src/third_party/skia/src/effects/SkHighContrastFilter.cpp - cobalt - Git at Google

 /*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

 #include "SkHighContrastFilter.h"
 #include "SkPM4f.h"
 #include "SkArenaAlloc.h"
 #include "SkRasterPipeline.h"
 #include "SkReadBuffer.h"
 #include "SkString.h"
 #include "SkWriteBuffer.h"
 #include "../jumper/SkJumper.h"

 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "glsl/GrGLSLFragmentProcessor.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #endif

 using InvertStyle = SkHighContrastConfig::InvertStyle;

 class SkHighContrast_Filter : public SkColorFilter {
 public:
     SkHighContrast_Filter(const SkHighContrastConfig& config) {
         fConfig = config;
         // Clamp contrast to just inside -1 to 1 to avoid division by zero.
         fConfig.fContrast = SkScalarPin(fConfig.fContrast,
                                         -1.0f + FLT_EPSILON,
                                         1.0f - FLT_EPSILON);
     }

     ~SkHighContrast_Filter() override {}

 #if SK_SUPPORT_GPU
     sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*, SkColorSpace*) const override;
  #endif

     void onAppendStages(SkRasterPipeline* p,
                         SkColorSpace* dst,
                         SkArenaAlloc* scratch,
                         bool shaderIsOpaque) const override;

     SK_TO_STRING_OVERRIDE()

     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkHighContrast_Filter)

 protected:
     void flatten(SkWriteBuffer&) const override;

 private:
     SkHighContrastConfig fConfig;

     friend class SkHighContrastFilter;

     typedef SkColorFilter INHERITED;
 };

 void SkHighContrast_Filter::onAppendStages(SkRasterPipeline* p,
                                            SkColorSpace* dstCS,
                                            SkArenaAlloc* alloc,
                                            bool shaderIsOpaque) const {
     if (!shaderIsOpaque) {
         p->append(SkRasterPipeline::unpremul);
     }

     if (!dstCS) {
         // In legacy draws this effect approximately linearizes by squaring.
         // When non-legacy, we're already (better) linearized.
         auto square = alloc->make<SkJumper_ParametricTransferFunction>();
         square->G = 2.0f; square->A = 1.0f;
         square->B = square->C = square->D = square->E = square->F = 0;

         p->append(SkRasterPipeline::parametric_r, square);
         p->append(SkRasterPipeline::parametric_g, square);
         p->append(SkRasterPipeline::parametric_b, square);
     }

     if (fConfig.fGrayscale) {
         float r = SK_LUM_COEFF_R;
         float g = SK_LUM_COEFF_G;
         float b = SK_LUM_COEFF_B;
         float* matrix = alloc->makeArray<float>(12);
         matrix[0] = matrix[1] = matrix[2] = r;
         matrix[3] = matrix[4] = matrix[5] = g;
         matrix[6] = matrix[7] = matrix[8] = b;
         p->append(SkRasterPipeline::matrix_3x4, matrix);
     }

     if (fConfig.fInvertStyle == InvertStyle::kInvertBrightness) {
         float* matrix = alloc->makeArray<float>(12);
         matrix[0] = matrix[4] = matrix[8] = -1;
         matrix[9] = matrix[10] = matrix[11] = 1;
         p->append(SkRasterPipeline::matrix_3x4, matrix);
     } else if (fConfig.fInvertStyle == InvertStyle::kInvertLightness) {
         p->append(SkRasterPipeline::rgb_to_hsl);
         float* matrix = alloc->makeArray<float>(12);
         matrix[0] = matrix[4] = matrix[11] = 1;
         matrix[8] = -1;
         p->append(SkRasterPipeline::matrix_3x4, matrix);
         p->append(SkRasterPipeline::hsl_to_rgb);
     }

     if (fConfig.fContrast != 0.0) {
         float* matrix = alloc->makeArray<float>(12);
         float c = fConfig.fContrast;
         float m = (1 + c) / (1 - c);
         float b = (-0.5f * m + 0.5f);
         matrix[0] = matrix[4] = matrix[8] = m;
         matrix[9] = matrix[10] = matrix[11] = b;
         p->append(SkRasterPipeline::matrix_3x4, matrix);
     }

     p->append(SkRasterPipeline::clamp_0);
     p->append(SkRasterPipeline::clamp_1);

     if (!dstCS) {
         // See the previous if(!dstCS) { ... }
         auto sqrt = alloc->make<SkJumper_ParametricTransferFunction>();
         sqrt->G = 0.5f; sqrt->A = 1.0f;
         sqrt->B = sqrt->C = sqrt->D = sqrt->E = sqrt->F = 0;

         p->append(SkRasterPipeline::parametric_r, sqrt);
         p->append(SkRasterPipeline::parametric_g, sqrt);
         p->append(SkRasterPipeline::parametric_b, sqrt);
     }

     if (!shaderIsOpaque) {
         p->append(SkRasterPipeline::premul);
     }
 }

 void SkHighContrast_Filter::flatten(SkWriteBuffer& buffer) const {
     buffer.writeBool(fConfig.fGrayscale);
     buffer.writeInt(static_cast<int>(fConfig.fInvertStyle));
     buffer.writeScalar(fConfig.fContrast);
 }

 sk_sp<SkFlattenable> SkHighContrast_Filter::CreateProc(SkReadBuffer& buffer) {
     SkHighContrastConfig config;
     config.fGrayscale = buffer.readBool();
     config.fInvertStyle = static_cast<InvertStyle>(buffer.readInt());
     config.fContrast = buffer.readScalar();
     return SkHighContrastFilter::Make(config);
 }

 sk_sp<SkColorFilter> SkHighContrastFilter::Make(
     const SkHighContrastConfig& config) {
     if (!config.isValid())
         return nullptr;
     return sk_make_sp<SkHighContrast_Filter>(config);
 }

 #ifndef SK_IGNORE_TO_STRING
 void SkHighContrast_Filter::toString(SkString* str) const {
     str->append("SkHighContrastColorFilter ");
 }
 #endif

 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkHighContrastFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkHighContrast_Filter)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END

 #if SK_SUPPORT_GPU
 class HighContrastFilterEffect : public GrFragmentProcessor {
 public:
     static sk_sp<GrFragmentProcessor> Make(const SkHighContrastConfig& config) {
         return sk_sp<GrFragmentProcessor>(new HighContrastFilterEffect(config));
     }

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

     const SkHighContrastConfig& config() const { return fConfig; }

 private:
     HighContrastFilterEffect(const SkHighContrastConfig& config)
         : INHERITED(kNone_OptimizationFlags)
         , fConfig(config) {
         this->initClassID<HighContrastFilterEffect>();
     }

     GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;

     virtual void onGetGLSLProcessorKey(const GrShaderCaps& caps,
                                        GrProcessorKeyBuilder* b) const override;

     bool onIsEqual(const GrFragmentProcessor& other) const override {
         const HighContrastFilterEffect& that = other.cast<HighContrastFilterEffect>();
         return fConfig.fGrayscale == that.fConfig.fGrayscale &&
             fConfig.fInvertStyle == that.fConfig.fInvertStyle &&
             fConfig.fContrast == that.fConfig.fContrast;
     }

     SkHighContrastConfig fConfig;

     typedef GrFragmentProcessor INHERITED;
 };

 class GLHighContrastFilterEffect : public GrGLSLFragmentProcessor {
 public:
     static void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder*);

     GLHighContrastFilterEffect(const SkHighContrastConfig& config);

 protected:
     void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
     void emitCode(EmitArgs& args) override;

 private:
     UniformHandle fContrastUni;
     SkHighContrastConfig fConfig;

     typedef GrGLSLFragmentProcessor INHERITED;
 };

 GrGLSLFragmentProcessor* HighContrastFilterEffect::onCreateGLSLInstance() const {
     return new GLHighContrastFilterEffect(fConfig);
 }

 void HighContrastFilterEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
                                                      GrProcessorKeyBuilder* b) const {
     GLHighContrastFilterEffect::GenKey(*this, caps, b);
 }

 void GLHighContrastFilterEffect::onSetData(const GrGLSLProgramDataManager& pdm,
                                            const GrFragmentProcessor& proc) {
     const HighContrastFilterEffect& hcfe = proc.cast<HighContrastFilterEffect>();
     pdm.set1f(fContrastUni, hcfe.config().fContrast);
 }

 GLHighContrastFilterEffect::GLHighContrastFilterEffect(const SkHighContrastConfig& config)
     : INHERITED()
     , fConfig(config) {
 }

 void GLHighContrastFilterEffect::GenKey(
     const GrProcessor& proc, const GrShaderCaps&, GrProcessorKeyBuilder* b) {
   const HighContrastFilterEffect& hcfe = proc.cast<HighContrastFilterEffect>();
   b->add32(static_cast<uint32_t>(hcfe.config().fGrayscale));
   b->add32(static_cast<uint32_t>(hcfe.config().fInvertStyle));
 }

 void GLHighContrastFilterEffect::emitCode(EmitArgs& args) {
     const char* contrast;
     fContrastUni = args.fUniformHandler->addUniform(kFragment_GrShaderFlag,
                                                     kFloat_GrSLType, kDefault_GrSLPrecision,
                                                     "contrast", &contrast);

     if (nullptr == args.fInputColor) {
         args.fInputColor = "vec4(1)";
     }

     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;

     fragBuilder->codeAppendf("vec4 color = %s;", args.fInputColor);

     // Unpremultiply. The max() is to guard against 0 / 0.
     fragBuilder->codeAppendf("float nonZeroAlpha = max(color.a, 0.00001);");
     fragBuilder->codeAppendf("color = vec4(color.rgb / nonZeroAlpha, nonZeroAlpha);");

     // Grayscale.
     if (fConfig.fGrayscale) {
         fragBuilder->codeAppendf("float luma = dot(color, vec4(%f, %f, %f, 0));",
                                  SK_LUM_COEFF_R, SK_LUM_COEFF_G, SK_LUM_COEFF_B);
         fragBuilder->codeAppendf("color = vec4(luma, luma, luma, 0);");
     }

     if (fConfig.fInvertStyle == InvertStyle::kInvertBrightness) {
         fragBuilder->codeAppendf("color = vec4(1, 1, 1, 1) - color;");
     }

     if (fConfig.fInvertStyle == InvertStyle::kInvertLightness) {
         // Convert from RGB to HSL.
         fragBuilder->codeAppendf("float fmax = max(color.r, max(color.g, color.b));");
         fragBuilder->codeAppendf("float fmin = min(color.r, min(color.g, color.b));");
         fragBuilder->codeAppendf("float l = (fmax + fmin) / 2;");

         fragBuilder->codeAppendf("float h;");
         fragBuilder->codeAppendf("float s;");

         fragBuilder->codeAppendf("if (fmax == fmin) {");
         fragBuilder->codeAppendf("  h = 0;");
         fragBuilder->codeAppendf("  s = 0;");
         fragBuilder->codeAppendf("} else {");
         fragBuilder->codeAppendf("  float d = fmax - fmin;");
         fragBuilder->codeAppendf("  s = l > 0.5 ?");
         fragBuilder->codeAppendf("      d / (2 - fmax - fmin) :");
         fragBuilder->codeAppendf("      d / (fmax + fmin);");
         fragBuilder->codeAppendf("  if (fmax == color.r) {");
         fragBuilder->codeAppendf("    h = (color.g - color.b) / d + ");
         fragBuilder->codeAppendf("        (color.g < color.b ? 6 : 0);");
         fragBuilder->codeAppendf("  } else if (fmax == color.g) {");
         fragBuilder->codeAppendf("    h = (color.b - color.r) / d + 2;");
         fragBuilder->codeAppendf("  } else {");
         fragBuilder->codeAppendf("    h = (color.r - color.g) / d + 4;");
         fragBuilder->codeAppendf("  }");
         fragBuilder->codeAppendf("}");
         fragBuilder->codeAppendf("h /= 6;");
         fragBuilder->codeAppendf("l = 1.0 - l;");
         // Convert back from HSL to RGB.
         SkString hue2rgbFuncName;
         static const GrShaderVar gHue2rgbArgs[] = {
             GrShaderVar("p", kFloat_GrSLType),
             GrShaderVar("q", kFloat_GrSLType),
             GrShaderVar("t", kFloat_GrSLType),
         };
         fragBuilder->emitFunction(kFloat_GrSLType,
                                   "hue2rgb",
                                   SK_ARRAY_COUNT(gHue2rgbArgs),
                                   gHue2rgbArgs,
                                   "if (t < 0)"
                                   "  t += 1;"
                                   "if (t > 1)"
                                   "  t -= 1;"
                                   "if (t < 1/6.)"
                                   "  return p + (q - p) * 6 * t;"
                                   "if (t < 1/2.)"
                                   "  return q;"
                                   "if (t < 2/3.)"
                                   "  return p + (q - p) * (2/3. - t) * 6;"
                                   "return p;",
                                   &hue2rgbFuncName);
         fragBuilder->codeAppendf("if (s == 0) {");
         fragBuilder->codeAppendf("  color = vec4(l, l, l, 0);");
         fragBuilder->codeAppendf("} else {");
         fragBuilder->codeAppendf("  float q = l < 0.5 ? l * (1 + s) : l + s - l * s;");
         fragBuilder->codeAppendf("  float p = 2 * l - q;");
         fragBuilder->codeAppendf("  color.r = %s(p, q, h + 1/3.);", hue2rgbFuncName.c_str());
         fragBuilder->codeAppendf("  color.g = %s(p, q, h);", hue2rgbFuncName.c_str());
         fragBuilder->codeAppendf("  color.b = %s(p, q, h - 1/3.);", hue2rgbFuncName.c_str());
         fragBuilder->codeAppendf("}");
     }

     // Contrast.
     fragBuilder->codeAppendf("if (%s != 0) {", contrast);
     fragBuilder->codeAppendf("  float m = (1 + %s) / (1 - %s);", contrast, contrast);
     fragBuilder->codeAppendf("  float off = (-0.5 * m + 0.5);");
     fragBuilder->codeAppendf("  color = m * color + off;");
     fragBuilder->codeAppendf("}");

     // Clamp.
     fragBuilder->codeAppendf("color = clamp(color, 0, 1);");

     // Restore the original alpha and premultiply.
     fragBuilder->codeAppendf("color.a = %s.a;", args.fInputColor);
     fragBuilder->codeAppendf("color.rgb *= color.a;");

     // Copy to the output color.
     fragBuilder->codeAppendf("%s = color;", args.fOutputColor);
 }

 sk_sp<GrFragmentProcessor> SkHighContrast_Filter::asFragmentProcessor(GrContext*, SkColorSpace*) const {
     return HighContrastFilterEffect::Make(fConfig);
 }
 #endif
	/*
	* Copyright 2017 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "SkHighContrastFilter.h"
	#include "SkPM4f.h"
	#include "SkArenaAlloc.h"
	#include "SkRasterPipeline.h"
	#include "SkReadBuffer.h"
	#include "SkString.h"
	#include "SkWriteBuffer.h"
	#include "../jumper/SkJumper.h"

	#if SK_SUPPORT_GPU
	#include "GrContext.h"
	#include "glsl/GrGLSLFragmentProcessor.h"
	#include "glsl/GrGLSLFragmentShaderBuilder.h"
	#endif

	using InvertStyle = SkHighContrastConfig::InvertStyle;

	class SkHighContrast_Filter : public SkColorFilter {
	public:
	SkHighContrast_Filter(const SkHighContrastConfig& config) {
	fConfig = config;
	// Clamp contrast to just inside -1 to 1 to avoid division by zero.
	fConfig.fContrast = SkScalarPin(fConfig.fContrast,
	-1.0f + FLT_EPSILON,
	1.0f - FLT_EPSILON);
	}

	~SkHighContrast_Filter() override {}

	#if SK_SUPPORT_GPU
	sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext, SkColorSpace) const override;
	#endif

	void onAppendStages(SkRasterPipeline* p,
	SkColorSpace* dst,
	SkArenaAlloc* scratch,
	bool shaderIsOpaque) const override;

	SK_TO_STRING_OVERRIDE()

	SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkHighContrast_Filter)

	protected:
	void flatten(SkWriteBuffer&) const override;

	private:
	SkHighContrastConfig fConfig;

	friend class SkHighContrastFilter;

	typedef SkColorFilter INHERITED;
	};

	void SkHighContrast_Filter::onAppendStages(SkRasterPipeline* p,
	SkColorSpace* dstCS,
	SkArenaAlloc* alloc,
	bool shaderIsOpaque) const {
	if (!shaderIsOpaque) {
	p->append(SkRasterPipeline::unpremul);
	}

	if (!dstCS) {
	// In legacy draws this effect approximately linearizes by squaring.
	// When non-legacy, we're already (better) linearized.
	auto square = alloc->make<SkJumper_ParametricTransferFunction>();
	square->G = 2.0f; square->A = 1.0f;
	square->B = square->C = square->D = square->E = square->F = 0;

	p->append(SkRasterPipeline::parametric_r, square);
	p->append(SkRasterPipeline::parametric_g, square);
	p->append(SkRasterPipeline::parametric_b, square);
	}

	if (fConfig.fGrayscale) {
	float r = SK_LUM_COEFF_R;
	float g = SK_LUM_COEFF_G;
	float b = SK_LUM_COEFF_B;
	float* matrix = alloc->makeArray<float>(12);
	matrix[0] = matrix[1] = matrix[2] = r;
	matrix[3] = matrix[4] = matrix[5] = g;
	matrix[6] = matrix[7] = matrix[8] = b;
	p->append(SkRasterPipeline::matrix_3x4, matrix);
	}

	if (fConfig.fInvertStyle == InvertStyle::kInvertBrightness) {
	float* matrix = alloc->makeArray<float>(12);
	matrix[0] = matrix[4] = matrix[8] = -1;
	matrix[9] = matrix[10] = matrix[11] = 1;
	p->append(SkRasterPipeline::matrix_3x4, matrix);
	} else if (fConfig.fInvertStyle == InvertStyle::kInvertLightness) {
	p->append(SkRasterPipeline::rgb_to_hsl);
	float* matrix = alloc->makeArray<float>(12);
	matrix[0] = matrix[4] = matrix[11] = 1;
	matrix[8] = -1;
	p->append(SkRasterPipeline::matrix_3x4, matrix);
	p->append(SkRasterPipeline::hsl_to_rgb);
	}

	if (fConfig.fContrast != 0.0) {
	float* matrix = alloc->makeArray<float>(12);
	float c = fConfig.fContrast;
	float m = (1 + c) / (1 - c);
	float b = (-0.5f * m + 0.5f);
	matrix[0] = matrix[4] = matrix[8] = m;
	matrix[9] = matrix[10] = matrix[11] = b;
	p->append(SkRasterPipeline::matrix_3x4, matrix);
	}

	p->append(SkRasterPipeline::clamp_0);
	p->append(SkRasterPipeline::clamp_1);

	if (!dstCS) {
	// See the previous if(!dstCS) { ... }
	auto sqrt = alloc->make<SkJumper_ParametricTransferFunction>();
	sqrt->G = 0.5f; sqrt->A = 1.0f;
	sqrt->B = sqrt->C = sqrt->D = sqrt->E = sqrt->F = 0;

	p->append(SkRasterPipeline::parametric_r, sqrt);
	p->append(SkRasterPipeline::parametric_g, sqrt);
	p->append(SkRasterPipeline::parametric_b, sqrt);
	}

	if (!shaderIsOpaque) {
	p->append(SkRasterPipeline::premul);
	}
	}

	void SkHighContrast_Filter::flatten(SkWriteBuffer& buffer) const {
	buffer.writeBool(fConfig.fGrayscale);
	buffer.writeInt(static_cast<int>(fConfig.fInvertStyle));
	buffer.writeScalar(fConfig.fContrast);
	}

	sk_sp<SkFlattenable> SkHighContrast_Filter::CreateProc(SkReadBuffer& buffer) {
	SkHighContrastConfig config;
	config.fGrayscale = buffer.readBool();
	config.fInvertStyle = static_cast<InvertStyle>(buffer.readInt());
	config.fContrast = buffer.readScalar();
	return SkHighContrastFilter::Make(config);
	}

	sk_sp<SkColorFilter> SkHighContrastFilter::Make(
	const SkHighContrastConfig& config) {
	if (!config.isValid())
	return nullptr;
	return sk_make_sp<SkHighContrast_Filter>(config);
	}

	#ifndef SK_IGNORE_TO_STRING
	void SkHighContrast_Filter::toString(SkString* str) const {
	str->append("SkHighContrastColorFilter ");
	}
	#endif

	SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkHighContrastFilter)
	SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkHighContrast_Filter)
	SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END

	#if SK_SUPPORT_GPU
	class HighContrastFilterEffect : public GrFragmentProcessor {
	public:
	static sk_sp<GrFragmentProcessor> Make(const SkHighContrastConfig& config) {
	return sk_sp<GrFragmentProcessor>(new HighContrastFilterEffect(config));
	}

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

	const SkHighContrastConfig& config() const { return fConfig; }

	private:
	HighContrastFilterEffect(const SkHighContrastConfig& config)
	: INHERITED(kNone_OptimizationFlags)
	, fConfig(config) {
	this->initClassID<HighContrastFilterEffect>();
	}

	GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;

	virtual void onGetGLSLProcessorKey(const GrShaderCaps& caps,
	GrProcessorKeyBuilder* b) const override;

	bool onIsEqual(const GrFragmentProcessor& other) const override {
	const HighContrastFilterEffect& that = other.cast<HighContrastFilterEffect>();
	return fConfig.fGrayscale == that.fConfig.fGrayscale &&
	fConfig.fInvertStyle == that.fConfig.fInvertStyle &&
	fConfig.fContrast == that.fConfig.fContrast;
	}

	SkHighContrastConfig fConfig;

	typedef GrFragmentProcessor INHERITED;
	};

	class GLHighContrastFilterEffect : public GrGLSLFragmentProcessor {
	public:
	static void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder*);

	GLHighContrastFilterEffect(const SkHighContrastConfig& config);

	protected:
	void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) override;
	void emitCode(EmitArgs& args) override;

	private:
	UniformHandle fContrastUni;
	SkHighContrastConfig fConfig;

	typedef GrGLSLFragmentProcessor INHERITED;
	};

	GrGLSLFragmentProcessor* HighContrastFilterEffect::onCreateGLSLInstance() const {
	return new GLHighContrastFilterEffect(fConfig);
	}

	void HighContrastFilterEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
	GrProcessorKeyBuilder* b) const {
	GLHighContrastFilterEffect::GenKey(*this, caps, b);
	}

	void GLHighContrastFilterEffect::onSetData(const GrGLSLProgramDataManager& pdm,
	const GrFragmentProcessor& proc) {
	const HighContrastFilterEffect& hcfe = proc.cast<HighContrastFilterEffect>();
	pdm.set1f(fContrastUni, hcfe.config().fContrast);
	}

	GLHighContrastFilterEffect::GLHighContrastFilterEffect(const SkHighContrastConfig& config)
	: INHERITED()
	, fConfig(config) {
	}

	void GLHighContrastFilterEffect::GenKey(
	const GrProcessor& proc, const GrShaderCaps&, GrProcessorKeyBuilder* b) {
	const HighContrastFilterEffect& hcfe = proc.cast<HighContrastFilterEffect>();
	b->add32(static_cast<uint32_t>(hcfe.config().fGrayscale));
	b->add32(static_cast<uint32_t>(hcfe.config().fInvertStyle));
	}

	void GLHighContrastFilterEffect::emitCode(EmitArgs& args) {
	const char* contrast;
	fContrastUni = args.fUniformHandler->addUniform(kFragment_GrShaderFlag,
	kFloat_GrSLType, kDefault_GrSLPrecision,
	"contrast", &contrast);

	if (nullptr == args.fInputColor) {
	args.fInputColor = "vec4(1)";
	}

	GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;

	fragBuilder->codeAppendf("vec4 color = %s;", args.fInputColor);

	// Unpremultiply. The max() is to guard against 0 / 0.
	fragBuilder->codeAppendf("float nonZeroAlpha = max(color.a, 0.00001);");
	fragBuilder->codeAppendf("color = vec4(color.rgb / nonZeroAlpha, nonZeroAlpha);");

	// Grayscale.
	if (fConfig.fGrayscale) {
	fragBuilder->codeAppendf("float luma = dot(color, vec4(%f, %f, %f, 0));",
	SK_LUM_COEFF_R, SK_LUM_COEFF_G, SK_LUM_COEFF_B);
	fragBuilder->codeAppendf("color = vec4(luma, luma, luma, 0);");
	}

	if (fConfig.fInvertStyle == InvertStyle::kInvertBrightness) {
	fragBuilder->codeAppendf("color = vec4(1, 1, 1, 1) - color;");
	}

	if (fConfig.fInvertStyle == InvertStyle::kInvertLightness) {
	// Convert from RGB to HSL.
	fragBuilder->codeAppendf("float fmax = max(color.r, max(color.g, color.b));");
	fragBuilder->codeAppendf("float fmin = min(color.r, min(color.g, color.b));");
	fragBuilder->codeAppendf("float l = (fmax + fmin) / 2;");

	fragBuilder->codeAppendf("float h;");
	fragBuilder->codeAppendf("float s;");

	fragBuilder->codeAppendf("if (fmax == fmin) {");
	fragBuilder->codeAppendf(" h = 0;");
	fragBuilder->codeAppendf(" s = 0;");
	fragBuilder->codeAppendf("} else {");
	fragBuilder->codeAppendf(" float d = fmax - fmin;");
	fragBuilder->codeAppendf(" s = l > 0.5 ?");
	fragBuilder->codeAppendf(" d / (2 - fmax - fmin) :");
	fragBuilder->codeAppendf(" d / (fmax + fmin);");
	fragBuilder->codeAppendf(" if (fmax == color.r) {");
	fragBuilder->codeAppendf(" h = (color.g - color.b) / d + ");
	fragBuilder->codeAppendf(" (color.g < color.b ? 6 : 0);");
	fragBuilder->codeAppendf(" } else if (fmax == color.g) {");
	fragBuilder->codeAppendf(" h = (color.b - color.r) / d + 2;");
	fragBuilder->codeAppendf(" } else {");
	fragBuilder->codeAppendf(" h = (color.r - color.g) / d + 4;");
	fragBuilder->codeAppendf(" }");
	fragBuilder->codeAppendf("}");
	fragBuilder->codeAppendf("h /= 6;");
	fragBuilder->codeAppendf("l = 1.0 - l;");
	// Convert back from HSL to RGB.
	SkString hue2rgbFuncName;
	static const GrShaderVar gHue2rgbArgs[] = {
	GrShaderVar("p", kFloat_GrSLType),
	GrShaderVar("q", kFloat_GrSLType),
	GrShaderVar("t", kFloat_GrSLType),
	};
	fragBuilder->emitFunction(kFloat_GrSLType,
	"hue2rgb",
	SK_ARRAY_COUNT(gHue2rgbArgs),
	gHue2rgbArgs,
	"if (t < 0)"
	" t += 1;"
	"if (t > 1)"
	" t -= 1;"
	"if (t < 1/6.)"
	" return p + (q - p) * 6 * t;"
	"if (t < 1/2.)"
	" return q;"
	"if (t < 2/3.)"
	" return p + (q - p) * (2/3. - t) * 6;"
	"return p;",
	&hue2rgbFuncName);
	fragBuilder->codeAppendf("if (s == 0) {");
	fragBuilder->codeAppendf(" color = vec4(l, l, l, 0);");
	fragBuilder->codeAppendf("} else {");
	fragBuilder->codeAppendf(" float q = l < 0.5 ? l * (1 + s) : l + s - l * s;");
	fragBuilder->codeAppendf(" float p = 2 * l - q;");
	fragBuilder->codeAppendf(" color.r = %s(p, q, h + 1/3.);", hue2rgbFuncName.c_str());
	fragBuilder->codeAppendf(" color.g = %s(p, q, h);", hue2rgbFuncName.c_str());
	fragBuilder->codeAppendf(" color.b = %s(p, q, h - 1/3.);", hue2rgbFuncName.c_str());
	fragBuilder->codeAppendf("}");
	}

	// Contrast.
	fragBuilder->codeAppendf("if (%s != 0) {", contrast);
	fragBuilder->codeAppendf(" float m = (1 + %s) / (1 - %s);", contrast, contrast);
	fragBuilder->codeAppendf(" float off = (-0.5 * m + 0.5);");
	fragBuilder->codeAppendf(" color = m * color + off;");
	fragBuilder->codeAppendf("}");

	// Clamp.
	fragBuilder->codeAppendf("color = clamp(color, 0, 1);");

	// Restore the original alpha and premultiply.
	fragBuilder->codeAppendf("color.a = %s.a;", args.fInputColor);
	fragBuilder->codeAppendf("color.rgb *= color.a;");

	// Copy to the output color.
	fragBuilder->codeAppendf("%s = color;", args.fOutputColor);
	}

	sk_sp<GrFragmentProcessor> SkHighContrast_Filter::asFragmentProcessor(GrContext, SkColorSpace) const {
	return HighContrastFilterEffect::Make(fConfig);
	}
	#endif