xref: /aosp_15_r20/external/skia/tests/GeometryTest.cpp (revision c8dee2aa9b3f27cf6c858bd81872bdeb2c07ed17)
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/core/SkMatrix.h"
9 #include "include/core/SkPoint.h"
10 #include "include/core/SkScalar.h"
11 #include "include/core/SkSpan.h"
12 #include "include/core/SkTypes.h"
13 #include "include/private/base/SkDebug.h"
14 #include "src/base/SkRandom.h"
15 #include "src/core/SkGeometry.h"
16 #include "src/core/SkPointPriv.h"
17 #include "tests/Test.h"
18 
19 #include <array>
20 #include <cmath>
21 #include <cstdlib>
22 #include <limits>
23 #include <string>
24 
nearly_equal(const SkPoint & a,const SkPoint & b)25 static bool nearly_equal(const SkPoint& a, const SkPoint& b) {
26     return SkScalarNearlyEqual(a.fX, b.fX) && SkScalarNearlyEqual(a.fY, b.fY);
27 }
28 
testChopCubic(skiatest::Reporter * reporter)29 static void testChopCubic(skiatest::Reporter* reporter) {
30     /*
31         Inspired by this test, which used to assert that the tValues had dups
32 
33         <path stroke="#202020" d="M0,0 C0,0 1,1 2190,5130 C2190,5070 2220,5010 2205,4980" />
34      */
35     const SkPoint src[] = {
36         { SkIntToScalar(2190), SkIntToScalar(5130) },
37         { SkIntToScalar(2190), SkIntToScalar(5070) },
38         { SkIntToScalar(2220), SkIntToScalar(5010) },
39         { SkIntToScalar(2205), SkIntToScalar(4980) },
40     };
41     SkPoint dst[13];
42     SkScalar tValues[3];
43     // make sure we don't assert internally
44     int count = SkChopCubicAtMaxCurvature(src, dst, tValues);
45     if ((false)) { // avoid bit rot, suppress warning
46         REPORTER_ASSERT(reporter, count);
47     }
48     // Make sure src and dst can be the same pointer.
49     {
50         SkPoint pts[7];
51         for (int i = 0; i < 7; ++i) {
52             pts[i].set(i, i);
53         }
54         SkChopCubicAt(pts, pts, .5f);
55         for (int i = 0; i < 7; ++i) {
56             REPORTER_ASSERT(reporter, pts[i].fX == pts[i].fY);
57             REPORTER_ASSERT(reporter, pts[i].fX == i * .5f);
58         }
59     }
60 
61     static const float chopTs[] = {
62         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,
63         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,
64     };
65     float ones[] = {1,1,1,1,1};
66 
67     // Ensure an odd number of T values so we exercise the single chop code at the end of
68     // SkChopCubicAt form multiple T.
69     static_assert(std::size(chopTs) % 2 == 1);
70     static_assert(std::size(ones) % 2 == 1);
71 
72     SkRandom rand;
73     for (int iterIdx = 0; iterIdx < 5; ++iterIdx) {
74         SkPoint pts[4] = {{rand.nextF(), rand.nextF()}, {rand.nextF(), rand.nextF()},
75                           {rand.nextF(), rand.nextF()}, {rand.nextF(), rand.nextF()}};
76 
77         SkPoint allChops[4 + std::size(chopTs)*3];
78         SkChopCubicAt(pts, allChops, chopTs, std::size(chopTs));
79         int i = 3;
80         for (float chopT : chopTs) {
81             // Ensure we chop at approximately the correct points when we chop an entire list.
82             SkPoint expectedPt;
83             SkEvalCubicAt(pts, chopT, &expectedPt, nullptr, nullptr);
84             REPORTER_ASSERT(reporter, SkScalarNearlyEqual(allChops[i].x(), expectedPt.x()));
85             REPORTER_ASSERT(reporter, SkScalarNearlyEqual(allChops[i].y(), expectedPt.y()));
86             if (chopT == 0) {
87                 REPORTER_ASSERT(reporter, allChops[i] == pts[0]);
88             }
89             if (chopT == 1) {
90                 REPORTER_ASSERT(reporter, allChops[i] == pts[3]);
91             }
92             i += 3;
93 
94             // Ensure the middle is exactly degenerate when we chop at two equal points.
95             SkPoint localChops[10];
96             SkChopCubicAt(pts, localChops, chopT, chopT);
97             REPORTER_ASSERT(reporter, localChops[3] == localChops[4]);
98             REPORTER_ASSERT(reporter, localChops[3] == localChops[5]);
99             REPORTER_ASSERT(reporter, localChops[3] == localChops[6]);
100             if (chopT == 0) {
101                 // Also ensure the first curve is exactly p0 when we chop at T=0.
102                 REPORTER_ASSERT(reporter, localChops[0] == pts[0]);
103                 REPORTER_ASSERT(reporter, localChops[1] == pts[0]);
104                 REPORTER_ASSERT(reporter, localChops[2] == pts[0]);
105                 REPORTER_ASSERT(reporter, localChops[3] == pts[0]);
106             }
107             if (chopT == 1) {
108                 // Also ensure the last curve is exactly p3 when we chop at T=1.
109                 REPORTER_ASSERT(reporter, localChops[6] == pts[3]);
110                 REPORTER_ASSERT(reporter, localChops[7] == pts[3]);
111                 REPORTER_ASSERT(reporter, localChops[8] == pts[3]);
112                 REPORTER_ASSERT(reporter, localChops[9] == pts[3]);
113             }
114         }
115 
116         // Now test what happens when SkChopCubicAt does 0/0 and gets NaN values.
117         SkPoint oneChops[4 + std::size(ones)*3];
118         SkChopCubicAt(pts, oneChops, ones, std::size(ones));
119         REPORTER_ASSERT(reporter, oneChops[0] == pts[0]);
120         REPORTER_ASSERT(reporter, oneChops[1] == pts[1]);
121         REPORTER_ASSERT(reporter, oneChops[2] == pts[2]);
122         for (size_t index = 3; index < std::size(oneChops); ++index) {
123             REPORTER_ASSERT(reporter, oneChops[index] == pts[3]);
124         }
125     }
126 }
127 
check_pairs(skiatest::Reporter * reporter,int index,SkScalar t,const char name[],SkScalar x0,SkScalar y0,SkScalar x1,SkScalar y1)128 static void check_pairs(skiatest::Reporter* reporter, int index, SkScalar t, const char name[],
129                         SkScalar x0, SkScalar y0, SkScalar x1, SkScalar y1) {
130     bool eq = SkScalarNearlyEqual(x0, x1) && SkScalarNearlyEqual(y0, y1);
131     if (!eq) {
132         SkDebugf("%s [%d %g] p0 [%10.8f %10.8f] p1 [%10.8f %10.8f]\n",
133                  name, index, t, x0, y0, x1, y1);
134         REPORTER_ASSERT(reporter, eq);
135     }
136 }
137 
test_evalquadat(skiatest::Reporter * reporter)138 static void test_evalquadat(skiatest::Reporter* reporter) {
139     SkRandom rand;
140     for (int i = 0; i < 1000; ++i) {
141         SkPoint pts[3];
142         for (int j = 0; j < 3; ++j) {
143             pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
144         }
145         const SkScalar dt = SK_Scalar1 / 128;
146         SkScalar t = dt;
147         for (int j = 1; j < 128; ++j) {
148             SkPoint r0;
149             SkEvalQuadAt(pts, t, &r0);
150             SkPoint r1 = SkEvalQuadAt(pts, t);
151             check_pairs(reporter, i, t, "quad-pos", r0.fX, r0.fY, r1.fX, r1.fY);
152 
153             SkVector v0;
154             SkEvalQuadAt(pts, t, nullptr, &v0);
155             SkVector v1 = SkEvalQuadTangentAt(pts, t);
156             check_pairs(reporter, i, t, "quad-tan", v0.fX, v0.fY, v1.fX, v1.fY);
157 
158             t += dt;
159         }
160     }
161 }
162 
test_conic_eval_pos(skiatest::Reporter * reporter,const SkConic & conic,SkScalar t)163 static void test_conic_eval_pos(skiatest::Reporter* reporter, const SkConic& conic, SkScalar t) {
164     SkPoint p0, p1;
165     conic.evalAt(t, &p0, nullptr);
166     p1 = conic.evalAt(t);
167     check_pairs(reporter, 0, t, "conic-pos", p0.fX, p0.fY, p1.fX, p1.fY);
168 }
169 
test_conic_eval_tan(skiatest::Reporter * reporter,const SkConic & conic,SkScalar t)170 static void test_conic_eval_tan(skiatest::Reporter* reporter, const SkConic& conic, SkScalar t) {
171     SkVector v0, v1;
172     conic.evalAt(t, nullptr, &v0);
173     v1 = conic.evalTangentAt(t);
174     check_pairs(reporter, 0, t, "conic-tan", v0.fX, v0.fY, v1.fX, v1.fY);
175 }
176 
test_conic(skiatest::Reporter * reporter)177 static void test_conic(skiatest::Reporter* reporter) {
178     SkRandom rand;
179     for (int i = 0; i < 1000; ++i) {
180         SkPoint pts[3];
181         for (int j = 0; j < 3; ++j) {
182             pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
183         }
184         for (int k = 0; k < 10; ++k) {
185             SkScalar w = rand.nextUScalar1() * 2;
186             SkConic conic(pts, w);
187 
188             const SkScalar dt = SK_Scalar1 / 128;
189             SkScalar t = dt;
190             for (int j = 1; j < 128; ++j) {
191                 test_conic_eval_pos(reporter, conic, t);
192                 test_conic_eval_tan(reporter, conic, t);
193                 t += dt;
194             }
195         }
196     }
197 }
198 
test_quad_tangents(skiatest::Reporter * reporter)199 static void test_quad_tangents(skiatest::Reporter* reporter) {
200     SkPoint pts[] = {
201         {10, 20}, {10, 20}, {20, 30},
202         {10, 20}, {15, 25}, {20, 30},
203         {10, 20}, {20, 30}, {20, 30},
204     };
205     int count = (int) std::size(pts) / 3;
206     for (int index = 0; index < count; ++index) {
207         SkConic conic(&pts[index * 3], 0.707f);
208         SkVector start = SkEvalQuadTangentAt(&pts[index * 3], 0);
209         SkVector mid = SkEvalQuadTangentAt(&pts[index * 3], .5f);
210         SkVector end = SkEvalQuadTangentAt(&pts[index * 3], 1);
211         REPORTER_ASSERT(reporter, start.fX && start.fY);
212         REPORTER_ASSERT(reporter, mid.fX && mid.fY);
213         REPORTER_ASSERT(reporter, end.fX && end.fY);
214         REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
215         REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
216     }
217 }
218 
test_conic_tangents(skiatest::Reporter * reporter)219 static void test_conic_tangents(skiatest::Reporter* reporter) {
220     SkPoint pts[] = {
221         { 10, 20}, {10, 20}, {20, 30},
222         { 10, 20}, {15, 25}, {20, 30},
223         { 10, 20}, {20, 30}, {20, 30}
224     };
225     int count = (int) std::size(pts) / 3;
226     for (int index = 0; index < count; ++index) {
227         SkConic conic(&pts[index * 3], 0.707f);
228         SkVector start = conic.evalTangentAt(0);
229         SkVector mid = conic.evalTangentAt(.5f);
230         SkVector end = conic.evalTangentAt(1);
231         REPORTER_ASSERT(reporter, start.fX && start.fY);
232         REPORTER_ASSERT(reporter, mid.fX && mid.fY);
233         REPORTER_ASSERT(reporter, end.fX && end.fY);
234         REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
235         REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
236     }
237 }
238 
test_this_conic_to_quad(skiatest::Reporter * r,const SkPoint pts[3],SkScalar w)239 static void test_this_conic_to_quad(skiatest::Reporter* r, const SkPoint pts[3], SkScalar w) {
240     SkAutoConicToQuads quadder;
241     const SkPoint* qpts = quadder.computeQuads(pts, w, 0.25);
242     const int qcount = quadder.countQuads();
243     const int pcount = qcount * 2 + 1;
244 
245     REPORTER_ASSERT(r, SkPointPriv::AreFinite(qpts, pcount));
246 }
247 
248 /**
249  *  We need to ensure that when a conic is approximated by quads, that we always return finite
250  *  values in the quads.
251  *
252  *  Inspired by crbug_627414
253  */
test_conic_to_quads(skiatest::Reporter * reporter)254 static void test_conic_to_quads(skiatest::Reporter* reporter) {
255     const SkPoint triples[] = {
256         { 0, 0 }, { 1, 0 }, { 1, 1 },
257         { 0, 0 }, { 3.58732e-43f, 2.72084f }, { 3.00392f, 3.00392f },
258         { 0, 0 }, { 100000, 0 }, { 100000, 100000 },
259         { 0, 0 }, { 1e30f, 0 }, { 1e30f, 1e30f },
260     };
261     const int N = sizeof(triples) / sizeof(SkPoint);
262 
263     for (int i = 0; i < N; i += 3) {
264         const SkPoint* pts = &triples[i];
265 
266         SkScalar w = 1e30f;
267         do {
268             w *= 2;
269             test_this_conic_to_quad(reporter, pts, w);
270         } while (SkIsFinite(w));
271         test_this_conic_to_quad(reporter, pts, SK_ScalarNaN);
272     }
273 }
274 
test_cubic_tangents(skiatest::Reporter * reporter)275 static void test_cubic_tangents(skiatest::Reporter* reporter) {
276     SkPoint pts[] = {
277         { 10, 20}, {10, 20}, {20, 30}, {30, 40},
278         { 10, 20}, {15, 25}, {20, 30}, {30, 40},
279         { 10, 20}, {20, 30}, {30, 40}, {30, 40},
280     };
281     int count = (int) std::size(pts) / 4;
282     for (int index = 0; index < count; ++index) {
283         SkConic conic(&pts[index * 3], 0.707f);
284         SkVector start, mid, end;
285         SkEvalCubicAt(&pts[index * 4], 0, nullptr, &start, nullptr);
286         SkEvalCubicAt(&pts[index * 4], .5f, nullptr, &mid, nullptr);
287         SkEvalCubicAt(&pts[index * 4], 1, nullptr, &end, nullptr);
288         REPORTER_ASSERT(reporter, start.fX && start.fY);
289         REPORTER_ASSERT(reporter, mid.fX && mid.fY);
290         REPORTER_ASSERT(reporter, end.fX && end.fY);
291         REPORTER_ASSERT(reporter, SkScalarNearlyZero(start.cross(mid)));
292         REPORTER_ASSERT(reporter, SkScalarNearlyZero(mid.cross(end)));
293     }
294 }
295 
check_cubic_type(skiatest::Reporter * reporter,const std::array<SkPoint,4> & bezierPoints,SkCubicType expectedType,bool undefined=false)296 static void check_cubic_type(skiatest::Reporter* reporter,
297                              const std::array<SkPoint, 4>& bezierPoints, SkCubicType expectedType,
298                              bool undefined = false) {
299     // Classify the cubic even if the results will be undefined: check for crashes and asserts.
300     SkCubicType actualType = SkClassifyCubic(bezierPoints.data());
301     if (!undefined) {
302         REPORTER_ASSERT(reporter, actualType == expectedType,
303                         "%d != %d", (int)actualType, (int)expectedType);
304     }
305 }
306 
check_cubic_around_rect(std::string name,skiatest::Reporter * reporter,float x1,float y1,float x2,float y2,bool undefined=false)307 static void check_cubic_around_rect(std::string name, skiatest::Reporter* reporter,
308                                     float x1, float y1, float x2, float y2,
309                                     bool undefined = false) {
310     skiatest::ReporterContext subtest(reporter, name);
311     static constexpr SkCubicType expectations[24] = {
312         SkCubicType::kLoop,
313         SkCubicType::kCuspAtInfinity,
314         SkCubicType::kLocalCusp,
315         SkCubicType::kLocalCusp,
316         SkCubicType::kCuspAtInfinity,
317         SkCubicType::kLoop,
318         SkCubicType::kCuspAtInfinity,
319         SkCubicType::kLoop,
320         SkCubicType::kCuspAtInfinity,
321         SkCubicType::kLoop,
322         SkCubicType::kLocalCusp,
323         SkCubicType::kLocalCusp,
324         SkCubicType::kLocalCusp,
325         SkCubicType::kLocalCusp,
326         SkCubicType::kLoop,
327         SkCubicType::kCuspAtInfinity,
328         SkCubicType::kLoop,
329         SkCubicType::kCuspAtInfinity,
330         SkCubicType::kLoop,
331         SkCubicType::kCuspAtInfinity,
332         SkCubicType::kLocalCusp,
333         SkCubicType::kLocalCusp,
334         SkCubicType::kCuspAtInfinity,
335         SkCubicType::kLoop,
336     };
337     SkPoint points[] = {{x1, y1}, {x2, y1}, {x2, y2}, {x1, y2}};
338     std::array<SkPoint, 4> bezier;
339     for (int i=0; i < 4; ++i) {
340         bezier[0] = points[i];
341         for (int j=0; j < 3; ++j) {
342             int jidx = (j < i) ? j : j+1;
343             bezier[1] = points[jidx];
344             for (int k=0, kidx=0; k < 2; ++k, ++kidx) {
345                 for (int n = 0; n < 2; ++n) {
346                     kidx = (kidx == i || kidx == jidx) ? kidx+1 : kidx;
347                 }
348                 bezier[2] = points[kidx];
349                 for (int l = 0; l < 4; ++l) {
350                     if (l != i && l != jidx && l != kidx) {
351                         bezier[3] = points[l];
352                         break;
353                     }
354                 }
355                 check_cubic_type(reporter, bezier, expectations[i*6 + j*2 + k], undefined);
356             }
357         }
358     }
359     for (int i=0; i < 4; ++i) {
360         bezier[0] = points[i];
361         for (int j=0; j < 3; ++j) {
362             int jidx = (j < i) ? j : j+1;
363             bezier[1] = points[jidx];
364             bezier[2] = points[jidx];
365             for (int k=0, kidx=0; k < 2; ++k, ++kidx) {
366                 for (int n = 0; n < 2; ++n) {
367                     kidx = (kidx == i || kidx == jidx) ? kidx+1 : kidx;
368                 }
369                 bezier[3] = points[kidx];
370                 check_cubic_type(reporter, bezier, SkCubicType::kSerpentine, undefined);
371             }
372         }
373     }
374 }
375 
376 static std::array<SkPoint, 4> kSerpentines[] = {
377     {{{149.325f, 107.705f}, {149.325f, 103.783f}, {151.638f, 100.127f}, {156.263f, 96.736f}}},
378     {{{225.694f, 223.15f}, {209.831f, 224.837f}, {195.994f, 230.237f}, {184.181f, 239.35f}}},
379     {{{4.873f, 5.581f}, {5.083f, 5.2783f}, {5.182f, 4.8593f}, {5.177f, 4.3242f}}},
380     {{{285.625f, 499.687f}, {411.625f, 808.188f}, {1064.62f, 135.688f}, {1042.63f, 585.187f}}}
381 };
382 
383 static std::array<SkPoint, 4> kLoops[] = {
384     {{{635.625f, 614.687f}, {171.625f, 236.188f}, {1064.62f, 135.688f}, {516.625f, 570.187f}}},
385     {{{653.050f, 725.049f}, {663.000f, 176.000f}, {1189.000f, 508.000f}, {288.050f, 564.950f}}},
386     {{{631.050f, 478.049f}, {730.000f, 302.000f}, {870.000f, 350.000f}, {905.050f, 528.950f}}},
387     {{{631.050f, 478.0499f}, {221.000f, 230.000f}, {1265.000f, 451.000f}, {905.050f, 528.950f}}}
388 };
389 
390 static std::array<SkPoint, 4> kLinearCubics[] = {
391     {{{0, 0}, {0, 1}, {0, 2}, {0, 3}}},  // 0-degree flat line.
392     {{{0, 0}, {1, 0}, {1, 0}, {0, 0}}},  // 180-degree flat line
393     {{{0, 1}, {0, 0}, {0, 2}, {0, 3}}},  // 180-degree flat line
394     {{{0, 1}, {0, 0}, {0, 3}, {0, 2}}},  // 360-degree flat line
395     {{{0, 0}, {2, 0}, {1, 0}, {64, 0}}},  // 360-degree flat line
396     {{{1, 0}, {0, 0}, {3, 0}, {-64, 0}}}  // 360-degree flat line
397 };
398 
test_classify_cubic(skiatest::Reporter * reporter)399 static void test_classify_cubic(skiatest::Reporter* reporter) {
400     for (const auto& serp : kSerpentines) {
401         check_cubic_type(reporter, serp, SkCubicType::kSerpentine);
402     }
403     for (const auto& loop : kLoops) {
404         check_cubic_type(reporter, loop, SkCubicType::kLoop);
405     }
406     for (const auto& loop : kLinearCubics) {
407         check_cubic_type(reporter, loop, SkCubicType::kLineOrPoint);
408     }
409     check_cubic_around_rect("small box", reporter, 0, 0, 1, 1);
410     check_cubic_around_rect("biggest box", reporter,
411                             -std::numeric_limits<float>::max(),
412                             -std::numeric_limits<float>::max(),
413                             +std::numeric_limits<float>::max(),
414                             +std::numeric_limits<float>::max());
415     check_cubic_around_rect("large quadrant", reporter, 1, 1,
416                             +std::numeric_limits<float>::min(),
417                             +std::numeric_limits<float>::max());
418     check_cubic_around_rect("smallest box", reporter,
419                             -std::numeric_limits<float>::min(),
420                             -std::numeric_limits<float>::min(),
421                             +std::numeric_limits<float>::min(),
422                             +std::numeric_limits<float>::min());
423     check_cubic_around_rect("slightly negative box",reporter,
424                             +1, -std::numeric_limits<float>::min(), -1, -1);
425     check_cubic_around_rect("infinite box", reporter,
426                             -std::numeric_limits<float>::infinity(),
427                             -std::numeric_limits<float>::infinity(),
428                             +std::numeric_limits<float>::infinity(),
429                             +std::numeric_limits<float>::infinity(),
430                             true);
431     check_cubic_around_rect("one sided infinite box", reporter,
432                             0, 0, 1, +std::numeric_limits<float>::infinity(), true);
433     check_cubic_around_rect("nan box", reporter,
434                             -std::numeric_limits<float>::quiet_NaN(),
435                             -std::numeric_limits<float>::quiet_NaN(),
436                             +std::numeric_limits<float>::quiet_NaN(),
437                             +std::numeric_limits<float>::quiet_NaN(),
438                             true);
439     check_cubic_around_rect("partial nan box", reporter,
440                             0, 0, 1, +std::numeric_limits<float>::quiet_NaN(), true);
441 }
442 
443 static std::array<SkPoint, 4> kCusps[] = {
444     {{{0, 0}, {1, 1}, {1, 0}, {0, 1}}},
445     {{{0, 0}, {1, 1}, {0, 1}, {1, 0}}},
446     {{{0, 1}, {1, 0}, {0, 0}, {1, 1}}},
447     {{{0, 1}, {1, 0}, {1, 1}, {0, 0}}},
448 };
449 
test_cubic_cusps(skiatest::Reporter * reporter)450 static void test_cubic_cusps(skiatest::Reporter* reporter) {
451     std::array<SkPoint, 4> noCusps[] = {
452         {{{0, 0}, {1, 1}, {2, 2}, {3, 3}}},
453         {{{0, 0}, {1, 0}, {1, 1}, {0, 1}}},
454         {{{0, 0}, {1, 0}, {2, 1}, {2, 2}}},
455         {{{0, 0}, {1, 0}, {1, 1}, {2, 1}}},
456     };
457     for (auto noCusp : noCusps) {
458         REPORTER_ASSERT(reporter, SkFindCubicCusp(noCusp.data()) < 0);
459     }
460     for (auto cusp : kCusps) {
461         REPORTER_ASSERT(reporter, SkFindCubicCusp(cusp.data()) > 0);
462     }
463 }
464 
465 static SkMatrix kSkewMatrices[] = {
466     SkMatrix::MakeAll(1,0,0, 0,1,0, 0,0,1),
467     SkMatrix::MakeAll(1,-1,0, 1,1,0, 0,0,1),
468     SkMatrix::MakeAll(.889f,.553f,0, -.443f,.123f,0, 0,0,1),
469 };
470 
test_chop_quad_at_midtangent(skiatest::Reporter * reporter,const SkPoint pts[3])471 static void test_chop_quad_at_midtangent(skiatest::Reporter* reporter, const SkPoint pts[3]) {
472     constexpr float kTolerance = 1e-3f;
473     for (const SkMatrix& m : kSkewMatrices) {
474         SkPoint mapped[3];
475         m.mapPoints(mapped, pts, 3);
476         float fullRotation = SkMeasureQuadRotation(pts);
477         SkPoint chopped[5];
478         SkChopQuadAtMidTangent(pts, chopped);
479         float leftRotation = SkMeasureQuadRotation(chopped);
480         float rightRotation = SkMeasureQuadRotation(chopped+2);
481         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(leftRotation, fullRotation/2, kTolerance));
482         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(rightRotation, fullRotation/2, kTolerance));
483     }
484 }
485 
test_chop_cubic_at_midtangent(skiatest::Reporter * reporter,const SkPoint pts[4],SkCubicType cubicType)486 static void test_chop_cubic_at_midtangent(skiatest::Reporter* reporter, const SkPoint pts[4],
487                                           SkCubicType cubicType) {
488     constexpr float kTolerance = 1e-3f;
489     int n = std::size(kSkewMatrices);
490     if (cubicType == SkCubicType::kLocalCusp || cubicType == SkCubicType::kLineOrPoint) {
491         // FP precision isn't always enough to get the exact correct T value of the mid-tangent on
492         // cusps and lines. Only test the identity matrix and the matrix with all 1's.
493         n = 2;
494     }
495     for (int i = 0; i < n; ++i) {
496         SkPoint mapped[4];
497         kSkewMatrices[i].mapPoints(mapped, pts, 4);
498         float fullRotation = SkMeasureNonInflectCubicRotation(mapped);
499         SkPoint chopped[7];
500         SkChopCubicAtMidTangent(mapped, chopped);
501         float leftRotation = SkMeasureNonInflectCubicRotation(chopped);
502         float rightRotation = SkMeasureNonInflectCubicRotation(chopped+3);
503         if (cubicType == SkCubicType::kLineOrPoint &&
504             (SkScalarNearlyEqual(fullRotation, 2*SK_ScalarPI, kTolerance) ||
505              SkScalarNearlyEqual(fullRotation, 0, kTolerance))) {
506             // 0- and 360-degree flat lines don't have single points of midtangent.
507             // (tangent == midtangent at every point on these curves except the cusp points.)
508             // Instead verify the promise from SkChopCubicAtMidTangent that neither side will rotate
509             // more than 180 degrees.
510             REPORTER_ASSERT(reporter, std::abs(leftRotation) - kTolerance <= SK_ScalarPI);
511             REPORTER_ASSERT(reporter, std::abs(rightRotation) - kTolerance <= SK_ScalarPI);
512             continue;
513         }
514         float expectedChoppedRotation = fullRotation/2;
515         if (cubicType == SkCubicType::kLocalCusp ||
516             (cubicType == SkCubicType::kLineOrPoint &&
517              SkScalarNearlyEqual(fullRotation, SK_ScalarPI, kTolerance))) {
518             // If we chop a cubic at a cusp, we lose 180 degrees of rotation.
519             expectedChoppedRotation = (fullRotation - SK_ScalarPI)/2;
520         }
521         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(leftRotation, expectedChoppedRotation,
522                                                       kTolerance));
523         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(rightRotation, expectedChoppedRotation,
524                                                       kTolerance));
525     }
526 }
527 
528 static std::array<SkPoint, 3> kQuads[] = {
529     {{{10, 20}, {15, 35}, {30, 40}}},
530     {{{176.324f, 392.705f}, {719.325f, 205.782f}, {297.263f, 347.735f}}},
531     {{{652.050f, 602.049f}, {481.000f, 533.000f}, {288.050f, 564.950f}}},
532     {{{460.625f, 557.187f}, {707.121f, 209.688f}, {779.628f, 577.687f}}},
533     {{{359.050f, 578.049f}, {759.000f, 274.000f}, {288.050f, 564.950f}}}
534 };
535 
lerp(const SkPoint & a,const SkPoint & b,float t)536 SkPoint lerp(const SkPoint& a, const SkPoint& b, float t) {
537     return a * (1 - t) + b * t;
538 }
539 
test_measure_rotation(skiatest::Reporter * reporter)540 static void test_measure_rotation(skiatest::Reporter* reporter) {
541     static SkPoint kFlatCubic[4] = {{0, 0}, {0, 1}, {0, 2}, {0, 3}};
542     REPORTER_ASSERT(reporter, SkScalarNearlyZero(SkMeasureNonInflectCubicRotation(kFlatCubic)));
543 
544     static SkPoint kFlatCubic180_1[4] = {{0, 0}, {1, 0}, {3, 0}, {2, 0}};
545     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic180_1),
546                                                   SK_ScalarPI));
547 
548     static SkPoint kFlatCubic180_2[4] = {{0, 1}, {0, 0}, {0, 2}, {0, 3}};
549     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic180_2),
550                                                   SK_ScalarPI));
551 
552     static SkPoint kFlatCubic360[4] = {{0, 1}, {0, 0}, {0, 3}, {0, 2}};
553     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kFlatCubic360),
554                                                   2*SK_ScalarPI));
555 
556     static SkPoint kSquare180[4] = {{0, 0}, {0, 1}, {1, 1}, {1, 0}};
557     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(kSquare180),
558                                                   SK_ScalarPI));
559 
560     auto checkQuadRotation = [=](const SkPoint pts[3], float expectedRotation) {
561         float r = SkMeasureQuadRotation(pts);
562         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(r, expectedRotation));
563 
564         SkPoint cubic1[4] = {pts[0], pts[0], pts[1], pts[2]};
565         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic1),
566                                                       expectedRotation));
567 
568         SkPoint cubic2[4] = {pts[0], pts[1], pts[1], pts[2]};
569         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic2),
570                                                       expectedRotation));
571 
572         SkPoint cubic3[4] = {pts[0], pts[1], pts[2], pts[2]};
573         REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SkMeasureNonInflectCubicRotation(cubic3),
574                                                       expectedRotation));
575     };
576 
577     static SkPoint kFlatQuad[4] = {{0, 0}, {0, 1}, {0, 2}};
578     checkQuadRotation(kFlatQuad, 0);
579 
580     static SkPoint kFlatQuad180_1[4] = {{1, 0}, {0, 0}, {2, 0}};
581     checkQuadRotation(kFlatQuad180_1, SK_ScalarPI);
582 
583     static SkPoint kFlatQuad180_2[4] = {{0, 0}, {0, 2}, {0, 1}};
584     checkQuadRotation(kFlatQuad180_2, SK_ScalarPI);
585 
586     static SkPoint kTri120[3] = {{0, 0}, {.5f, std::sqrt(3.f)/2}, {1, 0}};
587     checkQuadRotation(kTri120, 2*SK_ScalarPI/3);
588 }
589 
test_chop_at_midtangent(skiatest::Reporter * reporter)590 static void test_chop_at_midtangent(skiatest::Reporter* reporter) {
591     SkPoint chops[10];
592     for (const auto& serp : kSerpentines) {
593         REPORTER_ASSERT(reporter, SkClassifyCubic(serp.data()) == SkCubicType::kSerpentine);
594         int n = SkChopCubicAtInflections(serp.data(), chops);
595         for (int i = 0; i < n; ++i) {
596             test_chop_cubic_at_midtangent(reporter, chops + i*3, SkCubicType::kSerpentine);
597         }
598     }
599     for (const auto& loop : kLoops) {
600         REPORTER_ASSERT(reporter, SkClassifyCubic(loop.data()) == SkCubicType::kLoop);
601         test_chop_cubic_at_midtangent(reporter, loop.data(), SkCubicType::kLoop);
602     }
603     for (const auto& line : kLinearCubics) {
604         REPORTER_ASSERT(reporter, SkClassifyCubic(line.data()) == SkCubicType::kLineOrPoint);
605         test_chop_cubic_at_midtangent(reporter, line.data(), SkCubicType::kLineOrPoint);
606     }
607     for (const auto& cusp : kCusps) {
608         REPORTER_ASSERT(reporter, SkClassifyCubic(cusp.data()) == SkCubicType::kLocalCusp);
609         test_chop_cubic_at_midtangent(reporter, cusp.data(), SkCubicType::kLocalCusp);
610     }
611     for (const auto& quad : kQuads) {
612         test_chop_quad_at_midtangent(reporter, quad.data());
613         SkPoint asCubic[4] = {
614                 quad[0], lerp(quad[0], quad[1], 2/3.f), lerp(quad[1], quad[2], 1/3.f), quad[2]};
615         test_chop_cubic_at_midtangent(reporter, asCubic, SkCubicType::kQuadratic);
616     }
617 
618     static const SkPoint kExactQuad[4] = {{0,0}, {6,2}, {10,2}, {12,0}};
619     REPORTER_ASSERT(reporter, SkClassifyCubic(kExactQuad) == SkCubicType::kQuadratic);
620     test_chop_cubic_at_midtangent(reporter, kExactQuad, SkCubicType::kQuadratic);
621 
622     static const SkPoint kExactCuspAtInf[4] = {{0,0}, {1,0}, {0,1}, {1,1}};
623     REPORTER_ASSERT(reporter, SkClassifyCubic(kExactCuspAtInf) == SkCubicType::kCuspAtInfinity);
624     int n = SkChopCubicAtInflections(kExactCuspAtInf, chops);
625     for (int i = 0; i < n; ++i) {
626         test_chop_cubic_at_midtangent(reporter, chops + i*3, SkCubicType::kCuspAtInfinity);
627     }
628 }
629 
DEF_TEST(Geometry,reporter)630 DEF_TEST(Geometry, reporter) {
631     SkPoint pts[5];
632 
633     pts[0].set(0, 0);
634     pts[1].set(100, 50);
635     pts[2].set(0, 100);
636 
637     int count = SkChopQuadAtMaxCurvature(pts, pts);  // Ensure src and dst can be the same pointer.
638     REPORTER_ASSERT(reporter, count == 1 || count == 2);
639 
640     // This previously crashed because the computed t of max curvature is NaN and SkChopQuadAt
641     // asserts that the passed t is in 0..1. Passes by not asserting.
642     pts[0].set(15.1213f, 7.77647f);
643     pts[1].set(6.2168e+19f, 1.51338e+20f);
644     pts[2].set(1.4579e+19f, 1.55558e+21f);
645     count = SkChopQuadAtMaxCurvature(pts, pts);
646 
647     pts[0].set(0, 0);
648     pts[1].set(3, 0);
649     pts[2].set(3, 3);
650     SkConvertQuadToCubic(pts, pts);
651     const SkPoint cubic[] = {
652         { 0, 0, }, { 2, 0, }, { 3, 1, }, { 3, 3 },
653     };
654     for (int i = 0; i < 4; ++i) {
655         REPORTER_ASSERT(reporter, nearly_equal(cubic[i], pts[i]));
656     }
657 
658     testChopCubic(reporter);
659     test_evalquadat(reporter);
660     test_conic(reporter);
661     test_cubic_tangents(reporter);
662     test_quad_tangents(reporter);
663     test_conic_tangents(reporter);
664     test_conic_to_quads(reporter);
665     test_classify_cubic(reporter);
666     test_cubic_cusps(reporter);
667     test_measure_rotation(reporter);
668     test_chop_at_midtangent(reporter);
669 }
670 
testChopMonoCubicAtY(skiatest::Reporter * reporter,std::string name,SkSpan<const SkPoint> curveInputs,SkScalar yToChopAt,SkSpan<const SkPoint> expectedOutputs)671 static void testChopMonoCubicAtY(skiatest::Reporter* reporter, std::string name,
672                                  SkSpan<const SkPoint> curveInputs, SkScalar yToChopAt,
673                                  SkSpan<const SkPoint> expectedOutputs) {
674     skiatest::ReporterContext subtest(reporter, name);
675     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(expectedOutputs[3].y(), yToChopAt),
676                     "Invalid test case. 4th point's Y should be %f", yToChopAt);
677 
678     SkPoint outputs[7];
679     // Make sure it actually chopped
680     REPORTER_ASSERT(reporter, SkChopMonoCubicAtY(curveInputs.begin(), yToChopAt, outputs));
681 
682     for (int i = 0; i < 7; ++i) {
683         REPORTER_ASSERT(reporter, nearly_equal(expectedOutputs[i], outputs[i]),
684                         "(%f, %f) != (%f, %f) at index %d",
685                         expectedOutputs[i].x(), expectedOutputs[i].y(),
686                         outputs[i].x(), outputs[i].y(), i);
687     }
688 }
689 
DEF_TEST(GeometryChopMonoCubicAtY_Successful,reporter)690 DEF_TEST(GeometryChopMonoCubicAtY_Successful, reporter) {
691     // These cubics are all arbitrary, picked using Desmos for something that looked "nice".
692 
693     testChopMonoCubicAtY(reporter, "straight, positive slope @ 2.5",
694         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
695         2.5f,
696         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  1.065055f,  1.065055f },
697          {  2.500000f,  2.500000f },
698          {  5.461981f,  5.461981f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
699     );
700     testChopMonoCubicAtY(reporter, "straight, positive slope @ 5.0",
701         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
702         5.0f,
703         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  2.500000f,  2.500000f },
704          {  5.000000f,  5.000000f },
705          {  7.500000f,  7.500000f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
706     );
707     testChopMonoCubicAtY(reporter, "straight, positive slope @ 9.0",
708         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
709         9.0f,
710         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  6.467375f,  6.467375f },
711          {  9.000000f,  9.000000f },
712          {  9.616623f,  9.616623f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
713     );
714     testChopMonoCubicAtY(reporter, "straight, positive slope @ 10.0",
715         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
716         10.0f,
717         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, { 10.000000f, 10.000000f },
718          { 10.000000f, 10.000000f },
719          { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
720     );
721 
722     testChopMonoCubicAtY(reporter, "curve, positive slope @ 2.0",
723         {{ 1, 1 }, { 5, 2 }, { 7, 4 }, { 8, 7 }},
724         2.0f,
725         {{  1.000000f,  1.000000f }, {  2.055050f,  1.263763f }, {  2.970959f,  1.597096f },
726          {  3.766077f,  2.000000f },
727          {  5.985480f,  3.124621f }, {  7.263762f,  4.791288f }, {  8.000000f,  7.000000f }}
728     );
729     testChopMonoCubicAtY(reporter, "curve, positive slope @ 5.0",
730         {{ 1, 1 }, { 5, 2 }, { 7, 4 }, { 8, 7 }},
731         5.0f,
732         {{  1.000000f,  1.000000f }, {  4.033223f,  1.758306f }, {  5.916391f,  3.091639f },
733          {  7.085550f,  5.000000f },
734          {  7.458195f,  5.608251f }, {  7.758306f,  6.274917f }, {  8.000000f,  7.000000f }}
735     );
736 
737     testChopMonoCubicAtY(reporter, "curve, negative slope @ 5.0",
738         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
739         5.0f,
740         {{  2.000000f,  7.000000f }, {  2.162856f,  6.185719f }, {  2.378757f,  5.530570f },
741          {  2.647702f,  5.000000f },
742          {  4.030182f,  2.272668f }, {  6.814281f,  2.837144f }, { 11.000000f,  2.000000f }}
743     );
744     testChopMonoCubicAtY(reporter, "curve, negative slope @ 3.0",
745         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
746         3.0f,
747         {{  2.000000f,  7.000000f }, {  2.500000f,  4.500000f }, {  3.500000f,  3.500000f },
748          {  5.000000f,  3.000000f },
749          {  6.500000f,  2.500000f }, {  8.500000f,  2.500000f }, { 11.000000f,  2.000000f }}
750     );
751     testChopMonoCubicAtY(reporter, "curve, negative slope @ 2.5",
752         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
753         2.5f,
754         {{  2.000000f,  7.000000f }, {  2.750000f,  3.250000f }, {  4.625000f,  2.875000f },
755          {  7.625000f,  2.500000f },
756          {  8.625000f,  2.375000f }, {  9.750000f,  2.250000f }, { 11.000000f,  2.000000f }}
757     );
758 
759     // This is the same curve as above, just the 4 points given in the opposite order.
760     // We would expect the math to result in the same chop points, with the outputs
761     // in the opposite order too.
762     testChopMonoCubicAtY(reporter, "inverted curve, negative slope @ 5.0",
763         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
764         5.0f,
765         {{ 11.000000f,  2.000000f }, {  6.814281f,  2.837144f }, {  4.030182f,  2.272668f },
766          {  2.647702f,  5.000000f },
767          {  2.378757f,  5.530570f }, {  2.162856f,  6.185719f }, {  2.000000f,  7.000000f }}
768     );
769     testChopMonoCubicAtY(reporter, "inverted curve, negative slope @ 3.0",
770         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
771         3.0f,
772         {{ 11.000000f,  2.000000f }, {  8.500000f,  2.500000f }, {  6.500000f,  2.500000f },
773          {  5.000000f,  3.000000f },
774          {  3.500000f,  3.500000f }, {  2.500000f,  4.500000f }, {  2.000000f,  7.000000f }}
775     );
776     testChopMonoCubicAtY(reporter, "inverted curve, negative slope @ 2.5",
777         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
778         2.5f,
779         {{ 11.000000f,  2.000000f }, {  9.750000f,  2.250000f }, {  8.625000f,  2.375000f },
780          {  7.625000f,  2.500000f },
781          {  4.625000f,  2.875000f }, {  2.750000f,  3.250000f }, {  2.000000f,  7.000000f }}
782     );
783 
784     testChopMonoCubicAtY(reporter, "big curve, negative slope @ 90",
785         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
786         90.f,
787         {{ -2.000000f,100.000000f }, { -1.930979f, 96.548965f }, { -1.864341f, 93.217033f },
788          { -1.795892f, 90.000000f },
789          {  0.119096f, -0.002382f }, {  3.451032f, -0.069021f }, {100.000000f, -2.000000f }}
790     );
791     testChopMonoCubicAtY(reporter, "big curve, negative slope @ 10",
792         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
793         10.f,
794         {{ -2.000000f,100.000000f }, { -0.937505f, 46.875271f }, { -0.439458f, 21.972910f },
795          { 14.787060f, 10.000000f },
796          { 28.222368f, -0.564447f }, { 53.124729f, -1.062495f }, {100.000000f, -2.000000f }}
797     );
798     testChopMonoCubicAtY(reporter, "big curve, negative slope @ 0",
799         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
800         0.f,
801         {{ -2.000000f,100.000000f }, { -0.426983f, 21.349131f }, { -0.091157f,  4.557854f },
802          { 48.633648f, 0.000000f },
803          { 61.859592f, -1.237192f }, { 78.650871f, -1.573017f }, {100.000000f, -2.000000f }}
804     );
805 
806     testChopMonoCubicAtY(reporter, "ossfuzz:55680 curve barely crosses Y axis",
807         {{-250.121582f, -1180.09509f}, {10.007843f, -1180.09509f},
808          {20.015685f, -786.041259f}, {40.0313721f, 2.0664072f}},
809         0.f,
810         {{-250.121582f, -1180.095093f}, {9.780392f, -1180.095093f}, {19.997992f, -786.730042f},
811          {39.978889f, 0.000000f},
812          {39.996376f, 0.688501f}, {40.013870f, 1.377304f}, {40.031372f, 2.066407f}}
813     );
814 }
815 
DEF_TEST(GeometryChopMonoCubicAtY_OutOfRangeReturnFalse,reporter)816 DEF_TEST(GeometryChopMonoCubicAtY_OutOfRangeReturnFalse, reporter) {
817     SkPoint inputs[] = {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }};
818     SkPoint outputs[7];
819 
820     // Too low
821     REPORTER_ASSERT(reporter, !SkChopMonoCubicAtY(inputs, -10, outputs));
822     // Too high
823     REPORTER_ASSERT(reporter, !SkChopMonoCubicAtY(inputs, 20, outputs));
824 }
825 
testChopMonoCubicAtX(skiatest::Reporter * reporter,std::string name,SkSpan<const SkPoint> curveInputs,SkScalar xToChopAt,SkSpan<const SkPoint> expectedOutputs)826 static void testChopMonoCubicAtX(skiatest::Reporter* reporter, std::string name,
827                                  SkSpan<const SkPoint> curveInputs, SkScalar xToChopAt,
828                                  SkSpan<const SkPoint> expectedOutputs) {
829     skiatest::ReporterContext subtest(reporter, name);
830     REPORTER_ASSERT(reporter, curveInputs.size() == 4,
831                     "Invalid test case. Input curve should have 4 points");
832     REPORTER_ASSERT(reporter, expectedOutputs.size() == 7,
833                     "Invalid test case. Outputs should have 7 points");
834     REPORTER_ASSERT(reporter, SkScalarNearlyEqual(expectedOutputs[3].x(), xToChopAt),
835                     "Invalid test case. 4th point's X should be %f", xToChopAt);
836 
837     SkPoint outputs[7];
838     // Make sure it actually chopped
839     REPORTER_ASSERT(reporter, SkChopMonoCubicAtX(curveInputs.begin(), xToChopAt, outputs));
840 
841     for (int i = 0; i < 7; ++i) {
842         REPORTER_ASSERT(reporter, nearly_equal(expectedOutputs[i], outputs[i]),
843                         "(%f, %f) != (%f, %f) at index %d",
844                         expectedOutputs[i].x(), expectedOutputs[i].y(),
845                         outputs[i].x(), outputs[i].y(), i);
846     }
847 }
848 
DEF_TEST(GeometryChopMonoCubicAtX_Successful,reporter)849 DEF_TEST(GeometryChopMonoCubicAtX_Successful, reporter) {
850     // These cubics are all arbitrary, picked using Desmos for something that looked "nice".
851 
852     testChopMonoCubicAtX(reporter, "straight, positive slope @ 2.5",
853         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
854         2.5f,
855         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  1.065055f,  1.065055f },
856          {  2.500000f,  2.500000f },
857          {  5.461981f,  5.461981f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
858     );
859     testChopMonoCubicAtX(reporter, "straight, positive slope @ 5.0",
860         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
861         5.0f,
862         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  2.500000f,  2.500000f },
863          {  5.000000f,  5.000000f },
864          {  7.500000f,  7.500000f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
865     );
866     testChopMonoCubicAtX(reporter, "straight, positive slope @ 9.0",
867         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
868         9.0f,
869         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, {  6.467375f,  6.467375f },
870          {  9.000000f,  9.000000f },
871          {  9.616623f,  9.616623f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
872     );
873     testChopMonoCubicAtX(reporter, "straight, positive slope @ 10.0",
874         {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }},
875         10.0f,
876         {{  0.000000f,  0.000000f }, {  0.000000f,  0.000000f }, { 10.000000f, 10.000000f },
877          { 10.000000f, 10.000000f },
878          { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }, { 10.000000f, 10.000000f }}
879     );
880 
881     testChopMonoCubicAtX(reporter, "curve, positive slope @ 2.0",
882         {{ 1, 1 }, { 5, 2 }, { 7, 4 }, { 8, 7 }},
883         2.0f,
884         {{  1.000000f,  1.000000f }, {  1.348275f,  1.087069f }, {  1.681389f,  1.181719f },
885          {  2.000000f,  1.283949f },
886          {  5.340694f,  2.355856f }, {  7.087069f,  4.261207f }, {  8.000000f,  7.000000f }}
887     );
888     testChopMonoCubicAtX(reporter, "curve, positive slope @ 5.0",
889         {{ 1, 1 }, { 5, 2 }, { 7, 4 }, { 8, 7 }},
890         5.0f,
891         {{  1.000000f,  1.000000f }, {  2.650396f,  1.412599f }, {  3.960316f,  1.995436f },
892          {  5.000000f,  2.748511f },
893          {  6.480158f,  3.820634f }, {  7.412599f,  5.237797f }, {  8.000000f,  7.000000f }}
894     );
895 
896     testChopMonoCubicAtX(reporter, "curve, negative slope @ 5.0",
897         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
898         5.0f,
899         {{  2.000000f,  7.000000f }, {  2.500000f,  4.500000f }, {  3.500000f,  3.500000f },
900          {  5.000000f,  3.000000f },
901          {  6.500000f,  2.500000f }, {  8.500000f,  2.500000f }, { 11.000000f,  2.000000f }}
902     );
903     testChopMonoCubicAtX(reporter, "curve, negative slope @ 3.0",
904         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
905         3.0f,
906         {{  2.000000f,  7.000000f }, {  2.228714f,  5.856432f }, {  2.562047f,  5.026724f },
907          {  3.000000f,  4.415163f },
908          {  4.476901f,  2.352807f }, {  7.143568f,  2.771286f }, { 11.000000f,  2.000000f }}
909     );
910     testChopMonoCubicAtX(reporter, "curve, negative slope @ 2.5",
911         {{ 2, 7 }, { 3, 2 }, { 6, 3 }, { 11, 2 }},
912         2.5f,
913         {{  2.000000f,  7.000000f }, {  2.131881f,  6.340593f }, {  2.298548f,  5.785543f },
914          {  2.500000f,  5.316498f },
915          {  3.826073f,  2.228977f }, {  6.659407f,  2.868119f }, { 11.000000f,  2.000000f }}
916     );
917 
918     // This is the same curve as above, just the 4 points given in the opposite order.
919     // We would expect the math to result in the same chop points, with the outputs
920     // in the opposite order too.
921     testChopMonoCubicAtX(reporter, "inverted curve, negative slope @ 5.0",
922         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
923         5.0f,
924         {{ 11.000000f,  2.000000f }, {  8.500000f,  2.500000f }, {  6.500000f,  2.500000f },
925          {  5.000000f,  3.000000f },
926          {  3.500000f,  3.500000f }, {  2.500000f,  4.500000f }, {  2.000000f,  7.000000f }}
927     );
928     testChopMonoCubicAtX(reporter, "inverted curve, negative slope @ 3.0",
929         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
930         3.0f,
931         {{ 11.000000f,  2.000000f }, {  7.143568f,  2.771286f }, {  4.476901f,  2.352807f },
932          {  3.000000f,  4.415163f },
933          {  2.562047f,  5.026724f }, {  2.228714f,  5.856432f }, {  2.000000f,  7.000000f }}
934     );
935     testChopMonoCubicAtX(reporter, "inverted curve, negative slope @ 2.5",
936         {{ 11, 2 }, { 6, 3 }, { 3, 2 }, { 2, 7 }},
937         2.5f,
938         {{ 11.000000f,  2.000000f }, {  6.659407f,  2.868119f }, {  3.826073f,  2.228977f },
939          {  2.500000f,  5.316498f },
940          {  2.298548f,  5.785543f }, {  2.131881f,  6.340593f }, {  2.000000f,  7.000000f }}
941     );
942 
943     testChopMonoCubicAtX(reporter, "big curve, negative slope @ 90",
944         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
945         90.f,
946         {{ -2.000000f,100.000000f }, { -0.069021f,  3.451032f }, { -0.002382f,  0.119096f },
947          { 90.000000f, -1.795892f },
948          { 93.217033f, -1.864341f }, { 96.548965f, -1.930979f }, {100.000000f, -2.000000f }}
949     );
950     testChopMonoCubicAtX(reporter, "big curve, negative slope @ 10",
951         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
952         10.f,
953         {{ -2.000000f,100.000000f }, { -1.062495f, 53.124729f }, { -0.564447f, 28.222368f },
954          { 10.000000f, 14.787060f },
955          { 21.972910f, -0.439458f }, { 46.875271f, -0.937505f }, {100.000000f, -2.000000f }}
956     );
957     testChopMonoCubicAtX(reporter, "big curve, negative slope @ 0",
958         {{ -2, 100 }, { 0, 0 }, { 0, 0 }, { 100, -2 }},
959         0.f,
960         {{ -2.000000f,100.000000f }, { -1.573017f, 78.650871f }, { -1.237192f, 61.859592f },
961          {  0.000000f, 48.633648f },
962          {  4.557854f, -0.091157f }, { 21.349131f, -0.426983f }, {100.000000f, -2.000000f }}
963     );
964 }
965 
DEF_TEST(GeometryChopMonoCubicAtX_OutOfRangeReturnFalse,reporter)966 DEF_TEST(GeometryChopMonoCubicAtX_OutOfRangeReturnFalse, reporter) {
967     SkPoint inputs[] = {{ 0, 0 }, { 0, 0 }, { 10, 10 }, { 10, 10 }};
968     SkPoint outputs[7];
969 
970     // Too low
971     REPORTER_ASSERT(reporter, !SkChopMonoCubicAtX(inputs, -10, outputs));
972     // Too high
973     REPORTER_ASSERT(reporter, !SkChopMonoCubicAtX(inputs, 20, outputs));
974 }
975