SkGaussFilterTest.cpp File Reference

#include "src/core/SkGaussFilter.h"
#include "tests/Test.h"
#include <cmath>
#include <cstdlib>
#include <initializer_list>
#include <tuple>
#include <vector>

Go to the source code of this file.

Functions
static double	careful_add (int n, double *gauss)
	DEF_TEST (SkGaussFilterCommon, r)
	DEF_TEST (SkGaussFilterSweep, r)

Variables
static constexpr double	kEpsilon = 0.000001

Function Documentation

careful_add()

static double careful_add ( int  n, double *  gauss  )

static

Definition at line 20 of file SkGaussFilterTest.cpp.

                                                {
    // Sum smallest to largest to retain precision.
    double sum = 0;
    for (int i = n - 1; i >= 1; i--) {
        sum += 2.0 * gauss[i];
    }
    sum += gauss[0];
    return sum;
}

DEF_TEST() [1/2]

DEF_TEST	(	SkGaussFilterCommon	,
		r
	)

Definition at line 30 of file SkGaussFilterTest.cpp.

                                 {
    using Test = std::tuple<double, std::vector<double>>;
 
    auto golden_check = [&](const Test& test) {
        double sigma; std::vector<double> golden;
        std::tie(sigma, golden) = test;
        SkGaussFilter filter{sigma};
        double result[SkGaussFilter::kGaussArrayMax];
        int n = 0;
        for (auto d : filter) {
            result[n++] = d;
        }
        REPORTER_ASSERT(r, static_cast<size_t>(n) == golden.size());
        double sum = careful_add(n, result);
        REPORTER_ASSERT(r, sum == 1.0);
        for (size_t i = 0; i < golden.size(); i++) {
            REPORTER_ASSERT(r, std::abs(golden[i] - result[i]) < kEpsilon);
        }
    };
 
    // The following two sigmas account for about 85% of all sigmas used for masks.
    // Golden values generated using Mathematica.
    auto tests = {
        // GaussianMatrix[{{Automatic}, {.788675}}]
        Test{0.788675,   {0.593605, 0.176225, 0.0269721}},
 
        // GaussianMatrix[{{4}, {1.07735}}, Method -> "Bessel"]
        Test{1.07735,  {0.429537, 0.214955, 0.059143, 0.0111337}},
    };
 
    for (auto& test : tests) {
        golden_check(test);
    }
}

DEF_TEST() [2/2]

DEF_TEST	(	SkGaussFilterSweep	,
		r
	)

Definition at line 65 of file SkGaussFilterTest.cpp.

                                {
    // The double just before 2.0.
    const double maxSigma = nextafter(2.0, 0.0);
    auto check = [&](double sigma) {
        SkGaussFilter filter{sigma};
        double result[SkGaussFilter::kGaussArrayMax];
        int n = 0;
        for (auto d : filter) {
            result[n++] = d;
        }
        REPORTER_ASSERT(r, n <= SkGaussFilter::kGaussArrayMax);
        double sum = careful_add(n, result);
        REPORTER_ASSERT(r, sum == 1.0);
    };
 
    for (double sigma = 0.0; sigma < 2.0; sigma += 0.1) {
        check(sigma);
    }
    check(maxSigma);
}

Variable Documentation

kEpsilon

constexpr double kEpsilon = 0.000001

staticconstexpr

Definition at line 18 of file SkGaussFilterTest.cpp.