Create GrDraw and start fast pathing src over rects

src/gpu/batches/GrBatch.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrBatch_DEFINED
 #define GrBatch_DEFINED
 
 #include <new>
 #include "GrNonAtomicRef.h"
 
 #include "SkRect.h"
 #include "SkString.h"
 
+#include "draws/GrDraw.h"
+
+#include "../private/SkTemplates.h"
+
 class GrCaps;
 class GrBatchFlushState;
 
 /**
  * GrBatch is the base class for all Ganesh deferred geometry generators.  To facilitate
  * reorderable batching, Ganesh does not generate geometry inline with draw calls.  Instead, it
  * captures the arguments to the draw and then generates the geometry on demand.  This gives GrBatch
  * subclasses complete freedom to decide how / what they can batch.
  *
  * Batches are created when GrContext processes a draw call. Batches of the same  subclass may be
@@ skipping 75 matching lines @@
     /** Issues the batches commands to GrGpu. */
     void draw(GrBatchFlushState* state) { this->onDraw(state); }
 
     /** Used to block batching across render target changes. Remove this once we store
         GrBatches for different RTs in different targets. */
     virtual uint32_t renderTargetUniqueID() const = 0;
 
     /** Used for spewing information about batches when debugging. */
     virtual SkString dumpInfo() const = 0;
 
+    template <typename T, typename... Args> void initSnapStorage(Args&&... args) {
+        SkASSERT(!fSnap && sizeof(T) < fSnapStorage.size());
+        fSnap = new (SkTCast<T*>(fSnapStorage.get())) T(skstd::forward<Args>(args)...);
+    }
+    const GrDrawSnap* getDrawSnap() 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
     void setBounds(const SkRect& newBounds) { fBounds = newBounds; }
 
     void joinBounds(const SkRect& otherBounds) {
         return fBounds.joinPossiblyEmptyRect(otherBounds);
     }
 
     static uint32_t GenBatchClassID() { return GenID(&gCurrBatchClassID); }
@@ skipping 16 matching lines @@
         }
         return id;
     }
 
     enum {
         kIllegalBatchID = 0,
     };
 
     SkDEBUGCODE(bool                    fUsed;)
     const uint32_t                      fClassID;
+    GrDrawSnap*                         fSnap;
+    SkAlignedSStorage<128>              fSnapStorage; // 128 bytes should be more than enough
 #if GR_BATCH_SPEW
     static uint32_t GenBatchID() { return GenID(&gCurrBatchUniqueID); }
     const uint32_t                      fUniqueID;
     static int32_t                      gCurrBatchUniqueID;
 #endif
+
     static int32_t                      gCurrBatchClassID;
     typedef GrNonAtomicRef INHERITED;
 };
 
 #endif