Add XP to handle the cases where we disable color write.

include/gpu/effects/GrPorterDuffXferProcessor.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrPorterDuffXferProcessor_DEFINED
 #define GrPorterDuffXferProcessor_DEFINED
 
 #include "GrTypes.h"
 #include "GrXferProcessor.h"
 #include "SkXfermode.h"
 
-class GrInvariantOutput;
 class GrProcOptInfo;
 
 class GrPorterDuffXferProcessor : public GrXferProcessor {
 public:
     static GrXferProcessor* Create(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend,
                                    GrColor constant = 0) {
         return SkNEW_ARGS(GrPorterDuffXferProcessor, (srcBlend, dstBlend, constant));
     }
 
-    virtual ~GrPorterDuffXferProcessor();
+    ~GrPorterDuffXferProcessor() SK_OVERRIDE;
 
-    virtual const char* name() const SK_OVERRIDE { return "Porter Duff"; }
+    const char* name() const SK_OVERRIDE { return "Porter Duff"; }
 
     void getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const SK_OVERRIDE;
 
     GrGLXferProcessor* createGLInstance() const SK_OVERRIDE;
 
-    virtual bool hasSecondaryOutput() const SK_OVERRIDE;
+    bool hasSecondaryOutput() const SK_OVERRIDE;
 
     ///////////////////////////////////////////////////////////////////////////
     /// @name Stage Output Types
     ////
 
     enum PrimaryOutputType {
         kNone_PrimaryOutputType,
         kColor_PrimaryOutputType,
         kCoverage_PrimaryOutputType,
         // Modulate color and coverage, write result as the color output.
@@ skipping 17 matching lines @@
         kCoverageISC_SecondaryOutputType,
 
         kSecondaryOutputTypeCnt,
     };
 
     PrimaryOutputType primaryOutputType() const { return fPrimaryOutputType; }
     SecondaryOutputType secondaryOutputType() const { return fSecondaryOutputType; }
 
     GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
                                                const GrProcOptInfo& coveragePOI,
-                                               bool colorWriteDisabled,
                                                bool doesStencilWrite,
                                                GrColor* overrideColor,
                                                const GrDrawTargetCaps& caps) SK_OVERRIDE;
 
     void getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const SK_OVERRIDE {
         blendInfo->fSrcBlend = fSrcBlend;
         blendInfo->fDstBlend = fDstBlend;
         blendInfo->fBlendConstant = fBlendConstant;
     }
 
 private:
     GrPorterDuffXferProcessor(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend, GrColor constant);
 
     bool onIsEqual(const GrXferProcessor& xpBase) const SK_OVERRIDE {
         const GrPorterDuffXferProcessor& xp = xpBase.cast<GrPorterDuffXferProcessor>();
         if (fSrcBlend != xp.fSrcBlend ||
             fDstBlend != xp.fDstBlend ||
             fBlendConstant != xp.fBlendConstant ||
             fPrimaryOutputType != xp.fPrimaryOutputType || 
             fSecondaryOutputType != xp.fSecondaryOutputType) {
             return false;
         }
         return true;
     }
 
     GrXferProcessor::OptFlags internalGetOptimizations(const GrProcOptInfo& colorPOI,
                                                        const GrProcOptInfo& coveragePOI,
-                                                       bool colorWriteDisabled,
                                                        bool doesStencilWrite);
 
     void calcOutputTypes(GrXferProcessor::OptFlags blendOpts, const GrDrawTargetCaps& caps,
                          bool hasSolidCoverage, bool readDst);
 
     GrBlendCoeff fSrcBlend;
     GrBlendCoeff fDstBlend;
     GrColor      fBlendConstant;
     PrimaryOutputType fPrimaryOutputType;
     SecondaryOutputType fSecondaryOutputType;
@@ skipping 13 matching lines @@
 
     static GrXPFactory* Create(GrBlendCoeff src, GrBlendCoeff dst) {
         return SkNEW_ARGS(GrPorterDuffXPFactory, (src, dst));
     }
 
     GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
                                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
 
     bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const SK_OVERRIDE;
 
-    bool canApplyCoverage(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                          bool colorWriteDisabled) const SK_OVERRIDE;
+    bool canApplyCoverage(const GrProcOptInfo& colorPOI,
+                          const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
 
     bool canTweakAlphaForCoverage() const SK_OVERRIDE;
 
     void getInvariantOutput(const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI,
-                            bool colorWriteDisabled,
                             GrXPFactory::InvariantOutput*) const SK_OVERRIDE;
 
+    bool willReadDst(const GrProcOptInfo& colorPOI,
+                     const GrProcOptInfo& coveragePOI) const SK_OVERRIDE;
+
 private:
     GrPorterDuffXPFactory(GrBlendCoeff src, GrBlendCoeff dst); 
 
     bool onIsEqual(const GrXPFactory& xpfBase) const SK_OVERRIDE {
         const GrPorterDuffXPFactory& xpf = xpfBase.cast<GrPorterDuffXPFactory>();
         return (fSrcCoeff == xpf.fSrcCoeff && fDstCoeff == xpf.fDstCoeff);
     }
 
     GR_DECLARE_XP_FACTORY_TEST;
 
     GrBlendCoeff fSrcCoeff;
     GrBlendCoeff fDstCoeff;
 
     typedef GrXPFactory INHERITED;
 };
 
 #endif