Don't create a GXPFactory when blend is SrcOver

BUG=skia:

Review URL: https://codereview.chromium.org/1471053002

5 files changed, 47 insertions, 32 deletions

diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index cb9557f92c..91268ab5f1 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -204,18 +204,26 @@ public:
                                      const GrFragmentProcessor* dst) const;
 
     /** A subclass may implement this factory function to work with the GPU backend. It is legal
-        to call this with xpf NULL to simply test the return value. If xpf is non-NULL then the
-        xfermode may optionally allocate a factory to return to the caller as *xpf. The caller
-        will install it and own a ref to it. Since the xfermode may or may not assign *xpf, the
-        caller should set *xpf to NULL beforehand. XferProcessors cannot use a background texture.
-     */
+      to call this with xpf NULL to simply test the return value. If xpf is non-NULL then the
+      xfermode may optionally allocate a factory to return to the caller as *xpf. The caller
+      will install it and own a ref to it. Since the xfermode may or may not assign *xpf, the
+      caller should set *xpf to NULL beforehand. XferProcessors cannot use a background texture.
+      */
     virtual bool asXPFactory(GrXPFactory** xpf) const;
 
     /** Returns true if the xfermode can be expressed as an xfer processor factory (xpFactory).
-        This helper calls the asXPFactory() virtual. If the xfermode is NULL, it is treated as
-        kSrcOver_Mode. It is legal to call this with xpf param NULL to simply test the return value.
-     */
-    static bool AsXPFactory(SkXfermode*, GrXPFactory**);
+      This helper calls the asXPFactory() virtual. If the xfermode is NULL, it is treated as
+      kSrcOver_Mode. It is legal to call this with xpf param NULL to simply test the return value.
+      */
+    static inline bool AsXPFactory(SkXfermode* xfermode, GrXPFactory** xpf) {
+        if (nullptr == xfermode) {
+            if (xpf) {
+                *xpf = nullptr;
+            }
+            return true;
+        }
+        return xfermode->asXPFactory(xpf);
+    }
 
     SK_TO_STRING_PUREVIRT()
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
diff --git a/include/gpu/GrPaint.h b/include/gpu/GrPaint.h
index 9d0fe5575e..152cb51d7e 100644
--- a/include/gpu/GrPaint.h
+++ b/include/gpu/GrPaint.h
@@ -57,7 +57,7 @@ public:
     bool isAntiAlias() const { return fAntiAlias; }
 
     const GrXPFactory* setXPFactory(const GrXPFactory* xpFactory) {
-        fXPFactory.reset(SkRef(xpFactory));
+        fXPFactory.reset(SkSafeRef(xpFactory));
         return xpFactory;
     }
 
@@ -100,10 +100,7 @@ public:
                                               this->numCoverageFragmentProcessors(); }
 
     const GrXPFactory* getXPFactory() const {
-        if (!fXPFactory) {
-            fXPFactory.reset(GrPorterDuffXPFactory::Create(SkXfermode::kSrc_Mode));
-        }
-        return fXPFactory.get();
+        return fXPFactory;
     }
 
     const GrFragmentProcessor* getColorFragmentProcessor(int i) const {
@@ -127,7 +124,7 @@ public:
             fCoverageFragmentProcessors[i]->ref();
         }
 
-        fXPFactory.reset(SkRef(paint.getXPFactory()));
+        fXPFactory.reset(SkSafeRef(paint.getXPFactory()));
 
         return *this;
     }
diff --git a/include/gpu/GrXferProcessor.h b/include/gpu/GrXferProcessor.h
index 4accbc84fa..64a0e1ab55 100644
--- a/include/gpu/GrXferProcessor.h
+++ b/include/gpu/GrXferProcessor.h
@@ -316,14 +316,6 @@ public:
                                          bool hasMixedSamples,
                                          const DstTexture*,
                                          const GrCaps& caps) const;
-
-    /**
-     * This function returns true if the GrXferProcessor generated from this factory will be able to
-     * correctly blend when using RGB coverage. The knownColor and knownColorFlags represent the
-     * final computed color from the color stages.
-     */
-    virtual bool supportsRGBCoverage(GrColor knownColor, uint32_t knownColorFlags) const = 0;
-
     /**
      * Known color information after blending, but before accounting for any coverage.
      */
diff --git a/include/gpu/effects/GrCoverageSetOpXP.h b/include/gpu/effects/GrCoverageSetOpXP.h
index 8511074cbd..a17cf81232 100644
--- a/include/gpu/effects/GrCoverageSetOpXP.h
+++ b/include/gpu/effects/GrCoverageSetOpXP.h
@@ -23,11 +23,6 @@ class GrCoverageSetOpXPFactory : public GrXPFactory {
 public:
     static GrXPFactory* Create(SkRegion::Op regionOp, bool invertCoverage = false);
 
-    bool supportsRGBCoverage(GrColor /*knownColor*/,
-                             uint32_t /*knownColorFlags*/) const override {
-        return true;
-    }
-
     void getInvariantBlendedColor(const GrProcOptInfo& colorPOI,
                                   GrXPFactory::InvariantBlendedColor*) const override;
 
diff --git a/include/gpu/effects/GrPorterDuffXferProcessor.h b/include/gpu/effects/GrPorterDuffXferProcessor.h
index d297e32908..3dc503305f 100644
--- a/include/gpu/effects/GrPorterDuffXferProcessor.h
+++ b/include/gpu/effects/GrPorterDuffXferProcessor.h
@@ -18,13 +18,36 @@ class GrPorterDuffXPFactory : public GrXPFactory {
 public:
     static GrXPFactory* Create(SkXfermode::Mode mode); 
 
-    bool supportsRGBCoverage(GrColor /*knownColor*/, uint32_t /*knownColorFlags*/) const override {
-        return true;
-    }
-
     void getInvariantBlendedColor(const GrProcOptInfo& colorPOI,
                                   GrXPFactory::InvariantBlendedColor*) const override;
 
+    static GrXferProcessor* CreateSrcOverXferProcessor(const GrCaps& caps,
+                                                       const GrProcOptInfo& colorPOI,
+                                                       const GrProcOptInfo& coveragePOI,
+                                                       bool hasMixedSamples,
+                                                       const GrXferProcessor::DstTexture*);
+
+    static inline void SrcOverInvariantBlendedColor(
+                                                GrColor inputColor,
+                                                GrColorComponentFlags validColorFlags,
+                                                bool isOpaque,
+                                                GrXPFactory::InvariantBlendedColor* blendedColor) {
+        if (!isOpaque) {
+            blendedColor->fWillBlendWithDst = true;
+            blendedColor->fKnownColorFlags = kNone_GrColorComponentFlags;
+            return;
+        }
+        blendedColor->fWillBlendWithDst = false;
+
+        blendedColor->fKnownColor = inputColor;
+        blendedColor->fKnownColorFlags = validColorFlags;
+    }
+
+    static bool SrcOverWillNeedDstTexture(const GrCaps& caps,
+                                          const GrProcOptInfo& colorPOI,
+                                          const GrProcOptInfo& coveragePOI,
+                                          bool hasMixedSamples);
+
 private:
     GrPorterDuffXPFactory(SkXfermode::Mode);