src/gpu/GrFragmentProcessor.cpp - skia - Git at Google

 /*
 * 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 "src/gpu/GrFragmentProcessor.h"
 #include "src/gpu/GrPipeline.h"
 #include "src/gpu/GrProcessorAnalysis.h"
 #include "src/gpu/effects/GrBlendFragmentProcessor.h"
 #include "src/gpu/effects/generated/GrClampFragmentProcessor.h"
 #include "src/gpu/effects/generated/GrConstColorProcessor.h"
 #include "src/gpu/effects/generated/GrOverrideInputFragmentProcessor.h"
 #include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
 #include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
 #include "src/gpu/glsl/GrGLSLProgramDataManager.h"
 #include "src/gpu/glsl/GrGLSLUniformHandler.h"

 bool GrFragmentProcessor::isEqual(const GrFragmentProcessor& that) const {
     if (this->classID() != that.classID()) {
         return false;
     }
     if (this->usesVaryingCoordsDirectly() != that.usesVaryingCoordsDirectly()) {
         return false;
     }
     if (!this->onIsEqual(that)) {
         return false;
     }
     if (this->numChildProcessors() != that.numChildProcessors()) {
         return false;
     }
     for (int i = 0; i < this->numChildProcessors(); ++i) {
         auto thisChild = this->childProcessor(i),
              thatChild = that .childProcessor(i);
         if (SkToBool(thisChild) != SkToBool(thatChild)) {
             return false;
         }
         if (thisChild && !thisChild->isEqual(*thatChild)) {
             return false;
         }
     }
     return true;
 }

 void GrFragmentProcessor::visitProxies(const GrOp::VisitProxyFunc& func) const {
     this->visitTextureEffects([&func](const GrTextureEffect& te) {
         func(te.view().proxy(), te.samplerState().mipmapped());
     });
 }

 void GrFragmentProcessor::visitTextureEffects(
         const std::function<void(const GrTextureEffect&)>& func) const {
     if (auto* te = this->asTextureEffect()) {
         func(*te);
     }
     for (auto& child : fChildProcessors) {
         if (child) {
             child->visitTextureEffects(func);
         }
     }
 }

 GrTextureEffect* GrFragmentProcessor::asTextureEffect() {
     if (this->classID() == kGrTextureEffect_ClassID) {
         return static_cast<GrTextureEffect*>(this);
     }
     return nullptr;
 }

 const GrTextureEffect* GrFragmentProcessor::asTextureEffect() const {
     if (this->classID() == kGrTextureEffect_ClassID) {
         return static_cast<const GrTextureEffect*>(this);
     }
     return nullptr;
 }

 #if GR_TEST_UTILS
 static void recursive_dump_tree_info(const GrFragmentProcessor& fp,
                                      SkString indent,
                                      SkString* text) {
     for (int index = 0; index < fp.numChildProcessors(); ++index) {
         text->appendf("\n%s(#%d) -> ", indent.c_str(), index);
         if (const GrFragmentProcessor* childFP = fp.childProcessor(index)) {
             text->append(childFP->dumpInfo());
             indent.append("\t");
             recursive_dump_tree_info(*childFP, indent, text);
         } else {
             text->append("null");
         }
     }
 }

 SkString GrFragmentProcessor::dumpTreeInfo() const {
     SkString text = this->dumpInfo();
     recursive_dump_tree_info(*this, SkString("\t"), &text);
     text.append("\n");
     return text;
 }
 #endif

 GrGLSLFragmentProcessor* GrFragmentProcessor::createGLSLInstance() const {
     GrGLSLFragmentProcessor* glFragProc = this->onCreateGLSLInstance();
     glFragProc->fChildProcessors.push_back_n(fChildProcessors.count());
     for (int i = 0; i < fChildProcessors.count(); ++i) {
         glFragProc->fChildProcessors[i] =
                 fChildProcessors[i] ? fChildProcessors[i]->createGLSLInstance() : nullptr;
     }
     return glFragProc;
 }

 void GrFragmentProcessor::addAndPushFlagToChildren(PrivateFlags flag) {
     // This propagates down, so if we've already marked it, all our children should have it too
     if (!(fFlags & flag)) {
         fFlags |= flag;
         for (auto& child : fChildProcessors) {
             if (child) {
                 child->addAndPushFlagToChildren(flag);
             }
         }
     }
 #ifdef SK_DEBUG
     for (auto& child : fChildProcessors) {
         SkASSERT(!child || (child->fFlags & flag));
     }
 #endif
 }

 int GrFragmentProcessor::numNonNullChildProcessors() const {
     return std::count_if(fChildProcessors.begin(), fChildProcessors.end(),
                          [](const auto& c) { return c != nullptr; });
 }

 #ifdef SK_DEBUG
 bool GrFragmentProcessor::isInstantiated() const {
     bool result = true;
     this->visitTextureEffects([&result](const GrTextureEffect& te) {
         if (!te.texture()) {
             result = false;
         }
     });
     return result;
 }
 #endif

 void GrFragmentProcessor::registerChild(std::unique_ptr<GrFragmentProcessor> child,
                                         SkSL::SampleUsage sampleUsage) {
     if (!child) {
         fChildProcessors.push_back(nullptr);
         return;
     }

     // The child should not have been attached to another FP already and not had any sampling
     // strategy set on it.
     SkASSERT(!child->fParent && !child->sampleUsage().isSampled() &&
              !child->isSampledWithExplicitCoords() && !child->hasPerspectiveTransform());

     // If a child is sampled directly (sample(child)), and with a single uniform matrix, we need to
     // treat it as if it were sampled with multiple matrices (eg variable).
     bool variableMatrix = sampleUsage.hasVariableMatrix() ||
                           (sampleUsage.fPassThrough && sampleUsage.hasUniformMatrix());

     // Configure child's sampling state first
     child->fUsage = sampleUsage;

     // When an FP is sampled using variable matrix expressions, it is effectively being sampled
     // explicitly, except that the call site will automatically evaluate the matrix expression to
     // produce the float2 passed into this FP.
     if (sampleUsage.fExplicitCoords || variableMatrix) {
         child->addAndPushFlagToChildren(kSampledWithExplicitCoords_Flag);
     }

     // Push perspective matrix type to children
     if (sampleUsage.fHasPerspective) {
         child->addAndPushFlagToChildren(kNetTransformHasPerspective_Flag);
     }

     // If the child is sampled with a variable matrix expression, auto-generated code in
     // invokeChildWithMatrix() for this FP will refer to the local coordinates.
     if (variableMatrix) {
         this->setUsesSampleCoordsDirectly();
     }

     // If the child is not sampled explicitly and not already accessing sample coords directly
     // (through reference or variable matrix expansion), then mark that this FP tree relies on
     // coordinates at a lower level. If the child is sampled with explicit coordinates and
     // there isn't any other direct reference to the sample coords, we halt the upwards propagation
     // because it means this FP is determining coordinates on its own.
     if (!child->isSampledWithExplicitCoords()) {
         if ((child->fFlags & kUsesSampleCoordsDirectly_Flag ||
              child->fFlags & kUsesSampleCoordsIndirectly_Flag)) {
             fFlags |= kUsesSampleCoordsIndirectly_Flag;
         }
     }

     fRequestedFeatures |= child->fRequestedFeatures;

     // Record that the child is attached to us; this FP is the source of any uniform data needed
     // to evaluate the child sample matrix.
     child->fParent = this;
     fChildProcessors.push_back(std::move(child));

     // Validate: our sample strategy comes from a parent we shouldn't have yet.
     SkASSERT(!this->isSampledWithExplicitCoords() && !this->hasPerspectiveTransform() &&
              !fUsage.isSampled() && !fParent);
 }

 void GrFragmentProcessor::cloneAndRegisterAllChildProcessors(const GrFragmentProcessor& src) {
     for (int i = 0; i < src.numChildProcessors(); ++i) {
         if (auto fp = src.childProcessor(i)) {
             this->registerChild(fp->clone(), fp->sampleUsage());
         } else {
             this->registerChild(nullptr);
         }
     }
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MulChildByInputAlpha(
         std::unique_ptr<GrFragmentProcessor> fp) {
     if (!fp) {
         return nullptr;
     }
     return GrBlendFragmentProcessor::Make(/*src=*/nullptr, std::move(fp), SkBlendMode::kDstIn);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MulInputByChildAlpha(
         std::unique_ptr<GrFragmentProcessor> fp) {
     if (!fp) {
         return nullptr;
     }
     return GrBlendFragmentProcessor::Make(/*src=*/nullptr, std::move(fp), SkBlendMode::kSrcIn);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ModulateAlpha(
         std::unique_ptr<GrFragmentProcessor> inputFP, const SkPMColor4f& color) {
     auto colorFP = GrConstColorProcessor::Make(color);
     return GrBlendFragmentProcessor::Make(
             std::move(colorFP), std::move(inputFP), SkBlendMode::kSrcIn,
             GrBlendFragmentProcessor::BlendBehavior::kSkModeBehavior);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ModulateRGBA(
         std::unique_ptr<GrFragmentProcessor> inputFP, const SkPMColor4f& color) {
     auto colorFP = GrConstColorProcessor::Make(color);
     return GrBlendFragmentProcessor::Make(
             std::move(colorFP), std::move(inputFP), SkBlendMode::kModulate,
             GrBlendFragmentProcessor::BlendBehavior::kSkModeBehavior);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ClampPremulOutput(
         std::unique_ptr<GrFragmentProcessor> fp) {
     if (!fp) {
         return nullptr;
     }
     return GrClampFragmentProcessor::Make(std::move(fp), /*clampToPremul=*/true);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::SwizzleOutput(
         std::unique_ptr<GrFragmentProcessor> fp, const GrSwizzle& swizzle) {
     class SwizzleFragmentProcessor : public GrFragmentProcessor {
     public:
         static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> fp,
                                                          const GrSwizzle& swizzle) {
             return std::unique_ptr<GrFragmentProcessor>(
                     new SwizzleFragmentProcessor(std::move(fp), swizzle));
         }

         const char* name() const override { return "Swizzle"; }
         const GrSwizzle& swizzle() const { return fSwizzle; }

         std::unique_ptr<GrFragmentProcessor> clone() const override {
             return Make(this->childProcessor(0)->clone(), fSwizzle);
         }

     private:
         SwizzleFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp, const GrSwizzle& swizzle)
                 : INHERITED(kSwizzleFragmentProcessor_ClassID, ProcessorOptimizationFlags(fp.get()))
                 , fSwizzle(swizzle) {
             this->registerChild(std::move(fp));
         }

         GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
             class GLFP : public GrGLSLFragmentProcessor {
             public:
                 void emitCode(EmitArgs& args) override {
                     SkString childColor = this->invokeChild(0, args);

                     const SwizzleFragmentProcessor& sfp = args.fFp.cast<SwizzleFragmentProcessor>();
                     const GrSwizzle& swizzle = sfp.swizzle();
                     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;

                     fragBuilder->codeAppendf("return %s.%s;",
                                              childColor.c_str(), swizzle.asString().c_str());
                 }
             };
             return new GLFP;
         }

         void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder* b) const override {
             b->add32(fSwizzle.asKey());
         }

         bool onIsEqual(const GrFragmentProcessor& other) const override {
             const SwizzleFragmentProcessor& sfp = other.cast<SwizzleFragmentProcessor>();
             return fSwizzle == sfp.fSwizzle;
         }

         SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& input) const override {
             return fSwizzle.applyTo(input);
         }

         GrSwizzle fSwizzle;

         using INHERITED = GrFragmentProcessor;
     };

     if (!fp) {
         return nullptr;
     }
     if (GrSwizzle::RGBA() == swizzle) {
         return fp;
     }
     return SwizzleFragmentProcessor::Make(std::move(fp), swizzle);
 }

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MakeInputPremulAndMulByOutput(
         std::unique_ptr<GrFragmentProcessor> fp) {
     class PremulFragmentProcessor : public GrFragmentProcessor {
     public:
         static std::unique_ptr<GrFragmentProcessor> Make(
                 std::unique_ptr<GrFragmentProcessor> processor) {
             return std::unique_ptr<GrFragmentProcessor>(
                     new PremulFragmentProcessor(std::move(processor)));
         }

         const char* name() const override { return "Premultiply"; }

         std::unique_ptr<GrFragmentProcessor> clone() const override {
             return Make(this->childProcessor(0)->clone());
         }

     private:
         PremulFragmentProcessor(std::unique_ptr<GrFragmentProcessor> processor)
                 : INHERITED(kPremulFragmentProcessor_ClassID, OptFlags(processor.get())) {
             this->registerChild(std::move(processor));
         }

         GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
             class GLFP : public GrGLSLFragmentProcessor {
             public:
                 void emitCode(EmitArgs& args) override {
                     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
                     SkString temp = this->invokeChild(/*childIndex=*/0, "half4(1)", args);
                     fragBuilder->codeAppendf("half4 color = %s;", temp.c_str());
                     fragBuilder->codeAppendf("color.rgb *= %s.rgb;", args.fInputColor);
                     fragBuilder->codeAppendf("return color * %s.a;", args.fInputColor);
                 }
             };
             return new GLFP;
         }

         void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override {}

         bool onIsEqual(const GrFragmentProcessor&) const override { return true; }

         static OptimizationFlags OptFlags(const GrFragmentProcessor* inner) {
             OptimizationFlags flags = kNone_OptimizationFlags;
             if (inner->preservesOpaqueInput()) {
                 flags |= kPreservesOpaqueInput_OptimizationFlag;
             }
             if (inner->hasConstantOutputForConstantInput()) {
                 flags |= kConstantOutputForConstantInput_OptimizationFlag;
             }
             return flags;
         }

         SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& input) const override {
             SkPMColor4f childColor = ConstantOutputForConstantInput(this->childProcessor(0),
                                                                     SK_PMColor4fWHITE);
             SkPMColor4f premulInput = SkColor4f{ input.fR, input.fG, input.fB, input.fA }.premul();
             return premulInput * childColor;
         }

         using INHERITED = GrFragmentProcessor;
     };
     if (!fp) {
         return nullptr;
     }
     return PremulFragmentProcessor::Make(std::move(fp));
 }

 //////////////////////////////////////////////////////////////////////////////

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(
         std::unique_ptr<GrFragmentProcessor> fp, const SkPMColor4f& color, bool useUniform) {
     if (!fp) {
         return nullptr;
     }
     return GrOverrideInputFragmentProcessor::Make(std::move(fp), color, useUniform);
 }

 //////////////////////////////////////////////////////////////////////////////

 std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::Compose(
         std::unique_ptr<GrFragmentProcessor> f, std::unique_ptr<GrFragmentProcessor> g) {
     class ComposeProcessor : public GrFragmentProcessor {
     public:
         static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> f,
                                                          std::unique_ptr<GrFragmentProcessor> g) {
             return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(std::move(f),
                                                                              std::move(g)));
         }

         const char* name() const override { return "Compose"; }

         std::unique_ptr<GrFragmentProcessor> clone() const override {
             return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(*this));
         }

     private:
         GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
             class GLFP : public GrGLSLFragmentProcessor {
             public:
                 void emitCode(EmitArgs& args) override {
                     SkString result = this->invokeChild(0, args);
                     result = this->invokeChild(1, result.c_str(), args);
                     args.fFragBuilder->codeAppendf("return %s;", result.c_str());
                 }
             };
             return new GLFP;
         }

         ComposeProcessor(std::unique_ptr<GrFragmentProcessor> f,
                          std::unique_ptr<GrFragmentProcessor> g)
                 : INHERITED(kSeriesFragmentProcessor_ClassID,
                             f->optimizationFlags() & g->optimizationFlags()) {
             this->registerChild(std::move(f));
             this->registerChild(std::move(g));
         }

         ComposeProcessor(const ComposeProcessor& that)
                 : INHERITED(kSeriesFragmentProcessor_ClassID, that.optimizationFlags()) {
             this->cloneAndRegisterAllChildProcessors(that);
         }

         void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override {}

         bool onIsEqual(const GrFragmentProcessor&) const override { return true; }

         SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& inColor) const override {
             SkPMColor4f color = inColor;
             color = ConstantOutputForConstantInput(this->childProcessor(0), color);
             color = ConstantOutputForConstantInput(this->childProcessor(1), color);
             return color;
         }

         using INHERITED = GrFragmentProcessor;
     };

     // Allow either of the composed functions to be null.
     if (f == nullptr) {
         return g;
     }
     if (g == nullptr) {
         return f;
     }

     // Run an optimization pass on this composition.
     GrProcessorAnalysisColor inputColor;
     inputColor.setToUnknown();

     std::unique_ptr<GrFragmentProcessor> series[2] = {std::move(f), std::move(g)};
     GrColorFragmentProcessorAnalysis info(inputColor, series, SK_ARRAY_COUNT(series));

     SkPMColor4f knownColor;
     int leadingFPsToEliminate = info.initialProcessorsToEliminate(&knownColor);
     switch (leadingFPsToEliminate) {
         default:
             // We shouldn't eliminate more than we started with.
             SkASSERT(leadingFPsToEliminate <= 2);
             [[fallthrough]];
         case 0:
             // Compose the two processors as requested.
             return ComposeProcessor::Make(std::move(series[0]), std::move(series[1]));
         case 1:
             // Replace the first processor with a constant color.
             return ComposeProcessor::Make(GrConstColorProcessor::Make(knownColor),
                                           std::move(series[1]));
         case 2:
             // Replace the entire composition with a constant color.
             return GrConstColorProcessor::Make(knownColor);
     }
 }

 //////////////////////////////////////////////////////////////////////////////

 GrFragmentProcessor::CIter::CIter(const GrPaint& paint) {
     if (paint.hasCoverageFragmentProcessor()) {
         fFPStack.push_back(paint.getCoverageFragmentProcessor());
     }
     if (paint.hasColorFragmentProcessor()) {
         fFPStack.push_back(paint.getColorFragmentProcessor());
     }
 }

 GrFragmentProcessor::CIter::CIter(const GrPipeline& pipeline) {
     for (int i = pipeline.numFragmentProcessors() - 1; i >= 0; --i) {
         fFPStack.push_back(&pipeline.getFragmentProcessor(i));
     }
 }

 GrFragmentProcessor::CIter& GrFragmentProcessor::CIter::operator++() {
     SkASSERT(!fFPStack.empty());
     const GrFragmentProcessor* back = fFPStack.back();
     fFPStack.pop_back();
     for (int i = back->numChildProcessors() - 1; i >= 0; --i) {
         if (auto child = back->childProcessor(i)) {
             fFPStack.push_back(child);
         }
     }
     return *this;
 }
	/*
	* 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 "src/gpu/GrFragmentProcessor.h"
	#include "src/gpu/GrPipeline.h"
	#include "src/gpu/GrProcessorAnalysis.h"
	#include "src/gpu/effects/GrBlendFragmentProcessor.h"
	#include "src/gpu/effects/generated/GrClampFragmentProcessor.h"
	#include "src/gpu/effects/generated/GrConstColorProcessor.h"
	#include "src/gpu/effects/generated/GrOverrideInputFragmentProcessor.h"
	#include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
	#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
	#include "src/gpu/glsl/GrGLSLProgramDataManager.h"
	#include "src/gpu/glsl/GrGLSLUniformHandler.h"

	bool GrFragmentProcessor::isEqual(const GrFragmentProcessor& that) const {
	if (this->classID() != that.classID()) {
	return false;
	}
	if (this->usesVaryingCoordsDirectly() != that.usesVaryingCoordsDirectly()) {
	return false;
	}
	if (!this->onIsEqual(that)) {
	return false;
	}
	if (this->numChildProcessors() != that.numChildProcessors()) {
	return false;
	}
	for (int i = 0; i < this->numChildProcessors(); ++i) {
	auto thisChild = this->childProcessor(i),
	thatChild = that .childProcessor(i);
	if (SkToBool(thisChild) != SkToBool(thatChild)) {
	return false;
	}
	if (thisChild && !thisChild->isEqual(*thatChild)) {
	return false;
	}
	}
	return true;
	}

	void GrFragmentProcessor::visitProxies(const GrOp::VisitProxyFunc& func) const {
	this->visitTextureEffects([&func](const GrTextureEffect& te) {
	func(te.view().proxy(), te.samplerState().mipmapped());
	});
	}

	void GrFragmentProcessor::visitTextureEffects(
	const std::function<void(const GrTextureEffect&)>& func) const {
	if (auto* te = this->asTextureEffect()) {
	func(*te);
	}
	for (auto& child : fChildProcessors) {
	if (child) {
	child->visitTextureEffects(func);
	}
	}
	}

	GrTextureEffect* GrFragmentProcessor::asTextureEffect() {
	if (this->classID() == kGrTextureEffect_ClassID) {
	return static_cast<GrTextureEffect*>(this);
	}
	return nullptr;
	}

	const GrTextureEffect* GrFragmentProcessor::asTextureEffect() const {
	if (this->classID() == kGrTextureEffect_ClassID) {
	return static_cast<const GrTextureEffect*>(this);
	}
	return nullptr;
	}

	#if GR_TEST_UTILS
	static void recursive_dump_tree_info(const GrFragmentProcessor& fp,
	SkString indent,
	SkString* text) {
	for (int index = 0; index < fp.numChildProcessors(); ++index) {
	text->appendf("\n%s(#%d) -> ", indent.c_str(), index);
	if (const GrFragmentProcessor* childFP = fp.childProcessor(index)) {
	text->append(childFP->dumpInfo());
	indent.append("\t");
	recursive_dump_tree_info(*childFP, indent, text);
	} else {
	text->append("null");
	}
	}
	}

	SkString GrFragmentProcessor::dumpTreeInfo() const {
	SkString text = this->dumpInfo();
	recursive_dump_tree_info(*this, SkString("\t"), &text);
	text.append("\n");
	return text;
	}
	#endif

	GrGLSLFragmentProcessor* GrFragmentProcessor::createGLSLInstance() const {
	GrGLSLFragmentProcessor* glFragProc = this->onCreateGLSLInstance();
	glFragProc->fChildProcessors.push_back_n(fChildProcessors.count());
	for (int i = 0; i < fChildProcessors.count(); ++i) {
	glFragProc->fChildProcessors[i] =
	fChildProcessors[i] ? fChildProcessors[i]->createGLSLInstance() : nullptr;
	}
	return glFragProc;
	}

	void GrFragmentProcessor::addAndPushFlagToChildren(PrivateFlags flag) {
	// This propagates down, so if we've already marked it, all our children should have it too
	if (!(fFlags & flag)) {
	fFlags \|= flag;
	for (auto& child : fChildProcessors) {
	if (child) {
	child->addAndPushFlagToChildren(flag);
	}
	}
	}
	#ifdef SK_DEBUG
	for (auto& child : fChildProcessors) {
	SkASSERT(!child \|\| (child->fFlags & flag));
	}
	#endif
	}

	int GrFragmentProcessor::numNonNullChildProcessors() const {
	return std::count_if(fChildProcessors.begin(), fChildProcessors.end(),
	[](const auto& c) { return c != nullptr; });
	}

	#ifdef SK_DEBUG
	bool GrFragmentProcessor::isInstantiated() const {
	bool result = true;
	this->visitTextureEffects([&result](const GrTextureEffect& te) {
	if (!te.texture()) {
	result = false;
	}
	});
	return result;
	}
	#endif

	void GrFragmentProcessor::registerChild(std::unique_ptr<GrFragmentProcessor> child,
	SkSL::SampleUsage sampleUsage) {
	if (!child) {
	fChildProcessors.push_back(nullptr);
	return;
	}

	// The child should not have been attached to another FP already and not had any sampling
	// strategy set on it.
	SkASSERT(!child->fParent && !child->sampleUsage().isSampled() &&
	!child->isSampledWithExplicitCoords() && !child->hasPerspectiveTransform());

	// If a child is sampled directly (sample(child)), and with a single uniform matrix, we need to
	// treat it as if it were sampled with multiple matrices (eg variable).
	bool variableMatrix = sampleUsage.hasVariableMatrix() \|\|
	(sampleUsage.fPassThrough && sampleUsage.hasUniformMatrix());

	// Configure child's sampling state first
	child->fUsage = sampleUsage;

	// When an FP is sampled using variable matrix expressions, it is effectively being sampled
	// explicitly, except that the call site will automatically evaluate the matrix expression to
	// produce the float2 passed into this FP.
	if (sampleUsage.fExplicitCoords \|\| variableMatrix) {
	child->addAndPushFlagToChildren(kSampledWithExplicitCoords_Flag);
	}

	// Push perspective matrix type to children
	if (sampleUsage.fHasPerspective) {
	child->addAndPushFlagToChildren(kNetTransformHasPerspective_Flag);
	}

	// If the child is sampled with a variable matrix expression, auto-generated code in
	// invokeChildWithMatrix() for this FP will refer to the local coordinates.
	if (variableMatrix) {
	this->setUsesSampleCoordsDirectly();
	}

	// If the child is not sampled explicitly and not already accessing sample coords directly
	// (through reference or variable matrix expansion), then mark that this FP tree relies on
	// coordinates at a lower level. If the child is sampled with explicit coordinates and
	// there isn't any other direct reference to the sample coords, we halt the upwards propagation
	// because it means this FP is determining coordinates on its own.
	if (!child->isSampledWithExplicitCoords()) {
	if ((child->fFlags & kUsesSampleCoordsDirectly_Flag \|\|
	child->fFlags & kUsesSampleCoordsIndirectly_Flag)) {
	fFlags \|= kUsesSampleCoordsIndirectly_Flag;
	}
	}

	fRequestedFeatures \|= child->fRequestedFeatures;

	// Record that the child is attached to us; this FP is the source of any uniform data needed
	// to evaluate the child sample matrix.
	child->fParent = this;
	fChildProcessors.push_back(std::move(child));

	// Validate: our sample strategy comes from a parent we shouldn't have yet.
	SkASSERT(!this->isSampledWithExplicitCoords() && !this->hasPerspectiveTransform() &&
	!fUsage.isSampled() && !fParent);
	}

	void GrFragmentProcessor::cloneAndRegisterAllChildProcessors(const GrFragmentProcessor& src) {
	for (int i = 0; i < src.numChildProcessors(); ++i) {
	if (auto fp = src.childProcessor(i)) {
	this->registerChild(fp->clone(), fp->sampleUsage());
	} else {
	this->registerChild(nullptr);
	}
	}
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MulChildByInputAlpha(
	std::unique_ptr<GrFragmentProcessor> fp) {
	if (!fp) {
	return nullptr;
	}
	return GrBlendFragmentProcessor::Make(/src=/nullptr, std::move(fp), SkBlendMode::kDstIn);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MulInputByChildAlpha(
	std::unique_ptr<GrFragmentProcessor> fp) {
	if (!fp) {
	return nullptr;
	}
	return GrBlendFragmentProcessor::Make(/src=/nullptr, std::move(fp), SkBlendMode::kSrcIn);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ModulateAlpha(
	std::unique_ptr<GrFragmentProcessor> inputFP, const SkPMColor4f& color) {
	auto colorFP = GrConstColorProcessor::Make(color);
	return GrBlendFragmentProcessor::Make(
	std::move(colorFP), std::move(inputFP), SkBlendMode::kSrcIn,
	GrBlendFragmentProcessor::BlendBehavior::kSkModeBehavior);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ModulateRGBA(
	std::unique_ptr<GrFragmentProcessor> inputFP, const SkPMColor4f& color) {
	auto colorFP = GrConstColorProcessor::Make(color);
	return GrBlendFragmentProcessor::Make(
	std::move(colorFP), std::move(inputFP), SkBlendMode::kModulate,
	GrBlendFragmentProcessor::BlendBehavior::kSkModeBehavior);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::ClampPremulOutput(
	std::unique_ptr<GrFragmentProcessor> fp) {
	if (!fp) {
	return nullptr;
	}
	return GrClampFragmentProcessor::Make(std::move(fp), /clampToPremul=/true);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::SwizzleOutput(
	std::unique_ptr<GrFragmentProcessor> fp, const GrSwizzle& swizzle) {
	class SwizzleFragmentProcessor : public GrFragmentProcessor {
	public:
	static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> fp,
	const GrSwizzle& swizzle) {
	return std::unique_ptr<GrFragmentProcessor>(
	new SwizzleFragmentProcessor(std::move(fp), swizzle));
	}

	const char* name() const override { return "Swizzle"; }
	const GrSwizzle& swizzle() const { return fSwizzle; }

	std::unique_ptr<GrFragmentProcessor> clone() const override {
	return Make(this->childProcessor(0)->clone(), fSwizzle);
	}

	private:
	SwizzleFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp, const GrSwizzle& swizzle)
	: INHERITED(kSwizzleFragmentProcessor_ClassID, ProcessorOptimizationFlags(fp.get()))
	, fSwizzle(swizzle) {
	this->registerChild(std::move(fp));
	}

	GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
	class GLFP : public GrGLSLFragmentProcessor {
	public:
	void emitCode(EmitArgs& args) override {
	SkString childColor = this->invokeChild(0, args);

	const SwizzleFragmentProcessor& sfp = args.fFp.cast<SwizzleFragmentProcessor>();
	const GrSwizzle& swizzle = sfp.swizzle();
	GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;

	fragBuilder->codeAppendf("return %s.%s;",
	childColor.c_str(), swizzle.asString().c_str());
	}
	};
	return new GLFP;
	}

	void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder* b) const override {
	b->add32(fSwizzle.asKey());
	}

	bool onIsEqual(const GrFragmentProcessor& other) const override {
	const SwizzleFragmentProcessor& sfp = other.cast<SwizzleFragmentProcessor>();
	return fSwizzle == sfp.fSwizzle;
	}

	SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& input) const override {
	return fSwizzle.applyTo(input);
	}

	GrSwizzle fSwizzle;

	using INHERITED = GrFragmentProcessor;
	};

	if (!fp) {
	return nullptr;
	}
	if (GrSwizzle::RGBA() == swizzle) {
	return fp;
	}
	return SwizzleFragmentProcessor::Make(std::move(fp), swizzle);
	}

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::MakeInputPremulAndMulByOutput(
	std::unique_ptr<GrFragmentProcessor> fp) {
	class PremulFragmentProcessor : public GrFragmentProcessor {
	public:
	static std::unique_ptr<GrFragmentProcessor> Make(
	std::unique_ptr<GrFragmentProcessor> processor) {
	return std::unique_ptr<GrFragmentProcessor>(
	new PremulFragmentProcessor(std::move(processor)));
	}

	const char* name() const override { return "Premultiply"; }

	std::unique_ptr<GrFragmentProcessor> clone() const override {
	return Make(this->childProcessor(0)->clone());
	}

	private:
	PremulFragmentProcessor(std::unique_ptr<GrFragmentProcessor> processor)
	: INHERITED(kPremulFragmentProcessor_ClassID, OptFlags(processor.get())) {
	this->registerChild(std::move(processor));
	}

	GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
	class GLFP : public GrGLSLFragmentProcessor {
	public:
	void emitCode(EmitArgs& args) override {
	GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
	SkString temp = this->invokeChild(/childIndex=/0, "half4(1)", args);
	fragBuilder->codeAppendf("half4 color = %s;", temp.c_str());
	fragBuilder->codeAppendf("color.rgb *= %s.rgb;", args.fInputColor);
	fragBuilder->codeAppendf("return color * %s.a;", args.fInputColor);
	}
	};
	return new GLFP;
	}

	void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override {}

	bool onIsEqual(const GrFragmentProcessor&) const override { return true; }

	static OptimizationFlags OptFlags(const GrFragmentProcessor* inner) {
	OptimizationFlags flags = kNone_OptimizationFlags;
	if (inner->preservesOpaqueInput()) {
	flags \|= kPreservesOpaqueInput_OptimizationFlag;
	}
	if (inner->hasConstantOutputForConstantInput()) {
	flags \|= kConstantOutputForConstantInput_OptimizationFlag;
	}
	return flags;
	}

	SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& input) const override {
	SkPMColor4f childColor = ConstantOutputForConstantInput(this->childProcessor(0),
	SK_PMColor4fWHITE);
	SkPMColor4f premulInput = SkColor4f{ input.fR, input.fG, input.fB, input.fA }.premul();
	return premulInput * childColor;
	}

	using INHERITED = GrFragmentProcessor;
	};
	if (!fp) {
	return nullptr;
	}
	return PremulFragmentProcessor::Make(std::move(fp));
	}

	//////////////////////////////////////////////////////////////////////////////

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(
	std::unique_ptr<GrFragmentProcessor> fp, const SkPMColor4f& color, bool useUniform) {
	if (!fp) {
	return nullptr;
	}
	return GrOverrideInputFragmentProcessor::Make(std::move(fp), color, useUniform);
	}

	//////////////////////////////////////////////////////////////////////////////

	std::unique_ptr<GrFragmentProcessor> GrFragmentProcessor::Compose(
	std::unique_ptr<GrFragmentProcessor> f, std::unique_ptr<GrFragmentProcessor> g) {
	class ComposeProcessor : public GrFragmentProcessor {
	public:
	static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> f,
	std::unique_ptr<GrFragmentProcessor> g) {
	return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(std::move(f),
	std::move(g)));
	}

	const char* name() const override { return "Compose"; }

	std::unique_ptr<GrFragmentProcessor> clone() const override {
	return std::unique_ptr<GrFragmentProcessor>(new ComposeProcessor(*this));
	}

	private:
	GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
	class GLFP : public GrGLSLFragmentProcessor {
	public:
	void emitCode(EmitArgs& args) override {
	SkString result = this->invokeChild(0, args);
	result = this->invokeChild(1, result.c_str(), args);
	args.fFragBuilder->codeAppendf("return %s;", result.c_str());
	}
	};
	return new GLFP;
	}

	ComposeProcessor(std::unique_ptr<GrFragmentProcessor> f,
	std::unique_ptr<GrFragmentProcessor> g)
	: INHERITED(kSeriesFragmentProcessor_ClassID,
	f->optimizationFlags() & g->optimizationFlags()) {
	this->registerChild(std::move(f));
	this->registerChild(std::move(g));
	}

	ComposeProcessor(const ComposeProcessor& that)
	: INHERITED(kSeriesFragmentProcessor_ClassID, that.optimizationFlags()) {
	this->cloneAndRegisterAllChildProcessors(that);
	}

	void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override {}

	bool onIsEqual(const GrFragmentProcessor&) const override { return true; }

	SkPMColor4f constantOutputForConstantInput(const SkPMColor4f& inColor) const override {
	SkPMColor4f color = inColor;
	color = ConstantOutputForConstantInput(this->childProcessor(0), color);
	color = ConstantOutputForConstantInput(this->childProcessor(1), color);
	return color;
	}

	using INHERITED = GrFragmentProcessor;
	};

	// Allow either of the composed functions to be null.
	if (f == nullptr) {
	return g;
	}
	if (g == nullptr) {
	return f;
	}

	// Run an optimization pass on this composition.
	GrProcessorAnalysisColor inputColor;
	inputColor.setToUnknown();

	std::unique_ptr<GrFragmentProcessor> series[2] = {std::move(f), std::move(g)};
	GrColorFragmentProcessorAnalysis info(inputColor, series, SK_ARRAY_COUNT(series));

	SkPMColor4f knownColor;
	int leadingFPsToEliminate = info.initialProcessorsToEliminate(&knownColor);
	switch (leadingFPsToEliminate) {
	default:
	// We shouldn't eliminate more than we started with.
	SkASSERT(leadingFPsToEliminate <= 2);
	[[fallthrough]];
	case 0:
	// Compose the two processors as requested.
	return ComposeProcessor::Make(std::move(series[0]), std::move(series[1]));
	case 1:
	// Replace the first processor with a constant color.
	return ComposeProcessor::Make(GrConstColorProcessor::Make(knownColor),
	std::move(series[1]));
	case 2:
	// Replace the entire composition with a constant color.
	return GrConstColorProcessor::Make(knownColor);
	}
	}

	//////////////////////////////////////////////////////////////////////////////

	GrFragmentProcessor::CIter::CIter(const GrPaint& paint) {
	if (paint.hasCoverageFragmentProcessor()) {
	fFPStack.push_back(paint.getCoverageFragmentProcessor());
	}
	if (paint.hasColorFragmentProcessor()) {
	fFPStack.push_back(paint.getColorFragmentProcessor());
	}
	}

	GrFragmentProcessor::CIter::CIter(const GrPipeline& pipeline) {
	for (int i = pipeline.numFragmentProcessors() - 1; i >= 0; --i) {
	fFPStack.push_back(&pipeline.getFragmentProcessor(i));
	}
	}

	GrFragmentProcessor::CIter& GrFragmentProcessor::CIter::operator++() {
	SkASSERT(!fFPStack.empty());
	const GrFragmentProcessor* back = fFPStack.back();
	fFPStack.pop_back();
	for (int i = back->numChildProcessors() - 1; i >= 0; --i) {
	if (auto child = back->childProcessor(i)) {
	fFPStack.push_back(child);
	}
	}
	return *this;
	}