/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "effects/GrCustomXfermode.h"
#include "GrCaps.h"
#include "GrCoordTransform.h"
#include "GrFragmentProcessor.h"
#include "GrPipeline.h"
#include "GrProcessor.h"
#include "GrShaderCaps.h"
#include "glsl/GrGLSLBlend.h"
#include "glsl/GrGLSLFragmentProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLProgramDataManager.h"
#include "glsl/GrGLSLUniformHandler.h"
#include "glsl/GrGLSLXferProcessor.h"
bool GrCustomXfermode::IsSupportedMode(SkBlendMode mode) {
return (int)mode > (int)SkBlendMode::kLastCoeffMode &&
(int)mode <= (int)SkBlendMode::kLastMode;
}
///////////////////////////////////////////////////////////////////////////////
// Static helpers
///////////////////////////////////////////////////////////////////////////////
static constexpr GrBlendEquation hw_blend_equation(SkBlendMode mode) {
// In C++14 this could be a constexpr int variable.
#define EQ_OFFSET (kOverlay_GrBlendEquation - (int)SkBlendMode::kOverlay)
GR_STATIC_ASSERT(kOverlay_GrBlendEquation == (int)SkBlendMode::kOverlay + EQ_OFFSET);
GR_STATIC_ASSERT(kDarken_GrBlendEquation == (int)SkBlendMode::kDarken + EQ_OFFSET);
GR_STATIC_ASSERT(kLighten_GrBlendEquation == (int)SkBlendMode::kLighten + EQ_OFFSET);
GR_STATIC_ASSERT(kColorDodge_GrBlendEquation == (int)SkBlendMode::kColorDodge + EQ_OFFSET);
GR_STATIC_ASSERT(kColorBurn_GrBlendEquation == (int)SkBlendMode::kColorBurn + EQ_OFFSET);
GR_STATIC_ASSERT(kHardLight_GrBlendEquation == (int)SkBlendMode::kHardLight + EQ_OFFSET);
GR_STATIC_ASSERT(kSoftLight_GrBlendEquation == (int)SkBlendMode::kSoftLight + EQ_OFFSET);
GR_STATIC_ASSERT(kDifference_GrBlendEquation == (int)SkBlendMode::kDifference + EQ_OFFSET);
GR_STATIC_ASSERT(kExclusion_GrBlendEquation == (int)SkBlendMode::kExclusion + EQ_OFFSET);
GR_STATIC_ASSERT(kMultiply_GrBlendEquation == (int)SkBlendMode::kMultiply + EQ_OFFSET);
GR_STATIC_ASSERT(kHSLHue_GrBlendEquation == (int)SkBlendMode::kHue + EQ_OFFSET);
GR_STATIC_ASSERT(kHSLSaturation_GrBlendEquation == (int)SkBlendMode::kSaturation + EQ_OFFSET);
GR_STATIC_ASSERT(kHSLColor_GrBlendEquation == (int)SkBlendMode::kColor + EQ_OFFSET);
GR_STATIC_ASSERT(kHSLLuminosity_GrBlendEquation == (int)SkBlendMode::kLuminosity + EQ_OFFSET);
// There's an illegal GrBlendEquation that corresponds to no SkBlendMode, hence the extra +1.
GR_STATIC_ASSERT(kGrBlendEquationCnt == (int)SkBlendMode::kLastMode + 1 + 1 + EQ_OFFSET);
return static_cast<GrBlendEquation>((int)mode + EQ_OFFSET);
#undef EQ_OFFSET
}
static bool can_use_hw_blend_equation(GrBlendEquation equation,
GrProcessorAnalysisCoverage coverage, const GrCaps& caps) {
if (!caps.advancedBlendEquationSupport()) {
return false;
}
if (GrProcessorAnalysisCoverage::kLCD == coverage) {
return false; // LCD coverage must be applied after the blend equation.
}
if (caps.isAdvancedBlendEquationBlacklisted(equation)) {
return false;
}
return true;
}
///////////////////////////////////////////////////////////////////////////////
// Xfer Processor
///////////////////////////////////////////////////////////////////////////////
class CustomXP : public GrXferProcessor {
public:
CustomXP(SkBlendMode mode, GrBlendEquation hwBlendEquation)
: INHERITED(kCustomXP_ClassID)
, fMode(mode)
, fHWBlendEquation(hwBlendEquation) {}
CustomXP(bool hasMixedSamples, SkBlendMode mode, GrProcessorAnalysisCoverage coverage)
: INHERITED(kCustomXP_ClassID, true, hasMixedSamples, coverage)
, fMode(mode)
, fHWBlendEquation(kIllegal_GrBlendEquation) {
}
const char* name() const override { return "Custom Xfermode"; }
GrGLSLXferProcessor* createGLSLInstance() const override;
SkBlendMode mode() const { return fMode; }
bool hasHWBlendEquation() const { return kIllegal_GrBlendEquation != fHWBlendEquation; }
GrBlendEquation hwBlendEquation() const {
SkASSERT(this->hasHWBlendEquation());
return fHWBlendEquation;
}
GrXferBarrierType xferBarrierType(const GrCaps&) const override;
private:
void onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override;
void onGetBlendInfo(BlendInfo*) const override;
bool onIsEqual(const GrXferProcessor& xpBase) const override;
const SkBlendMode fMode;
const GrBlendEquation fHWBlendEquation;
typedef GrXferProcessor INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
class GLCustomXP : public GrGLSLXferProcessor {
public:
GLCustomXP(const GrXferProcessor&) {}
~GLCustomXP() override {}
static void GenKey(const GrXferProcessor& p, const GrShaderCaps& caps,
GrProcessorKeyBuilder* b) {
const CustomXP& xp = p.cast<CustomXP>();
uint32_t key = 0;
if (xp.hasHWBlendEquation()) {
SkASSERT(caps.advBlendEqInteraction() > 0); // 0 will mean !xp.hasHWBlendEquation().
key |= caps.advBlendEqInteraction();
GR_STATIC_ASSERT(GrShaderCaps::kLast_AdvBlendEqInteraction < 4);
}
if (!xp.hasHWBlendEquation() || caps.mustEnableSpecificAdvBlendEqs()) {
key |= (int)xp.mode() << 3;
}
b->add32(key);
}
private:
void emitOutputsForBlendState(const EmitArgs& args) override {
const CustomXP& xp = args.fXP.cast<CustomXP>();
SkASSERT(xp.hasHWBlendEquation());
GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder;
fragBuilder->enableAdvancedBlendEquationIfNeeded(xp.hwBlendEquation());
// Apply coverage by multiplying it into the src color before blending. Mixed samples will
// "just work" automatically. (See onGetOptimizations())
fragBuilder->codeAppendf("%s = %s * %s;", args.fOutputPrimary, args.fInputCoverage,
args.fInputColor);
}
void emitBlendCodeForDstRead(GrGLSLXPFragmentBuilder* fragBuilder,
GrGLSLUniformHandler* uniformHandler,
const char* srcColor,
const char* srcCoverage,
const char* dstColor,
const char* outColor,
const char* outColorSecondary,
const GrXferProcessor& proc) override {
const CustomXP& xp = proc.cast<CustomXP>();
SkASSERT(!xp.hasHWBlendEquation());
GrGLSLBlend::AppendMode(fragBuilder, srcColor, dstColor, outColor, xp.mode());
// Apply coverage.
INHERITED::DefaultCoverageModulation(fragBuilder, srcCoverage, dstColor, outColor,
outColorSecondary, xp);
}
void onSetData(const GrGLSLProgramDataManager&, const GrXferProcessor&) override {}
typedef GrGLSLXferProcessor INHERITED;
};
///////////////////////////////////////////////////////////////////////////////
void CustomXP::onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const {
GLCustomXP::GenKey(*this, caps, b);
}
GrGLSLXferProcessor* CustomXP::createGLSLInstance() const {
SkASSERT(this->willReadDstColor() != this->hasHWBlendEquation());
return new GLCustomXP(*this);
}
bool CustomXP::onIsEqual(const GrXferProcessor& other) const {
const CustomXP& s = other.cast<CustomXP>();
return fMode == s.fMode && fHWBlendEquation == s.fHWBlendEquation;
}
GrXferBarrierType CustomXP::xferBarrierType(const GrCaps& caps) const {
if (this->hasHWBlendEquation() && !caps.advancedCoherentBlendEquationSupport()) {
return kBlend_GrXferBarrierType;
}
return kNone_GrXferBarrierType;
}
void CustomXP::onGetBlendInfo(BlendInfo* blendInfo) const {
if (this->hasHWBlendEquation()) {
blendInfo->fEquation = this->hwBlendEquation();
}
}
///////////////////////////////////////////////////////////////////////////////
// See the comment above GrXPFactory's definition about this warning suppression.
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
#endif
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wnon-virtual-dtor"
#endif
class CustomXPFactory : public GrXPFactory {
public:
constexpr CustomXPFactory(SkBlendMode mode)
: fMode(mode), fHWBlendEquation(hw_blend_equation(mode)) {}
private:
sk_sp<const GrXferProcessor> makeXferProcessor(const GrProcessorAnalysisColor&,
GrProcessorAnalysisCoverage,
bool hasMixedSamples,
const GrCaps&) const override;
AnalysisProperties analysisProperties(const GrProcessorAnalysisColor&,
const GrProcessorAnalysisCoverage&,
const GrCaps&) const override;
GR_DECLARE_XP_FACTORY_TEST
SkBlendMode fMode;
GrBlendEquation fHWBlendEquation;
typedef GrXPFactory INHERITED;
};
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
sk_sp<const GrXferProcessor> CustomXPFactory::makeXferProcessor(
const GrProcessorAnalysisColor&,
GrProcessorAnalysisCoverage coverage,
bool hasMixedSamples,
const GrCaps& caps) const {
SkASSERT(GrCustomXfermode::IsSupportedMode(fMode));
if (can_use_hw_blend_equation(fHWBlendEquation, coverage, caps)) {
return sk_sp<GrXferProcessor>(new CustomXP(fMode, fHWBlendEquation));
}
return sk_sp<GrXferProcessor>(new CustomXP(hasMixedSamples, fMode, coverage));
}
GrXPFactory::AnalysisProperties CustomXPFactory::analysisProperties(
const GrProcessorAnalysisColor&, const GrProcessorAnalysisCoverage& coverage,
const GrCaps& caps) const {
/*
The general SVG blend equation is defined in the spec as follows:
Dca' = B(Sc, Dc) * Sa * Da + Y * Sca * (1-Da) + Z * Dca * (1-Sa)
Da' = X * Sa * Da + Y * Sa * (1-Da) + Z * Da * (1-Sa)
(Note that Sca, Dca indicate RGB vectors that are premultiplied by alpha,
and that B(Sc, Dc) is a mode-specific function that accepts non-multiplied
RGB colors.)
For every blend mode supported by this class, i.e. the "advanced" blend
modes, X=Y=Z=1 and this equation reduces to the PDF blend equation.
It can be shown that when X=Y=Z=1, these equations can modulate alpha for
coverage.
== Color ==
We substitute Y=Z=1 and define a blend() function that calculates Dca' in
terms of premultiplied alpha only:
blend(Sca, Dca, Sa, Da) = {Dca : if Sa == 0,
Sca : if Da == 0,
B(Sca/Sa, Dca/Da) * Sa * Da + Sca * (1-Da) + Dca * (1-Sa) : if
Sa,Da != 0}
And for coverage modulation, we use a post blend src-over model:
Dca'' = f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
(Where f is the fractional coverage.)
Next we show that canTweakAlphaForCoverage() is true by proving the
following relationship:
blend(f*Sca, Dca, f*Sa, Da) == f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
General case (f,Sa,Da != 0):
f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * (B(Sca/Sa, Dca/Da) * Sa * Da + Sca * (1-Da) + Dca * (1-Sa)) + (1-f) * Dca [Sa,Da !=
0, definition of blend()]
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + f*Dca * (1-Sa) + Dca - f*Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca - f*Sca * Da + f*Dca - f*Dca * Sa + Dca - f*Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca - f*Sca * Da - f*Dca * Sa + Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) - f*Dca * Sa + Dca
= B(Sca/Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + Dca * (1 - f*Sa)
= B(f*Sca/f*Sa, Dca/Da) * f*Sa * Da + f*Sca * (1-Da) + Dca * (1 - f*Sa) [f!=0]
= blend(f*Sca, Dca, f*Sa, Da) [definition of blend()]
Corner cases (Sa=0, Da=0, and f=0):
Sa=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * Dca + (1-f) * Dca [Sa=0, definition of blend()]
= Dca
= blend(0, Dca, 0, Da) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [Sa=0]
Da=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= f * Sca + (1-f) * Dca [Da=0, definition of blend()]
= f * Sca [Da=0]
= blend(f*Sca, 0, f*Sa, 0) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [Da=0]
f=0: f * blend(Sca, Dca, Sa, Da) + (1-f) * Dca
= Dca [f=0]
= blend(0, Dca, 0, Da) [definition of blend()]
= blend(f*Sca, Dca, f*Sa, Da) [f=0]
== Alpha ==
We substitute X=Y=Z=1 and define a blend() function that calculates Da':
blend(Sa, Da) = Sa * Da + Sa * (1-Da) + Da * (1-Sa)
= Sa * Da + Sa - Sa * Da + Da - Da * Sa
= Sa + Da - Sa * Da
We use the same model for coverage modulation as we did with color:
Da'' = f * blend(Sa, Da) + (1-f) * Da
And show that canTweakAlphaForCoverage() is true by proving the following
relationship:
blend(f*Sa, Da) == f * blend(Sa, Da) + (1-f) * Da
f * blend(Sa, Da) + (1-f) * Da
= f * (Sa + Da - Sa * Da) + (1-f) * Da
= f*Sa + f*Da - f*Sa * Da + Da - f*Da
= f*Sa - f*Sa * Da + Da
= f*Sa + Da - f*Sa * Da
= blend(f*Sa, Da)
*/
if (can_use_hw_blend_equation(fHWBlendEquation, coverage, caps)) {
if (caps.blendEquationSupport() == GrCaps::kAdvancedCoherent_BlendEquationSupport) {
return AnalysisProperties::kCompatibleWithAlphaAsCoverage;
} else {
return AnalysisProperties::kCompatibleWithAlphaAsCoverage |
AnalysisProperties::kRequiresNonOverlappingDraws;
}
}
return AnalysisProperties::kCompatibleWithAlphaAsCoverage |
AnalysisProperties::kReadsDstInShader;
}
GR_DEFINE_XP_FACTORY_TEST(CustomXPFactory);
#if GR_TEST_UTILS
const GrXPFactory* CustomXPFactory::TestGet(GrProcessorTestData* d) {
int mode = d->fRandom->nextRangeU((int)SkBlendMode::kLastCoeffMode + 1,
(int)SkBlendMode::kLastSeparableMode);
return GrCustomXfermode::Get((SkBlendMode)mode);
}
#endif
///////////////////////////////////////////////////////////////////////////////
const GrXPFactory* GrCustomXfermode::Get(SkBlendMode mode) {
// If these objects are constructed as static constexpr by cl.exe (2015 SP2) the vtables are
// null.
#ifdef SK_BUILD_FOR_WIN
#define _CONSTEXPR_
#else
#define _CONSTEXPR_ constexpr
#endif
static _CONSTEXPR_ const CustomXPFactory gOverlay(SkBlendMode::kOverlay);
static _CONSTEXPR_ const CustomXPFactory gDarken(SkBlendMode::kDarken);
static _CONSTEXPR_ const CustomXPFactory gLighten(SkBlendMode::kLighten);
static _CONSTEXPR_ const CustomXPFactory gColorDodge(SkBlendMode::kColorDodge);
static _CONSTEXPR_ const CustomXPFactory gColorBurn(SkBlendMode::kColorBurn);
static _CONSTEXPR_ const CustomXPFactory gHardLight(SkBlendMode::kHardLight);
static _CONSTEXPR_ const CustomXPFactory gSoftLight(SkBlendMode::kSoftLight);
static _CONSTEXPR_ const CustomXPFactory gDifference(SkBlendMode::kDifference);
static _CONSTEXPR_ const CustomXPFactory gExclusion(SkBlendMode::kExclusion);
static _CONSTEXPR_ const CustomXPFactory gMultiply(SkBlendMode::kMultiply);
static _CONSTEXPR_ const CustomXPFactory gHue(SkBlendMode::kHue);
static _CONSTEXPR_ const CustomXPFactory gSaturation(SkBlendMode::kSaturation);
static _CONSTEXPR_ const CustomXPFactory gColor(SkBlendMode::kColor);
static _CONSTEXPR_ const CustomXPFactory gLuminosity(SkBlendMode::kLuminosity);
#undef _CONSTEXPR_
switch (mode) {
case SkBlendMode::kOverlay:
return &gOverlay;
case SkBlendMode::kDarken:
return &gDarken;
case SkBlendMode::kLighten:
return &gLighten;
case SkBlendMode::kColorDodge:
return &gColorDodge;
case SkBlendMode::kColorBurn:
return &gColorBurn;
case SkBlendMode::kHardLight:
return &gHardLight;
case SkBlendMode::kSoftLight:
return &gSoftLight;
case SkBlendMode::kDifference:
return &gDifference;
case SkBlendMode::kExclusion:
return &gExclusion;
case SkBlendMode::kMultiply:
return &gMultiply;
case SkBlendMode::kHue:
return &gHue;
case SkBlendMode::kSaturation:
return &gSaturation;
case SkBlendMode::kColor:
return &gColor;
case SkBlendMode::kLuminosity:
return &gLuminosity;
default:
SkASSERT(!GrCustomXfermode::IsSupportedMode(mode));
return nullptr;
}
}