tests/MatrixTest.cpp

#include "Test.h"
#include "SkMatrix.h"

static bool nearly_equal_scalar(SkScalar a, SkScalar b) {
    // Note that we get more compounded error for multiple operations when
    // SK_SCALAR_IS_FIXED.
#ifdef SK_SCALAR_IS_FLOAT
    const SkScalar tolerance = SK_Scalar1 / 200000;
#else
    const SkScalar tolerance = SK_Scalar1 / 1024;
#endif

    return SkScalarAbs(a - b) <= tolerance;
}

static bool nearly_equal(const SkMatrix& a, const SkMatrix& b) {
    for (int i = 0; i < 9; i++) {
        if (!nearly_equal_scalar(a[i], b[i])) {
            printf("not equal %g %g\n", (float)a[i], (float)b[i]);
            return false;
        }
    }
    return true;
}

static bool is_identity(const SkMatrix& m) {
    SkMatrix identity;
    identity.reset();
    return nearly_equal(m, identity);
}

static void test_flatten(skiatest::Reporter* reporter, const SkMatrix& m) {
    // add 100 in case we have a bug, I don't want to kill my stack in the test
    char buffer[SkMatrix::kMaxFlattenSize + 100];
    uint32_t size1 = m.flatten(NULL);
    uint32_t size2 = m.flatten(buffer);
    REPORTER_ASSERT(reporter, size1 == size2);
    REPORTER_ASSERT(reporter, size1 <= SkMatrix::kMaxFlattenSize);
    
    SkMatrix m2;
    uint32_t size3 = m2.unflatten(buffer);
    REPORTER_ASSERT(reporter, size1 == size2);
    REPORTER_ASSERT(reporter, m == m2);
    
    char buffer2[SkMatrix::kMaxFlattenSize + 100];
    size3 = m2.flatten(buffer2);
    REPORTER_ASSERT(reporter, size1 == size2);
    REPORTER_ASSERT(reporter, memcmp(buffer, buffer2, size1) == 0);
}

void TestMatrix(skiatest::Reporter* reporter) {
    SkMatrix    mat, inverse, iden1, iden2;

    mat.reset();
    mat.setTranslate(SK_Scalar1, SK_Scalar1);
    mat.invert(&inverse);
    iden1.setConcat(mat, inverse);
    REPORTER_ASSERT(reporter, is_identity(iden1));

    mat.setScale(SkIntToScalar(2), SkIntToScalar(2));
    mat.invert(&inverse);
    iden1.setConcat(mat, inverse);
    REPORTER_ASSERT(reporter, is_identity(iden1));
    test_flatten(reporter, mat);

    mat.setScale(SK_Scalar1/2, SK_Scalar1/2);
    mat.invert(&inverse);
    iden1.setConcat(mat, inverse);
    REPORTER_ASSERT(reporter, is_identity(iden1));
    test_flatten(reporter, mat);

    mat.setScale(SkIntToScalar(3), SkIntToScalar(5), SkIntToScalar(20), 0);
    mat.postRotate(SkIntToScalar(25));
    REPORTER_ASSERT(reporter, mat.invert(NULL));
    mat.invert(&inverse);
    iden1.setConcat(mat, inverse);
    REPORTER_ASSERT(reporter, is_identity(iden1));
    iden2.setConcat(inverse, mat);
    REPORTER_ASSERT(reporter, is_identity(iden2));
    test_flatten(reporter, mat);
    test_flatten(reporter, iden2);

    // rectStaysRect test
    {
        static const struct {
            SkScalar    m00, m01, m10, m11;
            bool        mStaysRect;
        }
        gRectStaysRectSamples[] = {
            {          0,          0,          0,           0, false },
            {          0,          0,          0,  SK_Scalar1, false },
            {          0,          0, SK_Scalar1,           0, false },
            {          0,          0, SK_Scalar1,  SK_Scalar1, false },
            {          0, SK_Scalar1,          0,           0, false },
            {          0, SK_Scalar1,          0,  SK_Scalar1, false },
            {          0, SK_Scalar1, SK_Scalar1,           0, true },
            {          0, SK_Scalar1, SK_Scalar1,  SK_Scalar1, false },
            { SK_Scalar1,          0,          0,           0, false },
            { SK_Scalar1,          0,          0,  SK_Scalar1, true },
            { SK_Scalar1,          0, SK_Scalar1,           0, false },
            { SK_Scalar1,          0, SK_Scalar1,  SK_Scalar1, false },
            { SK_Scalar1, SK_Scalar1,          0,           0, false },
            { SK_Scalar1, SK_Scalar1,          0,  SK_Scalar1, false },
            { SK_Scalar1, SK_Scalar1, SK_Scalar1,           0, false },
            { SK_Scalar1, SK_Scalar1, SK_Scalar1,  SK_Scalar1, false }
        };

        for (size_t i = 0; i < SK_ARRAY_COUNT(gRectStaysRectSamples); i++) {
            SkMatrix    m;

            m.reset();
            m.set(SkMatrix::kMScaleX, gRectStaysRectSamples[i].m00);
            m.set(SkMatrix::kMSkewX,  gRectStaysRectSamples[i].m01);
            m.set(SkMatrix::kMSkewY,  gRectStaysRectSamples[i].m10);
            m.set(SkMatrix::kMScaleY, gRectStaysRectSamples[i].m11);
            REPORTER_ASSERT(reporter,
                    m.rectStaysRect() == gRectStaysRectSamples[i].mStaysRect);
        }
    }
}

#include "TestClassDef.h"
DEFINE_TESTCLASS("Matrix", MatrixTestClass, TestMatrix)