1 /*
2 * Copyright 2018 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/SkCubicMap.h"
9 #include "include/core/SkPoint.h"
10 #include "include/core/SkScalar.h"
11 #include "include/core/SkTypes.h"
12 #include "include/private/base/SkDebug.h"
13 #include "src/base/SkCubics.h"
14 #include "src/base/SkVx.h"
15 #include "src/core/SkGeometry.h"
16 #include "tests/Test.h"
17
accurate_t(float A,float B,float C,float D)18 static float accurate_t(float A, float B, float C, float D) {
19 double roots[3];
20 SkDEBUGCODE(int count =) SkCubics::RootsValidT(A, B, C, D, roots);
21 SkASSERT(count == 1);
22 return (float)roots[0];
23 }
24
accurate_solve(SkPoint p1,SkPoint p2,SkScalar x)25 static float accurate_solve(SkPoint p1, SkPoint p2, SkScalar x) {
26 SkPoint array[] = { {0, 0}, p1, p2, {1,1} };
27 SkCubicCoeff coeff(array);
28
29 float t = accurate_t(coeff.fA[0], coeff.fB[0], coeff.fC[0], coeff.fD[0] - x);
30 SkASSERT(t >= 0 && t <= 1);
31 float y = coeff.eval(t)[1];
32 SkASSERT(y >= 0 && y <= 1.0001f);
33 return y;
34 }
35
nearly_le(SkScalar a,SkScalar b)36 static bool nearly_le(SkScalar a, SkScalar b) {
37 return a <= b || SkScalarNearlyZero(a - b);
38 }
39
exercise_cubicmap(SkPoint p1,SkPoint p2,skiatest::Reporter * reporter)40 static void exercise_cubicmap(SkPoint p1, SkPoint p2, skiatest::Reporter* reporter) {
41 const SkScalar MAX_SOLVER_ERR = 0.008f; // found by running w/ current impl
42
43 SkCubicMap cmap(p1, p2);
44
45 SkScalar prev_y = 0;
46 SkScalar dx = 1.0f / 512;
47 for (SkScalar x = dx; x < 1; x += dx) {
48 SkScalar y = cmap.computeYFromX(x);
49 // are we valid and (mostly) monotonic?
50 if (!nearly_le(prev_y, y)) {
51 cmap.computeYFromX(x);
52 REPORTER_ASSERT(reporter, false);
53 }
54 prev_y = y;
55
56 // are we close to the "correct" answer?
57 SkScalar yy = accurate_solve(p1, p2, x);
58 SkScalar diff = SkScalarAbs(yy - y);
59 REPORTER_ASSERT(reporter, diff < MAX_SOLVER_ERR);
60 }
61 }
62
DEF_TEST(CubicMap,r)63 DEF_TEST(CubicMap, r) {
64 const SkScalar values[] = {
65 0, 1, 0.5f, 0.0000001f, 0.999999f,
66 };
67
68 for (SkScalar x0 : values) {
69 for (SkScalar y0 : values) {
70 for (SkScalar x1 : values) {
71 for (SkScalar y1 : values) {
72 exercise_cubicmap({ x0, y0 }, { x1, y1 }, r);
73 }
74 }
75 }
76 }
77 }
78