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 d39163c6df00989f9da0df5731cdb74875c8e6b9..1b4ec7fe620e83053a0ea69ac731ed8d285745c4 100644
--- a/include/gpu/GrXferProcessor.h
+++ b/include/gpu/GrXferProcessor.h
@@ -14,6 +14,7 @@
 #include "GrTypes.h"
 #include "SkXfermode.h"
 
+class GrPipelineBuilder;
 class GrShaderCaps;
 class GrGLSLCaps;
 class GrGLXferProcessor;
@@ -228,10 +229,7 @@ public:
         bool            fWriteColor;
     };
 
-    void getBlendInfo(BlendInfo* blendInfo) const {
-        blendInfo->reset();
-        this->onGetBlendInfo(blendInfo);
-    }
+    void getBlendInfo(BlendInfo* blendInfo) const;
 
     bool willReadDstColor() const { return fWillReadDstColor; }
 
@@ -252,15 +250,22 @@ public:
     }
 
     /**
+     * If we are performing a dst read, returns whether this class will use mixed samples to
+     * antialias the shader's final output. (If not doing a dst read, the subclass is responsible to
+     * account for any mixed samples.)
+     */
+    bool dstReadUsesMixedSamples() const { return fDstReadUsesMixedSamples; }
+
+    /**
      * Returns whether or not the XP will look at coverage when doing its blending.
      */
     bool readsCoverage() const { return fReadsCoverage; }
 
-    /** 
+    /**
      * Returns whether or not this xferProcossor will set a secondary output to be used with dual
      * source blending.
      */
-    virtual bool hasSecondaryOutput() const { return false; }
+    bool hasSecondaryOutput() const;
 
     /** Returns true if this and other processor conservatively draw identically. It can only return
         true when the two processor are of the same subclass (i.e. they return the same object from
@@ -285,12 +290,15 @@ 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 GrPipelineBuilder&, const DstTexture*, bool willReadDstColor);
 
 private:
     virtual OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
@@ -317,15 +325,23 @@ private:
     }
 
     /**
-     * Retrieves the hardware blend state required by this Xfer processor. The BlendInfo struct
-     * comes initialized to default values, so the Xfer processor only needs to set the state it
-     * needs. It may not even need to override this method at all.
+     * If we are not performing a dst read, returns whether the subclass will set a secondary
+     * output. If we are doing a dst read, 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. If we are doing a dst read, 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;
@@ -351,7 +367,8 @@ GR_MAKE_BITFIELD_OPS(GrXferProcessor::OptFlags);
 class GrXPFactory : public SkRefCnt {
 public:
     typedef GrXferProcessor::DstTexture DstTexture;
-    GrXferProcessor* createXferProcessor(const GrProcOptInfo& colorPOI,
+    GrXferProcessor* createXferProcessor(const GrPipelineBuilder&,

[Chris Dalton, 2015/06/04 01:19:18]

I thought it might be nicer to just send in a PipelineBuilder rather than a
parameter like 'bool hasMixedSamples'.

(In the future we may also be able to hang the dst texture and/or POIs off the
PipelineBuilder?)

+                                         const GrProcOptInfo& colorPOI,
                                          const GrProcOptInfo& coveragePOI,
                                          const DstTexture*,
                                          const GrCaps& caps) const;
@@ -381,8 +398,8 @@ public:
     virtual void getInvariantBlendedColor(const GrProcOptInfo& colorPOI,
                                           InvariantBlendedColor*) const = 0;
 
-    bool willNeedDstTexture(const GrCaps& caps, const GrProcOptInfo& colorPOI,
-                            const GrProcOptInfo& coveragePOI) const;
+    bool willNeedDstTexture(const GrCaps& caps, const GrPipelineBuilder&,
+                            const GrProcOptInfo& colorPOI, const GrProcOptInfo& coveragePOI) const;
 
     bool isEqual(const GrXPFactory& that) const {
         if (this->classID() != that.classID()) {
@@ -410,6 +427,7 @@ protected:
 
 private:
     virtual GrXferProcessor* onCreateXferProcessor(const GrCaps& caps,
+                                                   const GrPipelineBuilder&,
                                                    const GrProcOptInfo& colorPOI,
                                                    const GrProcOptInfo& coveragePOI,
                                                    const DstTexture*) const = 0;
@@ -418,6 +436,7 @@ private:
      *  shader.
      */
     virtual bool willReadDstColor(const GrCaps& caps,
+                                  const GrPipelineBuilder&,
                                   const GrProcOptInfo& colorPOI,
                                   const GrProcOptInfo& coveragePOI) const = 0;