blob: 240bbb0e9a84709f8746a526582ef70624a2d94a [file] [log] [blame]
/*
* Copyright 2020 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "include/core/SkCanvas.h"
#include "include/core/SkImage.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSamplingOptions.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTypes.h"
#include "src/base/SkRandom.h"
#include "src/core/SkSamplingPriv.h"
#include "tests/Test.h"
#include "tools/Resources.h"
#include "tools/ToolUtils.h"
#include <initializer_list>
// In general, sampling under identity matrix should not affect the pixels. However,
// cubic resampling when B != 0 is expected to change pixels.
//
DEF_TEST(sampling_with_identity_matrix, r) {
const char* names[] = {
"images/mandrill_128.png", "images/color_wheel.jpg",
};
SkRandom rand;
for (auto name : names) {
auto src = GetResourceAsImage(name);
auto surf = SkSurface::MakeRasterN32Premul(src->width(), src->height());
auto canvas = surf->getCanvas();
auto dotest = [&](const SkSamplingOptions& sampling, bool expect_same) {
canvas->clear(0);
canvas->drawImage(src.get(), 0, 0, sampling, nullptr);
auto dst = surf->makeImageSnapshot();
REPORTER_ASSERT(r, SkSamplingPriv::NoChangeWithIdentityMatrix(sampling) == expect_same);
REPORTER_ASSERT(r, ToolUtils::equal_pixels(src.get(), dst.get()) == expect_same);
};
// Exercise all non-cubics -- expecting no changes
for (auto m : {SkMipmapMode::kNone, SkMipmapMode::kNearest, SkMipmapMode::kLinear}) {
for (auto f : {SkFilterMode::kNearest, SkFilterMode::kLinear}) {
dotest(SkSamplingOptions(f, m), true);
}
}
// Exercise cubic variants with B zero and non-zero
constexpr int N = 30; // try a bunch of random values
for (int i = 0; i < N; ++i) {
float C = rand.nextF();
dotest(SkSamplingOptions({0, C}), true);
float B = rand.nextF() * 0.9f + 0.05f; // non-zero but still within (0,,,1]
SkASSERT(B != 0);
dotest(SkSamplingOptions({B, C}), false);
}
}
}