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/*
* Copyright 2023 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <cmath>
#include "include/core/SkAlphaType.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorSpace.h"
#include "include/core/SkColorType.h"
#include "include/core/SkImage.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPixmap.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSamplingOptions.h"
#include "include/core/SkShader.h"
#include "include/private/SkGainmapInfo.h"
#include "include/private/SkGainmapShader.h"
#include "include/private/base/SkFloatingPoint.h"
#include "tests/Test.h"
static bool approx_equal(const SkColor4f& a, const SkColor4f& b) {
constexpr float kEpsilon = 1e-3f;
return std::abs(a.fR - b.fR) < kEpsilon && std::abs(a.fG - b.fG) < kEpsilon &&
std::abs(a.fB - b.fB) < kEpsilon && std::abs(a.fA - b.fA) < kEpsilon;
}
// Create a 1x1 image with a specified color.
static sk_sp<SkImage> make_1x1_image(
sk_sp<SkColorSpace> imageColorSpace,
SkAlphaType imageAlphaType,
SkColor4f imageColor,
sk_sp<SkColorSpace> imageColorColorSpace = SkColorSpace::MakeSRGBLinear()) {
SkImageInfo bmInfo =
SkImageInfo::Make(1, 1, kRGBA_F32_SkColorType, imageAlphaType, imageColorSpace);
SkBitmap bm;
bm.allocPixels(bmInfo);
SkImageInfo writePixelsInfo = SkImageInfo::Make(
1, 1, kRGBA_F32_SkColorType, kUnpremul_SkAlphaType, imageColorColorSpace);
SkPixmap writePixelsPixmap(writePixelsInfo, &imageColor, writePixelsInfo.minRowBytes());
bm.writePixels(writePixelsPixmap, 0, 0);
return SkImage::MakeFromBitmap(bm);
}
// Return gainmap info that will scale 1 up to the specified hdrRatioMax.
static SkGainmapInfo simple_gainmap_info(float hdrRatioMax) {
SkGainmapInfo gainmapInfo;
const float logHdrRatioMax = sk_float_log(hdrRatioMax);
gainmapInfo.fHdrRatioMax = hdrRatioMax;
gainmapInfo.fEpsilonSdr = 0.f;
gainmapInfo.fEpsilonHdr = 0.f;
gainmapInfo.fLogRatioMin = {0.f, 0.f, 0.f, 0.f};
gainmapInfo.fLogRatioMax = {logHdrRatioMax, logHdrRatioMax, logHdrRatioMax, 1.f};
return gainmapInfo;
}
// Draw using a gainmap to a canvas with the specified HDR to SDR ratio and the specified color
// space. Return the result as unpremultiplied sRGB linear.
static SkColor4f draw_1x1_gainmap(sk_sp<SkImage> baseImage,
sk_sp<SkImage> gainmapImage,
const SkGainmapInfo& gainmapInfo,
float dstRatio,
sk_sp<SkColorSpace> dstColorSpace = SkColorSpace::MakeSRGB()) {
constexpr auto kRect = SkRect::MakeWH(1.f, 1.f);
SkImageInfo canvasInfo =
SkImageInfo::Make(1, 1, kRGBA_F32_SkColorType, kPremul_SkAlphaType, dstColorSpace);
SkBitmap canvasBitmap;
canvasBitmap.allocPixels(canvasInfo);
canvasBitmap.eraseColor(SK_ColorTRANSPARENT);
sk_sp<SkShader> shader = SkGainmapShader::Make(baseImage,
kRect,
SkSamplingOptions(),
gainmapImage,
kRect,
SkSamplingOptions(),
gainmapInfo,
kRect,
dstRatio,
dstColorSpace);
SkPaint paint;
paint.setShader(shader);
SkCanvas canvas(canvasBitmap);
canvas.drawRect(kRect, paint);
SkColor4f result = {0.f, 0.f, 0.f, 0.f};
SkImageInfo readPixelsInfo = SkImageInfo::Make(
1, 1, kRGBA_F32_SkColorType, kUnpremul_SkAlphaType, SkColorSpace::MakeSRGBLinear());
canvas.readPixels(readPixelsInfo, &result, sizeof(result), 0, 0);
return result;
}
// Verify that the gainmap shader correctly applies the base, gainmap, and destination rectangles.
DEF_TEST(GainmapShader_rects, r) {
SkColor4f sdrColors[5][2] = {
{{-1.f, -1.f, -1.f, 1.0f}, {-1.f, -1.f, -1.f, 1.0f}},
{{1.0f, 1.0f, 1.0f, 1.0f}, {1.0f, 1.0f, 0.5f, 1.0f}},
{{1.0f, 0.5f, 1.0f, 1.0f}, {1.0f, 0.5f, 0.5f, 1.0f}},
{{0.5f, 1.0f, 1.0f, 1.0f}, {0.5f, 1.0f, 0.5f, 1.0f}},
{{0.5f, 0.5f, 1.0f, 1.0f}, {0.5f, 0.5f, 0.5f, 1.0f}},
};
SkPixmap sdrPixmap(SkImageInfo::Make(2, 5, kRGBA_F32_SkColorType, kOpaque_SkAlphaType),
sdrColors,
2 * sizeof(SkColor4f));
auto sdrImage = SkImage::MakeFromRaster(sdrPixmap, nullptr, nullptr);
const auto sdrImageRect = SkRect::MakeXYWH(0.f, 1.f, 2.f, 4.f);
// The top pixel indicates to gain only red, and the bottom pixel indicates to gain everything
// except red.
SkColor4f gainmapColors[2][2] = {
{{-1.f, -1.f, -1.f, 1.f}, {1.0f, 0.0f, 0.0f, 1.f}},
{{-1.f, -1.f, -1.f, 1.f}, {0.0f, 1.0f, 1.0f, 1.f}},
};
SkPixmap gainmapPixmap(SkImageInfo::Make(2, 2, kRGBA_F32_SkColorType, kOpaque_SkAlphaType),
gainmapColors,
2 * sizeof(SkColor4f));
auto gainmapImage = SkImage::MakeFromRaster(gainmapPixmap, nullptr, nullptr);
const auto gainmapImageRect = SkRect::MakeXYWH(1.f, 0.f, 1.f, 2.f);
const SkGainmapInfo gainmapInfo = simple_gainmap_info(2.f);
SkImageInfo canvasInfo = SkImageInfo::Make(
4, 6, kRGBA_F32_SkColorType, kPremul_SkAlphaType, SkColorSpace::MakeSRGB());
SkBitmap canvasBitmap;
canvasBitmap.allocPixels(canvasInfo);
canvasBitmap.eraseColor(SK_ColorTRANSPARENT);
const auto canvasRect = SkRect::MakeXYWH(1.f, 1.f, 2.f, 4.f);
sk_sp<SkShader> shader = SkGainmapShader::Make(sdrImage,
sdrImageRect,
SkSamplingOptions(),
gainmapImage,
gainmapImageRect,
SkSamplingOptions(),
gainmapInfo,
canvasRect,
gainmapInfo.fHdrRatioMax,
canvasInfo.refColorSpace());
SkPaint paint;
paint.setShader(shader);
SkCanvas canvas(canvasBitmap);
canvas.drawRect(canvasRect, paint);
// Compute and compare the expected colors.
constexpr float k10G = 1.353256028586302f; // This is linearToSRGB(2.0).
constexpr float k05G = 0.6858361015012847f; // This is linearToSRGB(srgbToLinear(0.5)*2.0)
SkColor4f expectedColors[4][2] = {
{{k10G, 1.0f, 1.0f, 1.0f}, {k10G, 1.0f, 0.5f, 1.0f}},
{{k10G, 0.5f, 1.0f, 1.0f}, {k10G, 0.5f, 0.5f, 1.0f}},
{{0.5f, k10G, k10G, 1.0f}, {0.5f, k10G, k05G, 1.0f}},
{{0.5f, k05G, k10G, 1.0f}, {0.5f, k05G, k05G, 1.0f}},
};
for (int y = 0; y < 4; ++y) {
for (int x = 0; x < 2; ++x) {
auto color = canvasBitmap.getColor4f(x + 1, y + 1);
REPORTER_ASSERT(r, approx_equal(color, expectedColors[y][x]));
}
}
}
// Verify that the gainmap shader isn't affected by the color spaces of the base, gainmap, or
// destination.
DEF_TEST(GainmapShader_colorSpace, r) {
auto sdrColorSpace =
SkColorSpace::MakeRGB(SkNamedTransferFn::k2Dot2, SkNamedGamut::kSRGB)->makeColorSpin();
auto gainmapColorSpace = SkColorSpace::MakeRGB(SkNamedTransferFn::kPQ, SkNamedGamut::kRec2020);
auto dstColorSpace = SkColorSpace::MakeRGB(SkNamedTransferFn::kHLG, SkNamedGamut::kDisplayP3);
constexpr SkColor4f kSdrColor = {0.25f, 0.5f, 1.f, 1.f};
constexpr SkColor4f kGainmapColor = {
0.0f, // The sRGB G channel will have a exp2(0.0)=1.000 gain.
0.5f, // The sRGB B channel will have a exp2(0.5)=0.707 gain.
1.0f, // The sRGB R channel will have a exp2(1.0)=2.000 gain.
1.f};
constexpr SkColor4f kExpectedColor = {0.5f, 0.5f, 1.414f, 1.f};
auto sdrImage = make_1x1_image(sdrColorSpace, kOpaque_SkAlphaType, kSdrColor);
auto gainmapImage = make_1x1_image(
gainmapColorSpace, kOpaque_SkAlphaType, kGainmapColor, gainmapColorSpace);
SkGainmapInfo gainmapInfo = simple_gainmap_info(2.f);
auto color = draw_1x1_gainmap(
sdrImage, gainmapImage, gainmapInfo, gainmapInfo.fHdrRatioMax, dstColorSpace);
REPORTER_ASSERT(r, approx_equal(color, kExpectedColor));
}