58 lines
2.0 KiB
C++
58 lines
2.0 KiB
C++
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/*
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* Copyright 2020 Google LLC
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "include/core/SkCanvas.h"
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#include "include/core/SkSurface.h"
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#include "include/utils/SkRandom.h"
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#include "src/core/SkSamplingPriv.h"
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#include "tests/Test.h"
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#include "tools/Resources.h"
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#include "tools/ToolUtils.h"
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// In general, sampling under identity matrix should not affect the pixels. However,
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// cubic resampling when B != 0 is expected to change pixels.
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//
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DEF_TEST(sampling_with_identity_matrix, r) {
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const char* names[] = {
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"images/mandrill_128.png", "images/color_wheel.jpg",
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};
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SkRandom rand;
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for (auto name : names) {
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auto src = GetResourceAsImage(name);
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auto surf = SkSurface::MakeRasterN32Premul(src->width(), src->height());
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auto canvas = surf->getCanvas();
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auto dotest = [&](const SkSamplingOptions& sampling, bool expect_same) {
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canvas->clear(0);
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canvas->drawImage(src.get(), 0, 0, sampling, nullptr);
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auto dst = surf->makeImageSnapshot();
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REPORTER_ASSERT(r, SkSamplingPriv::NoChangeWithIdentityMatrix(sampling) == expect_same);
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REPORTER_ASSERT(r, ToolUtils::equal_pixels(src.get(), dst.get()) == expect_same);
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};
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// Exercise all non-cubics -- expecting no changes
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for (auto m : {SkMipmapMode::kNone, SkMipmapMode::kNearest, SkMipmapMode::kLinear}) {
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for (auto f : {SkFilterMode::kNearest, SkFilterMode::kLinear}) {
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dotest(SkSamplingOptions(f, m), true);
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}
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}
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// Exercise cubic variants with B zero and non-zero
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constexpr int N = 30; // try a bunch of random values
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for (int i = 0; i < N; ++i) {
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float C = rand.nextF();
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dotest(SkSamplingOptions({0, C}), true);
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float B = rand.nextF() * 0.9f + 0.05f; // non-zero but still within (0,,,1]
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SkASSERT(B != 0);
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dotest(SkSamplingOptions({B, C}), false);
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}
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}
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}
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