Create fragment processor for performing input color blend with child processor

src/effects/SkColorFilters.cpp

Index: src/effects/SkColorFilters.cpp
diff --git a/src/effects/SkColorFilters.cpp b/src/effects/SkColorFilters.cpp
index c38328ccbbd8317c7e36e8e67cf29ddab274d512..ece3295107e58d2beab55fb3341d4ee201837219 100644
--- a/src/effects/SkColorFilters.cpp
+++ b/src/effects/SkColorFilters.cpp
@@ -65,305 +65,36 @@ SkFlattenable* SkModeColorFilter::CreateProc(SkReadBuffer& buffer) {
 ///////////////////////////////////////////////////////////////////////////////
 #if SK_SUPPORT_GPU
 #include "GrBlend.h"
-#include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
-#include "GrProcessorUnitTest.h"
+#include "effects/GrXfermodeFragmentProcessor.h"
+#include "effects/GrConstColorProcessor.h"
 #include "SkGr.h"
-#include "gl/GrGLFragmentProcessor.h"
-#include "gl/builders/GrGLProgramBuilder.h"
-
-namespace {
-/**
- * A definition of blend equation for one coefficient. Generates a
- * blend_coeff * value "expression".
- */
-template<typename ColorExpr>
-static inline ColorExpr blend_term(SkXfermode::Coeff coeff,
-                                   const ColorExpr& src,
-                                   const ColorExpr& dst,
-                                   const ColorExpr& value) {
-    switch (coeff) {
-    default:
-        SkFAIL("Unexpected xfer coeff.");
-    case SkXfermode::kZero_Coeff:    /** 0 */
-        return ColorExpr(0);
-    case SkXfermode::kOne_Coeff:     /** 1 */
-        return value;
-    case SkXfermode::kSC_Coeff:
-        return src * value;
-    case SkXfermode::kISC_Coeff:
-        return (ColorExpr(1) - src) * dst;
-    case SkXfermode::kDC_Coeff:
-        return dst * value;
-    case SkXfermode::kIDC_Coeff:
-        return (ColorExpr(1) - dst) * value;
-    case SkXfermode::kSA_Coeff:      /** src alpha */
-        return src.a() * value;
-    case SkXfermode::kISA_Coeff:     /** inverse src alpha (i.e. 1 - sa) */
-        return (typename ColorExpr::AExpr(1) - src.a()) * value;
-    case SkXfermode::kDA_Coeff:      /** dst alpha */
-        return dst.a() * value;
-    case SkXfermode::kIDA_Coeff:     /** inverse dst alpha (i.e. 1 - da) */
-        return (typename ColorExpr::AExpr(1) - dst.a()) *  value;
-    }
-}
-/**
- * Creates a color filter expression which modifies the color by
- * the specified color filter.
- */
-template <typename ColorExpr>
-static inline ColorExpr color_filter_expression(const SkXfermode::Mode& mode,
-                                                const ColorExpr& filterColor,
-                                                const ColorExpr& inColor) {
-    SkXfermode::Coeff colorCoeff;
-    SkXfermode::Coeff filterColorCoeff;
-    SkAssertResult(SkXfermode::ModeAsCoeff(mode, &filterColorCoeff, &colorCoeff));
-    return blend_term(colorCoeff, filterColor, inColor, inColor) +
-        blend_term(filterColorCoeff, filterColor, inColor, filterColor);
-}
-
-}
-
-class ModeColorFilterEffect : public GrFragmentProcessor {
-public:
-    static GrFragmentProcessor* Create(const GrColor& c, SkXfermode::Mode mode) {
-        // TODO: Make the effect take the coeffs rather than mode since we already do the
-        // conversion here.
-        SkXfermode::Coeff srcCoeff, dstCoeff;
-        if (!SkXfermode::ModeAsCoeff(mode, &srcCoeff, &dstCoeff)) {
-//            SkDebugf("Failing to create color filter for mode %d\n", mode);
-            return nullptr;
-        }
-        return new ModeColorFilterEffect(c, mode);
-    }
-
-    bool willUseFilterColor() const {
-        SkXfermode::Coeff dstCoeff;
-        SkXfermode::Coeff srcCoeff;
-        SkAssertResult(SkXfermode::ModeAsCoeff(fMode, &srcCoeff, &dstCoeff));
-        if (SkXfermode::kZero_Coeff == srcCoeff) {
-            return GrBlendCoeffRefsSrc(sk_blend_to_grblend(dstCoeff));
-        }
-        return true;
-    }
-
-    const char* name() const override { return "ModeColorFilterEffect"; }
-
-    SkXfermode::Mode mode() const { return fMode; }
-    GrColor color() const { return fColor; }
-
-    class GLProcessor : public GrGLFragmentProcessor {
-    public:
-        GLProcessor(const GrProcessor&) {
-        }
-
-        virtual void emitCode(EmitArgs& args) override {
-            SkXfermode::Mode mode = args.fFp.cast<ModeColorFilterEffect>().mode();
-
-            SkASSERT(SkXfermode::kDst_Mode != mode);
-            const char* colorFilterColorUniName = nullptr;
-            if (args.fFp.cast<ModeColorFilterEffect>().willUseFilterColor()) {
-                fFilterColorUni = args.fBuilder->addUniform(
-                                                      GrGLProgramBuilder::kFragment_Visibility,
-                                                      kVec4f_GrSLType, kDefault_GrSLPrecision,
-                                                      "FilterColor",
-                                                      &colorFilterColorUniName);
-            }
-
-            GrGLSLExpr4 filter =
-                color_filter_expression(mode, GrGLSLExpr4(colorFilterColorUniName),
-                                        GrGLSLExpr4(args.fInputColor));
-
-            args.fBuilder->getFragmentShaderBuilder()->
-                    codeAppendf("\t%s = %s;\n", args.fOutputColor, filter.c_str());
-        }
-
-        static void GenKey(const GrProcessor& fp, const GrGLSLCaps&,
-                           GrProcessorKeyBuilder* b) {
-            const ModeColorFilterEffect& colorModeFilter = fp.cast<ModeColorFilterEffect>();
-            // The SL code does not depend on filter color at the moment, so no need to represent it
-            // in the key.
-            b->add32(colorModeFilter.mode());
-        }
-
-    protected:
-        virtual void onSetData(const GrGLProgramDataManager& pdman,
-                             const GrProcessor& fp) override {
-            if (fFilterColorUni.isValid()) {
-                const ModeColorFilterEffect& colorModeFilter = fp.cast<ModeColorFilterEffect>();
-                GrGLfloat c[4];
-                GrColorToRGBAFloat(colorModeFilter.color(), c);
-                pdman.set4fv(fFilterColorUni, 1, c);
-            }
-        }
-
-    private:
-
-        GrGLProgramDataManager::UniformHandle fFilterColorUni;
-        typedef GrGLFragmentProcessor INHERITED;
-    };
-
-    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
-
-private:
-    ModeColorFilterEffect(GrColor color, SkXfermode::Mode mode)
-        : fMode(mode),
-          fColor(color) {
-        this->initClassID<ModeColorFilterEffect>();
-    }
-
-    GrGLFragmentProcessor* onCreateGLInstance() const override { return new GLProcessor(*this); }
-
-    virtual void onGetGLProcessorKey(const GrGLSLCaps& caps,
-                                     GrProcessorKeyBuilder* b) const override {
-        GLProcessor::GenKey(*this, caps, b);
-    }
-
-    bool onIsEqual(const GrFragmentProcessor& other) const override {
-        const ModeColorFilterEffect& s = other.cast<ModeColorFilterEffect>();
-        return fMode == s.fMode && fColor == s.fColor;
-    }
-
-    void onComputeInvariantOutput(GrInvariantOutput* inout) const override;
-
-    SkXfermode::Mode fMode;
-    GrColor fColor;
-
-    typedef GrFragmentProcessor INHERITED;
-};
-
-namespace {
-
-/** Function color_component_to_int tries to reproduce the GLSL rounding. The spec doesn't specify
- * to which direction the 0.5 goes.
- */
-static inline int color_component_to_int(float value) {
-    return sk_float_round2int(SkTMax(0.f, SkTMin(1.f, value)) * 255.f);
-}
-
-/** MaskedColorExpr is used to evaluate the color and valid color component flags through the
- * blending equation. It has members similar to GrGLSLExpr so that it can be used with the
- * templated helpers above.
- */
-class MaskedColorExpr {
-public:
-    MaskedColorExpr(const float color[], uint32_t flags)
-        : fFlags(flags) {
-        fColor[0] = color[0];
-        fColor[1] = color[1];
-        fColor[2] = color[2];
-        fColor[3] = color[3];
-    }
-
-    MaskedColorExpr(float v, uint32_t flags = kRGBA_GrColorComponentFlags)
-        : fFlags(flags) {
-        fColor[0] = v;
-        fColor[1] = v;
-        fColor[2] = v;
-        fColor[3] = v;
-    }
-
-    MaskedColorExpr operator*(const MaskedColorExpr& other) const {
-        float tmp[4];
-        tmp[0] = fColor[0] * other.fColor[0];
-        tmp[1] = fColor[1] * other.fColor[1];
-        tmp[2] = fColor[2] * other.fColor[2];
-        tmp[3] = fColor[3] * other.fColor[3];
-
-        return MaskedColorExpr(tmp, fFlags & other.fFlags);
-    }
-
-    MaskedColorExpr operator+(const MaskedColorExpr& other) const {
-        float tmp[4];
-        tmp[0] = fColor[0] + other.fColor[0];
-        tmp[1] = fColor[1] + other.fColor[1];
-        tmp[2] = fColor[2] + other.fColor[2];
-        tmp[3] = fColor[3] + other.fColor[3];
-
-        return MaskedColorExpr(tmp, fFlags & other.fFlags);
-    }
-
-    MaskedColorExpr operator-(const MaskedColorExpr& other) const {
-        float tmp[4];
-        tmp[0] = fColor[0] - other.fColor[0];
-        tmp[1] = fColor[1] - other.fColor[1];
-        tmp[2] = fColor[2] - other.fColor[2];
-        tmp[3] = fColor[3] - other.fColor[3];
-
-        return MaskedColorExpr(tmp, fFlags & other.fFlags);
-    }
-
-    MaskedColorExpr a() const {
-        uint32_t flags = (fFlags & kA_GrColorComponentFlag) ? kRGBA_GrColorComponentFlags : 0;
-        return MaskedColorExpr(fColor[3], flags);
-    }
-
-    GrColor getColor() const {
-        return GrColorPackRGBA(color_component_to_int(fColor[0]),
-                               color_component_to_int(fColor[1]),
-                               color_component_to_int(fColor[2]),
-                               color_component_to_int(fColor[3]));
-    }
-
-    uint32_t getValidComponents() const  { return fFlags; }
-
-    typedef MaskedColorExpr AExpr;
-private:
-    float fColor[4];
-    uint32_t fFlags;
-};
-
-}
-
-void ModeColorFilterEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
-    float inputColor[4];
-    GrColorToRGBAFloat(inout->color(), inputColor);
-    float filterColor[4];
-    GrColorToRGBAFloat(fColor, filterColor);
-    MaskedColorExpr result =
-        color_filter_expression(fMode,
-                                MaskedColorExpr(filterColor, kRGBA_GrColorComponentFlags),
-                                MaskedColorExpr(inputColor, inout->validFlags()));
-
-    // Check if we will use the input color
-    SkXfermode::Coeff dstCoeff;
-    SkXfermode::Coeff srcCoeff;
-    SkAssertResult(SkXfermode::ModeAsCoeff(fMode, &srcCoeff, &dstCoeff));
-    GrInvariantOutput::ReadInput readInput = GrInvariantOutput::kWill_ReadInput;
-    // These could be calculated from the blend equation with template trickery..
-    if (SkXfermode::kZero_Coeff == dstCoeff &&
-        !GrBlendCoeffRefsDst(sk_blend_to_grblend(srcCoeff))) {
-        readInput = GrInvariantOutput::kWillNot_ReadInput;
-    }
-    inout->setToOther(result.getValidComponents(), result.getColor(), readInput);
-}
-
-GR_DEFINE_FRAGMENT_PROCESSOR_TEST(ModeColorFilterEffect);
-const GrFragmentProcessor* ModeColorFilterEffect::TestCreate(GrProcessorTestData* d) {
-    SkXfermode::Mode mode = SkXfermode::kDst_Mode;
-    while (SkXfermode::kDst_Mode == mode) {
-        mode = static_cast<SkXfermode::Mode>(d->fRandom->nextRangeU(0, SkXfermode::kLastCoeffMode));
-    }
-
-    // pick a random premul color
-    uint8_t alpha = d->fRandom->nextULessThan(256);
-    GrColor color = GrColorPackRGBA(d->fRandom->nextRangeU(0, alpha),
-                                    d->fRandom->nextRangeU(0, alpha),
-                                    d->fRandom->nextRangeU(0, alpha),
-                                    alpha);
-    return ModeColorFilterEffect::Create(color, mode);
-}
 
 bool SkModeColorFilter::asFragmentProcessors(GrContext*, GrProcessorDataManager*,
-                                             SkTDArray<GrFragmentProcessor*>* array) const {
+                                             SkTDArray<const GrFragmentProcessor*>* array) const {
     if (SkXfermode::kDst_Mode != fMode) {
-        GrFragmentProcessor* frag = ModeColorFilterEffect::Create(SkColor2GrColor(fColor), fMode);
-        if (frag) {
+        SkAutoTUnref<const GrFragmentProcessor> constFP(
+            GrConstColorProcessor::Create(SkColor2GrColor(fColor),
+                                          GrConstColorProcessor::kIgnore_InputMode));
+        const GrFragmentProcessor* fp =
+            GrXfermodeFragmentProcessor::CreateFromSrcProcessor(constFP, fMode);
+        if (fp) {
+#ifdef SK_DEBUG
+            // With a solid color input this should always be able to compute the blended color
+            // (at least for coeff modes)
+            if (fMode <= SkXfermode::kLastCoeffMode) {
+                static SkRandom gRand;
+                GrInvariantOutput io(GrPremulColor(gRand.nextU()), kRGBA_GrColorComponentFlags,
+                                     false);
+                fp->computeInvariantOutput(&io);
+                SkASSERT(io.validFlags() == kRGBA_GrColorComponentFlags);
+            }
+#endif
             if (array) {
-                *array->append() = frag;
+                *array->append() = fp;
             } else {
-                frag->unref();
-                SkDEBUGCODE(frag = nullptr;)
+                fp->unref();
+                SkDEBUGCODE(fp = nullptr;)
             }
             return true;
         }