create and thread batch tracker object

src/gpu/GrGeometryProcessor.h

Index: src/gpu/GrGeometryProcessor.h
diff --git a/src/gpu/GrGeometryProcessor.h b/src/gpu/GrGeometryProcessor.h
index 4bf06140db28dd9d6354ad5d1957c4c7b43ede09..28b027b43e273459839635b02de82a5472ef16ca 100644
--- a/src/gpu/GrGeometryProcessor.h
+++ b/src/gpu/GrGeometryProcessor.h
@@ -12,6 +12,26 @@
 #include "GrProcessor.h"
 #include "GrShaderVar.h"
 
+/*
+ * A struct for tracking batching decisions.  While this lives on optstate, it is managed

[bsalomon, 2014/12/03 14:58:52]

Can you make optstate be GrOptState? I've noticed that when we don't use actual
class names in our comments, we wind up with stale comments because they get
missed by search/replace.

+ * entirely by the derived classes of the GP.
+ */
+class GrBatchTracker {
+public:
+    template <typename T> const T& cast() const {
+        return *reinterpret_cast<const T*>(fStorage.begin());
+    }
+
+    template <typename T> T* cast() { return reinterpret_cast<T*>(fStorage.begin()); }
+
+private:
+    // kPreAllocSize is actually more like a maxsize.

[bsalomon, 2014/12/03 14:38:19]

huh?

[bsalomon, 2014/12/03 14:58:52]

If it's a max size and it's preallocated then SkSTArray isn't the right thing.
Just stick a uint8_t fData[32] in there.

How does the client know how big this is? Seems like there should be a public
facing enum or something.

+    static const size_t kPreAllocSize = 32;
+    SkSTArray<kPreAllocSize, uint8_t, true> fStorage;
+};
+
+class GrOptDrawState;
+
 /**
  * A GrGeometryProcessor is used to perform computation in the vertex shader and
  * add support for custom vertex attributes. A GrGemeotryProcessor is typically
@@ -73,6 +93,15 @@ public:
         return this->onIsEqual(that);
     }
 
+    struct InitBT {

[bsalomon, 2014/12/03 14:38:19]

comments?

We're getting rid of fColor and fCoverage, right?

[bsalomon, 2014/12/03 14:58:52]

What I meant is that GrGP shouldn't have an input color and coverage and
GrOptState shouldn't have a constant color/coverage. The GP is (or should be)
output only.

+        bool fOutputColor;
+        bool fOutputCoverage;
+        GrColor fColor;
+        GrColor fCoverage;
+    };
+
+    virtual void initBatchTracker(GrBatchTracker*, const InitBT&) const {}
+
     // TODO this is a total hack until the gp can own whether or not it uses uniform
     // color / coverage
     bool hasVertexColor() const { return fHasVertexColor; }