Revert of Make all blending up to GrOptDrawState be handled by the xp/xp factory.

src/gpu/effects/GrPorterDuffXferProcessor.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "effects/GrPorterDuffXferProcessor.h"
 
-#include "GrBlend.h"
 #include "GrDrawState.h"
 #include "GrInvariantOutput.h"
 #include "GrProcessor.h"
 #include "GrTypes.h"
 #include "GrXferProcessor.h"
 #include "gl/GrGLProcessor.h"
 #include "gl/builders/GrGLFragmentShaderBuilder.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
-static bool can_tweak_alpha_for_coverage(GrBlendCoeff dstCoeff, bool isCoverageDrawing) {
-    /*
-     The fractional coverage is f.
-     The src and dst coeffs are Cs and Cd.
-     The dst and src colors are S and D.
-     We want the blend to compute: f*Cs*S + (f*Cd + (1-f))D. By tweaking the source color's alpha
-     we're replacing S with S'=fS. It's obvious that that first term will always be ok. The second
-     term can be rearranged as [1-(1-Cd)f]D. By substituting in the various possibilities for Cd we
-     find that only 1, ISA, and ISC produce the correct destination when applied to S' and D.
-     Also, if we're directly rendering coverage (isCoverageDrawing) then coverage is treated as
-     color by definition.
-     */
-    // TODO: Once we have a CoverageDrawing XP, we don't need to check is CoverageDrawing here
-    return kOne_GrBlendCoeff == dstCoeff ||
-           kISA_GrBlendCoeff == dstCoeff ||
-           kISC_GrBlendCoeff == dstCoeff ||
-           isCoverageDrawing;
-}
-
 class GrGLPorterDuffXferProcessor : public GrGLXferProcessor {
 public:
     GrGLPorterDuffXferProcessor(const GrProcessor&) {}
 
     virtual ~GrGLPorterDuffXferProcessor() {}
 
     virtual void emitCode(GrGLFPBuilder* builder,
                           const GrFragmentProcessor& fp,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray& coords,
                           const TextureSamplerArray& samplers) SK_OVERRIDE {
         GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
         fsBuilder->codeAppendf("%s = %s;", outputColor, inputColor);
     }
 
     virtual void setData(const GrGLProgramDataManager&, const GrProcessor&) SK_OVERRIDE {};
 
     static void GenKey(const GrProcessor&, const GrGLCaps& caps, GrProcessorKeyBuilder* b) {};
 
 private:
     typedef GrGLXferProcessor INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
-GrPorterDuffXferProcessor::GrPorterDuffXferProcessor(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend,
-                                                     GrColor constant)
-    : fSrcBlend(srcBlend), fDstBlend(dstBlend), fBlendConstant(constant) {
+GrPorterDuffXferProcessor::GrPorterDuffXferProcessor(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend)
+    : fSrcBlend(srcBlend), fDstBlend(dstBlend) {
     this->initClassID<GrPorterDuffXferProcessor>();
 }
 
 GrPorterDuffXferProcessor::~GrPorterDuffXferProcessor() {
 }
 
 void GrPorterDuffXferProcessor::getGLProcessorKey(const GrGLCaps& caps,
                                                   GrProcessorKeyBuilder* b) const {
     GrGLPorterDuffXferProcessor::GenKey(*this, caps, b);
 }
 
 GrGLFragmentProcessor* GrPorterDuffXferProcessor::createGLInstance() const {
     return SkNEW_ARGS(GrGLPorterDuffXferProcessor, (*this));
 }
 
 void GrPorterDuffXferProcessor::onComputeInvariantOutput(GrInvariantOutput* inout) const {
-    inout->setToUnknown(GrInvariantOutput::kWill_ReadInput);
+    inout->setToUnknown(GrInvariantOutput::kWillNot_ReadInput);
 }
 
-GrXferProcessor::OptFlags
-GrPorterDuffXferProcessor::getOptimizations(const GrProcOptInfo& colorPOI,
-                                            const GrProcOptInfo& coveragePOI,
-                                            bool isCoverageDrawing,
-                                            bool colorWriteDisabled,
-                                            bool doesStencilWrite,
-                                            GrColor* color, uint8_t* coverage) {
-    if (colorWriteDisabled) {
-        fSrcBlend = kZero_GrBlendCoeff;
-        fDstBlend = kOne_GrBlendCoeff;
-    }
-
-    bool srcAIsOne;
-    bool hasCoverage;
-    if (isCoverageDrawing) {
-        srcAIsOne = colorPOI.isOpaque() && coveragePOI.isOpaque();
-        hasCoverage = false;
-    } else {
-        srcAIsOne = colorPOI.isOpaque();
-        hasCoverage = !coveragePOI.isSolidWhite();
-    }
-
-    bool dstCoeffIsOne = kOne_GrBlendCoeff == fDstBlend ||
-                         (kSA_GrBlendCoeff == fDstBlend && srcAIsOne);
-    bool dstCoeffIsZero = kZero_GrBlendCoeff == fDstBlend ||
-                         (kISA_GrBlendCoeff == fDstBlend && srcAIsOne);
-
-    // Optimizations when doing RGB Coverage
-    if (!coveragePOI.isSingleComponent()) {
-        // We want to force our primary output to be alpha * Coverage, where alpha is the alpha
-        // value of the blend the constant. We should already have valid blend coeff's if we are at
-        // a point where we have RGB coverage. We don't need any color stages since the known color
-        // output is already baked into the blendConstant.
-        uint8_t alpha = GrColorUnpackA(fBlendConstant);
-        *color = GrColorPackRGBA(alpha, alpha, alpha, alpha);
-        return GrXferProcessor::kClearColorStages_OptFlag;
-    }
-
-    // When coeffs are (0,1) there is no reason to draw at all, unless
-    // stenciling is enabled. Having color writes disabled is effectively
-    // (0,1).
-    if ((kZero_GrBlendCoeff == fSrcBlend && dstCoeffIsOne)) {
-        if (doesStencilWrite) {
-            *color = 0xffffffff;
-            return GrXferProcessor::kClearColorStages_OptFlag |
-                   GrXferProcessor::kSetCoverageDrawing_OptFlag;
-        } else {
-            fDstBlend = kOne_GrBlendCoeff;
-            return GrXferProcessor::kSkipDraw_OptFlag;
-        }
-    }
-
-    // if we don't have coverage we can check whether the dst
-    // has to read at all. If not, we'll disable blending.
-    if (!hasCoverage) {
-        if (dstCoeffIsZero) {
-            if (kOne_GrBlendCoeff == fSrcBlend) {
-                // if there is no coverage and coeffs are (1,0) then we
-                // won't need to read the dst at all, it gets replaced by src
-                fDstBlend = kZero_GrBlendCoeff;
-                return GrXferProcessor::kNone_Opt;
-            } else if (kZero_GrBlendCoeff == fSrcBlend) {
-                // if the op is "clear" then we don't need to emit a color
-                // or blend, just write transparent black into the dst.
-                fSrcBlend = kOne_GrBlendCoeff;
-                fDstBlend = kZero_GrBlendCoeff;
-                *color = 0;
-                *coverage = 0xff;
-                return GrXferProcessor::kClearColorStages_OptFlag |
-                       GrXferProcessor::kClearCoverageStages_OptFlag;
-            }
-        }
-    } else if (isCoverageDrawing) {
-        // we have coverage but we aren't distinguishing it from alpha by request.
-        return GrXferProcessor::kSetCoverageDrawing_OptFlag;
-    } else {
-        // check whether coverage can be safely rolled into alpha
-        // of if we can skip color computation and just emit coverage
-        if (can_tweak_alpha_for_coverage(fDstBlend, isCoverageDrawing)) {
-            return GrXferProcessor::kSetCoverageDrawing_OptFlag;
-        }
-        if (dstCoeffIsZero) {
-            if (kZero_GrBlendCoeff == fSrcBlend) {
-                // the source color is not included in the blend
-                // the dst coeff is effectively zero so blend works out to:
-                // (c)(0)D + (1-c)D = (1-c)D.
-                fDstBlend = kISA_GrBlendCoeff;
-                *color = 0xffffffff;
-                return GrXferProcessor::kClearColorStages_OptFlag |
-                       GrXferProcessor::kSetCoverageDrawing_OptFlag;
-            } else if (srcAIsOne) {
-                // the dst coeff is effectively zero so blend works out to:
-                // cS + (c)(0)D + (1-c)D = cS + (1-c)D.
-                // If Sa is 1 then we can replace Sa with c
-                // and set dst coeff to 1-Sa.
-                fDstBlend = kISA_GrBlendCoeff;
-                return GrXferProcessor::kSetCoverageDrawing_OptFlag;
-            }
-        } else if (dstCoeffIsOne) {
-            // the dst coeff is effectively one so blend works out to:
-            // cS + (c)(1)D + (1-c)D = cS + D.
-            fDstBlend = kOne_GrBlendCoeff;
-            return GrXferProcessor::kSetCoverageDrawing_OptFlag;
-        }
-    }
-
-    return GrXferProcessor::kNone_Opt;
-}
 ///////////////////////////////////////////////////////////////////////////////
 
 GrPorterDuffXPFactory::GrPorterDuffXPFactory(GrBlendCoeff src, GrBlendCoeff dst)
-    : fSrcCoeff(src), fDstCoeff(dst) {
+    : fSrc(src), fDst(dst) {
     this->initClassID<GrPorterDuffXPFactory>();
 }
 
 GrXPFactory* GrPorterDuffXPFactory::Create(SkXfermode::Mode mode) {
     switch (mode) {
         case SkXfermode::kClear_Mode: {
             static GrPorterDuffXPFactory gClearPDXPF(kZero_GrBlendCoeff, kZero_GrBlendCoeff);
             return SkRef(&gClearPDXPF);
             break;
         }
@@ skipping 65 matching lines @@
         case SkXfermode::kScreen_Mode: {
             static GrPorterDuffXPFactory gScreenPDXPF(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
             return SkRef(&gScreenPDXPF);
             break;
         }
         default:
             return NULL;
     }
 }
 
-GrXferProcessor* GrPorterDuffXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
-                                                            const GrProcOptInfo& covPOI) const {
-    if (covPOI.isSingleComponent()) {
-        return GrPorterDuffXferProcessor::Create(fSrcCoeff, fDstCoeff);
-    } else {
-        if (this->supportsRGBCoverage(colorPOI.color(), colorPOI.validFlags())) {
-            SkASSERT(kRGBA_GrColorComponentFlags == colorPOI.validFlags());
-            GrColor blendConstant = GrUnPreMulColor(colorPOI.color());
-            return GrPorterDuffXferProcessor::Create(kConstC_GrBlendCoeff, kISC_GrBlendCoeff,
-                                                     blendConstant);
-        } else {
-            return NULL;
-        }
-    }
+const GrXferProcessor* GrPorterDuffXPFactory::createXferProcessor() const {
+    return GrPorterDuffXferProcessor::Create(fSrc, fDst);
 }
 
 bool GrPorterDuffXPFactory::supportsRGBCoverage(GrColor /*knownColor*/,
                                                 uint32_t knownColorFlags) const {
-    if (kOne_GrBlendCoeff == fSrcCoeff && kISA_GrBlendCoeff == fDstCoeff &&
+    if (kOne_GrBlendCoeff == fSrc && kISA_GrBlendCoeff == fDst &&
         kRGBA_GrColorComponentFlags == knownColorFlags) {
         return true;
     }
     return false;
 }
 
-bool GrPorterDuffXPFactory::canApplyCoverage(const GrProcOptInfo& colorPOI,
-                                             const GrProcOptInfo& coveragePOI,
-                                             bool isCoverageDrawing,
-                                             bool colorWriteDisabled) const {
-    bool srcAIsOne = colorPOI.isOpaque() && (!isCoverageDrawing || coveragePOI.isOpaque());
-
-    if (colorWriteDisabled) {
-        return true;
-    }
-
-    bool dstCoeffIsOne = kOne_GrBlendCoeff == fDstCoeff ||
-                         (kSA_GrBlendCoeff == fDstCoeff && srcAIsOne);
-    bool dstCoeffIsZero = kZero_GrBlendCoeff == fDstCoeff ||
-                         (kISA_GrBlendCoeff == fDstCoeff && srcAIsOne);
-
-    if ((kZero_GrBlendCoeff == fSrcCoeff && dstCoeffIsOne)) {
-        return true;
-    }
-
-    // if we don't have coverage we can check whether the dst
-    // has to read at all.
-    if (isCoverageDrawing) {
-        // we have coverage but we aren't distinguishing it from alpha by request.
-        return true;
-    } else {
-        // check whether coverage can be safely rolled into alpha
-        // of if we can skip color computation and just emit coverage
-        if (this->canTweakAlphaForCoverage(isCoverageDrawing)) {
-            return true;
-        }
-        if (dstCoeffIsZero) {
-            if (kZero_GrBlendCoeff == fSrcCoeff) {
-                return true;
-            } else if (srcAIsOne) {
-                return  true;
-            }
-        } else if (dstCoeffIsOne) {
-            return true;
-        }
-    }
-
-    // TODO: once all SkXferEffects are XP's then we will never reads dst here since only XP's
-    // will readDst and PD XP's don't read dst.
-    if ((colorPOI.readsDst() || coveragePOI.readsDst()) &&
-        kOne_GrBlendCoeff == fSrcCoeff && kZero_GrBlendCoeff == fDstCoeff) {
-        return true;
-    }
-
-    return false;
-}
-
-bool GrPorterDuffXPFactory::willBlendWithDst(const GrProcOptInfo& colorPOI,
-                                             const GrProcOptInfo& coveragePOI,
-                                             bool isCoverageDrawing,
-                                             bool colorWriteDisabled) const {
-    if (!(isCoverageDrawing || coveragePOI.isSolidWhite())) {
-        return true;
-    }
-
-    // TODO: once all SkXferEffects are XP's then we will never reads dst here since only XP's
-    // will readDst and PD XP's don't read dst.
-    if ((!colorWriteDisabled && colorPOI.readsDst()) || coveragePOI.readsDst()) {
-        return true;
-    }
-
-    if (GrBlendCoeffRefsDst(fSrcCoeff)) {
-        return true;
-    }
-
-    bool srcAIsOne = colorPOI.isOpaque() && (!isCoverageDrawing || coveragePOI.isOpaque());
-
-    if (!(kZero_GrBlendCoeff == fDstCoeff ||
-          (kISA_GrBlendCoeff == fDstCoeff && srcAIsOne))) {
-        return true;
-    }
-
-    return false;
-}
-
-bool GrPorterDuffXPFactory::canTweakAlphaForCoverage(bool isCoverageDrawing) const {
-    return can_tweak_alpha_for_coverage(fDstCoeff, isCoverageDrawing);
-}
-
-bool GrPorterDuffXPFactory::getOpaqueAndKnownColor(const GrProcOptInfo& colorPOI,
-                                                   const GrProcOptInfo& coveragePOI,
-                                                   GrColor* solidColor,
-                                                   uint32_t* solidColorKnownComponents) const {
-    if (!coveragePOI.isSolidWhite()) {
-        return false;
-    }
-
-    SkASSERT((NULL == solidColor) == (NULL == solidColorKnownComponents));
-
-    GrBlendCoeff srcCoeff = fSrcCoeff;
-    GrBlendCoeff dstCoeff = fDstCoeff;
-
-    // TODO: figure out to merge this simplify with other current optimization code paths and
-    // eventually remove from GrBlend
-    GrSimplifyBlend(&srcCoeff, &dstCoeff, colorPOI.color(), colorPOI.validFlags(),
-                    0, 0, 0);
-
-    bool opaque = kZero_GrBlendCoeff == dstCoeff && !GrBlendCoeffRefsDst(srcCoeff);
-    if (solidColor) {
-        if (opaque) {
-            switch (srcCoeff) {
-                case kZero_GrBlendCoeff:
-                    *solidColor = 0;
-                    *solidColorKnownComponents = kRGBA_GrColorComponentFlags;
-                    break;
-
-                case kOne_GrBlendCoeff:
-                    *solidColor = colorPOI.color();
-                    *solidColorKnownComponents = colorPOI.validFlags();
-                    break;
-
-                // The src coeff should never refer to the src and if it refers to dst then opaque
-                // should have been false.
-                case kSC_GrBlendCoeff:
-                case kISC_GrBlendCoeff:
-                case kDC_GrBlendCoeff:
-                case kIDC_GrBlendCoeff:
-                case kSA_GrBlendCoeff:
-                case kISA_GrBlendCoeff:
-                case kDA_GrBlendCoeff:
-                case kIDA_GrBlendCoeff:
-                default:
-                    SkFAIL("srcCoeff should not refer to src or dst.");
-                    break;
-
-                // TODO: update this once GrPaint actually has a const color.
-                case kConstC_GrBlendCoeff:
-                case kIConstC_GrBlendCoeff:
-                case kConstA_GrBlendCoeff:
-                case kIConstA_GrBlendCoeff:
-                    *solidColorKnownComponents = 0;
-                    break;
-            }
-        } else {
-            solidColorKnownComponents = 0;
-        }
-    }
-    return opaque;
-}
-
-