Add mixed samples support to XPs

include/gpu/GrXferProcessor.h

Index: include/gpu/GrXferProcessor.h
diff --git a/include/gpu/GrXferProcessor.h b/include/gpu/GrXferProcessor.h
index 7ed98a34bc049cbfd8832855437e525db12d22cd..8f2c69d9956e89de59ccc97041162e5c217b1751 100644
--- a/include/gpu/GrXferProcessor.h
+++ b/include/gpu/GrXferProcessor.h
@@ -252,6 +252,13 @@ public:
     }
 
     /**
+     * If we are performing a dst read, returns whether the base class will use mixed samples to
+     * antialias the shader's final output. If not doing a dst read, the subclass is responsible
+     * for antialiasing and this returns false.
+     */
+    bool dstReadUsesMixedSamples() const { return fDstReadUsesMixedSamples; }
+
+    /**
      * Returns whether or not the XP will look at coverage when doing its blending.
      */
     bool readsCoverage() const { return fReadsCoverage; }
@@ -285,12 +292,15 @@ public:
         if (this->fDstTextureOffset != that.fDstTextureOffset) {
             return false;
         }
+        if (this->fDstReadUsesMixedSamples != that.fDstReadUsesMixedSamples) {
+            return false;
+        }
         return this->onIsEqual(that);
     }
    
 protected:
     GrXferProcessor();
-    GrXferProcessor(const DstTexture*, bool willReadDstColor);
+    GrXferProcessor(const DstTexture*, bool willReadDstColor, bool hasMixedSamples);
 
 private:
     virtual OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
@@ -318,21 +328,22 @@ private:
 
     /**
      * If we are not performing a dst read, returns whether the subclass will set a secondary
-     * output. When using dst reads, the base class disables the secondary output and this method
+     * output. When using dst reads, the base class controls the secondary output and this method
      * will not be called.
      */
     virtual bool onHasSecondaryOutput() const { return false; }
 
     /**
      * If we are not performing a dst read, retrieves the fixed-function blend state required by the
-     * subclass. When using dst reads, the base class disables fixed-function blending and this
-     * method will not be called. The BlendInfo struct comes initialized to "no blending".
+     * subclass. When using dst reads, the base class controls the fixed-function blend state and
+     * this method will not be called. The BlendInfo struct comes initialized to "no blending".
      */
     virtual void onGetBlendInfo(BlendInfo*) const {}
 
     virtual bool onIsEqual(const GrXferProcessor&) const = 0;
 
     bool                    fWillReadDstColor;
+    bool                    fDstReadUsesMixedSamples;
     bool                    fReadsCoverage;
     SkIPoint                fDstTextureOffset;
     GrTextureAccess         fDstTexture;
@@ -360,6 +371,7 @@ public:
     typedef GrXferProcessor::DstTexture DstTexture;
     GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
                                          const GrProcOptInfo& coveragePOI,
+                                         bool hasMixedSamples,
                                          const DstTexture*,
                                          const GrCaps& caps) const;
 
@@ -389,7 +401,7 @@ public:
                                           InvariantBlendedColor*) const = 0;
 
     bool willNeedDstTexture(const GrCaps& caps, const GrProcOptInfo& colorPOI,
-                            const GrProcOptInfo& coveragePOI) const;
+                            const GrProcOptInfo& coveragePOI, bool hasMixedSamples) const;
 
     bool isEqual(const GrXPFactory& that) const {
         if (this->classID() != that.classID()) {
@@ -419,6 +431,7 @@ private:
     virtual GrXferProcessor* onCreateXferProcessor(const GrCaps& caps,
                                                    const GrProcOptInfo& colorPOI,
                                                    const GrProcOptInfo& coveragePOI,
+                                                   bool hasMixedSamples,
                                                    const DstTexture*) const = 0;
     /**
      *  Returns true if the XP generated by this factory will explicitly read dst in the fragment
@@ -426,7 +439,8 @@ private:
      */
     virtual bool willReadDstColor(const GrCaps& caps,
                                   const GrProcOptInfo& colorPOI,
-                                  const GrProcOptInfo& coveragePOI) const = 0;
+                                  const GrProcOptInfo& coveragePOI,
+                                  bool hasMixedSamples) const = 0;
 
     virtual bool onIsEqual(const GrXPFactory&) const = 0;