Create fragment processor for performing input color blend with child processor

src/effects/SkArithmeticMode_gpu.cpp

 /*
  * 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 "SkArithmeticMode_gpu.h"
 
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
 #include "GrProcessor.h"
 #include "GrTexture.h"
 #include "gl/GrGLCaps.h"
 #include "gl/GrGLFragmentProcessor.h"
 #include "gl/GrGLProgramDataManager.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 static const bool gUseUnpremul = false;
 
 static void add_arithmetic_code(GrGLFragmentBuilder* fsBuilder,
-                                const char* inputColor,
+                                const char* srcColor,
                                 const char* dstColor,
                                 const char* outputColor,
                                 const char* kUni,
                                 bool enforcePMColor) {
     // We don't try to optimize for this case at all
-    if (nullptr == inputColor) {
+    if (nullptr == srcColor) {
         fsBuilder->codeAppend("const vec4 src = vec4(1);");
     } else {
-        fsBuilder->codeAppendf("vec4 src = %s;", inputColor);
+        fsBuilder->codeAppendf("vec4 src = %s;", srcColor);
         if (gUseUnpremul) {
             fsBuilder->codeAppend("src.rgb = clamp(src.rgb / src.a, 0.0, 1.0);");
         }
     }
 
     fsBuilder->codeAppendf("vec4 dst = %s;", dstColor);
     if (gUseUnpremul) {
         fsBuilder->codeAppend("dst.rgb = clamp(dst.rgb / dst.a, 0.0, 1.0);");
     }
 
     fsBuilder->codeAppendf("%s = %s.x * src * dst + %s.y * src + %s.z * dst + %s.w;",
                            outputColor, kUni, kUni, kUni, kUni);
     fsBuilder->codeAppendf("%s = clamp(%s, 0.0, 1.0);\n", outputColor, outputColor);
     if (gUseUnpremul) {
         fsBuilder->codeAppendf("%s.rgb *= %s.a;", outputColor, outputColor);
     } else if (enforcePMColor) {
         fsBuilder->codeAppendf("%s.rgb = min(%s.rgb, %s.a);",
                                outputColor, outputColor, outputColor);
     }
 }
 
 class GLArithmeticFP : public GrGLFragmentProcessor {
 public:
-    GLArithmeticFP(const GrProcessor&)
-        : fEnforcePMColor(true) {
-    }
+    GLArithmeticFP(const GrProcessor&) : fEnforcePMColor(true) {}
 
     ~GLArithmeticFP() override {}
 
     void emitCode(EmitArgs& args) override {
         GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
-        fsBuilder->codeAppend("vec4 bgColor = ");
-        fsBuilder->appendTextureLookup(args.fSamplers[0], args.fCoords[0].c_str(),
-                                       args.fCoords[0].getType());
-        fsBuilder->codeAppendf(";");
-        const char* dstColor = "bgColor";
+        fsBuilder->codeAppend("vec4 _dstColor;");
+        this->emitChild(0, nullptr, "_dstColor", args);
 
         fKUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
-                                    kVec4f_GrSLType, kDefault_GrSLPrecision,
-                                    "k");
+                                          kVec4f_GrSLType, kDefault_GrSLPrecision,
+                                          "k");
         const char* kUni = args.fBuilder->getUniformCStr(fKUni);
 
-        add_arithmetic_code(fsBuilder, args.fInputColor, dstColor, args.fOutputColor, kUni,
+        add_arithmetic_code(fsBuilder, args.fInputColor, "_dstColor", args.fOutputColor, kUni,
                             fEnforcePMColor);
     }
 
     static void GenKey(const GrProcessor& proc, const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) {
         const GrArithmeticFP& arith = proc.cast<GrArithmeticFP>();
         uint32_t key = arith.enforcePMColor() ? 1 : 0;
         b->add32(key);
     }
 
 protected:
     void onSetData(const GrGLProgramDataManager& pdman, const GrProcessor& proc) override {
         const GrArithmeticFP& arith = proc.cast<GrArithmeticFP>();
         pdman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
         fEnforcePMColor = arith.enforcePMColor();
     }
 
 private:
     GrGLProgramDataManager::UniformHandle fKUni;
     bool fEnforcePMColor;
 
     typedef GrGLFragmentProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrArithmeticFP::GrArithmeticFP(GrProcessorDataManager*, float k1, float k2, float k3, float k4,
-                               bool enforcePMColor, GrTexture* background)
+                               bool enforcePMColor, const GrFragmentProcessor* dst)
   : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fEnforcePMColor(enforcePMColor) {
     this->initClassID<GrArithmeticFP>();
 
-    SkASSERT(background);
-
-    fBackgroundTransform.reset(kLocal_GrCoordSet, background,
-                               GrTextureParams::kNone_FilterMode);
-    this->addCoordTransform(&fBackgroundTransform);
-    fBackgroundAccess.reset(background);
-    this->addTextureAccess(&fBackgroundAccess);
+    SkASSERT(dst);
+    SkDEBUGCODE(int dstIndex = )this->registerChildProcessor(dst);
+    SkASSERT(0 == dstIndex);
 }
 
 void GrArithmeticFP::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
     GLArithmeticFP::GenKey(*this, caps, b);
 }
 
 GrGLFragmentProcessor* GrArithmeticFP::onCreateGLInstance() const {
     return new GLArithmeticFP(*this);
 }
 
@@ skipping 13 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
 const GrFragmentProcessor* GrArithmeticFP::TestCreate(GrProcessorTestData* d) {
     float k1 = d->fRandom->nextF();
     float k2 = d->fRandom->nextF();
     float k3 = d->fRandom->nextF();
     float k4 = d->fRandom->nextF();
     bool enforcePMColor = d->fRandom->nextBool();
 
-    return new GrArithmeticFP(d->fProcDataManager, k1, k2, k3, k4, enforcePMColor, d->fTextures[0]);
+    SkAutoTUnref<const GrFragmentProcessor> dst(GrProcessorUnitTest::CreateChildFP(d));
+    return new GrArithmeticFP(d->fProcDataManager, k1, k2, k3, k4, enforcePMColor, dst);
 }
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrArithmeticFP);
 
 ///////////////////////////////////////////////////////////////////////////////
 // Xfer Processor
 ///////////////////////////////////////////////////////////////////////////////
 
 class ArithmeticXP : public GrXferProcessor {
 public:
@@ skipping 141 matching lines @@
     float k1 = d->fRandom->nextF();
     float k2 = d->fRandom->nextF();
     float k3 = d->fRandom->nextF();
     float k4 = d->fRandom->nextF();
     bool enforcePMColor = d->fRandom->nextBool();
 
     return GrArithmeticXPFactory::Create(k1, k2, k3, k4, enforcePMColor);
 }
 
 #endif