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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "skia/ext/skcolorspace_trfn.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace skia {
namespace {
constexpr float kEpsilon = 0.001;
TEST(SkiaUtils, ScaleTrfn) {
skcms_TransferFunction x = SkNamedTransferFn::kIEC61966_2_1;
float alpha = 3.f;
// Ensure that we round-trip successfully.
skcms_TransferFunction y = ScaleTransferFunction(x, alpha);
float alpha_recovered = 0.f;
EXPECT_TRUE(IsScaledTransferFunction(x, y, &alpha_recovered));
EXPECT_NEAR(alpha, alpha_recovered, kEpsilon);
// Make sure that we actually scale the function correctly;
for (float t = 0.0; t <= 1.f; t += 1.f / 256.f) {
float x_of_t = skcms_TransferFunction_eval(&x, t);
float y_of_t = skcms_TransferFunction_eval(&y, t);
EXPECT_NEAR(y_of_t, alpha * x_of_t, kEpsilon);
}
// Ensure that all parameters are checked.
skcms_TransferFunction z;
z = y;
z.b *= 1.1;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.b *= 1.1;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.c *= 1.1;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.d += 0.04;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.e += 0.1;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.f += 0.04;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
z = y;
z.g += 1.f;
EXPECT_FALSE(IsScaledTransferFunction(x, z, &alpha_recovered));
}
} // namespace
} // namespace skia
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