Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2017 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 "SkGaussFilter.h" |
| 9 | |
| 10 | #include <cmath> |
| 11 | #include <tuple> |
| 12 | #include <vector> |
| 13 | #include "Test.h" |
| 14 | |
| 15 | // one part in a million |
| 16 | static constexpr double kEpsilon = 0.000001; |
| 17 | |
| 18 | static double careful_add(int n, double* gauss) { |
| 19 | // Sum smallest to largest to retain precision. |
| 20 | double sum = 0; |
| 21 | for (int i = n - 1; i >= 1; i--) { |
| 22 | sum += 2.0 * gauss[i]; |
| 23 | } |
| 24 | sum += gauss[0]; |
| 25 | return sum; |
| 26 | } |
| 27 | |
| 28 | DEF_TEST(SkGaussFilterCommon, r) { |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 29 | using Test = std::tuple<double, std::vector<double>>; |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 30 | |
| 31 | auto golden_check = [&](const Test& test) { |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 32 | double sigma; std::vector<double> golden; |
| 33 | std::tie(sigma, golden) = test; |
| 34 | SkGaussFilter filter{sigma}; |
Herb Derby | 7ceb0b8 | 2017-11-16 14:38:57 -0500 | [diff] [blame] | 35 | double result[SkGaussFilter::kGaussArrayMax]; |
| 36 | int n = 0; |
| 37 | for (auto d : filter) { |
| 38 | result[n++] = d; |
| 39 | } |
| 40 | REPORTER_ASSERT(r, static_cast<size_t>(n) == golden.size()); |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 41 | double sum = careful_add(n, result); |
| 42 | REPORTER_ASSERT(r, sum == 1.0); |
| 43 | for (size_t i = 0; i < golden.size(); i++) { |
| 44 | REPORTER_ASSERT(r, std::abs(golden[i] - result[i]) < kEpsilon); |
| 45 | } |
| 46 | }; |
| 47 | |
| 48 | // The following two sigmas account for about 85% of all sigmas used for masks. |
| 49 | // Golden values generated using Mathematica. |
| 50 | auto tests = { |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 51 | // GaussianMatrix[{{Automatic}, {.788675}}] |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 52 | Test{0.788675, {0.593605, 0.176225, 0.0269721}}, |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 53 | |
| 54 | // GaussianMatrix[{{4}, {1.07735}}, Method -> "Bessel"] |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 55 | Test{1.07735, {0.429537, 0.214955, 0.059143, 0.0111337}}, |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 56 | }; |
| 57 | |
| 58 | for (auto& test : tests) { |
| 59 | golden_check(test); |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | DEF_TEST(SkGaussFilterSweep, r) { |
| 64 | // The double just before 2.0. |
| 65 | const double maxSigma = nextafter(2.0, 0.0); |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 66 | auto check = [&](double sigma) { |
| 67 | SkGaussFilter filter{sigma}; |
Herb Derby | 7ceb0b8 | 2017-11-16 14:38:57 -0500 | [diff] [blame] | 68 | double result[SkGaussFilter::kGaussArrayMax]; |
| 69 | int n = 0; |
| 70 | for (auto d : filter) { |
| 71 | result[n++] = d; |
| 72 | } |
| 73 | REPORTER_ASSERT(r, n <= SkGaussFilter::kGaussArrayMax); |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 74 | double sum = careful_add(n, result); |
| 75 | REPORTER_ASSERT(r, sum == 1.0); |
| 76 | }; |
| 77 | |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 78 | for (double sigma = 0.0; sigma < 2.0; sigma += 0.1) { |
| 79 | check(sigma); |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 80 | } |
Mike Klein | 630e7d6 | 2018-11-06 17:05:32 -0500 | [diff] [blame] | 81 | check(maxSigma); |
Herb Derby | 66498bc | 2017-11-03 13:36:55 -0400 | [diff] [blame] | 82 | } |