{0, 1}, {0, 0}, {0, 2}, {0, 3}}},  // 180-degree flat line
383    {{{0, 1}, {0, 0}, {0, 3}, {0, 2}}},  // 360-degree flat line
384    {{{0, 0}, {2, 0}, {1, 0}, {64, 0}}},  // 360-degree flat line
385    {{{1, 0}, {0, 0}, {3, 0}, {-64, 0}}}  // 360-degree flat line
386};
387
388static void test_classify_cubic(skiatest::Reporter* reporter) {
389    for (const auto& serp : kSerpentines) {
390        check_cubic_type(reporter, serp, SkCubicType::kSerpentine);
391    }
392    for (const auto& loop : kLoops) {
393        check_cubic_type(reporter, loop, SkCubicType::kLoop);
394    }
395    for (const auto& loop : kLinearCubics) {
396        check_cubic_type(reporter, loop, SkCubicType::kLineOrPoint);
397    }
398    check_cubic_around_rect(reporter, 0, 0, 1, 1);
399    check_cubic_around_rect(reporter,
400                            -std::numeric_limits<float>::max(),
401                            -std::numeric_limits<float>::max(),
402                            +std::numeric_limits<float>::max(),
403                            +std::numeric_limits<float>::max());
404    check_cubic_around_rect(reporter, 1, 1,
405                            +std::numeric_limits<float>::min(),
406                            +std::numeric_limits<float>::max());
407    check_cubic_around_rect(reporter,
408                            -std::numeric_limits<float>::min(),
409                            -std::numeric_limits<float>::min(),
410                            +std::numeric_limits<float>::min(),
411                            +std::numeric_limits<float>::min());
412    check_cubic_around_rect(reporter, +1, -std::numeric_limits<float>::min(), -1, -1);
413    check_cubic_around_rect(reporter,
414                            -std::numeric_limits<float>::infinity(),
415                            -std::numeric_limits<float>::infinity(),
416                            +std::numeric_limits<float>::infinity(),
417                            +std::numeric_limits<float>::infinity(),
418                            true);
419    check_cubic_around_rect(reporter, 0, 0, 1, +std::numeric_limits<float>::infinity(), true);
420    check_cubic_around_rect(reporter,
421                            -std::numeric_limits<float>::quiet_NaN(),
422                            -std::numeric_limits<float>::quiet_NaN(),
423                            +std::numeric_limits<float>::quiet_NaN(),
424                            +std::numeric_limits<float>::quiet_NaN(),
425                            true);
426    check_cubic_around_rect(reporter, 0, 0, 1, +std::numeric_limits<float>::quiet_NaN(), true);
427}
428
429static std::array<SkPoint, 4> kCusps[] = {
430    {{{0, 0}, {1, 1}, {1, 0}, {0, 1}}},
431    {{{0, 0}, {1, 1}, {0, 1}, {1, 0}}},
432    {{{0, 1}, {1, 0}, {0, 0}, {1, 1}}},
433    {{{0, 1}, {1, 0}, {1, 1}, {0, 0}}},
434};
435
436static void test_cubic_cusps(skiatest::Reporter* reporter) {
437    std::array<SkPoint, 4> noCusps[] = {
438        {{{0, 0}, {1, 1}, {2, 2}, {3, 3}}},
439        {{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
440        {{{0, 0}, {1, 0}, {2, 1}, {2, 2}}},
441        {{{0, 0}, {1, 0}, {1, 1}, {2, 1}}},
442    };
443    for (auto noCusp : noCusps) {
444        REPORTER_ASSERT(reporter, SkFindCubicCusp(noCusp.data()) < 0);
445    }
446    for (auto cusp : kCusps) {
447        REPORTER_ASSERT(reporter, SkFindCubicCusp(cusp.data()) > 0);
448    }
449}
450
451static SkMatrix kSkewMatrices[] = {
452    SkMatrix::MakeAll(1,0,0, 0,1,0, 0,0,1),
453    SkMatrix::MakeAll(1,-1,0, 1,1,0, 0,0,1),
454    SkMatrix::MakeAll(.889f,.553f,0, -.443f,.123f,0, 0,0,1),
455};
456
457static void test_chop_quad_at_midtangent(skiatest::Reporter* reporter, const SkPoint pts[3]) {
458    constexpr float kTolerance = 1e-3f;
459    for (const SkMatrix& m : kSkewMatrices) {
460        SkPoint mapped[3];
461        m.mapPoints(mapped, pts, 3);
462        float fullRotation = SkMeasureQuadRotation(pts);
463        SkPoint chopped[5];
464        SkChopQuadAtMidTangent(pts, chopped);
465        float leftRotation = SkMeasureQuadRotation(chopped);
466        float rightRotation = SkMeasureQuadRotation(chopped+2);
467        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(leftRotation, fullRotation/2, kTolerance));
468        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(rightRotation, fullRotation/2, kTolerance));
469    }
470}
471
472static void test_chop_cubic_at_midtangent(skiatest::Reporter* reporter, const SkPoint pts[4],
473                                          SkCubicType cubicType) {
474    constexpr float kTolerance = 1e-3f;
475    int n = SK_ARRAY_COUNT(kSkewMatrices);
476    if (cubicType == SkCubicType::kLocalCusp || cubicType == SkCubicType::kLineOrPoint) {
477        // FP precision isn't always enough to get the exact correct T value of the mid-tangent on
478        // cusps and lines. Only test the identity matrix and the matrix with all 1's.
479        n = 2;
480    }
481    for (int i = 0; i < n; ++i) {
482        SkPoint mapped[4];
483        kSkewMatrices[i].mapPoints(mapped, pts, 4);
484        float fullRotation = SkMeasureNonInflectCubicRotation(mapped);
485        SkPoint chopped[7];
486        SkChopCubicAtMidTangent(mapped, chopped);
487        float leftRotation = SkMeasureNonInflectCubicRotation(chopped);
488        float rightRotation = SkMeasureNonInflectCubicRotation(chopped+3);
489        if (cubicType == SkCubicType::kLineOrPoint &&
490            (SkScalarNearlyEqual(fullRotation, 2*SK_ScalarPI, kTolerance) ||
491             SkScalarNearlyEqual(fullRotation, 0, kTolerance))) {
492            // 0- and 360-degree flat lines don't have single points of midtangent.
493            // (tangent == midtangent at every point on these curves except the cusp points.)
494            // Instead verify the promise from SkChopCubicAtMidTangent that neither side will rotate
495            // more than 180 degrees.
496            REPORTER_ASSERT(reporter, std::abs(leftRotation) - kTolerance <= SK_ScalarPI);
497            REPORTER_ASSERT(reporter, std::abs(rightRotation) - kTolerance <= SK_ScalarPI);
498            continue;
499        }
500        float expectedChoppedRotation = fullRotation/2;
501        if (cubicType == SkCubicType::kLocalCusp ||
502            (cubicType == SkCubicType::kLineOrPoint &&
503             SkScalarNearlyEqual(fullRotation, SK_ScalarPI, kTolerance))) {
504            // If we chop a cubic at a cusp, we lose 180 degrees of rotation.
505            expectedChoppedRotation = (fullRotation - SK_ScalarPI)/2;
506        }
507        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(leftRotation, expectedChoppedRotation,
508                                                      kTolerance));
509        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(rightRotation, expectedChoppedRotation,
510                                                      kTolerance));
511    }
512}
513
514static std::array<SkPoint, 3> kQuads[] = {
515    {{{10, 20}, {15, 35}, {30, 40}}},
516    {{{176.324f, 392.705f}, {719.325f, 205.782f}, {297.263f, 347.735f}}},
517    {{{652.050f, 602.049f}, {481.000f, 533.000f}, {288.050f, 564.950f}}},
518    {{{460.625f, 557.187f}, {707.121f, 209.688f}, {779.628f, 577.687f}}},
519    {{{359.050f, 578.049f}, {759.000f, 274.000f}, {288.050f, 564.950f}}}
520};
521
522SkPoint lerp(const SkPoint& a, const SkPoint& b, float t) {
523    return a * (1 - t) + b * t;
524}
525
526static void test_measure_rotation(skiatest::Reporter* reporter) {
527    static SkPoint kFlatCubic[4] = {{0, 0}, {0, 1}, {0, 2}, {0, 3}};
528    REPORTER_ASSERT(reporter, SkScalarNearlyZero(SkMeasureNonInflectCubicRotation(kFlatCubic)));
529
530    static SkPoint kFlatCubic180_1[4] = {{0, 0}, {1, 0}, {3, 0}, {2, 0}};
531    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic180_1),
532                                                  SK_ScalarPI));
533
534    static SkPoint kFlatCubic180_2[4] = {{0, 1}, {0, 0}, {0, 2}, {0, 3}};
535    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic180_2),
536                                                  SK_ScalarPI));
537
538    static SkPoint kFlatCubic360[4] = {{0, 1}, {0, 0}, {0, 3}, {0, 2}};
539    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic360),
540                                                  2*SK_ScalarPI));
541
542    static SkPoint kSquare180[4] = {{0, 0}, {0, 1}, {1, 1}, {1, 0}};
543    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kSquare180),
544                                                  SK_ScalarPI));
545
546    auto checkQuadRotation = [=](const SkPoint pts[3], float expectedRotation) {
547        float r = SkMeasureQuadRotation(pts);
548        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(r, expectedRotation));
549
550        SkPoint cubic1[4] = {pts[0], pts[0], pts[1], pts[2]};
551        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic1),
552                                                      expectedRotation));
553
554        SkPoint cubic2[4] = {pts[0], pts[1], pts[1], pts[2]};
555        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic2),
556                                                      expectedRotation));
557
558        SkPoint cubic3[4] = {pts[0], pts[1], pts[2], pts[2]};
559        REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic3),
560                                                      expectedRotation));
561    };
562
563    static SkPoint kFlatQuad[4] = {{0, 0}, {0, 1}, {0, 2}};
564    checkQuadRotation(kFlatQuad, 0);
565
566    static SkPoint kFlatQuad180_1[4] = {{1, 0}, {0, 0}, {2, 0}};
567    checkQuadRotation(kFlatQuad180_1, SK_ScalarPI);
568
569    static SkPoint kFlatQuad180_2[4] = {{0, 0}, {0, 2}, {0, 1}};
570    checkQuadRotation(kFlatQuad180_2, SK_ScalarPI);
571
572    static SkPoint kTri120[3] = {{0, 0}, {.5f, std::sqrt(3.f)/2}, {1, 0}};
573    checkQuadRotation(kTri120, 2*SK_ScalarPI/3);
574}
575
576static void test_chop_at_midtangent(skiatest::Reporter* reporter) {
577    SkPoint chops[10];
578    for (const auto& serp : kSerpentines) {
579        REPORTER_ASSERT(reporter, SkClassifyCubic(serp.data()) == SkCubicType::kSerpentine);
580        int n = SkChopCubicAtInflections(serp.data(), chops);
581        for (int i = 0; i < n; ++i) {
582            test_chop_cubic_at_midtangent(reporter, chops + i*3, SkCubicType::kSerpentine);
583        }
584    }
585    for (const auto& loop : kLoops) {
586        REPORTER_ASSERT(reporter, SkClassifyCubic(loop.data()) == SkCubicType::kLoop);
587        test_chop_cubic_at_midtangent(reporter, loop.data(), SkCubicType::kLoop);
588    }
589    for (const auto& line : kLinearCubics) {
590        REPORTER_ASSERT(reporter, SkClassifyCubic(line.data()) == SkCubicType::kLineOrPoint);
591        test_chop_cubic_at_midtangent(reporter, line.data(), SkCubicType::kLineOrPoint);
592    }
593    for (const auto& cusp : kCusps) {
594        REPORTER_ASSERT(reporter, SkClassifyCubic(cusp.data()) == SkCubicType::kLocalCusp);
595        test_chop_cubic_at_midtangent(reporter, cusp.data(), SkCubicType::kLocalCusp);
596    }
597    for (const auto& quad : kQuads) {
598        test_chop_quad_at_midtangent(reporter, quad.data());
599        SkPoint asCubic[4] = {
600                quad[0], lerp(quad[0], quad[1], 2/3.f), lerp(quad[1], quad[2], 1/3.f), quad[2]};
601        test_chop_cubic_at_midtangent(reporter, asCubic, SkCubicType::kQuadratic);
602    }
603
604    static const SkPoint kExactQuad[4] = {{0,0}, {6,2}, {10,2}, {12,0}};
605    REPORTER_ASSERT(reporter, SkClassifyCubic(kExactQuad) == SkCubicType::kQuadratic);
606    test_chop_cubic_at_midtangent(reporter, kExactQuad, SkCubicType::kQuadratic);
607
608    static const SkPoint kExactCuspAtInf[4] = {{0,0}, {1,0}, {0,1}, {1,1}};
609    REPORTER_ASSERT(reporter, SkClassifyCubic(kExactCuspAtInf) == SkCubicType::kCuspAtInfinity);
610    int n = SkChopCubicAtInflections(kExactCuspAtInf, chops);
611    for (int i = 0; i < n; ++i) {
612        test_chop_cubic_at_midtangent(reporter, chops + i*3, SkCubicType::kCuspAtInfinity);
613    }
614}
615
616DEF_TEST(Geometry, reporter) {
617    SkPoint pts[5];
618
619    pts[0].set(0, 0);
620    pts[1].set(100, 50);
621    pts[2].set(0, 100);
622
623    int count = SkChopQuadAtMaxCurvature(pts, pts);  // Ensure src and dst can be the same pointer.
624    REPORTER_ASSERT(reporter, count == 1 || count == 2);
625
626    // This previously crashed because the computed t of max curvature is NaN and SkChopQuadAt
627    // asserts that the passed t is in 0..1. Passes by not asserting.
628    pts[0].set(15.1213f, 7.77647f);
629    pts[1].set(6.2168e+19f, 1.51338e+20f);
630    pts[2].set(1.4579e+19f, 1.55558e+21f);
631    count = SkChopQuadAtMaxCurvature(pts, pts);
632
633    pts[0].set(0, 0);
634    pts[1].set(3, 0);
635    pts[2].set(3, 3);
636    SkConvertQuadToCubic(pts, pts);
637    const SkPoint cubic[] = {
638        { 0, 0, }, { 2, 0, }, { 3, 1, }, { 3, 3 },
639    };
640    for (int i = 0; i < 4; ++i) {
641        REPORTER_ASSERT(reporter, nearly_equal(cubic[i], pts[i]));
642    }
643
644    testChopCubic(reporter);
645    test_evalquadat(reporter);
646    test_conic(reporter);
647    test_cubic_tangents(reporter);
648    test_quad_tangents(reporter);
649    test_conic_tangents(reporter);
650    test_conic_to_quads(reporter);
651    test_classify_cubic(reporter);
652    test_cubic_cusps(reporter);
653    test_measure_rotation(reporter);
654    test_chop_at_midtangent(reporter);
655}
656