First pass at pre-rendering saveLayers for GPU

src/gpu/GrPictureUtils.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPictureUtils.h"
 #include "SkDevice.h"
 #include "SkDraw.h"
 #include "SkPaintPriv.h"
+#include "SkPicturePlayback.h"
 
 // The GrGather device performs GPU-backend-specific preprocessing on
 // a picture. The results are stored in a GPUAccelData.
 //
 // Currently the only interesting work is done in drawDevice (i.e., when a
 // saveLayer is collapsed back into its parent) and, maybe, in onCreateDevice.
 // All the current work could be done much more efficiently by just traversing the
 // raw op codes in the SkPicture (although we would still need to replay all the
 // clip calls).
 class GrGatherDevice : public SkBaseDevice {
@@ skipping 214 matching lines @@
             return;
         }
 
         this->clipRect(SkRect::MakeWH(SkIntToScalar(fPicture->width()),
                                       SkIntToScalar(fPicture->height())),
                        SkRegion::kIntersect_Op, false);
         this->drawPicture(*fPicture);
     }
 
     virtual void drawPicture(SkPicture& picture) SK_OVERRIDE {
+        // BBH-based rendering doesn't re-issue many of the operations the gather
+        // process cares about (e.g., saves and restores) so it must be disabled.
+        if (NULL != picture.fPlayback) {
+            picture.fPlayback->setUseBBH(false);
+        }
         picture.draw(this);
+        if (NULL != picture.fPlayback) {
+            picture.fPlayback->setUseBBH(true);
+        }
     }
 protected:
     // disable aa for speed
     virtual void onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
         this->INHERITED::onClipRect(rect, op, kHard_ClipEdgeStyle);
     }
 
     // for speed, just respect the bounds, and disable AA. May give us a few
     // false positives and negatives.
     virtual void onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
@@ skipping 15 matching lines @@
 void GatherGPUInfo(SkPicture* pict, GPUAccelData* accelData) {
     if (0 == pict->width() || 0 == pict->height()) {
         return ;
     }
 
     GrGatherDevice device(pict->width(), pict->height(), pict, accelData, 0);
     GrGatherCanvas canvas(&device, pict);
 
     canvas.gather();
 }