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 15 class GrGLSRGBEffect : public GrGLSLFragmentProcessor { 16 public: 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", kFloat_GrSLType), 24 }; 25 switch (srgbe.mode()) { 26 case GrSRGBEffect::Mode::kLinearToSRGB: 27 fragBuilder->emitFunction(kFloat_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(kFloat_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 = "vec4(1)"; 48 } 49 50 fragBuilder->codeAppendf("vec4 color = %s;", args.fInputColor); 51 if (srgbe.alpha() == GrSRGBEffect::Alpha::kPremul) { 52 fragBuilder->codeAppendf("float nonZeroAlpha = max(color.a, 0.00001);"); 53 fragBuilder->codeAppendf("color = vec4(color.rgb / nonZeroAlpha, color.a);"); 54 } 55 fragBuilder->codeAppendf("color = vec4(%s(color.r), %s(color.g), %s(color.b), color.a);", 56 srgbFuncName.c_str(), 57 srgbFuncName.c_str(), 58 srgbFuncName.c_str()); 59 if (srgbe.alpha() == GrSRGBEffect::Alpha::kPremul) { 60 fragBuilder->codeAppendf("color = vec4(color.rgb, 1) * color.a;"); 61 } 62 fragBuilder->codeAppendf("%s = color;", args.fOutputColor); 63 } 64 65 static inline void GenKey(const GrProcessor& processor, const GrShaderCaps&, 66 GrProcessorKeyBuilder* b) { 67 const GrSRGBEffect& srgbe = processor.cast<GrSRGBEffect>(); 68 uint32_t key = static_cast<uint32_t>(srgbe.mode()) | 69 (static_cast<uint32_t>(srgbe.alpha()) << 1); 70 b->add32(key); 71 } 72 73 private: 74 typedef GrGLSLFragmentProcessor INHERITED; 75 }; 76 77 /////////////////////////////////////////////////////////////////////////////// 78 79 GrSRGBEffect::GrSRGBEffect(Mode mode, Alpha alpha) 80 : INHERITED(kPreservesOpaqueInput_OptimizationFlag | 81 kConstantOutputForConstantInput_OptimizationFlag) 82 , fMode(mode) 83 , fAlpha(alpha) 84 { 85 this->initClassID<GrSRGBEffect>(); 86 } 87 88 bool GrSRGBEffect::onIsEqual(const GrFragmentProcessor& s) const { 89 const GrSRGBEffect& other = s.cast<GrSRGBEffect>(); 90 return other.fMode == fMode; 91 } 92 93 static inline float srgb_to_linear(float srgb) { 94 return (srgb <= 0.04045f) ? srgb / 12.92f : powf((srgb + 0.055f) / 1.055f, 2.4f); 95 } 96 static inline float linear_to_srgb(float linear) { 97 return (linear <= 0.0031308) ? linear * 12.92f : 1.055f * powf(linear, 1.f / 2.4f) - 0.055f; 98 } 99 100 GrColor4f GrSRGBEffect::constantOutputForConstantInput(GrColor4f color) const { 101 color = color.unpremul(); 102 switch (fMode) { 103 case Mode::kLinearToSRGB: 104 color = GrColor4f(linear_to_srgb(color.fRGBA[0]), linear_to_srgb(color.fRGBA[1]), 105 linear_to_srgb(color.fRGBA[2]), color.fRGBA[3]); 106 break; 107 case Mode::kSRGBToLinear: 108 color = GrColor4f(srgb_to_linear(color.fRGBA[0]), srgb_to_linear(color.fRGBA[1]), 109 srgb_to_linear(color.fRGBA[2]), color.fRGBA[3]); 110 break; 111 } 112 return color.premul(); 113 } 114 115 /////////////////////////////////////////////////////////////////////////////// 116 117 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrSRGBEffect); 118 119 #if GR_TEST_UTILS 120 sk_sp<GrFragmentProcessor> GrSRGBEffect::TestCreate(GrProcessorTestData* d) { 121 Mode testMode = static_cast<Mode>(d->fRandom->nextRangeU(0, 1)); 122 return GrSRGBEffect::Make(testMode, Alpha::kPremul); 123 } 124 #endif 125 126 /////////////////////////////////////////////////////////////////////////////// 127 128 void GrSRGBEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps, 129 GrProcessorKeyBuilder* b) const { 130 GrGLSRGBEffect::GenKey(*this, caps, b); 131 } 132 133 GrGLSLFragmentProcessor* GrSRGBEffect::onCreateGLSLInstance() const { 134 return new GrGLSRGBEffect; 135 } 136 137