1/* 2 * Copyright 2016 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8#include "GrSRGBEffect.h" 9 10#include "GrFragmentProcessor.h" 11#include "GrProcessor.h" 12#include "glsl/GrGLSLFragmentProcessor.h" 13#include "glsl/GrGLSLFragmentShaderBuilder.h" 14 15class GrGLSRGBEffect : public GrGLSLFragmentProcessor { 16public: 17 void emitCode(EmitArgs& args) override { 18 const GrSRGBEffect& srgbe = args.fFp.cast<GrSRGBEffect>(); 19 GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder; 20 21 SkString srgbFuncName; 22 static const GrShaderVar gSrgbArgs[] = { 23 GrShaderVar("x", kHalf_GrSLType), 24 }; 25 switch (srgbe.mode()) { 26 case GrSRGBEffect::Mode::kLinearToSRGB: 27 fragBuilder->emitFunction(kHalf_GrSLType, 28 "linear_to_srgb", 29 SK_ARRAY_COUNT(gSrgbArgs), 30 gSrgbArgs, 31 "return (x <= 0.0031308) ? (x * 12.92) " 32 ": (1.055 * pow(x, 0.416666667) - 0.055);", 33 &srgbFuncName); 34 break; 35 case GrSRGBEffect::Mode::kSRGBToLinear: 36 fragBuilder->emitFunction(kHalf_GrSLType, 37 "srgb_to_linear", 38 SK_ARRAY_COUNT(gSrgbArgs), 39 gSrgbArgs, 40 "return (x <= 0.04045) ? (x / 12.92) " 41 ": pow((x + 0.055) / 1.055, 2.4);", 42 &srgbFuncName); 43 break; 44 } 45 46 if (nullptr == args.fInputColor) { 47 args.fInputColor = "half4(1)"; 48 } 49 50 // Mali Bifrost uses fp16 for mediump. Making the intermediate color variable highp causes 51 // calculations to be performed with sufficient precision. 52 fragBuilder->codeAppendf("float4 color = %s;", args.fInputColor); 53 if (srgbe.alpha() == GrSRGBEffect::Alpha::kPremul) { 54 fragBuilder->codeAppendf("half nonZeroAlpha = max(color.a, 0.00001);"); 55 fragBuilder->codeAppendf("color = half4(color.rgb / nonZeroAlpha, color.a);"); 56 } 57 fragBuilder->codeAppendf("color = half4(%s(color.r), %s(color.g), %s(color.b), color.a);", 58 srgbFuncName.c_str(), 59 srgbFuncName.c_str(), 60 srgbFuncName.c_str()); 61 if (srgbe.alpha() == GrSRGBEffect::Alpha::kPremul) { 62 fragBuilder->codeAppendf("color = half4(color.rgb, 1) * color.a;"); 63 } 64 fragBuilder->codeAppendf("%s = color;", args.fOutputColor); 65 } 66 67 static inline void GenKey(const GrProcessor& processor, const GrShaderCaps&, 68 GrProcessorKeyBuilder* b) { 69 const GrSRGBEffect& srgbe = processor.cast<GrSRGBEffect>(); 70 uint32_t key = static_cast<uint32_t>(srgbe.mode()) | 71 (static_cast<uint32_t>(srgbe.alpha()) << 1); 72 b->add32(key); 73 } 74 75private: 76 typedef GrGLSLFragmentProcessor INHERITED; 77}; 78 79/////////////////////////////////////////////////////////////////////////////// 80 81GrSRGBEffect::GrSRGBEffect(Mode mode, Alpha alpha) 82 : INHERITED(kGrSRGBEffect_ClassID, kPreservesOpaqueInput_OptimizationFlag | 83 kConstantOutputForConstantInput_OptimizationFlag) 84 , fMode(mode) 85 , fAlpha(alpha) 86{ 87} 88 89std::unique_ptr<GrFragmentProcessor> GrSRGBEffect::clone() const { return Make(fMode, fAlpha); } 90 91bool GrSRGBEffect::onIsEqual(const GrFragmentProcessor& s) const { 92 const GrSRGBEffect& other = s.cast<GrSRGBEffect>(); 93 return other.fMode == fMode; 94} 95 96static inline float srgb_to_linear(float srgb) { 97 return (srgb <= 0.04045f) ? srgb / 12.92f : powf((srgb + 0.055f) / 1.055f, 2.4f); 98} 99static inline float linear_to_srgb(float linear) { 100 return (linear <= 0.0031308) ? linear * 12.92f : 1.055f * powf(linear, 1.f / 2.4f) - 0.055f; 101} 102 103GrColor4f GrSRGBEffect::constantOutputForConstantInput(GrColor4f color) const { 104 color = color.unpremul(); 105 switch (fMode) { 106 case Mode::kLinearToSRGB: 107 color = GrColor4f(linear_to_srgb(color.fRGBA[0]), linear_to_srgb(color.fRGBA[1]), 108 linear_to_srgb(color.fRGBA[2]), color.fRGBA[3]); 109 break; 110 case Mode::kSRGBToLinear: 111 color = GrColor4f(srgb_to_linear(color.fRGBA[0]), srgb_to_linear(color.fRGBA[1]), 112 srgb_to_linear(color.fRGBA[2]), color.fRGBA[3]); 113 break; 114 } 115 return color.premul(); 116} 117 118/////////////////////////////////////////////////////////////////////////////// 119 120GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrSRGBEffect); 121 122#if GR_TEST_UTILS 123std::unique_ptr<GrFragmentProcessor> GrSRGBEffect::TestCreate(GrProcessorTestData* d) { 124 Mode testMode = static_cast<Mode>(d->fRandom->nextRangeU(0, 1)); 125 return GrSRGBEffect::Make(testMode, Alpha::kPremul); 126} 127#endif 128 129/////////////////////////////////////////////////////////////////////////////// 130 131void GrSRGBEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps, 132 GrProcessorKeyBuilder* b) const { 133 GrGLSRGBEffect::GenKey(*this, caps, b); 134} 135 136GrGLSLFragmentProcessor* GrSRGBEffect::onCreateGLSLInstance() const { 137 return new GrGLSRGBEffect; 138} 139 140