Add "sample locations" feature to GrProcessor

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index 147c4810200ea45daa192aa6e585fcc98f049ad8..da636138fe6bfebe94006ecc7f7e88745238dcf8 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -10,11 +10,13 @@
 
 #include "GrPipelineBuilder.h"
 #include "GrProgramDesc.h"
+#include "GrRenderTargetPriv.h"
 #include "GrStencil.h"
 #include "GrSwizzle.h"
 #include "GrTextureParamsAdjuster.h"
 #include "GrXferProcessor.h"
 #include "SkPath.h"
+#include <map>
 
 class GrBatchTracker;
 class GrContext;
@@ -333,6 +335,10 @@ public:
                      const SkIRect& srcRect,
                      const SkIPoint& dstPoint);
 
+    typedef GrRenderTargetPriv::MultisampleSpecs MultisampleSpecs;
+
+    const MultisampleSpecs& getMultisampleSpecs(GrRenderTarget*, const GrStencilSettings&);
+
     struct DrawArgs {
         DrawArgs(const GrPrimitiveProcessor* primProc,
                  const GrPipeline* pipeline,
@@ -487,6 +493,11 @@ protected:
         }
     }
 
+    class SamplePattern : public SkTArray<SkPoint, true> {

[bsalomon, 2016/02/22 20:28:25]

It seems a little odd to me for this to be a point array instead of just contain
one. Does the public array interface really make sense for this?

[Chris Dalton, 2016/02/22 21:19:11]

Yeah, that felt a little weird. The only reason this class even exists is to
overload the < operator. Maybe the better option would be to give std::map a
custom comparator. It would also eliminate the confusion around what the
SamplePattern < operator was for.

[Chris Dalton, 2016/02/22 22:17:55]

Done.

+    public:
+        bool operator <(const SamplePattern&) const;
+    };
+
     Stats                                   fStats;
     SkAutoTDelete<GrPathRendering>          fPathRendering;
     // Subclass must initialize this in its constructor.
@@ -566,6 +577,12 @@ private:
                                const SkIRect& srcRect,
                                const SkIPoint& dstPoint) = 0;
 
+    // overridden by backend specific derived class to perform the multisample queries
+    virtual void onGetMultisampleSpecs(GrRenderTarget*,
+                                       const GrStencilSettings&,
+                                       int* effectiveSampleCnt,
+                                       SamplePattern*) = 0;
+
     void resetContext() {
         this->onResetContext(fResetBits);
         fResetBits = 0;
@@ -574,6 +591,9 @@ private:
 
     ResetTimestamp                                                      fResetTimestamp;
     uint32_t                                                            fResetBits;
+    SkTArray<skstd::unique_ptr<MultisampleSpecs> >                      fRasterMultisampleSpecs;
+    std::map<SamplePattern, uint16_t>                                   fKnownSamplePatterns;
+    uint16_t                                                            fNextSamplePatternID;
     // The context owns us, not vice-versa, so this ptr is not ref'ed by Gpu.
     GrContext*                                                          fContext;