Add "sample locations" feature to GrProcessor

src/gpu/GrPipeline.h

Index: src/gpu/GrPipeline.h
diff --git a/src/gpu/GrPipeline.h b/src/gpu/GrPipeline.h
index 4f81ae40d0276223f2de88d4edd3238ea3576ebf..833228f24675c6b3a89aa5c7b48f3a63d6c65993 100644
--- a/src/gpu/GrPipeline.h
+++ b/src/gpu/GrPipeline.h
@@ -145,6 +145,7 @@ public:
 
     bool isHWAntialiasState() const { return SkToBool(fFlags & kHWAA_Flag); }
     bool snapVerticesToPixelCenters() const { return SkToBool(fFlags & kSnapVertices_Flag); }
+    bool hasSampleLocations() const { return SkToBool(fFlags & kSampleLocations_Flag); }
 
     GrXferBarrierType xferBarrierType(const GrCaps& caps) const {
         return this->getXferProcessor().xferBarrierType(fRenderTarget.get(), caps);
@@ -163,6 +164,28 @@ public:
     bool readsFragPosition() const { return fReadsFragPosition; }
     bool ignoresCoverage() const { return fIgnoresCoverage; }
 
+    ///////////////////////////////////////////////////////////////////////////
+
+    /**
+     * Returns the actual number of samples the hardware will run when using this pipeline.
+     * NOTE: this can be greater than the sample count in the render target's surface descriptor.
+     */
+    int effectiveSampleCount() const { return this->getMultisampleSpecs().fEffectiveSampleCnt; }
+
+    /**
+     * Returns a unique ID that identifies this pipeline's sample pattern, or 0 if sample locations
+     * are not supported.
+     */
+    uint16_t getSamplePatternID() const { return this->getMultisampleSpecs().fSamplePatternID; }
+
+    /**
+     * Returns this pipeline's sample locations, or nullptr if sample locations are not supported.
+     * The sample locations are stored in device space, with the center of the pixel at [0.5, 0.5].
+     */
+    const SkPoint* getSampleLocations() const {
+        return this->getMultisampleSpecs().fSampleLocations;
+    }
+
 private:
     GrPipeline() { /** Initialized in factory function*/ }
 
@@ -184,9 +207,15 @@ private:
     void setOutputStateInfo(const GrPipelineBuilder& ds, GrXferProcessor::OptFlags,
                             const GrCaps&);
 
+    const GrRenderTargetPriv::MultisampleSpecs& getMultisampleSpecs() const {
+        SkASSERT(this->isHWAntialiasState());
+        return this->getRenderTarget()->renderTargetPriv().getMultisampleSpecs(fStencilSettings);
+    }
+
     enum Flags {
         kHWAA_Flag              = 0x1,
         kSnapVertices_Flag      = 0x2,
+        kSampleLocations_Flag   = 0x4,
     };
 
     typedef GrPendingIOResource<GrRenderTarget, kWrite_GrIOType> RenderTarget;