skia2/tests/ApplyGammaTest.cpp

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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <initializer_list>
#include "Test.h"
#if SK_SUPPORT_GPU
#include "GrContext.h"
#include "GrTexture.h"
#include "GrTextureProvider.h"
#include "SkUtils.h"
// using anonymous namespace because these functions are used as template params.
namespace {
/** convert 0..1 linear value to 0..1 srgb */
float linear_to_srgb(float linear) {
if (linear <= 0.0031308) {
return linear * 12.92f;
} else {
return 1.055f * powf(linear, 1.f / 2.4f) - 0.055f;
}
}
}
bool check_gamma(uint32_t src, uint32_t dst, float gamma, float error, uint32_t* expected) {
if (SkScalarNearlyEqual(gamma, 1.f)) {
*expected = src;
return src == dst;
} else {
bool result = true;
uint32_t expectedColor = src & 0xff000000;
// Alpha should always be exactly preserved.
if ((src & 0xff000000) != (dst & 0xff000000)) {
result = false;
}
for (int c = 0; c < 3; ++c) {
uint8_t srcComponent = (src & (0xff << (c * 8))) >> (c * 8);
float lower = SkTMax(0.f, (float)srcComponent - error);
float upper = SkTMin(255.f, (float)srcComponent + error);
if (SkScalarNearlyEqual(gamma, 1.0f / 2.2f)) {
lower = linear_to_srgb(lower / 255.f);
upper = linear_to_srgb(upper / 255.f);
} else {
lower = powf(lower / 255.f, gamma);
upper = powf(upper / 255.f, gamma);
}
SkASSERT(lower >= 0.f && lower <= 255.f);
SkASSERT(upper >= 0.f && upper <= 255.f);
uint8_t dstComponent = (dst & (0xff << (c * 8))) >> (c * 8);
if (dstComponent < SkScalarFloorToInt(lower * 255.f) ||
dstComponent > SkScalarCeilToInt(upper * 255.f)) {
result = false;
}
uint8_t expectedComponent = SkScalarRoundToInt((lower + upper) * 127.5f);
expectedColor |= expectedComponent << (c * 8);
}
*expected = expectedColor;
return result;
}
}
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ApplyGamma, reporter, ctxInfo) {
GrContext* context = ctxInfo.grContext();
static const int kW = 10;
static const int kH = 10;
static const size_t kRowBytes = sizeof(uint32_t) * kW;
GrSurfaceDesc baseDesc;
baseDesc.fConfig = kRGBA_8888_GrPixelConfig;
baseDesc.fWidth = kW;
baseDesc.fHeight = kH;
SkAutoTMalloc<uint32_t> srcPixels(kW * kH);
for (int i = 0; i < kW * kH; ++i) {
srcPixels.get()[i] = i;
}
SkAutoTMalloc<uint32_t> dstPixels(kW * kH);
for (int i = 0; i < kW * kH; ++i) {
dstPixels.get()[i] = ~i;
}
SkAutoTMalloc<uint32_t> read(kW * kH);
// We allow more error on GPUs with lower precision shader variables.
float error = context->caps()->shaderCaps()->floatPrecisionVaries() ? 1.2f : 0.5f;
for (auto sOrigin : { kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin }) {
for (auto dOrigin : { kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin }) {
for (auto sFlags : { kRenderTarget_GrSurfaceFlag, kNone_GrSurfaceFlags }) {
for (auto gamma : { 1.0f, 1.0f / 1.8f, 1.0f / 2.2f }) {
GrSurfaceDesc srcDesc = baseDesc;
srcDesc.fOrigin = sOrigin;
srcDesc.fFlags = sFlags;
GrSurfaceDesc dstDesc = baseDesc;
dstDesc.fOrigin = dOrigin;
dstDesc.fFlags = kRenderTarget_GrSurfaceFlag;
SkAutoTUnref<GrTexture> src(
context->textureProvider()->createTexture(srcDesc, SkBudgeted::kNo,
srcPixels.get(),
kRowBytes));
SkAutoTUnref<GrTexture> dst(
context->textureProvider()->createTexture(dstDesc, SkBudgeted::kNo,
dstPixels.get(),
kRowBytes));
if (!src || !dst) {
ERRORF(reporter, "Could not create surfaces for copy surface test.");
continue;
}
bool result = context->applyGamma(dst->asRenderTarget(), src, gamma);
// To make the copied src rect correct we would apply any dst clipping
// back to the src rect, but we don't use it again so don't bother.
if (!result) {
ERRORF(reporter, "Unexpected failure from applyGamma.");
continue;
}
sk_memset32(read.get(), 0, kW * kH);
if (!dst->readPixels(0, 0, kW, kH, baseDesc.fConfig, read.get(), kRowBytes)) {
ERRORF(reporter, "Error calling readPixels");
continue;
}
bool abort = false;
// Validate that pixels were copied/transformed correctly.
for (int y = 0; y < kH && !abort; ++y) {
for (int x = 0; x < kW && !abort; ++x) {
uint32_t r = read.get()[y * kW + x];
uint32_t s = srcPixels.get()[y * kW + x];
uint32_t expected;
if (!check_gamma(s, r, gamma, error, &expected)) {
ERRORF(reporter, "Expected dst %d,%d to contain 0x%08x "
"from src 0x%08x and gamma %f. Got %08x",
x, y, expected, s, gamma, r);
abort = true;
break;
}
}
}
}
}
}
}
}
#endif