Create GrDraw and start fast pathing src over rects

src/gpu/batches/GrBatch.h

Index: src/gpu/batches/GrBatch.h
diff --git a/src/gpu/batches/GrBatch.h b/src/gpu/batches/GrBatch.h
index c5fc80c5d50dfbd622dfb69e3eb9adfbcd3c31f9..ea1712f6452c4bd84437ceaaf653b257c4948ec1 100644
--- a/src/gpu/batches/GrBatch.h
+++ b/src/gpu/batches/GrBatch.h
@@ -14,6 +14,8 @@
 #include "SkRect.h"
 #include "SkString.h"
 
+#include "draws/GrDraw.h"
+
 class GrCaps;
 class GrBatchFlushState;
 
@@ -109,6 +111,14 @@ public:
     /** Used for spewing information about batches when debugging. */
     virtual SkString dumpInfo() const = 0;
 
+    // TODO put on stack
+    template <class T> T* getSnapStorage() {

[bsalomon, 2015/09/23 13:49:38]

Can we do anything here with var args to forward constructor args a la
SkTLazy::init?

[joshualitt, 2015/09/25 18:17:12]

Acknowledged.

+        SkASSERT(sizeof(T) < fSnapStorage.size());
+        fSnap = reinterpret_cast<GrDrawSnap*>(fSnapStorage.get());
+        return reinterpret_cast<T*>(fSnap);
+    }
+    const GrDrawSnap* drawSnap() const { return fSnap; }
+
 protected:
     // NOTE, compute some bounds, even if extremely conservative.  Do *NOT* setLargest on the bounds
     // rect because we outset it for dst copy textures
@@ -150,6 +160,9 @@ private:
     const uint32_t                      fUniqueID;
     static int32_t                      gCurrBatchUniqueID;
 #endif
+    GrDrawSnap*                        fSnap;

[bsalomon, 2015/09/23 13:49:38]

alignment

[robertphillips, 2015/09/25 12:48:48]

How was 256 arrived at ?

[joshualitt, 2015/09/25 18:17:12]

magic!  I'll add a comment

[joshualitt, 2015/09/25 18:17:12]

Acknowledged.

+    SkAlignedSStorage<256>             fSnapStorage;
+
     static int32_t                      gCurrBatchClassID;
     typedef GrNonAtomicRef INHERITED;
 };